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to_be_filed/sf_code/esrgpcpj/shared/tk_base/tkimgppm.c revision 29 by dashley, Sat Oct 8 07:08:47 2016 UTC projs/trunk/shared_source/c_tk_base_7_5_w_mods/tkimgppm.c revision 71 by dashley, Sat Nov 5 11:07:06 2016 UTC
# Line 1  Line 1 
 /* $Header: /cvsroot/esrg/sfesrg/esrgpcpj/shared/tk_base/tkimgppm.c,v 1.1.1.1 2001/06/13 05:03:30 dtashley Exp $ */  
   
 /*  
  * tkImgPPM.c --  
  *  
  *      A photo image file handler for PPM (Portable PixMap) files.  
  *  
  * 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: tkimgppm.c,v 1.1.1.1 2001/06/13 05:03:30 dtashley Exp $  
  */  
   
 #define USE_OLD_IMAGE  
   
 #include "tkInt.h"  
 #include "tkPort.h"  
   
 /*  
  * The maximum amount of memory to allocate for data read from the  
  * file.  If we need more than this, we do it in pieces.  
  */  
   
 #define MAX_MEMORY      10000           /* don't allocate > 10KB */  
   
 /*  
  * Define PGM and PPM, i.e. gray images and color images.  
  */  
   
 #define PGM 1  
 #define PPM 2  
   
 /*  
  * The format record for the PPM file format:  
  */  
   
 static int              FileMatchPPM _ANSI_ARGS_((Tcl_Channel chan,  
                             char *fileName, char *formatString,  
                             int *widthPtr, int *heightPtr));  
 static int              FileReadPPM  _ANSI_ARGS_((Tcl_Interp *interp,  
                             Tcl_Channel chan, char *fileName,  
                             char *formatString, Tk_PhotoHandle imageHandle,  
                             int destX, int destY, int width, int height,  
                             int srcX, int srcY));  
 static int              FileWritePPM _ANSI_ARGS_((Tcl_Interp *interp,  
                             char *fileName, char *formatString,  
                             Tk_PhotoImageBlock *blockPtr));  
   
 Tk_PhotoImageFormat tkImgFmtPPM = {  
     "PPM",                      /* name */  
     FileMatchPPM,               /* fileMatchProc */  
     NULL,                       /* stringMatchProc */  
     FileReadPPM,                /* fileReadProc */  
     NULL,                       /* stringReadProc */  
     FileWritePPM,               /* fileWriteProc */  
     NULL,                       /* stringWriteProc */  
 };  
   
 /*  
  * Prototypes for local procedures defined in this file:  
  */  
   
 static int              ReadPPMFileHeader _ANSI_ARGS_((Tcl_Channel chan,  
                             int *widthPtr, int *heightPtr,  
                             int *maxIntensityPtr));  
   
 /*  
  *----------------------------------------------------------------------  
  *  
  * FileMatchPPM --  
  *  
  *      This procedure is invoked by the photo image type to see if  
  *      a file contains image data in PPM format.  
  *  
  * Results:  
  *      The return value is >0 if the first characters in file "f" look  
  *      like PPM data, and 0 otherwise.  
  *  
  * Side effects:  
  *      The access position in f may change.  
  *  
  *----------------------------------------------------------------------  
  */  
   
 static int  
 FileMatchPPM(chan, fileName, formatString, widthPtr, heightPtr)  
     Tcl_Channel chan;           /* The image file, open for reading. */  
     char *fileName;             /* The name of the image file. */  
     char *formatString;         /* User-specified format string, or NULL. */  
     int *widthPtr, *heightPtr;  /* The dimensions of the image are  
                                  * returned here if the file is a valid  
                                  * raw PPM file. */  
 {  
     int dummy;  
   
     return ReadPPMFileHeader(chan, widthPtr, heightPtr, &dummy);  
 }  
   
 /*  
  *----------------------------------------------------------------------  
  *  
  * FileReadPPM --  
  *  
  *      This procedure is called by the photo image type to read  
  *      PPM format data from a file and write it into a given  
  *      photo image.  
  *  
  * Results:  
  *      A standard TCL completion code.  If TCL_ERROR is returned  
  *      then an error message is left in the interp's result.  
  *  
  * Side effects:  
  *      The access position in file f is changed, and new data is  
  *      added to the image given by imageHandle.  
  *  
  *----------------------------------------------------------------------  
  */  
   
