shared_source/c_tk_base_7_5_w_mods/tkimgphoto.c

/* $Header$ */

/*
 * tkImgPhoto.c --
 *
 *      Implements images of type "photo" for Tk.  Photo images are
 *      stored in full color (32 bits per pixel) and displayed using
 *      dithering if necessary.
 *
 * Copyright (c) 1994 The Australian National University.
 * Copyright (c) 1994-1997 Sun Microsystems, Inc.
 *
 * See the file "license.terms" for information on usage and redistribution
 * of this file, and for a DISCLAIMER OF ALL WARRANTIES.
 *
 * Author: Paul Mackerras (paulus@cs.anu.edu.au),
 *         Department of Computer Science,
 *         Australian National University.
 *
 * RCS: @(#) $Id: tkimgphoto.c,v 1.1.1.1 2001/06/13 05:03:26 dtashley Exp $
 */

#include "tkInt.h"
#include "tkPort.h"
#include "tclMath.h"
#include <ctype.h>

#ifdef __WIN32__
#include "tkWinInt.h"
#endif

/*
 * Declaration for internal Xlib function used here:
 */

extern int _XInitImageFuncPtrs _ANSI_ARGS_((XImage *image));

/*
 * A signed 8-bit integral type.  If chars are unsigned and the compiler
 * isn't an ANSI one, then we have to use short instead (which wastes
 * space) to get signed behavior.
 */

#if defined(__STDC__) || defined(_AIX)
    typedef signed char schar;
#else
#   ifndef __CHAR_UNSIGNED__
        typedef char schar;
#   else
        typedef short schar;
#   endif
#endif

/*
 * An unsigned 32-bit integral type, used for pixel values.
 * We use int rather than long here to accommodate those systems
 * where longs are 64 bits.
 */

typedef unsigned int pixel;

/*
 * The maximum number of pixels to transmit to the server in a
 * single XPutImage call.
 */

#define MAX_PIXELS 65536

/*
 * The set of colors required to display a photo image in a window depends on:
 *      - the visual used by the window
 *      - the palette, which specifies how many levels of each primary
 *        color to use, and
 *      - the gamma value for the image.
 *
 * Pixel values allocated for specific colors are valid only for the
 * colormap in which they were allocated.  Sets of pixel values
 * allocated for displaying photos are re-used in other windows if
 * possible, that is, if the display, colormap, palette and gamma
 * values match.  A hash table is used to locate these sets of pixel
 * values, using the following data structure as key:
 */

typedef struct {
    Display *display;           /* Qualifies the colormap resource ID */
    Colormap colormap;          /* Colormap that the windows are using. */
    double gamma;               /* Gamma exponent value for images. */
    Tk_Uid palette;             /* Specifies how many shades of each primary
                                 * we want to allocate. */
} ColorTableId;

/*
 * For a particular (display, colormap, palette, gamma) combination,
 * a data structure of the following type is used to store the allocated
 * pixel values and other information:
 */

typedef struct ColorTable {
    ColorTableId id;            /* Information used in selecting this
                                 * color table. */
    int flags;                  /* See below. */
    int refCount;               /* Number of instances using this map. */
    int liveRefCount;           /* Number of instances which are actually
                                 * in use, using this map. */
    int numColors;              /* Number of colors allocated for this map. */

    XVisualInfo visualInfo;     /* Information about the visual for windows
                                 * using this color table. */

    pixel redValues[256];       /* Maps 8-bit values of red intensity
                                 * to a pixel value or index in pixelMap. */
    pixel greenValues[256];     /* Ditto for green intensity */
    pixel blueValues[256];      /* Ditto for blue intensity */
    unsigned long *pixelMap;    /* Actual pixel values allocated. */

    unsigned char colorQuant[3][256];
                                /* Maps 8-bit intensities to quantized
                                 * intensities.  The first index is 0 for
                                 * red, 1 for green, 2 for blue. */
} ColorTable;

/*
 * Bit definitions for the flags field of a ColorTable.
 * BLACK_AND_WHITE:             1 means only black and white colors are
 *                              available.
 * COLOR_WINDOW:                1 means a full 3-D color cube has been
 *                              allocated.
 * DISPOSE_PENDING:             1 means a call to DisposeColorTable has
 *                              been scheduled as an idle handler, but it
 *                              hasn't been invoked yet.
 * MAP_COLORS:                  1 means pixel values should be mapped
 *                              through pixelMap.
 */
#ifdef COLOR_WINDOW
#undef COLOR_WINDOW
#endif

#define BLACK_AND_WHITE         1
#define COLOR_WINDOW            2
#define DISPOSE_PENDING         4
#define MAP_COLORS              8

/*
 * Definition of the data associated with each photo image master.
 */

typedef struct PhotoMaster {
    Tk_ImageMaster tkMaster;    /* Tk's token for image master.  NULL means
                                 * the image is being deleted. */
    Tcl_Interp *interp;         /* Interpreter associated with the
                                 * application using this image. */
    Tcl_Command imageCmd;       /* Token for image command (used to delete
                                 * it when the image goes away).  NULL means
                                 * the image command has already been
                                 * deleted. */
    int flags;                  /* Sundry flags, defined below. */
    int width, height;          /* Dimensions of image. */
    int userWidth, userHeight;  /* User-declared image dimensions. */
    Tk_Uid palette;             /* User-specified default palette for
                                 * instances of this image. */
    double gamma;               /* Display gamma value to correct for. */
    char *fileString;           /* Name of file to read into image. */
    Tcl_Obj *dataString;        /* Object to use as contents of image. */
    Tcl_Obj *format;            /* User-specified format of data in image
                                 * file or string value. */
    unsigned char *pix24;       /* Local storage for 24-bit image. */
    int ditherX, ditherY;       /* Location of first incorrectly
                                 * dithered pixel in image. */
    TkRegion validRegion;       /* Tk region indicating which parts of
                                 * the image have valid image data. */
    struct PhotoInstance *instancePtr;
                                /* First in the list of instances
                                 * associated with this master. */
} PhotoMaster;

/*
 * Bit definitions for the flags field of a PhotoMaster.
 * COLOR_IMAGE:                 1 means that the image has different color
 *                              components.
 * IMAGE_CHANGED:               1 means that the instances of this image
 *                              need to be redithered.
 */

#define COLOR_IMAGE             1
#define IMAGE_CHANGED           2

/*
 * The following data structure represents all of the instances of
 * a photo image in windows on a given screen that are using the
 * same colormap.
 */

typedef struct PhotoInstance {
    PhotoMaster *masterPtr;     /* Pointer to master for image. */
    Display *display;           /* Display for windows using this instance. */
    Colormap colormap;          /* The image may only be used in windows with
                                 * this particular colormap. */
    struct PhotoInstance *nextPtr;
                                /* Pointer to the next instance in the list
                                 * of instances associated with this master. */
    int refCount;               /* Number of instances using this structure. */
    Tk_Uid palette;             /* Palette for these particular instances. */
    double gamma;               /* Gamma value for these instances. */
    Tk_Uid defaultPalette;      /* Default palette to use if a palette
                                 * is not specified for the master. */
    ColorTable *colorTablePtr;  /* Pointer to information about colors
                                 * allocated for image display in windows
                                 * like this one. */
    Pixmap pixels;              /* X pixmap containing dithered image. */
    int width, height;          /* Dimensions of the pixmap. */
    schar *error;               /* Error image, used in dithering. */
    XImage *imagePtr;           /* Image structure for converted pixels. */
    XVisualInfo visualInfo;     /* Information about the visual that these
                                 * windows are using. */
    GC gc;                      /* Graphics context for writing images
                                 * to the pixmap. */
} PhotoInstance;

/*
 * The following data structure is used to return information
 * from ParseSubcommandOptions:
 */

struct SubcommandOptions {
    int options;                /* Individual bits indicate which
                                 * options were specified - see below. */
    Tcl_Obj *name;              /* Name specified without an option. */
    int fromX, fromY;           /* Values specified for -from option. */
    int fromX2, fromY2;         /* Second coordinate pair for -from option. */
    int toX, toY;               /* Values specified for -to option. */
    int toX2, toY2;             /* Second coordinate pair for -to option. */
    int zoomX, zoomY;           /* Values specified for -zoom option. */
    int subsampleX, subsampleY; /* Values specified for -subsample option. */
    Tcl_Obj *format;            /* Value specified for -format option. */
    XColor *background;         /* Value specified for -background option. */
};

/*
 * Bit definitions for use with ParseSubcommandOptions:
 * Each bit is set in the allowedOptions parameter on a call to
 * ParseSubcommandOptions if that option is allowed for the current
 * photo image subcommand.  On return, the bit is set in the options
 * field of the SubcommandOptions structure if that option was specified.
 *
 * OPT_BACKGROUND:              Set if -format option allowed/specified.
 * OPT_FORMAT:                  Set if -format option allowed/specified.
 * OPT_FROM:                    Set if -from option allowed/specified.
 * OPT_GRAYSCALE:               Set if -grayscale option allowed/specified.
 * OPT_SHRINK:                  Set if -shrink option allowed/specified.
 * OPT_SUBSAMPLE:               Set if -subsample option allowed/spec'd.
 * OPT_TO:                      Set if -to option allowed/specified.
 * OPT_ZOOM:                    Set if -zoom option allowed/specified.
 */

#define OPT_BACKGROUND  1
#define OPT_FORMAT      2
#define OPT_FROM        4
#define OPT_GRAYSCALE   8
#define OPT_SHRINK      0x10
#define OPT_SUBSAMPLE   0x20
#define OPT_TO          0x40
#define OPT_ZOOM        0x80

/*
 * List of option names.  The order here must match the order of
 * declarations of the OPT_* constants above.
 */

static char *optionNames[] = {
    "-background",
    "-format",
    "-from",
    "-grayscale",
    "-shrink",
    "-subsample",
    "-to",
    "-zoom",
    (char *) NULL
};

/*
 * The type record for photo images:
 */

static int              ImgPhotoCreate _ANSI_ARGS_((Tcl_Interp *interp,
                            char *name, int objc, Tcl_Obj *CONST objv[],
                            Tk_ImageType *typePtr, Tk_ImageMaster master,
                            ClientData *clientDataPtr));
static ClientData       ImgPhotoGet _ANSI_ARGS_((Tk_Window tkwin,
                            ClientData clientData));
static void             ImgPhotoDisplay _ANSI_ARGS_((ClientData clientData,
                            Display *display, Drawable drawable,
                            int imageX, int imageY, int width, int height,
                            int drawableX, int drawableY));
static void             ImgPhotoFree _ANSI_ARGS_((ClientData clientData,
                            Display *display));
static void             ImgPhotoDelete _ANSI_ARGS_((ClientData clientData));
static int              ImgPhotoPostscript _ANSI_ARGS_((ClientData clientData,
                            Tcl_Interp *interp, Tk_Window tkwin,
                            Tk_PostscriptInfo psInfo, int x, int y, int width,
                            int height, int prepass));

Tk_ImageType tkPhotoImageType = {
    "photo",                    /* name */
    ImgPhotoCreate,             /* createProc */
    ImgPhotoGet,                /* getProc */
    ImgPhotoDisplay,            /* displayProc */
    ImgPhotoFree,               /* freeProc */
    ImgPhotoDelete,             /* deleteProc */
    ImgPhotoPostscript,         /* postscriptProc */
    (Tk_ImageType *) NULL       /* nextPtr */
};

typedef struct ThreadSpecificData {
    Tk_PhotoImageFormat *formatList;  /* Pointer to the first in the 
                                       * list of known photo image formats.*/
    Tk_PhotoImageFormat *oldFormatList;  /* Pointer to the first in the 
                                       * list of known photo image formats.*/
} ThreadSpecificData;
static Tcl_ThreadDataKey dataKey;

/*
 * Default configuration
 */

#define DEF_PHOTO_GAMMA         "1"
#define DEF_PHOTO_HEIGHT        "0"
#define DEF_PHOTO_PALETTE       ""
#define DEF_PHOTO_WIDTH         "0"

/*
 * Information used for parsing configuration specifications:
 */
static Tk_ConfigSpec configSpecs[] = {
    {TK_CONFIG_STRING, "-file", (char *) NULL, (char *) NULL,
         (char *) NULL, Tk_Offset(PhotoMaster, fileString), TK_CONFIG_NULL_OK},
    {TK_CONFIG_DOUBLE, "-gamma", (char *) NULL, (char *) NULL,
         DEF_PHOTO_GAMMA, Tk_Offset(PhotoMaster, gamma), 0},
    {TK_CONFIG_INT, "-height", (char *) NULL, (char *) NULL,
         DEF_PHOTO_HEIGHT, Tk_Offset(PhotoMaster, userHeight), 0},
    {TK_CONFIG_UID, "-palette", (char *) NULL, (char *) NULL,
         DEF_PHOTO_PALETTE, Tk_Offset(PhotoMaster, palette), 0},
    {TK_CONFIG_INT, "-width", (char *) NULL, (char *) NULL,
         DEF_PHOTO_WIDTH, Tk_Offset(PhotoMaster, userWidth), 0},
    {TK_CONFIG_END, (char *) NULL, (char *) NULL, (char *) NULL,
         (char *) NULL, 0, 0}
};

/*
 * Hash table used to hash from (display, colormap, palette, gamma)
 * to ColorTable address.
 */

static Tcl_HashTable imgPhotoColorHash;
static int imgPhotoColorHashInitialized;
#define N_COLOR_HASH    (sizeof(ColorTableId) / sizeof(int))

/*
 * Forward declarations
 */

static int              ImgPhotoCmd _ANSI_ARGS_((ClientData clientData,
                            Tcl_Interp *interp, int objc, Tcl_Obj *CONST objv[]));
static int              ParseSubcommandOptions _ANSI_ARGS_((
                            struct SubcommandOptions *optPtr,
                            Tcl_Interp *interp, int allowedOptions,
                            int *indexPtr, int objc, Tcl_Obj *CONST objv[]));
static void             ImgPhotoCmdDeletedProc _ANSI_ARGS_((
                            ClientData clientData));
static int              ImgPhotoConfigureMaster _ANSI_ARGS_((
                            Tcl_Interp *interp, PhotoMaster *masterPtr,
                            int objc, Tcl_Obj *CONST objv[], int flags));
static void             ImgPhotoConfigureInstance _ANSI_ARGS_((
                            PhotoInstance *instancePtr));
static void             ImgPhotoSetSize _ANSI_ARGS_((PhotoMaster *masterPtr,
                            int width, int height));
static void             ImgPhotoInstanceSetSize _ANSI_ARGS_((
                            PhotoInstance *instancePtr));
static int              ImgStringWrite _ANSI_ARGS_((Tcl_Interp *interp,
                            Tcl_Obj *formatString,
                            Tk_PhotoImageBlock *blockPtr));
static char *           ImgGetPhoto _ANSI_ARGS_((PhotoMaster *masterPtr,
                            Tk_PhotoImageBlock *blockPtr,
                            struct SubcommandOptions *optPtr));
static int              IsValidPalette _ANSI_ARGS_((PhotoInstance *instancePtr,
                            char *palette));
static int              CountBits _ANSI_ARGS_((pixel mask));
static void             GetColorTable _ANSI_ARGS_((PhotoInstance *instancePtr));
static void             FreeColorTable _ANSI_ARGS_((ColorTable *colorPtr,
                            int force));
static void             AllocateColors _ANSI_ARGS_((ColorTable *colorPtr));
static void             DisposeColorTable _ANSI_ARGS_((ClientData clientData));
static void             DisposeInstance _ANSI_ARGS_((ClientData clientData));
static int              ReclaimColors _ANSI_ARGS_((ColorTableId *id,
                            int numColors));
static int              MatchFileFormat _ANSI_ARGS_((Tcl_Interp *interp,
                            Tcl_Channel chan, char *fileName, Tcl_Obj *formatString,
                            Tk_PhotoImageFormat **imageFormatPtr,
                            int *widthPtr, int *heightPtr, int *oldformat));
static int              MatchStringFormat _ANSI_ARGS_((Tcl_Interp *interp,
                            Tcl_Obj *data, Tcl_Obj *formatString,
                            Tk_PhotoImageFormat **imageFormatPtr,
                            int *widthPtr, int *heightPtr, int *oldformat));
static Tcl_ObjCmdProc * PhotoOptionFind _ANSI_ARGS_((Tcl_Interp * interp,
                            Tcl_Obj *obj));
static void             DitherInstance _ANSI_ARGS_((PhotoInstance *instancePtr,
                            int x, int y, int width, int height));
static void             PhotoOptionCleanupProc _ANSI_ARGS_((
                            ClientData clientData, Tcl_Interp *interp));

#undef MIN
#define MIN(a, b)       ((a) < (b)? (a): (b))
#undef MAX
#define MAX(a, b)       ((a) > (b)? (a): (b))

/*
 *----------------------------------------------------------------------
 *
 * Tk_CreateOldPhotoImageFormat, Tk_CreatePhotoImageFormat --
 *
 *      This procedure is invoked by an image file handler to register
 *      a new photo image format and the procedures that handle the
 *      new format.  The procedure is typically invoked during
 *      Tcl_AppInit.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      The new image file format is entered into a table used in the
 *      photo image "read" and "write" subcommands.
 *
 *----------------------------------------------------------------------
 */
void
Tk_CreateOldPhotoImageFormat(formatPtr)
    Tk_PhotoImageFormat *formatPtr;
                                /* Structure describing the format.  All of
                                 * the fields except "nextPtr" must be filled
                                 * in by caller.  Must not have been passed
                                 * to Tk_CreatePhotoImageFormat previously. */
{
    Tk_PhotoImageFormat *copyPtr;
    ThreadSpecificData *tsdPtr = (ThreadSpecificData *) 
            Tcl_GetThreadData(&dataKey, sizeof(ThreadSpecificData));

    copyPtr = (Tk_PhotoImageFormat *) ckalloc(sizeof(Tk_PhotoImageFormat));
    *copyPtr = *formatPtr;
    copyPtr->name = (char *) ckalloc((unsigned) (strlen(formatPtr->name) + 1));
    strcpy(copyPtr->name, formatPtr->name);
    copyPtr->nextPtr = tsdPtr->oldFormatList;
    tsdPtr->oldFormatList = copyPtr;
}

void
Tk_CreatePhotoImageFormat(formatPtr)
    Tk_PhotoImageFormat *formatPtr;
                                /* Structure describing the format.  All of
                                 * the fields except "nextPtr" must be filled
                                 * in by caller.  Must not have been passed
                                 * to Tk_CreatePhotoImageFormat previously. */
{
    Tk_PhotoImageFormat *copyPtr;
    ThreadSpecificData *tsdPtr = (ThreadSpecificData *) 
            Tcl_GetThreadData(&dataKey, sizeof(ThreadSpecificData));

    copyPtr = (Tk_PhotoImageFormat *) ckalloc(sizeof(Tk_PhotoImageFormat));
    *copyPtr = *formatPtr;
    copyPtr->name = (char *) ckalloc((unsigned) (strlen(formatPtr->name) + 1));
    strcpy(copyPtr->name, formatPtr->name);
    if (isupper((unsigned char) *formatPtr->name)) {
        copyPtr->nextPtr = tsdPtr->oldFormatList;
        tsdPtr->oldFormatList = copyPtr;
    } else {
        copyPtr->nextPtr = tsdPtr->formatList;
        tsdPtr->formatList = copyPtr;
    }
}

/*
 *----------------------------------------------------------------------
 *
 * ImgPhotoCreate --
 *
 *      This procedure is called by the Tk image code to create
 *      a new photo image.
 *
 * Results:
 *      A standard Tcl result.
 *
 * Side effects:
 *      The data structure for a new photo image is allocated and
 *      initialized.
 *
 *----------------------------------------------------------------------
 */

static int
ImgPhotoCreate(interp, name, objc, objv, typePtr, master, clientDataPtr)
    Tcl_Interp *interp;         /* Interpreter for application containing
                                 * image. */
    char *name;                 /* Name to use for image. */
    int objc;                   /* Number of arguments. */
    Tcl_Obj *CONST objv[];      /* Argument objects for options (doesn't
                                 * include image name or type). */
    Tk_ImageType *typePtr;      /* Pointer to our type record (not used). */
    Tk_ImageMaster master;      /* Token for image, to be used by us in
                                 * later callbacks. */
    ClientData *clientDataPtr;  /* Store manager's token for image here;
                                 * it will be returned in later callbacks. */
{
    PhotoMaster *masterPtr;

    /*
     * Allocate and initialize the photo image master record.
     */

    masterPtr = (PhotoMaster *) ckalloc(sizeof(PhotoMaster));
    memset((void *) masterPtr, 0, sizeof(PhotoMaster));
    masterPtr->tkMaster = master;
    masterPtr->interp = interp;
    masterPtr->imageCmd = Tcl_CreateObjCommand(interp, name, ImgPhotoCmd,
            (ClientData) masterPtr, ImgPhotoCmdDeletedProc);
    masterPtr->palette = NULL;
    masterPtr->pix24 = NULL;
    masterPtr->instancePtr = NULL;
    masterPtr->validRegion = TkCreateRegion();