 static int  
 FileReadPPM(interp, chan, fileName, formatString, imageHandle, destX, destY,  
         width, height, srcX, srcY)  
     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. */  
     char *formatString;         /* User-specified format string, or NULL. */  
     Tk_PhotoHandle imageHandle; /* The photo image to write into. */  
     int destX, destY;           /* Coordinates of top-left pixel in  
                                  * photo image to be written to. */  
     int width, height;          /* Dimensions of block of photo image to  
                                  * be written to. */  
     int srcX, srcY;             /* Coordinates of top-left pixel to be used  
                                  * in image being read. */  
 {  
     int fileWidth, fileHeight, maxIntensity;  
     int nLines, nBytes, h, type, count;  
     unsigned char *pixelPtr;  
     Tk_PhotoImageBlock block;  
   
     type = ReadPPMFileHeader(chan, &fileWidth, &fileHeight, &maxIntensity);  
     if (type == 0) {  
         Tcl_AppendResult(interp, "couldn't read raw PPM header from file \"",  
                 fileName, "\"", NULL);  
         return TCL_ERROR;  
     }  
     if ((fileWidth <= 0) || (fileHeight <= 0)) {  
         Tcl_AppendResult(interp, "PPM image file \"", fileName,  
                 "\" has dimension(s) <= 0", (char *) NULL);  
         return TCL_ERROR;  
     }  
     if ((maxIntensity <= 0) || (maxIntensity >= 256)) {  
         char buffer[TCL_INTEGER_SPACE];  
   
         sprintf(buffer, "%d", maxIntensity);  
         Tcl_AppendResult(interp, "PPM image file \"", fileName,  
                 "\" has bad maximum intensity value ", buffer,  
                 (char *) NULL);  
         return TCL_ERROR;  
     }  
   
     if ((srcX + width) > fileWidth) {  
         width = fileWidth - srcX;  
     }  
     if ((srcY + height) > fileHeight) {  
         height = fileHeight - srcY;  
     }  
     if ((width <= 0) || (height <= 0)  
         || (srcX >= fileWidth) || (srcY >= fileHeight)) {  
         return TCL_OK;  
     }  
   
     if (type == PGM) {  
         block.pixelSize = 1;  
         block.offset[0] = 0;  
         block.offset[1] = 0;  
         block.offset[2] = 0;  
     }  
     else {  
         block.pixelSize = 3;  
         block.offset[0] = 0;  
         block.offset[1] = 1;  
         block.offset[2] = 2;  
     }  
     block.offset[3] = 0;  
     block.width = width;  
     block.pitch = block.pixelSize * fileWidth;  
   
     Tk_PhotoExpand(imageHandle, destX + width, destY + height);  
   
     if (srcY > 0) {  
         Tcl_Seek(chan, (srcY * block.pitch), SEEK_CUR);  
     }  
   
     nLines = (MAX_MEMORY + block.pitch - 1) / block.pitch;  
     if (nLines > height) {  
         nLines = height;  
     }  
     if (nLines <= 0) {  
         nLines = 1;  
     }  
     nBytes = nLines * block.pitch;  
     pixelPtr = (unsigned char *) ckalloc((unsigned) nBytes);  
     block.pixelPtr = pixelPtr + srcX * block.pixelSize;  
   
     for (h = height; h > 0; h -= nLines) {  
         if (nLines > h) {  
             nLines = h;  
             nBytes = nLines * block.pitch;  
         }  
         count = Tcl_Read(chan, (char *) pixelPtr, nBytes);  
         if (count != nBytes) {  
             Tcl_AppendResult(interp, "error reading PPM image file \"",  
                     fileName, "\": ",  
                     Tcl_Eof(chan) ? "not enough data" : Tcl_PosixError(interp),  
                     (char *) NULL);  
             ckfree((char *) pixelPtr);  
             return TCL_ERROR;  
         }  
         if (maxIntensity != 255) {  
             unsigned char *p;  
   