    /*
     * Process configuration options given in the image create command.
     */

    if (ImgPhotoConfigureMaster(interp, masterPtr, objc, objv, 0) != TCL_OK) {
        ImgPhotoDelete((ClientData) masterPtr);
        return TCL_ERROR;
    }

    *clientDataPtr = (ClientData) masterPtr;
    return TCL_OK;
}

/*
 *----------------------------------------------------------------------
 *
 * ImgPhotoCmd --
 *
 *      This procedure is invoked to process the Tcl command that
 *      corresponds to a photo image.  See the user documentation
 *      for details on what it does.
 *
 * Results:
 *      A standard Tcl result.
 *
 * Side effects:
 *      See the user documentation.
 *
 *----------------------------------------------------------------------
 */

static int
ImgPhotoCmd(clientData, interp, objc, objv)
    ClientData clientData;      /* Information about photo master. */
    Tcl_Interp *interp;         /* Current interpreter. */
    int objc;                   /* Number of arguments. */
    Tcl_Obj *CONST objv[];      /* Argument objects. */
{
    int oldformat = 0;
    static char *photoOptions[] = {
        "blank", "cget", "configure", "copy", "data", "get", "put",
        "read", "redither", "write", (char *) NULL
    };
    enum options {
        PHOTO_BLANK, PHOTO_CGET, PHOTO_CONFIGURE, PHOTO_COPY, PHOTO_DATA,
        PHOTO_GET, PHOTO_PUT, PHOTO_READ, PHOTO_REDITHER, PHOTO_WRITE
    };

    PhotoMaster *masterPtr = (PhotoMaster *) clientData;
    int result, index;
    int x, y, width, height;
    int dataWidth, dataHeight;
    struct SubcommandOptions options;
    int listArgc;
    char **listArgv;
    char **srcArgv;
    unsigned char *pixelPtr;
    Tk_PhotoImageBlock block;
    Tk_Window tkwin;
    XColor color;
    Tk_PhotoImageFormat *imageFormat;
    int imageWidth, imageHeight;
    int matched;
    Tcl_Channel chan;
    Tk_PhotoHandle srcHandle;
    size_t length;
    ThreadSpecificData *tsdPtr = (ThreadSpecificData *) 
            Tcl_GetThreadData(&dataKey, sizeof(ThreadSpecificData));

    if (objc < 2) {
        Tcl_WrongNumArgs(interp, 1, objv, "option ?arg arg ...?");
        return TCL_ERROR;
    }

    if (Tcl_GetIndexFromObj(interp, objv[1], photoOptions, "option", 0,
            &index) != TCL_OK) {
        Tcl_ObjCmdProc *proc;
        proc = PhotoOptionFind(interp, objv[1]);
        if (proc == (Tcl_ObjCmdProc *) NULL) {
            return TCL_ERROR;
        }
        return proc(clientData, interp, objc, objv);
    }
    switch ((enum options) index) {
      case PHOTO_BLANK: {
        /*
         * photo blank command - just call Tk_PhotoBlank.
         */

        if (objc == 2) {
            Tk_PhotoBlank(masterPtr);
        } else {
            Tcl_WrongNumArgs(interp, 2, objv, (char *) NULL);
            return TCL_ERROR;
        }
        break;
      }
      case PHOTO_CGET: {
        char *arg;
        if (objc != 3) {
            Tcl_WrongNumArgs(interp, 2, objv, "option");
            return TCL_ERROR;
        }
        arg = Tcl_GetStringFromObj(objv[2], (int *) &length);
        if (strncmp(arg,"-data", length) == 0) {
            if (masterPtr->dataString) {
                Tcl_SetObjResult(interp, masterPtr->dataString);
            }
            return TCL_OK;
        }
        if (strncmp(arg,"-format", length) == 0) {
            if (masterPtr->format) {
                Tcl_SetObjResult(interp, masterPtr->format);
            }
            return TCL_OK;
        }
        Tk_ConfigureValue(interp, Tk_MainWindow(interp), configSpecs,
                (char *) masterPtr, Tcl_GetString(objv[2]), 0);
        break;
      }
      case PHOTO_CONFIGURE: {
        /*
         * photo configure command - handle this in the standard way.
         */

        if (objc == 2) {
            Tcl_Obj *obj, *subobj;
            result = Tk_ConfigureInfo(interp, Tk_MainWindow(interp),
                    configSpecs, (char *) masterPtr, (char *) NULL, 0);
            if (result != TCL_OK) {
                return result;
            }
            obj = Tcl_NewObj();
            subobj = Tcl_NewStringObj("-data {} {} {}", 14);
            if (masterPtr->dataString) {
                Tcl_ListObjAppendElement(interp, subobj, masterPtr->dataString);
            } else {
                Tcl_AppendStringsToObj(subobj, " {}", (char *) NULL);
            }
            Tcl_ListObjAppendElement(interp, obj, subobj);
            subobj = Tcl_NewStringObj("-format {} {} {}", 16);
            if (masterPtr->format) {
                Tcl_ListObjAppendElement(interp, subobj, masterPtr->format);
            } else {
                Tcl_AppendStringsToObj(subobj, " {}", (char *) NULL);
            }
            Tcl_ListObjAppendElement(interp, obj, subobj);
            Tcl_ListObjAppendList(interp, obj, Tcl_GetObjResult(interp));
            Tcl_SetObjResult(interp, obj);
            return TCL_OK;
        }
        if (objc == 3) {
          char *arg = Tcl_GetStringFromObj(objv[2], (int *) &length);
          if (!strncmp(arg, "-data", length)) {
            Tcl_AppendStringsToObj(Tcl_GetObjResult(interp),
                "-data {} {} {}", (char *) NULL);
            if (masterPtr->dataString) {
                Tcl_ListObjAppendElement(interp, Tcl_GetObjResult(interp),
                        masterPtr->dataString);
            } else {
                Tcl_AppendStringsToObj(Tcl_GetObjResult(interp),
                " {}", (char *) NULL);
            }
            return TCL_OK;
          } else if (!strncmp(arg, "-format", length)) {
            Tcl_AppendStringsToObj(Tcl_GetObjResult(interp),
                "-format {} {} {}", (char *) NULL);
            if (masterPtr->format) {
                Tcl_ListObjAppendElement(interp, Tcl_GetObjResult(interp),
                        masterPtr->format);
            } else {
                Tcl_AppendStringsToObj(Tcl_GetObjResult(interp),
                " {}", (char *) NULL);
            }
            return TCL_OK;
          } else {
            return Tk_ConfigureInfo(interp, Tk_MainWindow(interp),
                    configSpecs, (char *) masterPtr, arg, 0);
          }
        }
        return ImgPhotoConfigureMaster(interp, masterPtr, objc-2, objv+2,
                TK_CONFIG_ARGV_ONLY);
        break;
      }
      case PHOTO_COPY: {
        /*
         * photo copy command - first parse options.
         */

        index = 2;
        memset((VOID *) &options, 0, sizeof(options));
        options.zoomX = options.zoomY = 1;
        options.subsampleX = options.subsampleY = 1;
        options.name = NULL;
        if (ParseSubcommandOptions(&options, interp,
                OPT_FROM | OPT_TO | OPT_ZOOM | OPT_SUBSAMPLE | OPT_SHRINK,
                &index, objc, objv) != TCL_OK) {
            return TCL_ERROR;
        }
        if (options.name == NULL || index < objc) {
            Tcl_WrongNumArgs(interp, 2, objv,
                    "source-image ?-from x1 y1 x2 y2? ?-to x1 y1 x2 y2? ?-zoom x y? ?-subsample x y?");
            return TCL_ERROR;
        }

        /*
         * Look for the source image and get a pointer to its image data.
         * Check the values given for the -from option.
         */

        if ((srcHandle = Tk_FindPhoto(interp, Tcl_GetString(options.name))) == NULL) {
            Tcl_AppendResult(interp, "image \"",
                    Tcl_GetString(options.name), "\" doesn't",
                    " exist or is not a photo image", (char *) NULL);
            return TCL_ERROR;
        }
        Tk_PhotoGetImage(srcHandle, &block);
        if ((options.fromX2 > block.width) || (options.fromY2 > block.height)
                || (options.fromX2 > block.width)
                || (options.fromY2 > block.height)) {
            Tcl_AppendResult(interp, "coordinates for -from option extend ",
                    "outside source image", (char *) NULL);
            return TCL_ERROR;
        }

        /*
         * Fill in default values for unspecified parameters.
         */

        if (((options.options & OPT_FROM) == 0) || (options.fromX2 < 0)) {
            options.fromX2 = block.width;
            options.fromY2 = block.height;
        }
        if (((options.options & OPT_TO) == 0) || (options.toX2 < 0)) {
            width = options.fromX2 - options.fromX;
            if (options.subsampleX > 0) {
                width = (width + options.subsampleX - 1) / options.subsampleX;
            } else if (options.subsampleX == 0) {
                width = 0;
            } else {
                width = (width - options.subsampleX - 1) / -options.subsampleX;
            }
            options.toX2 = options.toX + width * options.zoomX;

            height = options.fromY2 - options.fromY;
            if (options.subsampleY > 0) {
                height = (height + options.subsampleY - 1)
                        / options.subsampleY;
            } else if (options.subsampleY == 0) {
                height = 0;
            } else {
                height = (height - options.subsampleY - 1)
                        / -options.subsampleY;
            }
            options.toY2 = options.toY + height * options.zoomY;
        }

        /*
         * Set the destination image size if the -shrink option was specified.
         */

        if (options.options & OPT_SHRINK) {
            ImgPhotoSetSize(masterPtr, options.toX2, options.toY2);
        }

        /*
         * Copy the image data over using Tk_PhotoPutZoomedBlock.
         */

        block.pixelPtr += options.fromX * block.pixelSize
            + options.fromY * block.pitch;
        block.width = options.fromX2 - options.fromX;
        block.height = options.fromY2 - options.fromY;
        Tk_PhotoPutZoomedBlock((Tk_PhotoHandle) masterPtr, &block,
                options.toX, options.toY, options.toX2 - options.toX,
                options.toY2 - options.toY, options.zoomX, options.zoomY,
                options.subsampleX, options.subsampleY);

        break;
      }
      case PHOTO_DATA: {
        char *data;

        /*
         * photo data command - first parse and check any options given.
         */
        Tk_ImageStringWriteProc *stringWriteProc = NULL;

        index = 2;
        memset((VOID *) &options, 0, sizeof(options));
        options.name = NULL;
        options.format = NULL;
        options.fromX = 0;
        options.fromY = 0;
        if (ParseSubcommandOptions(&options, interp,
                OPT_FORMAT | OPT_FROM | OPT_GRAYSCALE | OPT_BACKGROUND,
                &index, objc, objv) != TCL_OK) {
            return TCL_ERROR;
        }
        if ((options.name != NULL) || (index < objc)) {
            Tcl_WrongNumArgs(interp, 2, objv, "?options?");
            return TCL_ERROR;
        }
        if ((options.fromX > masterPtr->width)
                || (options.fromY > masterPtr->height)
                || (options.fromX2 > masterPtr->width)
                || (options.fromY2 > masterPtr->height)) {
            Tcl_AppendResult(interp, "coordinates for -from option extend ",
                    "outside image", (char *) NULL);
            return TCL_ERROR;
        }

        /*
         * Fill in default values for unspecified parameters.
         */

        if (((options.options & OPT_FROM) == 0) || (options.fromX2 < 0)) {
            options.fromX2 = masterPtr->width;
            options.fromY2 = masterPtr->height;
        }

        /*
         * Search for an appropriate image string format handler.
         */

        if (options.options & OPT_FORMAT) {
            for (imageFormat = tsdPtr->formatList; imageFormat != NULL;
                imageFormat = imageFormat->nextPtr) {
                if ((strncasecmp(Tcl_GetString(options.format),
                        imageFormat->name, strlen(imageFormat->name)) == 0)) {
                    if (imageFormat->stringWriteProc != NULL) {
                        stringWriteProc = imageFormat->stringWriteProc;
                        break;
                    }
                }
            }
            if (stringWriteProc == NULL) {
                Tcl_AppendResult(interp, "image string format \"",
                        Tcl_GetString(options.format),
                        "\" is not supported", (char *) NULL);
                return TCL_ERROR;
            }
        } else {
            stringWriteProc = ImgStringWrite;
        }

        /*
         * Call the handler's string write procedure to write out
         * the image.
         */

        data = ImgGetPhoto(masterPtr, &block, &options);

        result =  ((int (*) _ANSI_ARGS_((Tcl_Interp *interp, Tcl_Obj *formatString,
                Tk_PhotoImageBlock *blockPtr, VOID *dummy))) stringWriteProc)
                (interp, options.format, &block, (VOID *) NULL);
        if (options.background) {
            Tk_FreeColor(options.background);
        }
        if (data) {
            ckfree(data);
        }
        return result;
        break;
      }
      case PHOTO_GET: {
        /*
         * photo get command - first parse and check parameters.
         */

        char string[TCL_INTEGER_SPACE * 3];

        if (objc != 4) {
            Tcl_WrongNumArgs(interp, 2, objv, "x y");
            return TCL_ERROR;
        }
        if ((Tcl_GetIntFromObj(interp, objv[2], &x) != TCL_OK)
                || (Tcl_GetIntFromObj(interp, objv[3], &y) != TCL_OK)) {
            return TCL_ERROR;
        }
        if ((x < 0) || (x >= masterPtr->width)
                || (y < 0) || (y >= masterPtr->height)) {
            Tcl_AppendResult(interp, Tcl_GetString(objv[0]), " get: ",
                    "coordinates out of range", (char *) NULL);
            return TCL_ERROR;
        }

        /*
         * Extract the value of the desired pixel and format it as a string.
         */

        pixelPtr = masterPtr->pix24 + (y * masterPtr->width + x) * 4;
        sprintf(string, "%d %d %d", pixelPtr[0], pixelPtr[1],
                pixelPtr[2]);
        Tcl_AppendResult(interp, string, (char *) NULL);
        break;
      }
      case PHOTO_PUT: {
        /*
         * photo put command - first parse the options and colors specified.
         */

        index = 2;
        memset((VOID *) &options, 0, sizeof(options));
        options.name = NULL;
        if (ParseSubcommandOptions(&options, interp, OPT_TO|OPT_FORMAT,
               &index, objc, objv) != TCL_OK) {
            return TCL_ERROR;
        }
        if ((options.name == NULL) || (index < objc)) {
            Tcl_WrongNumArgs(interp, 2, objv, "data ?options?");
            return TCL_ERROR;
        }

        if (MatchStringFormat(interp, options.name ? objv[2]:NULL, 
                options.format, &imageFormat, &imageWidth,
                &imageHeight, &oldformat) == TCL_OK) {
            Tcl_Obj *format;
            Tcl_Obj *data;
            if (((options.options & OPT_TO) == 0) || (options.toX2 < 0)) {
                options.toX2 = options.toX + imageWidth;
                options.toY2 = options.toY + imageHeight;
            }
            if (imageWidth > options.toX2 - options.toX) {
                imageWidth = options.toX2 - options.toX;
            }
            if (imageHeight > options.toY2 - options.toY) {
                imageHeight = options.toY2 - options.toY;
            }
            format = options.format;
            data = objv[2];
            if (oldformat) {
                if (format) {
                    format = (Tcl_Obj *) Tcl_GetString(format);
                }
                data = (Tcl_Obj *) Tcl_GetString(data);
            }
            if ((*imageFormat->stringReadProc)(interp, data,
                    format, (Tk_PhotoHandle) masterPtr,
                    0, 0, imageWidth, imageHeight, options.toX, options.toY)
                    != TCL_OK) {
                return TCL_ERROR;
            }
            masterPtr->flags |= IMAGE_CHANGED;
            return TCL_OK;
        }
        if (options.options & OPT_FORMAT) {
            return TCL_ERROR;
        }
        Tcl_ResetResult(interp);
        if (Tcl_SplitList(interp, Tcl_GetString(options.name),
                &dataHeight, &srcArgv)
                != TCL_OK) {
            return TCL_ERROR;
        }
        tkwin = Tk_MainWindow(interp);
        block.pixelPtr = NULL;
        dataWidth = 0;
        pixelPtr = NULL;
        for (y = 0; y < dataHeight; ++y) {
            if (Tcl_SplitList(interp, srcArgv[y], &listArgc, &listArgv)
                    != TCL_OK) {
                break;
            }
            if (y == 0) {
                dataWidth = listArgc;
                pixelPtr = (unsigned char *) ckalloc((unsigned)
                        dataWidth * dataHeight * 3);
                block.pixelPtr = pixelPtr;
            } else {
                if (listArgc != dataWidth) {
                    Tcl_AppendResult(interp, "all elements of color list must",
                             " have the same number of elements",
                            (char *) NULL);
                    ckfree((char *) listArgv);
                    break;
                }
            }
            for (x = 0; x < dataWidth; ++x) {
                if (!XParseColor(Tk_Display(tkwin), Tk_Colormap(tkwin),
                        listArgv[x], &color)) {
                    Tcl_AppendResult(interp, "can't parse color \"",
                            listArgv[x], "\"", (char *) NULL);
                    break;
                }
                *pixelPtr++ = color.red >> 8;
                *pixelPtr++ = color.green >> 8;
                *pixelPtr++ = color.blue >> 8;
            }
            ckfree((char *) listArgv);
            if (x < dataWidth)
                break;
        }
        ckfree((char *) srcArgv);
        if (y < dataHeight || dataHeight == 0 || dataWidth == 0) {
            if (block.pixelPtr != NULL) {
                ckfree((char *) block.pixelPtr);
            }
            if (y < dataHeight) {
                return TCL_ERROR;
            }
            return TCL_OK;
        }

        /*
         * Fill in default values for the -to option, then
         * copy the block in using Tk_PhotoPutBlock.
         */

        if (((options.options & OPT_TO) == 0) || (options.toX2 < 0)) {
            options.toX2 = options.toX + dataWidth;
            options.toY2 = options.toY + dataHeight;
        }
        block.width = dataWidth;
        block.height = dataHeight;
        block.pitch = dataWidth * 3;
        block.pixelSize = 3;
        block.offset[0] = 0;
        block.offset[1] = 1;
        block.offset[2] = 2;
        block.offset[3] = 0;
        Tk_PhotoPutBlock((ClientData)masterPtr, &block,
                options.toX, options.toY, options.toX2 - options.toX,
                options.toY2 - options.toY);
        ckfree((char *) block.pixelPtr);
        break;
      }
      case PHOTO_READ: {
        /*
         * photo read command - first parse the options specified.
         */

        Tcl_Obj *format;
        index = 2;
        memset((VOID *) &options, 0, sizeof(options));
        options.name = NULL;
        options.format = NULL;
        if (ParseSubcommandOptions(&options, interp,
                OPT_FORMAT | OPT_FROM | OPT_TO | OPT_SHRINK,
                &index, objc, objv) != TCL_OK) {
            return TCL_ERROR;
        }
        if ((options.name == NULL) || (index < objc)) {
            Tcl_WrongNumArgs(interp, 2, objv,
                    "fileName ?options?");
            return TCL_ERROR;
        }

        /*
         * Prevent file system access in safe interpreters.
         */

        if (Tcl_IsSafe(interp)) {
            Tcl_AppendResult(interp, "can't get image from a file in a",
                    " safe interpreter", (char *) NULL);
            return TCL_ERROR;
        }
        
        /*
         * Open the image file and look for a handler for it.
         */

        chan = Tcl_OpenFileChannel(interp,
                Tcl_GetString(options.name), "r", 0);
        if (chan == NULL) {
            return TCL_ERROR;
        }
        if (Tcl_SetChannelOption(interp, chan, "-translation", "binary")
                != TCL_OK) {
            return TCL_ERROR;
        }
        if (Tcl_SetChannelOption(interp, chan, "-encoding", "binary")
                != TCL_OK) {
            return TCL_ERROR;
        }
    
        if (MatchFileFormat(interp, chan,
                Tcl_GetString(options.name), options.format,
                &imageFormat, &imageWidth, &imageHeight, &oldformat) != TCL_OK) {
            Tcl_Close(NULL, chan);
            return TCL_ERROR;
        }

        /*
         * Check the values given for the -from option.
         */

        if ((options.fromX > imageWidth) || (options.fromY > imageHeight)
                || (options.fromX2 > imageWidth)
                || (options.fromY2 > imageHeight)) {
            Tcl_AppendResult(interp, "coordinates for -from option extend ",
                    "outside source image", (char *) NULL);
            Tcl_Close(NULL, chan);
            return TCL_ERROR;
        }
        if (((options.options & OPT_FROM) == 0) || (options.fromX2 < 0)) {
            width = imageWidth - options.fromX;
            height = imageHeight - options.fromY;
        } else {
            width = options.fromX2 - options.fromX;
            height = options.fromY2 - options.fromY;
        }

        /*
         * If the -shrink option was specified, set the size of the image.
         */

        if (options.options & OPT_SHRINK) {
            ImgPhotoSetSize(masterPtr, options.toX + width,
                    options.toY + height);
        }

        /*
         * Call the handler's file read procedure to read the data
         * into the image.
         */

        format = options.format;
        if (oldformat && format) {
            format = (Tcl_Obj *) Tcl_GetString(format);
        }
        result = (*imageFormat->fileReadProc)(interp, chan,
                Tcl_GetString(options.name),
                format, (Tk_PhotoHandle) masterPtr, options.toX,
                options.toY, width, height, options.fromX, options.fromY);
        if (chan != NULL) {
            Tcl_Close(NULL, chan);
        }
        return result;
        break;
      }
      case PHOTO_REDITHER: {
        if (objc == 2) {
            /*
             * Call Dither if any part of the image is not correctly
             * dithered at present.
             */

            x = masterPtr->ditherX;
            y = masterPtr->ditherY;
            if (masterPtr->ditherX != 0) {
                Tk_DitherPhoto((Tk_PhotoHandle) masterPtr, x, y, masterPtr->width - x, 1);
            }
            if (masterPtr->ditherY < masterPtr->height) {
                x = 0;
                Tk_DitherPhoto((Tk_PhotoHandle)masterPtr, 0, masterPtr->ditherY, masterPtr->width,
                        masterPtr->height - masterPtr->ditherY);
            }

            if (y < masterPtr->height) {
                /*
                 * Tell the core image code that part of the image has changed.
                 */

                Tk_ImageChanged(masterPtr->tkMaster, x, y,
                        (masterPtr->width - x), (masterPtr->height - y),
                        masterPtr->width, masterPtr->height);
            }

        } else {
            Tcl_WrongNumArgs(interp, 2, objv, (char *) NULL);
            return TCL_ERROR;
        }
        break;
      }
      case PHOTO_WRITE: {
        char *data;
        Tcl_Obj *format;

        /*
         * Prevent file system access in safe interpreters.
         */

        if (Tcl_IsSafe(interp)) {
            Tcl_AppendResult(interp, "can't write image to a file in a",
                    " safe interpreter", (char *) NULL);
            return TCL_ERROR;
        }
        
        /*
         * photo write command - first parse and check any options given.
         */

        index = 2;
        memset((VOID *) &options, 0, sizeof(options));
        options.name = NULL;
        options.format = NULL;
        if (ParseSubcommandOptions(&options, interp,
                OPT_FORMAT | OPT_FROM | OPT_GRAYSCALE | OPT_BACKGROUND,
                &index, objc, objv) != TCL_OK) {
            return TCL_ERROR;
        }
        if ((options.name == NULL) || (index < objc)) {
            Tcl_WrongNumArgs(interp, 2, objv, "fileName ?options?");
            return TCL_ERROR;
        }
        if ((options.fromX > masterPtr->width)
                || (options.fromY > masterPtr->height)
                || (options.fromX2 > masterPtr->width)
                || (options.fromY2 > masterPtr->height)) {
            Tcl_AppendResult(interp, "coordinates for -from option extend ",
                    "outside image", (char *) NULL);
            return TCL_ERROR;
        }

        /*
         * Fill in default values for unspecified parameters.
         */

        if (((options.options & OPT_FROM) == 0) || (options.fromX2 < 0)) {
            options.fromX2 = masterPtr->width;
            options.fromY2 = masterPtr->height;
        }

        /*
         * Search for an appropriate image file format handler,
         * and give an error if none is found.
         */

        matched = 0;
        for (imageFormat = tsdPtr->formatList; imageFormat != NULL;
             imageFormat = imageFormat->nextPtr) {
            if ((options.format == NULL)
                    || (strncasecmp(Tcl_GetString(options.format),
                    imageFormat->name, strlen(imageFormat->name)) == 0)) {
                matched = 1;
                if (imageFormat->fileWriteProc != NULL) {
                    break;
                }
            }
        }
        if (imageFormat == NULL) {
          oldformat = 1;
          for (imageFormat = tsdPtr->oldFormatList; imageFormat != NULL;
             imageFormat = imageFormat->nextPtr) {
            if ((options.format == NULL)
                    || (strncasecmp(Tcl_GetString(options.format),
                    imageFormat->name, strlen(imageFormat->name)) == 0)) {
                matched = 1;
                if (imageFormat->fileWriteProc != NULL) {
                    break;
                }
            }
          }
        }
        if (imageFormat == NULL) {
            if (options.format == NULL) {
                Tcl_AppendResult(interp, "no available image file format ",
                        "has file writing capability", (char *) NULL);
            } else if (!matched) {
                Tcl_AppendResult(interp, "image file format \"",
                        Tcl_GetString(options.format),
                        "\" is unknown", (char *) NULL);
            } else {
                Tcl_AppendResult(interp, "image file format \"",
                        Tcl_GetString(options.format),
                        "\" has no file writing capability",
                        (char *) NULL);
            }
            return TCL_ERROR;
        }

        /*
         * Call the handler's file write procedure to write out
         * the image.
         */

        data = ImgGetPhoto(masterPtr, &block, &options);
        format = options.format;
        if (oldformat && format) {
            format = (Tcl_Obj *) Tcl_GetString(options.format);
        }
        result = (*imageFormat->fileWriteProc)(interp,
                Tcl_GetString(options.name),
                format, &block);
        if (options.background) {
            Tk_FreeColor(options.background);
        }
        if (data) {
            ckfree(data);
        }
        return result;
        break;
      }
    }

    return TCL_OK;
}

/*
 *----------------------------------------------------------------------
 *
 * ParseSubcommandOptions --
 *
 *      This procedure is invoked to process one of the options
 *      which may be specified for the photo image subcommands,
 *      namely, -from, -to, -zoom, -subsample, -format, and -shrink.
 *
 * Results:
 *      A standard Tcl result.
 *
 * Side effects:
 *      Fields in *optPtr get filled in.
 *
 *----------------------------------------------------------------------
 */

static int
ParseSubcommandOptions(optPtr, interp, allowedOptions, optIndexPtr, objc, objv)
    struct SubcommandOptions *optPtr;
                                /* Information about the options specified
                                 * and the values given is returned here. */
    Tcl_Interp *interp;         /* Interpreter to use for reporting errors. */
    int allowedOptions;         /* Indicates which options are valid for
                                 * the current command. */
    int *optIndexPtr;           /* Points to a variable containing the
                                 * current index in objv; this variable is
                                 * updated by this procedure. */
    int objc;                   /* Number of arguments in objv[]. */
    Tcl_Obj *CONST objv[];      /* Arguments to be parsed. */
{
    int index, c, bit, currentBit;
    int length;
    char *option, **listPtr;
    int values[4];
    int numValues, maxValues, argIndex;

    for (index = *optIndexPtr; index < objc; *optIndexPtr = ++index) {
        /*
         * We can have one value specified without an option;
         * it goes into optPtr->name.
         */

        option = Tcl_GetStringFromObj(objv[index], &length);
        if (option[0] != '-') {
            if (optPtr->name == NULL) {
                optPtr->name = objv[index];
                continue;
            }
            break;
        }

        /*
         * Work out which option this is.
         */

        c = option[0];
        bit = 0;
        currentBit = 1;
        for (listPtr = optionNames; *listPtr != NULL; ++listPtr) {
            if ((c == *listPtr[0])
                    && (strncmp(option, *listPtr, (size_t) length) == 0)) {
                if (bit != 0) {
                    bit = 0;    /* An ambiguous option. */
                    break;
                }
                bit = currentBit;
            }
            currentBit <<= 1;
        }

        /*
         * If this option is not recognized and allowed, put
         * an error message in the interpreter and return.
         */

        if ((allowedOptions & bit) == 0) {
            Tcl_AppendResult(interp, "unrecognized option \"",
                    Tcl_GetString(objv[index]),
                    "\": must be ", (char *)NULL);
            bit = 1;
            for (listPtr = optionNames; *listPtr != NULL; ++listPtr) {
                if ((allowedOptions & bit) != 0) {
                    if ((allowedOptions & (bit - 1)) != 0) {
                        Tcl_AppendResult(interp, ", ", (char *) NULL);
                        if ((allowedOptions & ~((bit << 1) - 1)) == 0) {
                            Tcl_AppendResult(interp, "or ", (char *) NULL);
                        }
                    }
                    Tcl_AppendResult(interp, *listPtr, (char *) NULL);
                }
                bit <<= 1;
            }
            return TCL_ERROR;
        }

        /*
         * For the -from, -to, -zoom and -subsample options,
         * parse the values given.  Report an error if too few
         * or too many values are given.
         */

        if (bit == OPT_BACKGROUND) {
            /*
             * The -background option takes a single XColor value.
             */

            if (index + 1 < objc) {
                *optIndexPtr = ++index;
                optPtr->background = Tk_GetColor(interp, Tk_MainWindow(interp),
                        Tk_GetUid(Tcl_GetString(objv[index])));
                if (!optPtr->background) {
                    return TCL_ERROR;
                }
            } else {
                Tcl_AppendResult(interp, "the \"-background\" option ",
                        "requires a value", (char *) NULL);
                return TCL_ERROR;
            }
        } else if (bit == OPT_FORMAT) {
            /*
             * The -format option takes a single string value.
             */

            if (index + 1 < objc) {
                *optIndexPtr = ++index;
                optPtr->format = objv[index];
            } else {
                Tcl_AppendResult(interp, "the \"-format\" option ",
                        "requires a value", (char *) NULL);
                return TCL_ERROR;
            }
        } else if ((bit != OPT_SHRINK) && (bit != OPT_GRAYSCALE)) {
            char *val;
            maxValues = ((bit == OPT_FROM) || (bit == OPT_TO))? 4: 2;
            argIndex = index + 1;
            for (numValues = 0; numValues < maxValues; ++numValues) {
                if (argIndex >= objc) {
                    break;
                }
                val = Tcl_GetString(objv[argIndex]);
                if ((argIndex < objc) && (isdigit(UCHAR(val[0]))
                        || ((val[0] == '-') && isdigit(UCHAR(val[1]))))) {
                    if (Tcl_GetInt(interp, val, &values[numValues])
                            != TCL_OK) {
                        return TCL_ERROR;
                    }
                } else {
                    break;
                }
                ++argIndex;
            }

            if (numValues == 0) {
                Tcl_AppendResult(interp, "the \"", option, "\" option ",
                         "requires one ", maxValues == 2? "or two": "to four",
                         " integer values", (char *) NULL);
                return TCL_ERROR;
            }
            *optIndexPtr = (index += numValues);

            /*
             * Y values default to the corresponding X value if not specified.
             */

            if (numValues == 1) {
                values[1] = values[0];
            }
            if (numValues == 3) {
                values[3] = values[2];
            }

            /*
             * Check the values given and put them in the appropriate
             * field of the SubcommandOptions structure.
             */

            switch (bit) {
                case OPT_FROM:
                    if ((values[0] < 0) || (values[1] < 0) || ((numValues > 2)
                            && ((values[2] < 0) || (values[3] < 0)))) {
                        Tcl_AppendResult(interp, "value(s) for the -from",
                                " option must be non-negative", (char *) NULL);
                        return TCL_ERROR;
                    }
                    if (numValues <= 2) {
                        optPtr->fromX = values[0];
                        optPtr->fromY = values[1];
                        optPtr->fromX2 = -1;
                        optPtr->fromY2 = -1;
                    } else {
                        optPtr->fromX = MIN(values[0], values[2]);
                        optPtr->fromY = MIN(values[1], values[3]);
                        optPtr->fromX2 = MAX(values[0], values[2]);
                        optPtr->fromY2 = MAX(values[1], values[3]);
                    }
                    break;
                case OPT_SUBSAMPLE:
                    optPtr->subsampleX = values[0];
                    optPtr->subsampleY = values[1];
                    break;
                case OPT_TO:
                    if ((values[0] < 0) || (values[1] < 0) || ((numValues > 2)
                            && ((values[2] < 0) || (values[3] < 0)))) {
                        Tcl_AppendResult(interp, "value(s) for the -to",
                                " option must be non-negative", (char *) NULL);
                        return TCL_ERROR;
                    }
                    if (numValues <= 2) {
                        optPtr->toX = values[0];
                        optPtr->toY = values[1];
                        optPtr->toX2 = -1;
                        optPtr->toY2 = -1;
                    } else {
                        optPtr->toX = MIN(values[0], values[2]);
                        optPtr->toY = MIN(values[1], values[3]);
                        optPtr->toX2 = MAX(values[0], values[2]);
                        optPtr->toY2 = MAX(values[1], values[3]);
                    }
                    break;
                case OPT_ZOOM:
                    if ((values[0] <= 0) || (values[1] <= 0)) {
                        Tcl_AppendResult(interp, "value(s) for the -zoom",
                                " option must be positive", (char *) NULL);
                        return TCL_ERROR;
                    }
                    optPtr->zoomX = values[0];
                    optPtr->zoomY = values[1];
                    break;
            }
        }

        /*
         * Remember that we saw this option.
         */

        optPtr->options |= bit;
    }

    return TCL_OK;
}

/*
 *----------------------------------------------------------------------
 *
 * ImgPhotoConfigureMaster --
 *
 *      This procedure is called when a photo image is created or
 *      reconfigured.  It processes configuration options and resets
 *      any instances of the image.
 *
 * Results:
 *      A standard Tcl return value.  If TCL_ERROR is returned then
 *      an error message is left in the masterPtr->interp's result.
 *
 * Side effects:
 *      Existing instances of the image will be redisplayed to match
 *      the new configuration options.
 *
 *----------------------------------------------------------------------
 */

static int
ImgPhotoConfigureMaster(interp, masterPtr, objc, objv, flags)
    Tcl_Interp *interp;         /* Interpreter to use for reporting errors. */
    PhotoMaster *masterPtr;     /* Pointer to data structure describing
                                 * overall photo image to (re)configure. */
    int objc;                   /* Number of entries in objv. */
    Tcl_Obj *CONST objv[];      /* Pairs of configuration options for image. */
    int flags;                  /* Flags to pass to Tk_ConfigureWidget,
                                 * such as TK_CONFIG_ARGV_ONLY. */
{
    PhotoInstance *instancePtr;
    char *oldFileString, *oldPaletteString;
    Tcl_Obj *oldData, *data = NULL, *oldFormat, *format = NULL;
    int length, i, j;
    double oldGamma;
    int result;
    Tcl_Channel chan;
    Tk_PhotoImageFormat *imageFormat;
    int imageWidth, imageHeight;
    char **args;
    int oldformat;
    Tcl_Obj *tempdata, *tempformat;

    args = (char **) ckalloc((objc + 1) * sizeof(char *));
    for (i = 0, j = 0; i < objc; i++,j++) {
        args[j] = Tcl_GetStringFromObj(objv[i], &length);
        if ((length > 1) && (args[j][0] == '-')) {
            if ((args[j][1] == 'd') &&
                    !strncmp(args[j],"-data", (size_t) length)) {
                if (i < objc) {
                    data = objv[++i];
                    j--;
                }
            } else if ((args[j][1] == 'f') &&
                    !strncmp(args[j],"-format", (size_t) length)) {
                if (i < objc) {
                    format = objv[++i];
                    j--;
                }
            }
        }
    }

    /*
     * Save the current values for fileString and dataString, so we
     * can tell if the user specifies them anew.
     * IMPORTANT: if the format changes we have to interpret
     * "-file" and "-data" again as well!!!!!!! It might be
     * that the format string influences how "-data" or "-file"
     * is interpreted.
     */

    oldFileString = masterPtr->fileString;
    oldData = (oldFileString == NULL) ? masterPtr->dataString: NULL;
    oldFormat = masterPtr->format;
    oldPaletteString = masterPtr->palette;
    oldGamma = masterPtr->gamma;

    /*
     * Process the configuration options specified.
     */

    if (Tk_ConfigureWidget(interp, Tk_MainWindow(interp), configSpecs,
            j, args, (char *) masterPtr, flags) != TCL_OK) {
        ckfree((char *) args);
        return TCL_ERROR;
    }
    ckfree((char *) args);

    /*
     * Regard the empty string for -file, -data or -format as the null
     * value.
     */

    if ((masterPtr->fileString != NULL) && (masterPtr->fileString[0] == 0)) {
        ckfree(masterPtr->fileString);
        masterPtr->fileString = NULL;
    }
    if (data) {
        if (data->length
                || (data->typePtr == Tcl_GetObjType("bytearray")
                        && data->internalRep.otherValuePtr != NULL)) {
            Tcl_IncrRefCount(data);
        } else {
            data = NULL;
        }
        if (masterPtr->dataString) {
            Tcl_DecrRefCount(masterPtr->dataString);
        }
        masterPtr->dataString = data;
    }
    if (format) {
        if (format->length) {
            Tcl_IncrRefCount(format);
        } else {
            format = NULL;
        }
        if (masterPtr->format) {
            Tcl_DecrRefCount(masterPtr->format);
        }
        masterPtr->format = format;
    }
    /*
     * Set the image to the user-requested size, if any,
     * and make sure storage is correctly allocated for this image.
     */

    ImgPhotoSetSize(masterPtr, masterPtr->width, masterPtr->height);

    /*
     * Read in the image from the file or string if the user has
     * specified the -file or -data option.
     */

    if ((masterPtr->fileString != NULL)
            && ((masterPtr->fileString != oldFileString)
            || (masterPtr->format != oldFormat))) {

        /*
         * Prevent file system access in a safe interpreter.
         */

        if (Tcl_IsSafe(interp)) {
            Tcl_AppendResult(interp, "can't get image from a file in a",
                    " safe interpreter", (char *) NULL);
            return TCL_ERROR;
        }
        
        chan = Tcl_OpenFileChannel(interp, masterPtr->fileString, "r", 0);
        if (chan == NULL) {
            return TCL_ERROR;
        }
        if (Tcl_SetChannelOption(interp, chan, "-translation", "binary")
                != TCL_OK) {
            return TCL_ERROR;
        }
        if (Tcl_SetChannelOption(interp, chan, "-encoding", "binary")
                != TCL_OK) {
            return TCL_ERROR;
        }
        if (MatchFileFormat(interp, chan, masterPtr->fileString,
                masterPtr->format, &imageFormat, &imageWidth,
                &imageHeight, &oldformat) != TCL_OK) {
            Tcl_Close(NULL, chan);
            return TCL_ERROR;
        }
        ImgPhotoSetSize(masterPtr, imageWidth, imageHeight);
        tempformat = masterPtr->format;
        if (oldformat && tempformat) {
            tempformat = (Tcl_Obj *) Tcl_GetString(tempformat);
        }
        result = (*imageFormat->fileReadProc)(interp, chan,
                masterPtr->fileString, tempformat,
                (Tk_PhotoHandle) masterPtr, 0, 0,
                imageWidth, imageHeight, 0, 0);
        Tcl_Close(NULL, chan);
        if (result != TCL_OK) {
            return TCL_ERROR;
        }

        Tcl_ResetResult(interp);
        masterPtr->flags |= IMAGE_CHANGED;
    }

    if ((masterPtr->fileString == NULL) && (masterPtr->dataString != NULL)
            && ((masterPtr->dataString != oldData)
            || (masterPtr->format != oldFormat))) {

        if (MatchStringFormat(interp, masterPtr->dataString, 
                masterPtr->format, &imageFormat, &imageWidth,
                &imageHeight, &oldformat) != TCL_OK) {
            return TCL_ERROR;
        }
        ImgPhotoSetSize(masterPtr, imageWidth, imageHeight);
        tempformat = masterPtr->format;
        tempdata = masterPtr->dataString;
        if (oldformat) {
            if (tempformat) {
                tempformat = (Tcl_Obj *) Tcl_GetString(tempformat);
            }
            tempdata = (Tcl_Obj *) Tcl_GetString(tempdata);
        }
        if ((*imageFormat->stringReadProc)(interp, tempdata,
                tempformat, (Tk_PhotoHandle) masterPtr,
                0, 0, imageWidth, imageHeight, 0, 0) != TCL_OK) {
            return TCL_ERROR;
        }

        Tcl_ResetResult(interp);
        masterPtr->flags |= IMAGE_CHANGED;
    }

    /*
     * Enforce a reasonable value for gamma.
     */

    if (masterPtr->gamma <= 0) {
        masterPtr->gamma = 1.0;
    }

    if ((masterPtr->gamma != oldGamma)
            || (masterPtr->palette != oldPaletteString)) {
        masterPtr->flags |= IMAGE_CHANGED;
    }

    /*
     * Cycle through all of the instances of this image, regenerating
     * the information for each instance.  Then force the image to be
     * redisplayed everywhere that it is used.
     */

    for (instancePtr = masterPtr->instancePtr; instancePtr != NULL;
            instancePtr = instancePtr->nextPtr) {
        ImgPhotoConfigureInstance(instancePtr);
    }

    /*
     * Inform the generic image code that the image
     * has (potentially) changed.
     */