             for (p = pixelPtr; count > 0; count--, p++) {  
                 *p = (((int) *p) * 255)/maxIntensity;  
             }  
         }  
         block.height = nLines;  
         Tk_PhotoPutBlock(imageHandle, &block, destX, destY, width, nLines);  
         destY += nLines;  
     }  
   
     ckfree((char *) pixelPtr);  
     return TCL_OK;  
 }  
   
 /*  
  *----------------------------------------------------------------------  
  *  
  * FileWritePPM --  
  *  
  *      This procedure is invoked to write image data to a file in PPM  
  *      format.  
  *  
  * Results:  
  *      A standard TCL completion code.  If TCL_ERROR is returned  
  *      then an error message is left in the interp's result.  
  *  
  * Side effects:  
  *      Data is written to the file given by "fileName".  
  *  
  *----------------------------------------------------------------------  
  */  
   
 static int  
 FileWritePPM(interp, fileName, formatString, blockPtr)  
     Tcl_Interp *interp;  
     char *fileName;  
     char *formatString;  
     Tk_PhotoImageBlock *blockPtr;  
 {  
     Tcl_Channel chan;  
     int w, h;  
     int greenOffset, blueOffset, nBytes;  
     unsigned char *pixelPtr, *pixLinePtr;  
     char header[16 + TCL_INTEGER_SPACE * 2];  
   
     chan = Tcl_OpenFileChannel(interp, fileName, "w", 0666);  
     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;  
     }  
       
     sprintf(header, "P6\n%d %d\n255\n", blockPtr->width, blockPtr->height);  
     Tcl_Write(chan, header, -1);  
           
     pixLinePtr = blockPtr->pixelPtr + blockPtr->offset[0];  
     greenOffset = blockPtr->offset[1] - blockPtr->offset[0];  
     blueOffset = blockPtr->offset[2] - blockPtr->offset[0];  
   
     if ((greenOffset == 1) && (blueOffset == 2) && (blockPtr->pixelSize == 3)  
             && (blockPtr->pitch == (blockPtr->width * 3))) {  
         nBytes = blockPtr->height * blockPtr->pitch;  
         if (Tcl_Write(chan, (char *) pixLinePtr, nBytes) != nBytes) {  
             goto writeerror;  
         }  
     } else {  
         for (h = blockPtr->height; h > 0; h--) {  
             pixelPtr = pixLinePtr;  
             for (w = blockPtr->width; w > 0; w--) {  
                 if ((Tcl_Write(chan, (char *) &pixelPtr[0], 1) == -1)  
                         || (Tcl_Write(chan, (char *) &pixelPtr[greenOffset], 1) == -1)  
                         || (Tcl_Write(chan, (char *) &pixelPtr[blueOffset], 1) == -1)) {  
                     goto writeerror;  
                 }  
                 pixelPtr += blockPtr->pixelSize;  
             }  
             pixLinePtr += blockPtr->pitch;  
         }  
     }  
   
     if (Tcl_Close(NULL, chan) == 0) {  
         return TCL_OK;  
     }  
     chan = NULL;  
   
  writeerror:  
     Tcl_AppendResult(interp, "error writing \"", fileName, "\": ",  
             Tcl_PosixError(interp), (char *) NULL);  
     if (chan != NULL) {  
         Tcl_Close(NULL, chan);  
     }  
     return TCL_ERROR;  
 }  
   