    Tk_ImageChanged(masterPtr->tkMaster, 0, 0, masterPtr->width,
            masterPtr->height, masterPtr->width, masterPtr->height);
    masterPtr->flags &= ~IMAGE_CHANGED;

    return TCL_OK;
}

/*
 *----------------------------------------------------------------------
 *
 * ImgPhotoConfigureInstance --
 *
 *      This procedure is called to create displaying information for
 *      a photo image instance based on the configuration information
 *      in the master.  It is invoked both when new instances are
 *      created and when the master is reconfigured.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      Generates errors via Tcl_BackgroundError if there are problems
 *      in setting up the instance.
 *
 *----------------------------------------------------------------------
 */

static void
ImgPhotoConfigureInstance(instancePtr)
    PhotoInstance *instancePtr; /* Instance to reconfigure. */
{
    PhotoMaster *masterPtr = instancePtr->masterPtr;
    XImage *imagePtr;
    int bitsPerPixel;
    ColorTable *colorTablePtr;
    XRectangle validBox;

    /*
     * If the -palette configuration option has been set for the master,
     * use the value specified for our palette, but only if it is
     * a valid palette for our windows.  Use the gamma value specified
     * the master.
     */

    if ((masterPtr->palette && masterPtr->palette[0])
            && IsValidPalette(instancePtr, masterPtr->palette)) {
        instancePtr->palette = masterPtr->palette;
    } else {
        instancePtr->palette = instancePtr->defaultPalette;
    }
    instancePtr->gamma = masterPtr->gamma;

    /*
     * If we don't currently have a color table, or if the one we
     * have no longer applies (e.g. because our palette or gamma
     * has changed), get a new one.
     */

    colorTablePtr = instancePtr->colorTablePtr;
    if ((colorTablePtr == NULL)
            || (instancePtr->colormap != colorTablePtr->id.colormap)
            || (instancePtr->palette != colorTablePtr->id.palette)
            || (instancePtr->gamma != colorTablePtr->id.gamma)) {
        /*
         * Free up our old color table, and get a new one.
         */

        if (colorTablePtr != NULL) {
            colorTablePtr->liveRefCount -= 1;
            FreeColorTable(colorTablePtr, 0);
        }
        GetColorTable(instancePtr);

        /*
         * Create a new XImage structure for sending data to
         * the X server, if necessary.
         */

        if (instancePtr->colorTablePtr->flags & BLACK_AND_WHITE) {
            bitsPerPixel = 1;
        } else {
            bitsPerPixel = instancePtr->visualInfo.depth;
        }

        if ((instancePtr->imagePtr == NULL)
                || (instancePtr->imagePtr->bits_per_pixel != bitsPerPixel)) {
            if (instancePtr->imagePtr != NULL) {
                XFree((char *) instancePtr->imagePtr);
            }
            imagePtr = XCreateImage(instancePtr->display,
                    instancePtr->visualInfo.visual, (unsigned) bitsPerPixel,
                    (bitsPerPixel > 1? ZPixmap: XYBitmap), 0, (char *) NULL,
                    1, 1, 32, 0);
            instancePtr->imagePtr = imagePtr;

            /*
             * Determine the endianness of this machine.
             * We create images using the local host's endianness, rather
             * than the endianness of the server; otherwise we would have
             * to byte-swap any 16 or 32 bit values that we store in the
             * image in those situations where the server's endianness
             * is different from ours.
             */

            if (imagePtr != NULL) {
                union {
                    int i;
                    char c[sizeof(int)];
                } kludge;

                imagePtr->bitmap_unit = sizeof(pixel) * NBBY;
                kludge.i = 0;
                kludge.c[0] = 1;
                imagePtr->byte_order = (kludge.i == 1) ? LSBFirst : MSBFirst;
                _XInitImageFuncPtrs(imagePtr);
            }
        }
    }

    /*
     * If the user has specified a width and/or height for the master
     * which is different from our current width/height, set the size
     * to the values specified by the user.  If we have no pixmap, we
     * do this also, since it has the side effect of allocating a
     * pixmap for us.
     */

    if ((instancePtr->pixels == None) || (instancePtr->error == NULL)
            || (instancePtr->width != masterPtr->width)
            || (instancePtr->height != masterPtr->height)) {
        ImgPhotoInstanceSetSize(instancePtr);
    }

    /*
     * Redither this instance if necessary.
     */

    if ((masterPtr->flags & IMAGE_CHANGED)
            || (instancePtr->colorTablePtr != colorTablePtr)) {
        TkClipBox(masterPtr->validRegion, &validBox);
        if ((validBox.width > 0) && (validBox.height > 0)) {
            DitherInstance(instancePtr, validBox.x, validBox.y,
                    validBox.width, validBox.height);
        }
    }

}

/*
 *----------------------------------------------------------------------
 *
 * ImgPhotoGet --
 *
 *      This procedure is called for each use of a photo image in a
 *      widget.
 *
 * Results:
 *      The return value is a token for the instance, which is passed
 *      back to us in calls to ImgPhotoDisplay and ImgPhotoFree.
 *
 * Side effects:
 *      A data structure is set up for the instance (or, an existing
 *      instance is re-used for the new one).
 *
 *----------------------------------------------------------------------
 */

static ClientData
ImgPhotoGet(tkwin, masterData)
    Tk_Window tkwin;            /* Window in which the instance will be
                                 * used. */
    ClientData masterData;      /* Pointer to our master structure for the
                                 * image. */
{
    PhotoMaster *masterPtr = (PhotoMaster *) masterData;
    PhotoInstance *instancePtr;
    Colormap colormap;
    int mono, nRed, nGreen, nBlue;
    XVisualInfo visualInfo, *visInfoPtr;
    XRectangle validBox;
    char buf[TCL_INTEGER_SPACE * 3];
    int numVisuals;
    XColor *white, *black;
    XGCValues gcValues;

    /*
     * Table of "best" choices for palette for PseudoColor displays
     * with between 3 and 15 bits/pixel.
     */

    static int paletteChoice[13][3] = {
        /*  #red, #green, #blue */
         {2,  2,  2,                    /* 3 bits, 8 colors */},
         {2,  3,  2,                    /* 4 bits, 12 colors */},
         {3,  4,  2,                    /* 5 bits, 24 colors */},
         {4,  5,  3,                    /* 6 bits, 60 colors */},
         {5,  6,  4,                    /* 7 bits, 120 colors */},
         {7,  7,  4,                    /* 8 bits, 198 colors */},
         {8, 10,  6,                    /* 9 bits, 480 colors */},
        {10, 12,  8,                    /* 10 bits, 960 colors */},
        {14, 15,  9,                    /* 11 bits, 1890 colors */},
        {16, 20, 12,                    /* 12 bits, 3840 colors */},
        {20, 24, 16,                    /* 13 bits, 7680 colors */},
        {26, 30, 20,                    /* 14 bits, 15600 colors */},
        {32, 32, 30,                    /* 15 bits, 30720 colors */}
    };

    /*
     * See if there is already an instance for windows using
     * the same colormap.  If so then just re-use it.
     */

    colormap = Tk_Colormap(tkwin);
    for (instancePtr = masterPtr->instancePtr; instancePtr != NULL;
            instancePtr = instancePtr->nextPtr) {
        if ((colormap == instancePtr->colormap)
                && (Tk_Display(tkwin) == instancePtr->display)) {

            /*
             * Re-use this instance.
             */

            if (instancePtr->refCount == 0) {
                /*
                 * We are resurrecting this instance.
                 */

                Tcl_CancelIdleCall(DisposeInstance, (ClientData) instancePtr);
                if (instancePtr->colorTablePtr != NULL) {
                    FreeColorTable(instancePtr->colorTablePtr, 0);
                }
                GetColorTable(instancePtr);
            }
            instancePtr->refCount++;
            return (ClientData) instancePtr;
        }
    }

    /*
     * The image isn't already in use in a window with the same colormap.
     * Make a new instance of the image.
     */

    instancePtr = (PhotoInstance *) ckalloc(sizeof(PhotoInstance));
    instancePtr->masterPtr = masterPtr;
    instancePtr->display = Tk_Display(tkwin);
    instancePtr->colormap = Tk_Colormap(tkwin);
    Tk_PreserveColormap(instancePtr->display, instancePtr->colormap);
    instancePtr->refCount = 1;
    instancePtr->colorTablePtr = NULL;
    instancePtr->pixels = None;
    instancePtr->error = NULL;
    instancePtr->width = 0;
    instancePtr->height = 0;
    instancePtr->imagePtr = 0;
    instancePtr->nextPtr = masterPtr->instancePtr;
    masterPtr->instancePtr = instancePtr;

    /*
     * Obtain information about the visual and decide on the
     * default palette.
     */

    visualInfo.screen = Tk_ScreenNumber(tkwin);
    visualInfo.visualid = XVisualIDFromVisual(Tk_Visual(tkwin));
    visInfoPtr = XGetVisualInfo(Tk_Display(tkwin),
            VisualScreenMask | VisualIDMask, &visualInfo, &numVisuals);
    nRed = 2;
    nGreen = nBlue = 0;
    mono = 1;
    if (visInfoPtr != NULL) {
        instancePtr->visualInfo = *visInfoPtr;
        switch (visInfoPtr->class) {
            case DirectColor:
            case TrueColor:
                nRed = 1 << CountBits(visInfoPtr->red_mask);
                nGreen = 1 << CountBits(visInfoPtr->green_mask);
                nBlue = 1 << CountBits(visInfoPtr->blue_mask);
                mono = 0;
                break;
            case PseudoColor:
            case StaticColor:
                if (visInfoPtr->depth > 15) {
                    nRed = 32;
                    nGreen = 32;
                    nBlue = 32;
                    mono = 0;
                } else if (visInfoPtr->depth >= 3) {
                    int *ip = paletteChoice[visInfoPtr->depth - 3];
    
                    nRed = ip[0];
                    nGreen = ip[1];
                    nBlue = ip[2];
                    mono = 0;
                }
                break;
            case GrayScale:
            case StaticGray:
                nRed = 1 << visInfoPtr->depth;
                break;
        }
        XFree((char *) visInfoPtr);

    } else {
        panic("ImgPhotoGet couldn't find visual for window");
    }

    sprintf(buf, ((mono) ? "%d": "%d/%d/%d"), nRed, nGreen, nBlue);
    instancePtr->defaultPalette = Tk_GetUid(buf);

    /*
     * Make a GC with background = black and foreground = white.
     */

    white = Tk_GetColor(masterPtr->interp, tkwin, "white");
    black = Tk_GetColor(masterPtr->interp, tkwin, "black");
    gcValues.foreground = (white != NULL)? white->pixel:
            WhitePixelOfScreen(Tk_Screen(tkwin));
    gcValues.background = (black != NULL)? black->pixel:
            BlackPixelOfScreen(Tk_Screen(tkwin));
    gcValues.graphics_exposures = False;
    instancePtr->gc = Tk_GetGC(tkwin,
            GCForeground|GCBackground|GCGraphicsExposures, &gcValues);

    /*
     * Set configuration options and finish the initialization of the instance.
     */

    ImgPhotoConfigureInstance(instancePtr);

    /*
     * If this is the first instance, must set the size of the image.
     */

    if (instancePtr->nextPtr == NULL) {
        Tk_ImageChanged(masterPtr->tkMaster, 0, 0, 0, 0,
                masterPtr->width, masterPtr->height);
    }

    /*
     * Dither the image to fill in this instance's pixmap.
     */

    TkClipBox(masterPtr->validRegion, &validBox);
    if ((validBox.width > 0) && (validBox.height > 0)) {
        DitherInstance(instancePtr, validBox.x, validBox.y, validBox.width,
                validBox.height);
    }

    return (ClientData) instancePtr;
}

/*
 *----------------------------------------------------------------------
 *
 * ImgPhotoDisplay --
 *
 *      This procedure is invoked to draw a photo image.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      A portion of the image gets rendered in a pixmap or window.
 *
 *----------------------------------------------------------------------
 */

static void
ImgPhotoDisplay(clientData, display, drawable, imageX, imageY, width,
        height, drawableX, drawableY)
    ClientData clientData;      /* Pointer to PhotoInstance structure for
                                 * for instance to be displayed. */
    Display *display;           /* Display on which to draw image. */
    Drawable drawable;          /* Pixmap or window in which to draw image. */
    int imageX, imageY;         /* Upper-left corner of region within image
                                 * to draw. */
    int width, height;          /* Dimensions of region within image to draw. */
    int drawableX, drawableY;   /* Coordinates within drawable that
                                 * correspond to imageX and imageY. */
{
    PhotoInstance *instancePtr = (PhotoInstance *) clientData;

    /*
     * If there's no pixmap, it means that an error occurred
     * while creating the image instance so it can't be displayed.
     */

    if (instancePtr->pixels == None) {
        return;
    }

    /*
     * masterPtr->region describes which parts of the image contain
     * valid data.  We set this region as the clip mask for the gc,
     * setting its origin appropriately, and use it when drawing the
     * image.
     */

    TkSetRegion(display, instancePtr->gc, instancePtr->masterPtr->validRegion);
    XSetClipOrigin(display, instancePtr->gc, drawableX - imageX,
            drawableY - imageY);
    XCopyArea(display, instancePtr->pixels, drawable, instancePtr->gc,
            imageX, imageY, (unsigned) width, (unsigned) height,
            drawableX, drawableY);
    XSetClipMask(display, instancePtr->gc, None);
    XSetClipOrigin(display, instancePtr->gc, 0, 0);
}

/*
 *----------------------------------------------------------------------
 *
 * ImgPhotoFree --
 *
 *      This procedure is called when a widget ceases to use a
 *      particular instance of an image.  We don't actually get
 *      rid of the instance until later because we may be about
 *      to get this instance again.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      Internal data structures get cleaned up, later.
 *
 *----------------------------------------------------------------------
 */

static void
ImgPhotoFree(clientData, display)
    ClientData clientData;      /* Pointer to PhotoInstance structure for
                                 * for instance to be displayed. */
    Display *display;           /* Display containing window that used image. */
{
    PhotoInstance *instancePtr = (PhotoInstance *) clientData;
    ColorTable *colorPtr;

    instancePtr->refCount -= 1;
    if (instancePtr->refCount > 0) {
        return;
    }

    /*
     * There are no more uses of the image within this widget.
     * Decrement the count of live uses of its color table, so
     * that its colors can be reclaimed if necessary, and
     * set up an idle call to free the instance structure.
     */

    colorPtr = instancePtr->colorTablePtr;
    if (colorPtr != NULL) {
        colorPtr->liveRefCount -= 1;
    }
    
    Tcl_DoWhenIdle(DisposeInstance, (ClientData) instancePtr);
}

/*
 *----------------------------------------------------------------------
 *
 * ImgPhotoDelete --
 *
 *      This procedure is called by the image code to delete the
 *      master structure for an image.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      Resources associated with the image get freed.
 *
 *----------------------------------------------------------------------
 */

static void
ImgPhotoDelete(masterData)
    ClientData masterData;      /* Pointer to PhotoMaster structure for
                                 * image.  Must not have any more instances. */
{
    PhotoMaster *masterPtr = (PhotoMaster *) masterData;
    PhotoInstance *instancePtr;

    while ((instancePtr = masterPtr->instancePtr) != NULL) {
        if (instancePtr->refCount > 0) {
            panic("tried to delete photo image when instances still exist");
        }
        Tcl_CancelIdleCall(DisposeInstance, (ClientData) instancePtr);
        DisposeInstance((ClientData) instancePtr);
    }
    masterPtr->tkMaster = NULL;
    if (masterPtr->imageCmd != NULL) {
        Tcl_DeleteCommandFromToken(masterPtr->interp, masterPtr->imageCmd);
    }
    if (masterPtr->pix24 != NULL) {
        ckfree((char *) masterPtr->pix24);
    }
    if (masterPtr->validRegion != NULL) {
        TkDestroyRegion(masterPtr->validRegion);
    }
    if (masterPtr->dataString != NULL) {
        Tcl_DecrRefCount(masterPtr->dataString);
    }
    if (masterPtr->format != NULL) {
        Tcl_DecrRefCount(masterPtr->format);
    }
    Tk_FreeOptions(configSpecs, (char *) masterPtr, (Display *) NULL, 0);
    ckfree((char *) masterPtr);
}

/*
 *----------------------------------------------------------------------
 *
 * ImgPhotoCmdDeletedProc --
 *
 *      This procedure is invoked when the image command for an image
 *      is deleted.  It deletes the image.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      The image is deleted.
 *
 *----------------------------------------------------------------------
 */

static void
ImgPhotoCmdDeletedProc(clientData)
    ClientData clientData;      /* Pointer to PhotoMaster structure for
                                 * image. */
{
    PhotoMaster *masterPtr = (PhotoMaster *) clientData;

    masterPtr->imageCmd = NULL;
    if (masterPtr->tkMaster != NULL) {
        Tk_DeleteImage(masterPtr->interp, Tk_NameOfImage(masterPtr->tkMaster));
    }
}

/*
 *----------------------------------------------------------------------
 *
 * ImgPhotoSetSize --
 *
 *      This procedure reallocates the image storage and instance
 *      pixmaps for a photo image, as necessary, to change the
 *      image's size to `width' x `height' pixels.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      Storage gets reallocated, for the master and all its instances.
 *
 *----------------------------------------------------------------------
 */

static void
ImgPhotoSetSize(masterPtr, width, height)
    PhotoMaster *masterPtr;
    int width, height;
{
    unsigned char *newPix24;
    int h, offset, pitch;
    unsigned char *srcPtr, *destPtr;
    XRectangle validBox, clipBox;
    TkRegion clipRegion;
    PhotoInstance *instancePtr;

    if (masterPtr->userWidth > 0) {
        width = masterPtr->userWidth;
    }
    if (masterPtr->userHeight > 0) {
        height = masterPtr->userHeight;
    }

    /*
     * We have to trim the valid region if it is currently
     * larger than the new image size.
     */

    TkClipBox(masterPtr->validRegion, &validBox);
    if ((validBox.x + validBox.width > width)
            || (validBox.y + validBox.height > height)) {
        clipBox.x = 0;
        clipBox.y = 0;
        clipBox.width = width;
        clipBox.height = height;
        clipRegion = TkCreateRegion();
        TkUnionRectWithRegion(&clipBox, clipRegion, clipRegion);
        TkIntersectRegion(masterPtr->validRegion, clipRegion,
                masterPtr->validRegion);
        TkDestroyRegion(clipRegion);
        TkClipBox(masterPtr->validRegion, &validBox);
    }

    if ((width != masterPtr->width) || (height != masterPtr->height)
            || (masterPtr->pix24 == NULL)) {

        /*
         * Reallocate storage for the 24-bit image and copy
         * over valid regions.
         */

        pitch = width * 4;
        newPix24 = (unsigned char *) ckalloc((unsigned) (height * pitch));

        /*
         * Zero the new array.  The dithering code shouldn't read the
         * areas outside validBox, but they might be copied to another
         * photo image or written to a file.
         */

        if ((masterPtr->pix24 != NULL)
            && ((width == masterPtr->width) || (width == validBox.width))) {
            if (validBox.y > 0) {
                memset((VOID *) newPix24, 0, (size_t) (validBox.y * pitch));
            }
            h = validBox.y + validBox.height;
            if (h < height) {
                memset((VOID *) (newPix24 + h * pitch), 0,
                        (size_t) ((height - h) * pitch));
            }
        } else {
            memset((VOID *) newPix24, 0, (size_t) (height * pitch));
        }

        if (masterPtr->pix24 != NULL) {

            /*
             * Copy the common area over to the new array array and
             * free the old array.
             */

            if (width == masterPtr->width) {

                /*
                 * The region to be copied is contiguous.
                 */

                offset = validBox.y * pitch;
                memcpy((VOID *) (newPix24 + offset),
                        (VOID *) (masterPtr->pix24 + offset),
                        (size_t) (validBox.height * pitch));

            } else if ((validBox.width > 0) && (validBox.height > 0)) {

                /*
                 * Area to be copied is not contiguous - copy line by line.
                 */

                destPtr = newPix24 + (validBox.y * width + validBox.x) * 4;
                srcPtr = masterPtr->pix24 + (validBox.y * masterPtr->width
                        + validBox.x) * 4;
                for (h = validBox.height; h > 0; h--) {
                    memcpy((VOID *) destPtr, (VOID *) srcPtr,
                            (size_t) (validBox.width * 4));
                    destPtr += width * 4;
                    srcPtr += masterPtr->width * 4;
                }
            }

            ckfree((char *) masterPtr->pix24);
        }

        masterPtr->pix24 = newPix24;
        masterPtr->width = width;
        masterPtr->height = height;

        /*
         * Dithering will be correct up to the end of the last
         * pre-existing complete scanline.
         */

        if ((validBox.x > 0) || (validBox.y > 0)) {
            masterPtr->ditherX = 0;
            masterPtr->ditherY = 0;
        } else if (validBox.width == width) {
            if ((int) validBox.height < masterPtr->ditherY) {
                masterPtr->ditherX = 0;
                masterPtr->ditherY = validBox.height;
            }
        } else {
            if ((masterPtr->ditherY > 0)
                    || ((int) validBox.width < masterPtr->ditherX)) {
                masterPtr->ditherX = validBox.width;
                masterPtr->ditherY = 0;
            }
        }
    }