 /*  
  *----------------------------------------------------------------------  
  *  
  * ReadPPMFileHeader --  
  *  
  *      This procedure reads the PPM header from the beginning of a  
  *      PPM file and returns information from the header.  
  *  
  * Results:  
  *      The return value is PGM if file "f" appears to start with  
  *      a valid PGM header, PPM if "f" appears to start with a valid  
  *      PPM header, and 0 otherwise.  If the header is valid,  
  *      then *widthPtr and *heightPtr are modified to hold the  
  *      dimensions of the image and *maxIntensityPtr is modified to  
  *      hold the value of a "fully on" intensity value.  
  *  
  * Side effects:  
  *      The access position in f advances.  
  *  
  *----------------------------------------------------------------------  
  */  
   
 static int  
 ReadPPMFileHeader(chan, widthPtr, heightPtr, maxIntensityPtr)  
     Tcl_Channel chan;           /* Image file to read the header from */  
     int *widthPtr, *heightPtr;  /* The dimensions of the image are  
                                  * returned here. */  
     int *maxIntensityPtr;       /* The maximum intensity value for  
                                  * the image is stored here. */  
 {  
 #define BUFFER_SIZE 1000  
     char buffer[BUFFER_SIZE];  
     int i, numFields;  
     int type = 0;  
     char c;  
   
     /*  
      * Read 4 space-separated fields from the file, ignoring  
      * comments (any line that starts with "#").  
      */  
   
     if (Tcl_Read(chan, &c, 1) != 1) {  
         return 0;  
     }  
     i = 0;  
     for (numFields = 0; numFields < 4; numFields++) {  
         /*  
          * Skip comments and white space.  
          */  
   
         while (1) {  
             while (isspace(UCHAR(c))) {  
                 if (Tcl_Read(chan, &c, 1) != 1) {  
                     return 0;  
                 }  
             }  
             if (c != '#') {  
                 break;  
             }  
             do {  
                 if (Tcl_Read(chan, &c, 1) != 1) {  
                     return 0;  
                 }  
             } while (c != '\n');  
         }  
   
         /*  
          * Read a field (everything up to the next white space).  
          */  
   
         while (!isspace(UCHAR(c))) {  
             if (i < (BUFFER_SIZE-2)) {  
                 buffer[i] = c;  
                 i++;  
             }  
             if (Tcl_Read(chan, &c, 1) != 1) {  
                 goto done;  
             }  
         }  
         if (i < (BUFFER_SIZE-1)) {  
             buffer[i] = ' ';  
             i++;  
         }  
     }  
     done:  
     buffer[i] = 0;  
   
     /*  
      * Parse the fields, which are: id, width, height, maxIntensity.  
      */  
   
     if (strncmp(buffer, "P6 ", 3) == 0) {  
         type = PPM;  
     } else if (strncmp(buffer, "P5 ", 3) == 0) {  
         type = PGM;  
     } else {  
         return 0;  
     }  
     if (sscanf(buffer+3, "%d %d %d", widthPtr, heightPtr, maxIntensityPtr)  
             != 3) {  
         return 0;  
     }  
     return type;  
 }  
   
   
 /* $History: tkImgPPM.c $  
  *  
  * *****************  Version 1  *****************  
  * User: Dtashley     Date: 1/02/01    Time: 2:53a  
  * Created in $/IjuScripter, IjuConsole/Source/Tk Base  
  * Initial check-in.  
  */  
   