    /*
     * Now adjust the sizes of the pixmaps for all of the instances.
     */

    for (instancePtr = masterPtr->instancePtr; instancePtr != NULL;
            instancePtr = instancePtr->nextPtr) {
        ImgPhotoInstanceSetSize(instancePtr);
    }
}

/*
 *----------------------------------------------------------------------
 *
 * ImgPhotoInstanceSetSize --
 *
 *      This procedure reallocates the instance pixmap and dithering
 *      error array for a photo instance, as necessary, to change the
 *      image's size to `width' x `height' pixels.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      Storage gets reallocated, here and in the X server.
 *
 *----------------------------------------------------------------------
 */

static void
ImgPhotoInstanceSetSize(instancePtr)
    PhotoInstance *instancePtr;         /* Instance whose size is to be
                                         * changed. */
{
    PhotoMaster *masterPtr;
    schar *newError;
    schar *errSrcPtr, *errDestPtr;
    int h, offset;
    XRectangle validBox;
    Pixmap newPixmap;

    masterPtr = instancePtr->masterPtr;
    TkClipBox(masterPtr->validRegion, &validBox);

    if ((instancePtr->width != masterPtr->width)
            || (instancePtr->height != masterPtr->height)
            || (instancePtr->pixels == None)) {
        newPixmap = Tk_GetPixmap(instancePtr->display,
                RootWindow(instancePtr->display,
                    instancePtr->visualInfo.screen),
                (masterPtr->width > 0) ? masterPtr->width: 1,
                (masterPtr->height > 0) ? masterPtr->height: 1,
                instancePtr->visualInfo.depth);

        /*
         * The following is a gross hack needed to properly support colormaps
         * under Windows.  Before the pixels can be copied to the pixmap,
         * the relevent colormap must be associated with the drawable.
         * Normally we can infer this association from the window that
         * was used to create the pixmap.  However, in this case we're
         * using the root window, so we have to be more explicit.
         */

        TkSetPixmapColormap(newPixmap, instancePtr->colormap);

        if (instancePtr->pixels != None) {
            /*
             * Copy any common pixels from the old pixmap and free it.
             */
            XCopyArea(instancePtr->display, instancePtr->pixels, newPixmap,
                    instancePtr->gc, validBox.x, validBox.y,
                    validBox.width, validBox.height, validBox.x, validBox.y);
            Tk_FreePixmap(instancePtr->display, instancePtr->pixels);
        }
        instancePtr->pixels = newPixmap;
    }

    if ((instancePtr->width != masterPtr->width)
            || (instancePtr->height != masterPtr->height)
            || (instancePtr->error == NULL)) {

        newError = (schar *) ckalloc((unsigned)
                (masterPtr->height * masterPtr->width * 3 * sizeof(schar)));

        /*
         * Zero the new array so that we don't get bogus error values
         * propagating into areas we dither later.
         */

        if ((instancePtr->error != NULL)
            && ((instancePtr->width == masterPtr->width)
                || (validBox.width == masterPtr->width))) {
            if (validBox.y > 0) {
                memset((VOID *) newError, 0, (size_t)
                        (validBox.y * masterPtr->width * 3 * sizeof(schar)));
            }
            h = validBox.y + validBox.height;
            if (h < masterPtr->height) {
                memset((VOID *) (newError + h * masterPtr->width * 3), 0,
                        (size_t) ((masterPtr->height - h)
                            * masterPtr->width * 3 * sizeof(schar)));
            }
        } else {
            memset((VOID *) newError, 0, (size_t)
                    (masterPtr->height * masterPtr->width * 3 * sizeof(schar)));
        }

        if (instancePtr->error != NULL) {

            /*
             * Copy the common area over to the new array
             * and free the old array.
             */

            if (masterPtr->width == instancePtr->width) {

                offset = validBox.y * masterPtr->width * 3;
                memcpy((VOID *) (newError + offset),
                        (VOID *) (instancePtr->error + offset),
                        (size_t) (validBox.height
                        * masterPtr->width * 3 * sizeof(schar)));

            } else if (validBox.width > 0 && validBox.height > 0) {

                errDestPtr = newError
                        + (validBox.y * masterPtr->width + validBox.x) * 3;
                errSrcPtr = instancePtr->error
                        + (validBox.y * instancePtr->width + validBox.x) * 3;
                for (h = validBox.height; h > 0; --h) {
                    memcpy((VOID *) errDestPtr, (VOID *) errSrcPtr,
                            validBox.width * 3 * sizeof(schar));
                    errDestPtr += masterPtr->width * 3;
                    errSrcPtr += instancePtr->width * 3;
                }
            }
            ckfree((char *) instancePtr->error);
        }

        instancePtr->error = newError;
    }

    instancePtr->width = masterPtr->width;
    instancePtr->height = masterPtr->height;
}

/*
 *----------------------------------------------------------------------
 *
 * IsValidPalette --
 *
 *      This procedure is called to check whether a value given for
 *      the -palette option is valid for a particular instance
 *      of a photo image.
 *
 * Results:
 *      A boolean value: 1 if the palette is acceptable, 0 otherwise.
 *
 * Side effects:
 *      None.
 *
 *----------------------------------------------------------------------
 */

static int
IsValidPalette(instancePtr, palette)
    PhotoInstance *instancePtr;         /* Instance to which the palette
                                         * specification is to be applied. */
    char *palette;                      /* Palette specification string. */
{
    int nRed, nGreen, nBlue, mono, numColors;
    char *endp;

    /*
     * First parse the specification: it must be of the form
     * %d or %d/%d/%d.
     */

    nRed = strtol(palette, &endp, 10);
    if ((endp == palette) || ((*endp != 0) && (*endp != '/'))
            || (nRed < 2) || (nRed > 256)) {
        return 0;
    }

    if (*endp == 0) {
        mono = 1;
        nGreen = nBlue = nRed;
    } else {
        palette = endp + 1;
        nGreen = strtol(palette, &endp, 10);
        if ((endp == palette) || (*endp != '/') || (nGreen < 2)
                || (nGreen > 256)) {
            return 0;
        }
        palette = endp + 1;
        nBlue = strtol(palette, &endp, 10);
        if ((endp == palette) || (*endp != 0) || (nBlue < 2)
                || (nBlue > 256)) {
            return 0;
        }
        mono = 0;
    }

    switch (instancePtr->visualInfo.class) {
        case DirectColor:
        case TrueColor:
            if ((nRed > (1 << CountBits(instancePtr->visualInfo.red_mask)))
                    || (nGreen > (1
                        << CountBits(instancePtr->visualInfo.green_mask)))
                    || (nBlue > (1
                        << CountBits(instancePtr->visualInfo.blue_mask)))) {
                return 0;
            }
            break;
        case PseudoColor:
        case StaticColor:
            numColors = nRed;
            if (!mono) {
                numColors *= nGreen*nBlue;
            }
            if (numColors > (1 << instancePtr->visualInfo.depth)) {
                return 0;
            }
            break;
        case GrayScale:
        case StaticGray:
            if (!mono || (nRed > (1 << instancePtr->visualInfo.depth))) {
                return 0;
            }
            break;
    }

    return 1;
}

/*
 *----------------------------------------------------------------------
 *
 * CountBits --
 *
 *      This procedure counts how many bits are set to 1 in `mask'.
 *
 * Results:
 *      The integer number of bits.
 *
 * Side effects:
 *      None.
 *
 *----------------------------------------------------------------------
 */

static int
CountBits(mask)
    pixel mask;                 /* Value to count the 1 bits in. */
{
    int n;

    for( n = 0; mask != 0; mask &= mask - 1 )
        n++;
    return n;
}

/*
 *----------------------------------------------------------------------
 *
 * GetColorTable --
 *
 *      This procedure is called to allocate a table of colormap
 *      information for an instance of a photo image.  Only one such
 *      table is allocated for all photo instances using the same
 *      display, colormap, palette and gamma values, so that the
 *      application need only request a set of colors from the X
 *      server once for all such photo widgets.  This procedure
 *      maintains a hash table to find previously-allocated
 *      ColorTables.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      A new ColorTable may be allocated and placed in the hash
 *      table, and have colors allocated for it.
 *
 *----------------------------------------------------------------------
 */

static void
GetColorTable(instancePtr)
    PhotoInstance *instancePtr;         /* Instance needing a color table. */
{
    ColorTable *colorPtr;
    Tcl_HashEntry *entry;
    ColorTableId id;
    int isNew;

    /*
     * Look for an existing ColorTable in the hash table.
     */

    memset((VOID *) &id, 0, sizeof(id));
    id.display = instancePtr->display;
    id.colormap = instancePtr->colormap;
    id.palette = instancePtr->palette;
    id.gamma = instancePtr->gamma;
    if (!imgPhotoColorHashInitialized) {
        Tcl_InitHashTable(&imgPhotoColorHash, N_COLOR_HASH);
        imgPhotoColorHashInitialized = 1;
    }
    entry = Tcl_CreateHashEntry(&imgPhotoColorHash, (char *) &id, &isNew);

    if (!isNew) {
        /*
         * Re-use the existing entry.
         */

        colorPtr = (ColorTable *) Tcl_GetHashValue(entry);

    } else {
        /*
         * No color table currently available; need to make one.
         */

        colorPtr = (ColorTable *) ckalloc(sizeof(ColorTable));

        /*
         * The following line of code should not normally be needed due
         * to the assignment in the following line.  However, it compensates
         * for bugs in some compilers (HP, for example) where
         * sizeof(ColorTable) is 24 but the assignment only copies 20 bytes,
         * leaving 4 bytes uninitialized;  these cause problems when using
         * the id for lookups in imgPhotoColorHash, and can result in
         * core dumps.
         */

        memset((VOID *) &colorPtr->id, 0, sizeof(ColorTableId));
        colorPtr->id = id;
        Tk_PreserveColormap(colorPtr->id.display, colorPtr->id.colormap);
        colorPtr->flags = 0;
        colorPtr->refCount = 0;
        colorPtr->liveRefCount = 0;
        colorPtr->numColors = 0;
        colorPtr->visualInfo = instancePtr->visualInfo;
        colorPtr->pixelMap = NULL;
        Tcl_SetHashValue(entry, colorPtr);
    }

    colorPtr->refCount++;
    colorPtr->liveRefCount++;
    instancePtr->colorTablePtr = colorPtr;
    if (colorPtr->flags & DISPOSE_PENDING) {
        Tcl_CancelIdleCall(DisposeColorTable, (ClientData) colorPtr);
        colorPtr->flags &= ~DISPOSE_PENDING;
    }

    /*
     * Allocate colors for this color table if necessary.
     */

    if ((colorPtr->numColors == 0)
            && ((colorPtr->flags & BLACK_AND_WHITE) == 0)) {
        AllocateColors(colorPtr);
    }
}

/*
 *----------------------------------------------------------------------
 *
 * FreeColorTable --
 *
 *      This procedure is called when an instance ceases using a
 *      color table.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      If no other instances are using this color table, a when-idle
 *      handler is registered to free up the color table and the colors
 *      allocated for it.
 *
 *----------------------------------------------------------------------
 */

static void
FreeColorTable(colorPtr, force)
    ColorTable *colorPtr;       /* Pointer to the color table which is
                                 * no longer required by an instance. */
    int force;                  /* Force free to happen immediately. */
{
    colorPtr->refCount--;
    if (colorPtr->refCount > 0) {
        return;
    }
    if (force) {
        if ((colorPtr->flags & DISPOSE_PENDING) != 0) {
            Tcl_CancelIdleCall(DisposeColorTable, (ClientData) colorPtr);
            colorPtr->flags &= ~DISPOSE_PENDING;
        }
        DisposeColorTable((ClientData) colorPtr);
    } else if ((colorPtr->flags & DISPOSE_PENDING) == 0) {
        Tcl_DoWhenIdle(DisposeColorTable, (ClientData) colorPtr);
        colorPtr->flags |= DISPOSE_PENDING;
    }
}

/*
 *----------------------------------------------------------------------
 *
 * AllocateColors --
 *
 *      This procedure allocates the colors required by a color table,
 *      and sets up the fields in the color table data structure which
 *      are used in dithering.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      Colors are allocated from the X server.  Fields in the
 *      color table data structure are updated.
 *
 *----------------------------------------------------------------------
 */

static void
AllocateColors(colorPtr)
    ColorTable *colorPtr;       /* Pointer to the color table requiring
                                 * colors to be allocated. */
{
    int i, r, g, b, rMult, mono;
    int numColors, nRed, nGreen, nBlue;
    double fr, fg, fb, igam;
    XColor *colors;
    unsigned long *pixels;

    /* 16-bit intensity value for i/n of full intensity. */
#   define CFRAC(i, n)  ((i) * 65535 / (n))

    /* As for CFRAC, but apply exponent of g. */
#   define CGFRAC(i, n, g)      ((int)(65535 * pow((double)(i) / (n), (g))))

    /*
     * First parse the palette specification to get the required number of
     * shades of each primary.
     */

    mono = sscanf(colorPtr->id.palette, "%d/%d/%d", &nRed, &nGreen, &nBlue)
            <= 1;
    igam = 1.0 / colorPtr->id.gamma;

    /*
     * Each time around this loop, we reduce the number of colors we're
     * trying to allocate until we succeed in allocating all of the colors
     * we need.
     */

    for (;;) {
        /*
         * If we are using 1 bit/pixel, we don't need to allocate
         * any colors (we just use the foreground and background
         * colors in the GC).
         */

        if (mono && (nRed <= 2)) {
            colorPtr->flags |= BLACK_AND_WHITE;
            return;
        }

        /*
         * Calculate the RGB coordinates of the colors we want to
         * allocate and store them in *colors.
         */

        if ((colorPtr->visualInfo.class == DirectColor)
            || (colorPtr->visualInfo.class == TrueColor)) {

            /*
             * Direct/True Color: allocate shades of red, green, blue
             * independently.
             */

            if (mono) {
                numColors = nGreen = nBlue = nRed;
            } else {
                numColors = MAX(MAX(nRed, nGreen), nBlue);
            }
            colors = (XColor *) ckalloc(numColors * sizeof(XColor));

            for (i = 0; i < numColors; ++i) {
                if (igam == 1.0) {
                    colors[i].red = CFRAC(i, nRed - 1);
                    colors[i].green = CFRAC(i, nGreen - 1);
                    colors[i].blue = CFRAC(i, nBlue - 1);
                } else {
                    colors[i].red = CGFRAC(i, nRed - 1, igam);
                    colors[i].green = CGFRAC(i, nGreen - 1, igam);
                    colors[i].blue = CGFRAC(i, nBlue - 1, igam);
                }
            }
        } else {
            /*
             * PseudoColor, StaticColor, GrayScale or StaticGray visual:
             * we have to allocate each color in the color cube separately.
             */

            numColors = (mono) ? nRed: (nRed * nGreen * nBlue);
            colors = (XColor *) ckalloc(numColors * sizeof(XColor));

            if (!mono) {
                /*
                 * Color display using a PseudoColor or StaticColor visual.
                 */

                i = 0;
                for (r = 0; r < nRed; ++r) {
                    for (g = 0; g < nGreen; ++g) {
                        for (b = 0; b < nBlue; ++b) {
                            if (igam == 1.0) {
                                colors[i].red = CFRAC(r, nRed - 1);
                                colors[i].green = CFRAC(g, nGreen - 1);
                                colors[i].blue = CFRAC(b, nBlue - 1);
                            } else {
                                colors[i].red = CGFRAC(r, nRed - 1, igam);
                                colors[i].green = CGFRAC(g, nGreen - 1, igam);
                                colors[i].blue = CGFRAC(b, nBlue - 1, igam);
                            }
                            i++;
                        }
                    }
                }
            } else {
                /*
                 * Monochrome display - allocate the shades of grey we want.
                 */

                for (i = 0; i < numColors; ++i) {
                    if (igam == 1.0) {
                        r = CFRAC(i, numColors - 1);
                    } else {
                        r = CGFRAC(i, numColors - 1, igam);
                    }
                    colors[i].red = colors[i].green = colors[i].blue = r;
                }
            }
        }

        /*
         * Now try to allocate the colors we've calculated.
         */

        pixels = (unsigned long *) ckalloc(numColors * sizeof(unsigned long));
        for (i = 0; i < numColors; ++i) {
            if (!XAllocColor(colorPtr->id.display, colorPtr->id.colormap,
                    &colors[i])) {

                /*
                 * Can't get all the colors we want in the default colormap;
                 * first try freeing colors from other unused color tables.
                 */

                if (!ReclaimColors(&colorPtr->id, numColors - i)
                        || !XAllocColor(colorPtr->id.display,
                        colorPtr->id.colormap, &colors[i])) {
                    /*
                     * Still can't allocate the color.
                     */
                    break;
                }
            }
            pixels[i] = colors[i].pixel;
        }

        /*
         * If we didn't get all of the colors, reduce the
         * resolution of the color cube, free the ones we got,
         * and try again.
         */

        if (i >= numColors) {
            break;
        }
        XFreeColors(colorPtr->id.display, colorPtr->id.colormap, pixels, i, 0);
        ckfree((char *) colors);
        ckfree((char *) pixels);

        if (!mono) {
            if ((nRed == 2) && (nGreen == 2) && (nBlue == 2)) {
                /*
                 * Fall back to 1-bit monochrome display.
                 */

                mono = 1;
            } else {
                /*
                 * Reduce the number of shades of each primary to about
                 * 3/4 of the previous value.  This should reduce the
                 * total number of colors required to about half the
                 * previous value for PseudoColor displays.
                 */

                nRed = (nRed * 3 + 2) / 4;
                nGreen = (nGreen * 3 + 2) / 4;
                nBlue = (nBlue * 3 + 2) / 4;
            }
        } else {
            /*
             * Reduce the number of shades of gray to about 1/2.
             */

            nRed = nRed / 2;
        }
    }
    
    /*
     * We have allocated all of the necessary colors:
     * fill in various fields of the ColorTable record.
     */

    if (!mono) {
        colorPtr->flags |= COLOR_WINDOW;

        /*
         * The following is a hairy hack.  We only want to index into
         * the pixelMap on colormap displays.  However, if the display
         * is on Windows, then we actually want to store the index not
         * the value since we will be passing the color table into the
         * TkPutImage call.
         */
        
#ifndef __WIN32__
        if ((colorPtr->visualInfo.class != DirectColor)
                && (colorPtr->visualInfo.class != TrueColor)) {
            colorPtr->flags |= MAP_COLORS;
        }
#endif /* __WIN32__ */
    }

    colorPtr->numColors = numColors;
    colorPtr->pixelMap = pixels;

    /*
     * Set up quantization tables for dithering.
     */
    rMult = nGreen * nBlue;
    for (i = 0; i < 256; ++i) {
        r = (i * (nRed - 1) + 127) / 255;
        if (mono) {
            fr = (double) colors[r].red / 65535.0;
            if (colorPtr->id.gamma != 1.0 ) {
                fr = pow(fr, colorPtr->id.gamma);
            }
            colorPtr->colorQuant[0][i] = (int)(fr * 255.99);
            colorPtr->redValues[i] = colors[r].pixel;
        } else {
            g = (i * (nGreen - 1) + 127) / 255;
            b = (i * (nBlue - 1) + 127) / 255;
            if ((colorPtr->visualInfo.class == DirectColor)
                    || (colorPtr->visualInfo.class == TrueColor)) {
                colorPtr->redValues[i] = colors[r].pixel
                    & colorPtr->visualInfo.red_mask;
                colorPtr->greenValues[i] = colors[g].pixel
                    & colorPtr->visualInfo.green_mask;
                colorPtr->blueValues[i] = colors[b].pixel
                    & colorPtr->visualInfo.blue_mask;
            } else {
                r *= rMult;
                g *= nBlue;
                colorPtr->redValues[i] = r;
                colorPtr->greenValues[i] = g;
                colorPtr->blueValues[i] = b;
            }
            fr = (double) colors[r].red / 65535.0;
            fg = (double) colors[g].green / 65535.0;
            fb = (double) colors[b].blue / 65535.0;
            if (colorPtr->id.gamma != 1.0) {
                fr = pow(fr, colorPtr->id.gamma);
                fg = pow(fg, colorPtr->id.gamma);
                fb = pow(fb, colorPtr->id.gamma);
            }
            colorPtr->colorQuant[0][i] = (int)(fr * 255.99);
            colorPtr->colorQuant[1][i] = (int)(fg * 255.99);
            colorPtr->colorQuant[2][i] = (int)(fb * 255.99);
        }
    }

    ckfree((char *) colors);
}

/*
 *----------------------------------------------------------------------
 *
 * DisposeColorTable --
 *
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      The colors in the argument color table are freed, as is the
 *      color table structure itself.  The color table is removed
 *      from the hash table which is used to locate color tables.
 *
 *----------------------------------------------------------------------
 */

static void
DisposeColorTable(clientData)
    ClientData clientData;      /* Pointer to the ColorTable whose
                                 * colors are to be released. */
{
    ColorTable *colorPtr;
    Tcl_HashEntry *entry;

    colorPtr = (ColorTable *) clientData;
    if (colorPtr->pixelMap != NULL) {
        if (colorPtr->numColors > 0) {
            XFreeColors(colorPtr->id.display, colorPtr->id.colormap,
                    colorPtr->pixelMap, colorPtr->numColors, 0);
            Tk_FreeColormap(colorPtr->id.display, colorPtr->id.colormap);
        }
        ckfree((char *) colorPtr->pixelMap);
    }

    entry = Tcl_FindHashEntry(&imgPhotoColorHash, (char *) &colorPtr->id);
    if (entry == NULL) {
        panic("DisposeColorTable couldn't find hash entry");
    }
    Tcl_DeleteHashEntry(entry);

    ckfree((char *) colorPtr);
}

/*
 *----------------------------------------------------------------------
 *
 * ReclaimColors --
 *
 *      This procedure is called to try to free up colors in the
 *      colormap used by a color table.  It looks for other color
 *      tables with the same colormap and with a zero live reference
 *      count, and frees their colors.  It only does so if there is
 *      the possibility of freeing up at least `numColors' colors.
 *
 * Results:
 *      The return value is TRUE if any colors were freed, FALSE
 *      otherwise.
 *
 * Side effects:
 *      ColorTables which are not currently in use may lose their
 *      color allocations.
 *
 *---------------------------------------------------------------------- */

static int
ReclaimColors(id, numColors)
    ColorTableId *id;           /* Pointer to information identifying
                                 * the color table which needs more colors. */
    int numColors;              /* Number of colors required. */
{
    Tcl_HashSearch srch;
    Tcl_HashEntry *entry;
    ColorTable *colorPtr;
    int nAvail;

    /*
     * First scan through the color hash table to get an
     * upper bound on how many colors we might be able to free.
     */

    nAvail = 0;
    entry = Tcl_FirstHashEntry(&imgPhotoColorHash, &srch);
    while (entry != NULL) {
        colorPtr = (ColorTable *) Tcl_GetHashValue(entry);
        if ((colorPtr->id.display == id->display)
            && (colorPtr->id.colormap == id->colormap)
            && (colorPtr->liveRefCount == 0 )&& (colorPtr->numColors != 0)
            && ((colorPtr->id.palette != id->palette)
                || (colorPtr->id.gamma != id->gamma))) {

            /*
             * We could take this guy's colors off him.
             */

            nAvail += colorPtr->numColors;
        }
        entry = Tcl_NextHashEntry(&srch);
    }

    /*
     * nAvail is an (over)estimate of the number of colors we could free.
     */

    if (nAvail < numColors) {
        return 0;
    }

    /*
     * Scan through a second time freeing colors.
     */

    entry = Tcl_FirstHashEntry(&imgPhotoColorHash, &srch);
    while ((entry != NULL) && (numColors > 0)) {
        colorPtr = (ColorTable *) Tcl_GetHashValue(entry);
        if ((colorPtr->id.display == id->display)
                && (colorPtr->id.colormap == id->colormap)
                && (colorPtr->liveRefCount == 0) && (colorPtr->numColors != 0)
                && ((colorPtr->id.palette != id->palette)
                    || (colorPtr->id.gamma != id->gamma))) {

            /*
             * Free the colors that this ColorTable has.
             */

            XFreeColors(colorPtr->id.display, colorPtr->id.colormap,
                    colorPtr->pixelMap, colorPtr->numColors, 0);
            numColors -= colorPtr->numColors;
            colorPtr->numColors = 0;
            ckfree((char *) colorPtr->pixelMap);
            colorPtr->pixelMap = NULL;
        }

        entry = Tcl_NextHashEntry(&srch);
    }
    return 1;                   /* we freed some colors */
}

/*
 *----------------------------------------------------------------------
 *
 * DisposeInstance --
 *
 *      This procedure is called to finally free up an instance
 *      of a photo image which is no longer required.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      The instance data structure and the resources it references
 *      are freed.
 *
 *----------------------------------------------------------------------
 */

static void
DisposeInstance(clientData)
    ClientData clientData;      /* Pointer to the instance whose resources
                                 * are to be released. */
{
    PhotoInstance *instancePtr = (PhotoInstance *) clientData;
    PhotoInstance *prevPtr;

    if (instancePtr->pixels != None) {
        Tk_FreePixmap(instancePtr->display, instancePtr->pixels);
    }
    if (instancePtr->gc != None) {
        Tk_FreeGC(instancePtr->display, instancePtr->gc);
    }
    if (instancePtr->imagePtr != NULL) {
        XFree((char *) instancePtr->imagePtr);
    }
    if (instancePtr->error != NULL) {
        ckfree((char *) instancePtr->error);
    }
    if (instancePtr->colorTablePtr != NULL) {
        FreeColorTable(instancePtr->colorTablePtr, 1);
    }

    if (instancePtr->masterPtr->instancePtr == instancePtr) {
        instancePtr->masterPtr->instancePtr = instancePtr->nextPtr;
    } else {
        for (prevPtr = instancePtr->masterPtr->instancePtr;
                prevPtr->nextPtr != instancePtr; prevPtr = prevPtr->nextPtr) {
            /* Empty loop body */
        }
        prevPtr->nextPtr = instancePtr->nextPtr;
    }
    Tk_FreeColormap(instancePtr->display, instancePtr->colormap);
    ckfree((char *) instancePtr);
}

/*
 *----------------------------------------------------------------------
 *
 * MatchFileFormat --
 *
 *      This procedure is called to find a photo image file format
 *      handler which can parse the image data in the given file.
 *      If a user-specified format string is provided, only handlers
 *      whose names match a prefix of the format string are tried.
 *
 * Results:
 *      A standard TCL return value.  If the return value is TCL_OK, a
 *      pointer to the image format record is returned in
 *      *imageFormatPtr, and the width and height of the image are
 *      returned in *widthPtr and *heightPtr.
 *
 * Side effects:
 *      None.
 *
 *----------------------------------------------------------------------
 */

static int
MatchFileFormat(interp, chan, fileName, formatObj, imageFormatPtr,
        widthPtr, heightPtr, oldformat)
    Tcl_Interp *interp;         /* Interpreter to use for reporting errors. */
    Tcl_Channel chan;           /* The image file, open for reading. */
    char *fileName;             /* The name of the image file. */
    Tcl_Obj *formatObj;         /* User-specified format string, or NULL. */
    Tk_PhotoImageFormat **imageFormatPtr;
                                /* A pointer to the photo image format
                                 * record is returned here. */
    int *widthPtr, *heightPtr;  /* The dimensions of the image are
                                 * returned here. */
    int *oldformat;
{
    int matched;
    int useoldformat = 0;
    Tk_PhotoImageFormat *formatPtr;
    ThreadSpecificData *tsdPtr = (ThreadSpecificData *) 
            Tcl_GetThreadData(&dataKey, sizeof(ThreadSpecificData));
    char *formatString = NULL;

    if (formatObj) {
        formatString = Tcl_GetString(formatObj);
    }

    /*
     * Scan through the table of file format handlers to find
     * one which can handle the image.
     */

    matched = 0;
    for (formatPtr = tsdPtr->formatList; formatPtr != NULL;
         formatPtr = formatPtr->nextPtr) {
        if (formatObj != NULL) {
            if (strncasecmp(formatString,
                    formatPtr->name, strlen(formatPtr->name)) != 0) {
                continue;
            }
            matched = 1;
            if (formatPtr->fileMatchProc == NULL) {
                Tcl_AppendResult(interp, "-file option isn't supported for ",
                        formatString, " images", (char *) NULL);
                return TCL_ERROR;
            }
        }
        if (formatPtr->fileMatchProc != NULL) {
            (void) Tcl_Seek(chan, 0L, SEEK_SET);
            
            if ((*formatPtr->fileMatchProc)(chan, fileName, formatObj,
                    widthPtr, heightPtr, interp)) {
                if (*widthPtr < 1) {
                    *widthPtr = 1;
                }
                if (*heightPtr < 1) {
                    *heightPtr = 1;
                }
                break;
            }
        }
    }
    if (formatPtr == NULL) {
      useoldformat = 1;
      for (formatPtr = tsdPtr->oldFormatList; formatPtr != NULL;
         formatPtr = formatPtr->nextPtr) {
        if (formatString != NULL) {
            if (strncasecmp(formatString,
                    formatPtr->name, strlen(formatPtr->name)) != 0) {
                continue;
            }
            matched = 1;
            if (formatPtr->fileMatchProc == NULL) {
                Tcl_AppendResult(interp, "-file option isn't supported for ",
                        formatString, " images", (char *) NULL);
                return TCL_ERROR;
            }
        }
        if (formatPtr->fileMatchProc != NULL) {
            (void) Tcl_Seek(chan, 0L, SEEK_SET);
            if ((*formatPtr->fileMatchProc)(chan, fileName, (Tcl_Obj *) formatString,
                    widthPtr, heightPtr, interp)) {
                if (*widthPtr < 1) {
                    *widthPtr = 1;
                }
                if (*heightPtr < 1) {
                    *heightPtr = 1;
                }
                break;
            }
        }
      }
    }

    if (formatPtr == NULL) {
        if ((formatObj != NULL) && !matched) {
            Tcl_AppendResult(interp, "image file format \"",
                    formatString,
                    "\" is not supported", (char *) NULL);
        } else {
            Tcl_AppendResult(interp,
                    "couldn't recognize data in image file \"",
                    fileName, "\"", (char *) NULL);
        }
        return TCL_ERROR;
    }

    *imageFormatPtr = formatPtr;
    *oldformat = useoldformat;
    (void) Tcl_Seek(chan, 0L, SEEK_SET);
    return TCL_OK;
}

/*
 *----------------------------------------------------------------------
 *
 * MatchStringFormat --
 *
 *      This procedure is called to find a photo image file format
 *      handler which can parse the image data in the given string.
 *      If a user-specified format string is provided, only handlers
 *      whose names match a prefix of the format string are tried.
 *
 * Results:
 *      A standard TCL return value.  If the return value is TCL_OK, a
 *      pointer to the image format record is returned in
 *      *imageFormatPtr, and the width and height of the image are
 *      returned in *widthPtr and *heightPtr.
 *
 * Side effects:
 *      None.
 *
 *----------------------------------------------------------------------
 */

static int
MatchStringFormat(interp, data, formatObj, imageFormatPtr,
        widthPtr, heightPtr, oldformat)
    Tcl_Interp *interp;         /* Interpreter to use for reporting errors. */
    Tcl_Obj *data;              /* Object containing the image data. */
    Tcl_Obj *formatObj;         /* User-specified format string, or NULL. */
    Tk_PhotoImageFormat **imageFormatPtr;
                                /* A pointer to the photo image format
                                 * record is returned here. */
    int *widthPtr, *heightPtr;  /* The dimensions of the image are
                                 * returned here. */
    int *oldformat;             /* returns 1 if the old image API is used */
{
    int matched;
    int useoldformat = 0;
    Tk_PhotoImageFormat *formatPtr;
    ThreadSpecificData *tsdPtr = (ThreadSpecificData *) 
            Tcl_GetThreadData(&dataKey, sizeof(ThreadSpecificData));
    char *formatString = NULL;
    
    if (formatObj) {
        formatString = Tcl_GetString(formatObj);
    }

    /*
     * Scan through the table of file format handlers to find
     * one which can handle the image.
     */

    matched = 0;
    for (formatPtr = tsdPtr->formatList; formatPtr != NULL;
            formatPtr = formatPtr->nextPtr) {
        if (formatObj != NULL) {
            if (strncasecmp(formatString,
                    formatPtr->name, strlen(formatPtr->name)) != 0) {
                continue;
            }
            matched = 1;
            if (formatPtr->stringMatchProc == NULL) {
                Tcl_AppendResult(interp, "-data option isn't supported for ",
                        formatString, " images", (char *) NULL);
                return TCL_ERROR;
            }
        }
        if ((formatPtr->stringMatchProc != NULL)
                && (formatPtr->stringReadProc != NULL)
                && (*formatPtr->stringMatchProc)(data, formatObj,
                widthPtr, heightPtr, interp)) {
            break;
        }
    }

    if (formatPtr == NULL) {
      useoldformat = 1;
      for (formatPtr = tsdPtr->oldFormatList; formatPtr != NULL;
            formatPtr = formatPtr->nextPtr) {
        if (formatObj != NULL) {
            if (strncasecmp(formatString,
                    formatPtr->name, strlen(formatPtr->name)) != 0) {
                continue;
            }
            matched = 1;
            if (formatPtr->stringMatchProc == NULL) {
                Tcl_AppendResult(interp, "-data option isn't supported for ",
                        formatString, " images", (char *) NULL);
                return TCL_ERROR;
            }
        }
        if ((formatPtr->stringMatchProc != NULL)
                && (formatPtr->stringReadProc != NULL)
                && (*formatPtr->stringMatchProc)((Tcl_Obj *) Tcl_GetString(data),
                        (Tcl_Obj *) formatString,
                widthPtr, heightPtr, interp)) {
            break;
        }
      } 
    }
    if (formatPtr == NULL) {
        if ((formatObj != NULL) && !matched) {
            Tcl_AppendResult(interp, "image format \"",
                    formatString,
                    "\" is not supported", (char *) NULL);
        } else {
            Tcl_AppendResult(interp, "couldn't recognize image data",
                    (char *) NULL);
        }
        return TCL_ERROR;
    }

    *imageFormatPtr = formatPtr;
    *oldformat = useoldformat;
    return TCL_OK;
}

/*
 *----------------------------------------------------------------------
 *
 * Tk_FindPhoto --
 *
 *      This procedure is called to get an opaque handle (actually a
 *      PhotoMaster *) for a given image, which can be used in
 *      subsequent calls to Tk_PhotoPutBlock, etc.  The `name'
 *      parameter is the name of the image.
 *
 * Results:
 *      The handle for the photo image, or NULL if there is no
 *      photo image with the name given.
 *
 * Side effects:
 *      None.
 *
 *----------------------------------------------------------------------
 */

Tk_PhotoHandle
Tk_FindPhoto(interp, imageName)
    Tcl_Interp *interp;         /* Interpreter (application) in which image
                                 * exists. */
    char *imageName;            /* Name of the desired photo image. */
{
    ClientData clientData;
    Tk_ImageType *typePtr;

    clientData = Tk_GetImageMasterData(interp, imageName, &typePtr);
    if (typePtr != &tkPhotoImageType) {
        return NULL;
    }
    return (Tk_PhotoHandle) clientData;
}

/*
 *----------------------------------------------------------------------
 *
 * Tk_PhotoPutBlock --
 *
 *      This procedure is called to put image data into a photo image.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      The image data is stored.  The image may be expanded.
 *      The Tk image code is informed that the image has changed.
 *
 *---------------------------------------------------------------------- */

void
Tk_PhotoPutBlock(handle, blockPtr, x, y, width, height)
    Tk_PhotoHandle handle;      /* Opaque handle for the photo image
                                 * to be updated. */
    register Tk_PhotoImageBlock *blockPtr;
                                /* Pointer to a structure describing the
                                 * pixel data to be copied into the image. */
    int x, y;                   /* Coordinates of the top-left pixel to
                                 * be updated in the image. */
    int width, height;          /* Dimensions of the area of the image
                                 * to be updated. */
{
    register PhotoMaster *masterPtr;
    int xEnd, yEnd;
    int greenOffset, blueOffset, alphaOffset;
    int wLeft, hLeft;
    int wCopy, hCopy;
    unsigned char *srcPtr, *srcLinePtr;
    unsigned char *destPtr, *destLinePtr;
    int pitch;
    XRectangle rect;

    masterPtr = (PhotoMaster *) handle;

    if ((masterPtr->userWidth != 0) && ((x + width) > masterPtr->userWidth)) {
        width = masterPtr->userWidth - x;
    }
    if ((masterPtr->userHeight != 0)
            && ((y + height) > masterPtr->userHeight)) {
        height = masterPtr->userHeight - y;
    }
    if ((width <= 0) || (height <= 0))
        return;

    xEnd = x + width;
    yEnd = y + height;
    if ((xEnd > masterPtr->width) || (yEnd > masterPtr->height)) {
        ImgPhotoSetSize(masterPtr, MAX(xEnd, masterPtr->width),
                MAX(yEnd, masterPtr->height));
    }

    if ((y < masterPtr->ditherY) || ((y == masterPtr->ditherY)
            && (x < masterPtr->ditherX))) {
        /*
         * The dithering isn't correct past the start of this block.
         */
        masterPtr->ditherX = x;
        masterPtr->ditherY = y;
    }

    /*
     * If this image block could have different red, green and blue
     * components, mark it as a color image.
     */

    greenOffset = blockPtr->offset[1] - blockPtr->offset[0];
    blueOffset = blockPtr->offset[2] - blockPtr->offset[0];
    alphaOffset = blockPtr->offset[3];
    if ((alphaOffset >= blockPtr->pixelSize) || (alphaOffset < 0)) {
        alphaOffset = 0;
    } else {
        alphaOffset -= blockPtr->offset[0];
    }
    if ((greenOffset != 0) || (blueOffset != 0)) {
        masterPtr->flags |= COLOR_IMAGE;
    }

    /*
     * Copy the data into our local 24-bit/pixel array.
     * If we can do it with a single memcpy, we do.
     */

    destLinePtr = masterPtr->pix24 + (y * masterPtr->width + x) * 4;
    pitch = masterPtr->width * 4;

    /*
     * This test is probably too restrictive.  We should also be able to
     * do a memcpy if pixelSize == 3 and alphaOffset == 0.  Maybe other cases
     * too.
     */
    if ((blockPtr->pixelSize == 4)
            && (greenOffset == 1) && (blueOffset == 2) && (alphaOffset == 3)
            && (width <= blockPtr->width) && (height <= blockPtr->height)
            && ((height == 1) || ((x == 0) && (width == masterPtr->width)
                && (blockPtr->pitch == pitch)))) {
        memcpy((VOID *) destLinePtr,
                (VOID *) (blockPtr->pixelPtr + blockPtr->offset[0]),
                (size_t) (height * width * 4));
    } else {
        for (hLeft = height; hLeft > 0;) {
            srcLinePtr = blockPtr->pixelPtr + blockPtr->offset[0];
            hCopy = MIN(hLeft, blockPtr->height);
            hLeft -= hCopy;
            for (; hCopy > 0; --hCopy) {
                destPtr = destLinePtr;
                for (wLeft = width; wLeft > 0;) {
                    wCopy = MIN(wLeft, blockPtr->width);
                    wLeft -= wCopy;
                    srcPtr = srcLinePtr;
                    for (; wCopy > 0; --wCopy) {
                      if (!destPtr[3]) {
                        destPtr[0] = destPtr[1] = destPtr[2] = 0xd9;
                      }
                      if (!alphaOffset || (srcPtr[alphaOffset] == 255)) {
                        *destPtr++ = srcPtr[0];
                        *destPtr++ = srcPtr[greenOffset];
                        *destPtr++ = srcPtr[blueOffset];
                        *destPtr++ = 255;
                      } else {
                        if (srcPtr[alphaOffset]) {
                            destPtr[0] += (srcPtr[0] - destPtr[0]) * srcPtr[alphaOffset] / 255;
                            destPtr[1] += (srcPtr[greenOffset] - destPtr[1]) * srcPtr[alphaOffset] / 255;
                            destPtr[2] += (srcPtr[blueOffset] - destPtr[2]) * srcPtr[alphaOffset] / 255;
                            destPtr[3] += (255 - destPtr[3]) * srcPtr[alphaOffset] / 255;
                        }
                        destPtr+=4;
                      }
                      srcPtr += blockPtr->pixelSize;
                    }
                }
                srcLinePtr += blockPtr->pitch;
                destLinePtr += pitch;
            }
        }
    }

    /*
     * Add this new block to the region which specifies which data is valid.
     */

  if (alphaOffset) {
    int x1, y1, end;
    
    /*
     * This block is grossly inefficient.  For each row in the image, it
     * finds each continguous string of transparent pixels, then marks those
     * areas as invalid in the validRegion mask.  This makes drawing very
     * efficient, because of the way we use X:  we just say, here's your
     * mask, and here's your data.  We need not worry about the current
     * background color, etc.  But this costs us a lot on the image setup.
     * Still, image setup only happens once, whereas the drawing happens
     * many times, so this might be the best way to go.
     *
     * An alternative might be to not set up this mask, and instead, at
     * drawing time, for each transparent pixel, set its color to the
     * color of the background behind that pixel.  This is what I suspect
     * most of programs do.  However, they don't have to deal with the canvas,
     * which could have many different background colors.  Determining the
     * correct bg color for a given pixel might be expensive.
     */
     
    destLinePtr = masterPtr->pix24 + (y * masterPtr->width + x) * 4 + 3;
    for (y1 = 0; y1 < height; y1++) {
        x1 = 0;
        destPtr = destLinePtr;
        while (x1 < width) {
            /* search for first non-transparent pixel */
            while ((x1 < width) && !*destPtr) {
                    x1++; destPtr += 4;
            }
            end = x1;
            /* search for first transparent pixel */
            while ((end < width) && *destPtr) {
                end++; destPtr += 4;
            }
            if (end > x1) {
                rect.x = x + x1;
                rect.y = y + y1;
                rect.width = end - x1;
                rect.height = 1;
                TkUnionRectWithRegion(&rect, masterPtr->validRegion,
                        masterPtr->validRegion);
            }
            x1 = end;
        }
        destLinePtr += masterPtr->width * 4;
    }
  } else {
    rect.x = x;
    rect.y = y;
    rect.width = width;
    rect.height = height;
    TkUnionRectWithRegion(&rect, masterPtr->validRegion,
            masterPtr->validRegion);
  }

    /*
     * Update each instance.
     */

    Tk_DitherPhoto((Tk_PhotoHandle)masterPtr, x, y, width, height);

    /*
     * Tell the core image code that this image has changed.
     */

    Tk_ImageChanged(masterPtr->tkMaster, x, y, width, height, masterPtr->width,
            masterPtr->height);
}

/*
 *----------------------------------------------------------------------
 *
 * Tk_PhotoPutZoomedBlock --
 *
 *      This procedure is called to put image data into a photo image,
 *      with possible subsampling and/or zooming of the pixels.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      The image data is stored.  The image may be expanded.
 *      The Tk image code is informed that the image has changed.
 *
 *----------------------------------------------------------------------
 */

void
Tk_PhotoPutZoomedBlock(handle, blockPtr, x, y, width, height, zoomX, zoomY,
        subsampleX, subsampleY)
    Tk_PhotoHandle handle;      /* Opaque handle for the photo image
                                 * to be updated. */
    register Tk_PhotoImageBlock *blockPtr;
                                /* Pointer to a structure describing the
                                 * pixel data to be copied into the image. */
    int x, y;                   /* Coordinates of the top-left pixel to
                                 * be updated in the image. */
    int width, height;          /* Dimensions of the area of the image
                                 * to be updated. */
    int zoomX, zoomY;           /* Zoom factors for the X and Y axes. */
    int subsampleX, subsampleY; /* Subsampling factors for the X and Y axes. */
{
    register PhotoMaster *masterPtr;
    int xEnd, yEnd;
    int greenOffset, blueOffset, alphaOffset;
    int wLeft, hLeft;
    int wCopy, hCopy;
    int blockWid, blockHt;
    unsigned char *srcPtr, *srcLinePtr, *srcOrigPtr;
    unsigned char *destPtr, *destLinePtr;
    int pitch;
    int xRepeat, yRepeat;
    int blockXSkip, blockYSkip;
    XRectangle rect;

    if ((zoomX == 1) && (zoomY == 1) && (subsampleX == 1)
            && (subsampleY == 1)) {
        Tk_PhotoPutBlock(handle, blockPtr, x, y, width, height);
        return;
    }

    masterPtr = (PhotoMaster *) handle;

    if ((zoomX <= 0) || (zoomY <= 0))
        return;
    if ((masterPtr->userWidth != 0) && ((x + width) > masterPtr->userWidth)) {
        width = masterPtr->userWidth - x;
    }
    if ((masterPtr->userHeight != 0)
            && ((y + height) > masterPtr->userHeight)) {
        height = masterPtr->userHeight - y;
    }
    if ((width <= 0) || (height <= 0))
        return;

    xEnd = x + width;
    yEnd = y + height;
    if ((xEnd > masterPtr->width) || (yEnd > masterPtr->height)) {
        int sameSrc = (blockPtr->pixelPtr == masterPtr->pix24);
        ImgPhotoSetSize(masterPtr, MAX(xEnd, masterPtr->width),
                MAX(yEnd, masterPtr->height));
        if (sameSrc) {
            blockPtr->pixelPtr = masterPtr->pix24;
        }
    }

    if ((y < masterPtr->ditherY) || ((y == masterPtr->ditherY)
           && (x < masterPtr->ditherX))) {
        /*
         * The dithering isn't correct past the start of this block.
         */

        masterPtr->ditherX = x;
        masterPtr->ditherY = y;
    }

    /*
     * If this image block could have different red, green and blue
     * components, mark it as a color image.
     */

    greenOffset = blockPtr->offset[1] - blockPtr->offset[0];
    blueOffset = blockPtr->offset[2] - blockPtr->offset[0];
    alphaOffset = blockPtr->offset[3];
    if ((alphaOffset >= blockPtr->pixelSize) || (alphaOffset < 0)) {
        alphaOffset = 0;
    } else {
        alphaOffset -= blockPtr->offset[0];
    }
    if ((greenOffset != 0) || (blueOffset != 0)) {
        masterPtr->flags |= COLOR_IMAGE;
    }

    /*
     * Work out what area the pixel data in the block expands to after
     * subsampling and zooming.
     */

    blockXSkip = subsampleX * blockPtr->pixelSize;
    blockYSkip = subsampleY * blockPtr->pitch;
    if (subsampleX > 0)
        blockWid = ((blockPtr->width + subsampleX - 1) / subsampleX) * zoomX;
    else if (subsampleX == 0)
        blockWid = width;
    else
        blockWid = ((blockPtr->width - subsampleX - 1) / -subsampleX) * zoomX;
    if (subsampleY > 0)
        blockHt = ((blockPtr->height + subsampleY - 1) / subsampleY) * zoomY;
    else if (subsampleY == 0)
        blockHt = height;
    else
        blockHt = ((blockPtr->height - subsampleY - 1) / -subsampleY) * zoomY;

    /*
     * Copy the data into our local 24-bit/pixel array.
     */

    destLinePtr = masterPtr->pix24 + (y * masterPtr->width + x) * 4;
    srcOrigPtr = blockPtr->pixelPtr + blockPtr->offset[0];
    if (subsampleX < 0) {
        srcOrigPtr += (blockPtr->width - 1) * blockPtr->pixelSize;
    }
    if (subsampleY < 0) {
        srcOrigPtr += (blockPtr->height - 1) * blockPtr->pitch;
    }

    pitch = masterPtr->width * 4;
    for (hLeft = height; hLeft > 0; ) {
        hCopy = MIN(hLeft, blockHt);
        hLeft -= hCopy;
        yRepeat = zoomY;
        srcLinePtr = srcOrigPtr;
        for (; hCopy > 0; --hCopy) {
            destPtr = destLinePtr;
            for (wLeft = width; wLeft > 0;) {
                wCopy = MIN(wLeft, blockWid);
                wLeft -= wCopy;
                srcPtr = srcLinePtr;
                for (; wCopy > 0; wCopy -= zoomX) {
                    for (xRepeat = MIN(wCopy, zoomX); xRepeat > 0; xRepeat--) {
                      if (!destPtr[3]) {
                        destPtr[0] = destPtr[1] = destPtr[2] = 0xd9;
                      }
                      if (!alphaOffset || (srcPtr[alphaOffset] == 255)) {
                        *destPtr++ = srcPtr[0];
                        *destPtr++ = srcPtr[greenOffset];
                        *destPtr++ = srcPtr[blueOffset];
                        *destPtr++ = 255;
                      } else {
                        if (srcPtr[alphaOffset]) {
                            destPtr[0] += (srcPtr[0] - destPtr[0]) * srcPtr[alphaOffset] / 255;
                            destPtr[1] += (srcPtr[greenOffset] - destPtr[1]) * srcPtr[alphaOffset] / 255;
                            destPtr[2] += (srcPtr[blueOffset] - destPtr[2]) * srcPtr[alphaOffset] / 255;
                            destPtr[3] += (255 - destPtr[3]) * srcPtr[alphaOffset] / 255;
                        }
                        destPtr+=4;
                      }
                    }
                    srcPtr += blockXSkip;
                }
            }
            destLinePtr += pitch;
            yRepeat--;
            if (yRepeat <= 0) {
                srcLinePtr += blockYSkip;
                yRepeat = zoomY;
            }
        }
    }

    /*
     * Add this new block to the region that specifies which data is valid.
     */

  if (alphaOffset) {
    int x1, y1, end;

    destLinePtr = masterPtr->pix24 + (y * masterPtr->width + x) * 4 + 3;
    for (y1 = 0; y1 < height; y1++) {
        x1 = 0;
        destPtr = destLinePtr;
        while (x1 < width) {
            /* search for first non-transparent pixel */
            while ((x1 < width) && !*destPtr) {
                    x1++; destPtr += 4;
            }
            end = x1;
            /* search for first transparent pixel */
            while ((end < width) && *destPtr) {
                end++; destPtr += 4;
            }
            if (end > x1) {
                rect.x = x + x1;
                rect.y = y + y1;
                rect.width = end - x1;
                rect.height = 1;
                TkUnionRectWithRegion(&rect, masterPtr->validRegion,
                        masterPtr->validRegion);
            }
            x1 = end;
        }
        destLinePtr += masterPtr->width * 4;
    }
  } else {
    rect.x = x;
    rect.y = y;
    rect.width = width;
    rect.height = height;
    TkUnionRectWithRegion(&rect, masterPtr->validRegion,
            masterPtr->validRegion);
  }

    /*
     * Update each instance.
     */

    Tk_DitherPhoto((Tk_PhotoHandle)masterPtr, x, y, width, height);

    /*
     * Tell the core image code that this image has changed.
     */

    Tk_ImageChanged(masterPtr->tkMaster, x, y, width, height, masterPtr->width,
            masterPtr->height);
}

/*
 *----------------------------------------------------------------------
 *
 * Tk_DitherPhoto --
 *
 *      This procedure is called to update an area of each instance's
 *      pixmap by dithering the corresponding area of the image master.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      The pixmap of each instance of this image gets updated.
 *      The fields in *masterPtr indicating which area of the image
 *      is correctly dithered get updated.
 *
 *----------------------------------------------------------------------
 */

void
Tk_DitherPhoto(photo, x, y, width, height)
    Tk_PhotoHandle photo;       /* Image master whose instances are
                                 * to be updated. */
    int x, y;                   /* Coordinates of the top-left pixel
                                 * in the area to be dithered. */
    int width, height;          /* Dimensions of the area to be dithered. */
{
    PhotoMaster *masterPtr = (PhotoMaster *) photo;
    PhotoInstance *instancePtr;

    if ((width <= 0) || (height <= 0)) {
        return;
    }

    for (instancePtr = masterPtr->instancePtr; instancePtr != NULL;
            instancePtr = instancePtr->nextPtr) {
        DitherInstance(instancePtr, x, y, width, height);
    }

    /*
     * Work out whether this block will be correctly dithered
     * and whether it will extend the correctly dithered region.
     */

    if (((y < masterPtr->ditherY)
            || ((y == masterPtr->ditherY) && (x <= masterPtr->ditherX)))
            && ((y + height) > (masterPtr->ditherY))) {

        /*
         * This block starts inside (or immediately after) the correctly
         * dithered region, so the first scan line at least will be right.
         * Furthermore this block extends into scanline masterPtr->ditherY.
         */

        if ((x == 0) && (width == masterPtr->width)) {
            /*
             * We are doing the full width, therefore the dithering
             * will be correct to the end.
             */

            masterPtr->ditherX = 0;
            masterPtr->ditherY = y + height;
        } else {
            /*
             * We are doing partial scanlines, therefore the
             * correctly-dithered region will be extended by
             * at most one scan line.
             */

            if (x <= masterPtr->ditherX) {
                masterPtr->ditherX = x + width;
                if (masterPtr->ditherX >= masterPtr->width) {
                    masterPtr->ditherX = 0;
                    masterPtr->ditherY++;
                }
            }
        }
    }

}    

/*
 *----------------------------------------------------------------------
 *
 * DitherInstance --
 *
 *      This procedure is called to update an area of an instance's
 *      pixmap by dithering the corresponding area of the master.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      The instance's pixmap gets updated.
 *
 *----------------------------------------------------------------------
 */

static void
DitherInstance(instancePtr, xStart, yStart, width, height)
    PhotoInstance *instancePtr; /* The instance to be updated. */
    int xStart, yStart;         /* Coordinates of the top-left pixel in the
                                 * block to be dithered. */
    int width, height;          /* Dimensions of the block to be dithered. */
{
    PhotoMaster *masterPtr;
    ColorTable *colorPtr;
    XImage *imagePtr;
    int nLines, bigEndian;
    int i, c, x, y;
    int xEnd, yEnd;
    int bitsPerPixel, bytesPerLine, lineLength;
    unsigned char *srcLinePtr, *srcPtr;
    schar *errLinePtr, *errPtr;
    unsigned char *destBytePtr, *dstLinePtr;
    pixel *destLongPtr;
    pixel firstBit, word, mask;
    int col[3];
    int doDithering = 1;

    colorPtr = instancePtr->colorTablePtr;
    masterPtr = instancePtr->masterPtr;

    /*
     * Turn dithering off in certain cases where it is not
     * needed (TrueColor, DirectColor with many colors).
     */

    if ((colorPtr->visualInfo.class == DirectColor)
            || (colorPtr->visualInfo.class == TrueColor)) {
        int nRed, nGreen, nBlue, result;

        result = sscanf(colorPtr->id.palette, "%d/%d/%d", &nRed,
                &nGreen, &nBlue);
        if ((nRed >= 256)
                && ((result == 1) || ((nGreen >= 256) && (nBlue >= 256)))) {
            doDithering = 0;
        }
    }

    /*
     * First work out how many lines to do at a time,
     * then how many bytes we'll need for pixel storage,
     * and allocate it.
     */

    nLines = (MAX_PIXELS + width - 1) / width;
    if (nLines < 1) {
        nLines = 1;
    }
    if (nLines > height ) {
        nLines = height;
    }

    imagePtr = instancePtr->imagePtr;
    if (imagePtr == NULL) {
        return;                 /* we must be really tight on memory */
    }
    bitsPerPixel = imagePtr->bits_per_pixel;
    bytesPerLine = ((bitsPerPixel * width + 31) >> 3) & ~3;
    imagePtr->width = width;
    imagePtr->height = nLines;
    imagePtr->bytes_per_line = bytesPerLine;
    imagePtr->data = (char *) ckalloc((unsigned) (imagePtr->bytes_per_line * nLines));
    bigEndian = imagePtr->bitmap_bit_order == MSBFirst;
    firstBit = bigEndian? (1 << (imagePtr->bitmap_unit - 1)): 1;

    lineLength = masterPtr->width * 3;
    srcLinePtr = masterPtr->pix24 + (yStart * masterPtr->width + xStart) * 4;
    errLinePtr = instancePtr->error + yStart * lineLength + xStart * 3;
    xEnd = xStart + width;

    /*
     * Loop over the image, doing at most nLines lines before
     * updating the screen image.
     */

    for (; height > 0; height -= nLines) {
        if (nLines > height) {
            nLines = height;
        }
        dstLinePtr = (unsigned char *) imagePtr->data;
        yEnd = yStart + nLines;
        for (y = yStart; y < yEnd; ++y) {
            srcPtr = srcLinePtr;
            errPtr = errLinePtr;
            destBytePtr = dstLinePtr;
            destLongPtr = (pixel *) dstLinePtr;
            if (colorPtr->flags & COLOR_WINDOW) {
                /*
                 * Color window.  We dither the three components
                 * independently, using Floyd-Steinberg dithering,
                 * which propagates errors from the quantization of
                 * pixels to the pixels below and to the right.
                 */

                for (x = xStart; x < xEnd; ++x) {
                    if (doDithering) {
                        for (i = 0; i < 3; ++i) {
                            /*
                             * Compute the error propagated into this pixel
                             * for this component.
                             * If e[x,y] is the array of quantization error
                             * values, we compute
                             *     7/16 * e[x-1,y] + 1/16 * e[x-1,y-1]
                             *   + 5/16 * e[x,y-1] + 3/16 * e[x+1,y-1]
                             * and round it to an integer.
                             *
                             * The expression ((c + 2056) >> 4) - 128
                             * computes round(c / 16), and works correctly on
                             * machines without a sign-extending right shift.
                             */
                            
                            c = (x > 0) ? errPtr[-3] * 7: 0;
                            if (y > 0) {
                                if (x > 0) {
                                    c += errPtr[-lineLength-3];
                                }
                                c += errPtr[-lineLength] * 5;
                                if ((x + 1) < masterPtr->width) {
                                    c += errPtr[-lineLength+3] * 3;
                                }
                            }
                            
                            /*
                             * Add the propagated error to the value of this
                             * component, quantize it, and store the
                             * quantization error.
                             */
                            
                            c = ((c + 2056) >> 4) - 128 + *srcPtr++;
                            if (c < 0) {
                                c = 0;
                            } else if (c > 255) {
                                c = 255;
                            }
                            col[i] = colorPtr->colorQuant[i][c];
                            *errPtr++ = c - col[i];
                        }
                    } else {
                        /* 
                         * Output is virtually continuous in this case,
                         * so don't bother dithering.
                         */

                        col[0] = *srcPtr++;
                        col[1] = *srcPtr++;
                        col[2] = *srcPtr++;
                    }
                    srcPtr++;

                    /*
                     * Translate the quantized component values into
                     * an X pixel value, and store it in the image.
                     */

                    i = colorPtr->redValues[col[0]]
                            + colorPtr->greenValues[col[1]]
                            + colorPtr->blueValues[col[2]];
                    if (colorPtr->flags & MAP_COLORS) {
                        i = colorPtr->pixelMap[i];
                    }
                    switch (bitsPerPixel) {
                        case NBBY:
                            *destBytePtr++ = i;
                            break;
#ifndef __WIN32__
/*
 * This case is not valid for Windows because the image format is different
 * from the pixel format in Win32.  Eventually we need to fix the image
 * code in Tk to use the Windows native image ordering.  This would speed
 * up the image code for all of the common sizes.
 */

                        case NBBY * sizeof(pixel):
                            *destLongPtr++ = i;
                            break;
#endif
                        default:
                            XPutPixel(imagePtr, x - xStart, y - yStart,
                                    (unsigned) i);
                    }
                }

            } else if (bitsPerPixel > 1) {
                /*
                 * Multibit monochrome window.  The operation here is similar
                 * to the color window case above, except that there is only
                 * one component.  If the master image is in color, use the
                 * luminance computed as
                 *      0.344 * red + 0.5 * green + 0.156 * blue.
                 */

                for (x = xStart; x < xEnd; ++x) {
                    c = (x > 0) ? errPtr[-1] * 7: 0;
                    if (y > 0) {
                        if (x > 0)  {
                            c += errPtr[-lineLength-1];
                        }
                        c += errPtr[-lineLength] * 5;
                        if (x + 1 < masterPtr->width) {
                            c += errPtr[-lineLength+1] * 3;
                        }
                    }
                    c = ((c + 2056) >> 4) - 128;

                    if ((masterPtr->flags & COLOR_IMAGE) == 0) {
                        c += srcPtr[0];
                    } else {
                        c += (unsigned)(srcPtr[0] * 11 + srcPtr[1] * 16
                                        + srcPtr[2] * 5 + 16) >> 5;
                    }
                    srcPtr += 4;

                    if (c < 0) {
                        c = 0;
                    } else if (c > 255) {
                        c = 255;
                    }
                    i = colorPtr->colorQuant[0][c];
                    *errPtr++ = c - i;
                    i = colorPtr->redValues[i];
                    switch (bitsPerPixel) {
                        case NBBY:
                            *destBytePtr++ = i;
                            break;
#ifndef __WIN32__
/*
 * This case is not valid for Windows because the image format is different
 * from the pixel format in Win32.  Eventually we need to fix the image
 * code in Tk to use the Windows native image ordering.  This would speed
 * up the image code for all of the common sizes.
 */

                        case NBBY * sizeof(pixel):
                            *destLongPtr++ = i;
                            break;
#endif
                        default:
                            XPutPixel(imagePtr, x - xStart, y - yStart,
                                    (unsigned) i);
                    }
                }
            } else {
                /*
                 * 1-bit monochrome window.  This is similar to the
                 * multibit monochrome case above, except that the
                 * quantization is simpler (we only have black = 0
                 * and white = 255), and we produce an XY-Bitmap.
                 */

                word = 0;
                mask = firstBit;
                for (x = xStart; x < xEnd; ++x) {
                    /*
                     * If we have accumulated a whole word, store it
                     * in the image and start a new word.
                     */

                    if (mask == 0) {
                        *destLongPtr++ = word;
                        mask = firstBit;
                        word = 0;
                    }

                    c = (x > 0) ? errPtr[-1] * 7: 0;
                    if (y > 0) {
                        if (x > 0) {
                            c += errPtr[-lineLength-1];
                        }
                        c += errPtr[-lineLength] * 5;
                        if (x + 1 < masterPtr->width) {
                            c += errPtr[-lineLength+1] * 3;
                        }
                    }
                    c = ((c + 2056) >> 4) - 128;

                    if ((masterPtr->flags & COLOR_IMAGE) == 0) {
                        c += srcPtr[0];
                    } else {
                        c += (unsigned)(srcPtr[0] * 11 + srcPtr[1] * 16
                                        + srcPtr[2] * 5 + 16) >> 5;
                    }
                    srcPtr += 4;

                    if (c < 0) {
                        c = 0;
                    } else if (c > 255) {
                        c = 255;
                    }
                    if (c >= 128) {
                        word |= mask;
                        *errPtr++ = c - 255;
                    } else {
                        *errPtr++ = c;
                    }
                    mask = bigEndian? (mask >> 1): (mask << 1);
                }
                *destLongPtr = word;
            }
            srcLinePtr += masterPtr->width * 4;
            errLinePtr += lineLength;
            dstLinePtr += bytesPerLine;
        }

        /*
         * Update the pixmap for this instance with the block of
         * pixels that we have just computed.
         */

        TkPutImage(colorPtr->pixelMap, colorPtr->numColors,
                instancePtr->display, instancePtr->pixels,
                instancePtr->gc, imagePtr, 0, 0, xStart, yStart,
                (unsigned) width, (unsigned) nLines);
        yStart = yEnd;
        
    }

    ckfree(imagePtr->data);
    imagePtr->data = NULL;
}

/*
 *----------------------------------------------------------------------
 *
 * Tk_PhotoBlank --
 *
 *      This procedure is called to clear an entire photo image.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      The valid region for the image is set to the null region.
 *      The generic image code is notified that the image has changed.
 *
 *----------------------------------------------------------------------
 */

void
Tk_PhotoBlank(handle)
    Tk_PhotoHandle handle;      /* Handle for the image to be blanked. */
{
    PhotoMaster *masterPtr;
    PhotoInstance *instancePtr;

    masterPtr = (PhotoMaster *) handle;
    masterPtr->ditherX = masterPtr->ditherY = 0;
    masterPtr->flags = 0;

    /*
     * The image has valid data nowhere.
     */

    if (masterPtr->validRegion != NULL) {
        TkDestroyRegion(masterPtr->validRegion);
    }
    masterPtr->validRegion = TkCreateRegion();

    /*
     * Clear out the 24-bit pixel storage array.
     * Clear out the dithering error arrays for each instance.
     */

    memset((VOID *) masterPtr->pix24, 0,
            (size_t) (masterPtr->width * masterPtr->height * 4));
    for (instancePtr = masterPtr->instancePtr; instancePtr != NULL;
            instancePtr = instancePtr->nextPtr) {
        if (instancePtr->error) {
            memset((VOID *) instancePtr->error, 0,
                    (size_t) (masterPtr->width * masterPtr->height
                    * 3 * sizeof(schar)));
        }
    }

    /*
     * Tell the core image code that this image has changed.
     */

    Tk_ImageChanged(masterPtr->tkMaster, 0, 0, masterPtr->width,
            masterPtr->height, masterPtr->width, masterPtr->height);
}

/*
 *----------------------------------------------------------------------
 *
 * Tk_PhotoExpand --
 *
 *      This procedure is called to request that a photo image be
 *      expanded if necessary to be at least `width' pixels wide and
 *      `height' pixels high.  If the user has declared a definite
 *      image size (using the -width and -height configuration
 *      options) then this call has no effect.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      The size of the photo image may change; if so the generic
 *      image code is informed.
 *
 *----------------------------------------------------------------------
 */

void
Tk_PhotoExpand(handle, width, height)
    Tk_PhotoHandle handle;      /* Handle for the image to be expanded. */
    int width, height;          /* Desired minimum dimensions of the image. */
{
    PhotoMaster *masterPtr;

    masterPtr = (PhotoMaster *) handle;

    if (width <= masterPtr->width) {
        width = masterPtr->width;
    }
    if (height <= masterPtr->height) {
        height = masterPtr->height;
    }
    if ((width != masterPtr->width) || (height != masterPtr->height)) {
        ImgPhotoSetSize(masterPtr, MAX(width, masterPtr->width),
                MAX(height, masterPtr->height));
        Tk_ImageChanged(masterPtr->tkMaster, 0, 0, 0, 0, masterPtr->width,
                masterPtr->height);
    }
}

/*
 *----------------------------------------------------------------------
 *
 * Tk_PhotoGetSize --
 *
 *      This procedure is called to obtain the current size of a photo
 *      image.
 *
 * Results:
 *      The image's width and height are returned in *widthp
 *      and *heightp.
 *
 * Side effects:
 *      None.
 *
 *----------------------------------------------------------------------
 */

void
Tk_PhotoGetSize(handle, widthPtr, heightPtr)
    Tk_PhotoHandle handle;      /* Handle for the image whose dimensions
                                 * are requested. */
    int *widthPtr, *heightPtr;  /* The dimensions of the image are returned
                                 * here. */
{
    PhotoMaster *masterPtr;

    masterPtr = (PhotoMaster *) handle;
    *widthPtr = masterPtr->width;
    *heightPtr = masterPtr->height;
}

/*
 *----------------------------------------------------------------------
 *
 * Tk_PhotoSetSize --
 *
 *      This procedure is called to set size of a photo image.
 *      This call is equivalent to using the -width and -height
 *      configuration options.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      The size of the image may change; if so the generic
 *      image code is informed.
 *
 *----------------------------------------------------------------------
 */

void
Tk_PhotoSetSize(handle, width, height)
    Tk_PhotoHandle handle;      /* Handle for the image whose size is to
                                 * be set. */
    int width, height;          /* New dimensions for the image. */
{
    PhotoMaster *masterPtr;

    masterPtr = (PhotoMaster *) handle;

    masterPtr->userWidth = width;
    masterPtr->userHeight = height;
    ImgPhotoSetSize(masterPtr, ((width > 0) ? width: masterPtr->width),
            ((height > 0) ? height: masterPtr->height));
    Tk_ImageChanged(masterPtr->tkMaster, 0, 0, 0, 0,
            masterPtr->width, masterPtr->height);
}

/*
 *----------------------------------------------------------------------
 *
 * ImgGetPhoto --
 *
 *      This procedure is called to obtain image data from a photo
 *      image.  This procedure fills in the Tk_PhotoImageBlock structure
 *      pointed to by `blockPtr' with details of the address and
 *      layout of the image data in memory.
 *
 * Results:
 *      A pointer to the allocated data which should be freed later.
 *      NULL if there is no need to free data because
 *      blockPtr->pixelPtr points directly to the image data.
 *
 * Side effects:
 *      None.
 *
 *----------------------------------------------------------------------
 */

static char *
ImgGetPhoto(masterPtr, blockPtr, optPtr)
    PhotoMaster *masterPtr;     /* Handle for the photo image from which
                                 * image data is desired. */
    Tk_PhotoImageBlock *blockPtr;
                                /* Information about the address and layout
                                 * of the image data is returned here. */
    struct SubcommandOptions *optPtr;
{
    unsigned char *pixelPtr;
    int x, y, greenOffset, blueOffset, alphaOffset;

    Tk_PhotoGetImage((Tk_PhotoHandle) masterPtr, blockPtr);
    blockPtr->pixelPtr += optPtr->fromY * blockPtr->pitch
            + optPtr->fromX * blockPtr->pixelSize;
    blockPtr->width = optPtr->fromX2 - optPtr->fromX;
    blockPtr->height = optPtr->fromY2 - optPtr->fromY;

    if (!(masterPtr->flags & COLOR_IMAGE) &&
            (!(optPtr->options & OPT_BACKGROUND)
            || ((optPtr->background->red == optPtr->background->green)
            && (optPtr->background->red == optPtr->background->blue)))) {
        blockPtr->offset[0] = blockPtr->offset[1] =
                blockPtr->offset[2];
    }
    alphaOffset = 0;
    for (y = 0; y < blockPtr->height; y++) {
        pixelPtr = blockPtr->pixelPtr + (y * blockPtr->pitch)
                + blockPtr->pixelSize - 1;
        for (x = 0; x < blockPtr->width; x++) {
            if (*pixelPtr != 255) {
                alphaOffset = 3; break;
            }
            pixelPtr += blockPtr->pixelSize;
        }
        if (alphaOffset) break;
    }
    if (!alphaOffset) {
        blockPtr->pixelPtr--;
        blockPtr->offset[0]++;
        blockPtr->offset[1]++;
        blockPtr->offset[2]++;
    }
    greenOffset = blockPtr->offset[1] - blockPtr->offset[0];
    blueOffset = blockPtr->offset[2] - blockPtr->offset[0];
    if (((optPtr->options & OPT_BACKGROUND) && alphaOffset) ||
            ((optPtr->options & OPT_GRAYSCALE) && (greenOffset || blueOffset))) {
        int newPixelSize,x,y;
        unsigned char *srcPtr, *destPtr;
        char *data;

        newPixelSize =  (!(optPtr->options & OPT_BACKGROUND) && alphaOffset) ? 2 : 1;
        if ((greenOffset || blueOffset) && !(optPtr->options & OPT_GRAYSCALE)) {
            newPixelSize += 2;
        }
        data = ckalloc((unsigned int) (newPixelSize *
                blockPtr->width * blockPtr->height));
        srcPtr = blockPtr->pixelPtr + blockPtr->offset[0];
        destPtr = (unsigned char *) data;
        if (!greenOffset && !blueOffset) {
            for (y = blockPtr->height; y > 0; y--) {
                for (x = blockPtr->width; x > 0; x--) {
                    *destPtr = *srcPtr;
                    srcPtr += blockPtr->pixelSize;
                    destPtr += newPixelSize;
                }
                srcPtr += blockPtr->pitch - (blockPtr->width * blockPtr->pixelSize);
            }
        } else if (optPtr->options & OPT_GRAYSCALE) {
            for (y = blockPtr->height; y > 0; y--) {
                for (x = blockPtr->width; x > 0; x--) {
                    *destPtr = (unsigned char) ((srcPtr[0] * 11 + srcPtr[1] * 16
                            + srcPtr[2] * 5 + 16) >> 5);
                    srcPtr += blockPtr->pixelSize;
                    destPtr += newPixelSize;
                }
                srcPtr += blockPtr->pitch - (blockPtr->width * blockPtr->pixelSize);
            }
        } else {
            for (y = blockPtr->height; y > 0; y--) {
                for (x = blockPtr->width; x > 0; x--) {
                    destPtr[0] = srcPtr[0];
                    destPtr[1] = srcPtr[1];
                    destPtr[2] = srcPtr[2];
                    srcPtr += blockPtr->pixelSize;
                    destPtr += newPixelSize;
                }
                srcPtr += blockPtr->pitch - (blockPtr->width * blockPtr->pixelSize);
            }
        }
        srcPtr = blockPtr->pixelPtr + alphaOffset;
        destPtr = (unsigned char *) data;
        if (!alphaOffset) {
            /* nothing to be done */
        } else if (optPtr->options & OPT_BACKGROUND) {
            if (newPixelSize > 2) {
                int red = optPtr->background->red>>8;
                int green = optPtr->background->green>>8;
                int blue = optPtr->background->blue>>8;
                for (y = blockPtr->height; y > 0; y--) {
                    for (x = blockPtr->width; x > 0; x--) {
                        destPtr[0] += (unsigned char) (((255 - *srcPtr) *
                                (red-destPtr[0])) / 255);
                        destPtr[1] += (unsigned char) (((255 - *srcPtr) *
                                (green-destPtr[1])) / 255);
                        destPtr[2] += (unsigned char) (((255 - *srcPtr) *
                                (blue-destPtr[2])) / 255);
                        srcPtr += blockPtr->pixelSize;
                        destPtr += newPixelSize;
                    }
                    srcPtr += blockPtr->pitch - (blockPtr->width * blockPtr->pixelSize);
                }
            } else {
                int gray = (unsigned char) (((optPtr->background->red>>8) * 11
                            + (optPtr->background->green>>8) * 16
                            + (optPtr->background->blue>>8) * 5 + 16) >> 5);
                for (y = blockPtr->height; y > 0; y--) {
                    for (x = blockPtr->width; x > 0; x--) {
                        destPtr[0] += ((255 - *srcPtr) *
                                (gray-destPtr[0])) / 255;
                        srcPtr += blockPtr->pixelSize;
                        destPtr += newPixelSize;
                    }
                    srcPtr += blockPtr->pitch - (blockPtr->width * blockPtr->pixelSize);
                }
            }
        } else {
            destPtr += newPixelSize-1;
            for (y = blockPtr->height; y > 0; y--) {
                for (x = blockPtr->width; x > 0; x--) {
                    *destPtr = *srcPtr;
                    srcPtr += blockPtr->pixelSize;
                    destPtr += newPixelSize;
                }
                srcPtr += blockPtr->pitch - (blockPtr->width * blockPtr->pixelSize);
            }
        }
        blockPtr->pixelPtr = (unsigned char *) data;
        blockPtr->pixelSize = newPixelSize;
        blockPtr->pitch = newPixelSize * blockPtr->width;
        blockPtr->offset[0] = 0;
        if (newPixelSize>2) {
            blockPtr->offset[1]= 1;
            blockPtr->offset[2]= 2;
        } else {
            blockPtr->offset[1]= 0;
            blockPtr->offset[2]= 0;
        }
        return data;
    }
    return NULL;
}

/*
 *----------------------------------------------------------------------
 *
 * ImgStringWrite --
 *
 *      Default string write function. The data is formatted in
 *      the default format as accepted by the "<img> put" command.
 *
 * Results:
 *      A standard Tcl result.
 *
 * Side effects:
 *      See the user documentation.
 *
 *----------------------------------------------------------------------
 */

static int
ImgStringWrite(interp, formatString, blockPtr)
    Tcl_Interp *interp;
    Tcl_Obj *formatString;
    Tk_PhotoImageBlock *blockPtr;
{
    int row,col;
    char *line, *linePtr;
    unsigned char *pixelPtr;
    int greenOffset, blueOffset;
    Tcl_DString data;

    greenOffset = blockPtr->offset[1] - blockPtr->offset[0];
    blueOffset = blockPtr->offset[2] - blockPtr->offset[0];

    Tcl_DStringInit(&data);
    if ((blockPtr->width > 0) && (blockPtr->height > 0)) {
        line = (char *) ckalloc((unsigned int) ((8 * blockPtr->width) + 2));
        for (row=0; row<blockPtr->height; row++) {
            pixelPtr = blockPtr->pixelPtr + blockPtr->offset[0] +
                    row * blockPtr->pitch;
            linePtr = line;
            for (col=0; col<blockPtr->width; col++) {
                sprintf(linePtr, " #%02x%02x%02x", *pixelPtr,
                        pixelPtr[greenOffset], pixelPtr[blueOffset]);
                pixelPtr += blockPtr->pixelSize;
                linePtr += 8;
            }
            Tcl_DStringAppendElement(&data, line+1);
        }
        ckfree (line);
    }
    Tcl_DStringResult(interp, &data);
    return TCL_OK;
}

/*
 *----------------------------------------------------------------------
 *
 * Tk_PhotoGetImage --
 *
 *      This procedure is called to obtain image data from a photo
 *      image.  This procedure fills in the Tk_PhotoImageBlock structure
 *      pointed to by `blockPtr' with details of the address and
 *      layout of the image data in memory.
 *
 * Results:
 *      TRUE (1) indicating that image data is available,
 *      for backwards compatibility with the old photo widget.
 *
 * Side effects:
 *      None.
 *
 *----------------------------------------------------------------------
 */

int
Tk_PhotoGetImage(handle, blockPtr)
    Tk_PhotoHandle handle;      /* Handle for the photo image from which
                                 * image data is desired. */
    Tk_PhotoImageBlock *blockPtr;
                                /* Information about the address and layout
                                 * of the image data is returned here. */
{
    PhotoMaster *masterPtr;

    masterPtr = (PhotoMaster *) handle;
    blockPtr->pixelPtr = masterPtr->pix24;
    blockPtr->width = masterPtr->width;
    blockPtr->height = masterPtr->height;
    blockPtr->pitch = masterPtr->width * 4;
    blockPtr->pixelSize = 4;
    blockPtr->offset[0] = 0;
    blockPtr->offset[1] = 1;
    blockPtr->offset[2] = 2;
    blockPtr->offset[3] = 3;
    return 1;
}

/*
 *----------------------------------------------------------------------
 *
 * PhotoOptionFind --
 *
 *      Finds a specific Photo option.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      After commands are removed.
 *
 *----------------------------------------------------------------------
 */

typedef struct OptionAssocData {
    struct OptionAssocData *nextPtr;    /* pointer to next OptionAssocData */
    Tcl_ObjCmdProc *command;            /* command associated with this
                                         * option */
    char name[1];                       /* name of option (remaining chars) */
} OptionAssocData;

static Tcl_ObjCmdProc *
PhotoOptionFind(interp, obj)
    Tcl_Interp *interp;         /* Interpreter that is being deleted. */
    Tcl_Obj *obj;                       /* Name of option to be found. */
{
    size_t length;
    char *name = Tcl_GetStringFromObj(obj, (int *) &length);
    OptionAssocData *list;
    char *prevname = NULL;
    Tcl_ObjCmdProc *proc = (Tcl_ObjCmdProc *) NULL;
    list = (OptionAssocData *) Tcl_GetAssocData(interp, "photoOption",
            (Tcl_InterpDeleteProc **) NULL);
    while (list != (OptionAssocData *) NULL) {
        if (strncmp(name, list->name, length) == 0) {
            if (proc != (Tcl_ObjCmdProc *) NULL) {
                Tcl_ResetResult(interp);
                Tcl_AppendResult(interp, "ambiguous option \"", name,
                        "\": must be ", prevname, (char *) NULL);
                while (list->nextPtr != (OptionAssocData *) NULL) {
                    Tcl_AppendResult(interp, prevname, ", ",(char *) NULL);
                    list = list->nextPtr;
                    prevname = list->name;
                }
                Tcl_AppendResult(interp, ", or", prevname, (char *) NULL);
                return (Tcl_ObjCmdProc *) NULL;
            }
            proc = list->command;
            prevname = list->name;
        }
        list = list->nextPtr;
    }
    if (proc != (Tcl_ObjCmdProc *) NULL) {
        Tcl_ResetResult(interp);
    }
    return proc;
}

/*
 *----------------------------------------------------------------------
 *
 * PhotoOptionCleanupProc --
 *
 *      This procedure is invoked whenever an interpreter is deleted
 *      to cleanup the AssocData for "photoVisitor".
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      Photo Visitor options are removed.
 *
 *----------------------------------------------------------------------
 */

static void
PhotoOptionCleanupProc(clientData, interp)
    ClientData clientData;      /* Points to "photoVisitor" AssocData
                                 * for the interpreter. */
    Tcl_Interp *interp;         /* Interpreter that is being deleted. */
{
    OptionAssocData *list = (OptionAssocData *) clientData;
    OptionAssocData *ptr;

    while (list != NULL) {
        list = (ptr = list)->nextPtr;
        ckfree((char *) ptr);
    }
}

/*
 *--------------------------------------------------------------
 *
 * Tk_CreatePhotoOption --
 *
 *      This procedure may be invoked to add a new kind of photo
 *      option to the core photo command supported by Tk.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      From now on, the new option will be useable by the
 *      photo command.
 *
 *--------------------------------------------------------------
 */

void
Tk_CreatePhotoOption(interp, name, proc)
    Tcl_Interp *interp;                 /* interpreter */
    CONST char *name;                   /* option name */
    Tcl_ObjCmdProc *proc;               /* proc to execute command */
{
    OptionAssocData *typePtr2, *prevPtr, *ptr;
    OptionAssocData *list;

    list = (OptionAssocData *) Tcl_GetAssocData(interp, "photoOption",
            (Tcl_InterpDeleteProc **) NULL);

    /*
     * If there's already a photo option with the given name, remove it.
     */

    for (typePtr2 = list, prevPtr = NULL; typePtr2 != NULL;
            prevPtr = typePtr2, typePtr2 = typePtr2->nextPtr) {
        if (strcmp(typePtr2->name, name) == 0) {
            if (prevPtr == NULL) {
                list = typePtr2->nextPtr;
            } else {
                prevPtr->nextPtr = typePtr2->nextPtr;
            }
            ckfree((char *) typePtr2);
            break;
        }
    }
    ptr = (OptionAssocData *) ckalloc(sizeof(OptionAssocData) + strlen(name));
    strcpy(&(ptr->name[0]), name);
    ptr->command = proc;
    ptr->nextPtr = list;
    Tcl_SetAssocData(interp, "photoOption", PhotoOptionCleanupProc,
                (ClientData) ptr);
}

/*
 *--------------------------------------------------------------
 *
 * TkPostscriptPhoto --
 *
 *      This procedure is called to output the contents of a
 *      photo image in Postscript by calling the Tk_PostscriptPhoto
 *      function.
 *
 * Results:
 *      Returns a standard Tcl return value.
 *
 * Side effects:
 *      None.
 *
 *--------------------------------------------------------------
 */
static int
ImgPhotoPostscript(clientData, interp, tkwin, psInfo,
        x, y, width, height, prepass)
    ClientData clientData;
    Tcl_Interp *interp;
    Tk_Window tkwin;
    Tk_PostscriptInfo psInfo; /* postscript info */
    int x, y;   /* First pixel to output */
    int width, height;  /* Width and height of area */
    int prepass;
{
    Tk_PhotoImageBlock block;

    Tk_PhotoGetImage((Tk_PhotoHandle) clientData, &block);
    block.pixelPtr += y * block.pitch + x * block.pixelSize;

    return Tk_PostscriptPhoto(interp, &block, psInfo, width, height);
}

/* End of tkimgphoto.c */