 /* End of TKIMGPPM.C */  
1    /* $Header$ */
2    
3    /*
4     * tkImgPPM.c --
5     *
6     *      A photo image file handler for PPM (Portable PixMap) files.
7     *
8     * Copyright (c) 1994 The Australian National University.
9     * Copyright (c) 1994-1997 Sun Microsystems, Inc.
10     *
11     * See the file "license.terms" for information on usage and redistribution
12     * of this file, and for a DISCLAIMER OF ALL WARRANTIES.
13     *
14     * Author: Paul Mackerras (paulus@cs.anu.edu.au),
15     *         Department of Computer Science,
16     *         Australian National University.
17     *
18     * RCS: @(#) $Id: tkimgppm.c,v 1.1.1.1 2001/06/13 05:03:30 dtashley Exp $
19     */
20    
21    #define USE_OLD_IMAGE
22    
23    #include "tkInt.h"
24    #include "tkPort.h"
25    
26    /*
27     * The maximum amount of memory to allocate for data read from the
28     * file.  If we need more than this, we do it in pieces.
29     */
30    
31    #define MAX_MEMORY      10000           /* don't allocate > 10KB */
32    
33    /*
34     * Define PGM and PPM, i.e. gray images and color images.
35     */
36    
37    #define PGM 1
38    #define PPM 2
39    
40    /*
41     * The format record for the PPM file format:
42     */
43    
44    static int              FileMatchPPM _ANSI_ARGS_((Tcl_Channel chan,
45                                char *fileName, char *formatString,
46                                int *widthPtr, int *heightPtr));
47    static int              FileReadPPM  _ANSI_ARGS_((Tcl_Interp *interp,
48                                Tcl_Channel chan, char *fileName,
49                                char *formatString, Tk_PhotoHandle imageHandle,
50                                int destX, int destY, int width, int height,
51                                int srcX, int srcY));
52    static int              FileWritePPM _ANSI_ARGS_((Tcl_Interp *interp,
53                                char *fileName, char *formatString,
54                                Tk_PhotoImageBlock *blockPtr));
55    
56    Tk_PhotoImageFormat tkImgFmtPPM = {
57        "PPM",                      /* name */
58        FileMatchPPM,               /* fileMatchProc */
59        NULL,                       /* stringMatchProc */
60        FileReadPPM,                /* fileReadProc */
61        NULL,                       /* stringReadProc */
62        FileWritePPM,               /* fileWriteProc */
63        NULL,                       /* stringWriteProc */
64    };
65    
66    /*
67     * Prototypes for local procedures defined in this file:
68     */
69    
70    static int              ReadPPMFileHeader _ANSI_ARGS_((Tcl_Channel chan,
71                                int *widthPtr, int *heightPtr,
72                                int *maxIntensityPtr));
73    
74    /*
75     *----------------------------------------------------------------------
76     *
77     * FileMatchPPM --
78     *
79     *      This procedure is invoked by the photo image type to see if
80     *      a file contains image data in PPM format.
81     *
82     * Results:
83     *      The return value is >0 if the first characters in file "f" look
84     *      like PPM data, and 0 otherwise.
85     *
86     * Side effects:
87     *      The access position in f may change.
88     *
89     *----------------------------------------------------------------------
90     */
91    
92    static int
93    FileMatchPPM(chan, fileName, formatString, widthPtr, heightPtr)
94        Tcl_Channel chan;           /* The image file, open for reading. */
95        char *fileName;             /* The name of the image file. */
96        char *formatString;         /* User-specified format string, or NULL. */
97        int *widthPtr, *heightPtr;  /* The dimensions of the image are
98                                     * returned here if the file is a valid
99                                     * raw PPM file. */
100    {
101        int dummy;
102    
103        return ReadPPMFileHeader(chan, widthPtr, heightPtr, &dummy);
104    }
105    
106    /*
107     *----------------------------------------------------------------------
108     *
109     * FileReadPPM --
110     *
111     *      This procedure is called by the photo image type to read
112     *      PPM format data from a file and write it into a given
113     *      photo image.
114     *
115     * Results:
116     *      A standard TCL completion code.  If TCL_ERROR is returned
117     *      then an error message is left in the interp's result.
118     *
119     * Side effects:
120     *      The access position in file f is changed, and new data is
121     *      added to the image given by imageHandle.
122     *
123     *----------------------------------------------------------------------
124     */
125    
126    static int
127    FileReadPPM(interp, chan, fileName, formatString, imageHandle, destX, destY,
128            width, height, srcX, srcY)
129        Tcl_Interp *interp;         /* Interpreter to use for reporting errors. */
130        Tcl_Channel chan;           /* The image file, open for reading. */
131        char *fileName;             /* The name of the image file. */
132        char *formatString;         /* User-specified format string, or NULL. */
133        Tk_PhotoHandle imageHandle; /* The photo image to write into. */
134        int destX, destY;           /* Coordinates of top-left pixel in
135                                     * photo image to be written to. */
136        int width, height;          /* Dimensions of block of photo image to
137                                     * be written to. */
138        int srcX, srcY;             /* Coordinates of top-left pixel to be used
139                                     * in image being read. */
140    {
141        int fileWidth, fileHeight, maxIntensity;
142        int nLines, nBytes, h, type, count;
143        unsigned char *pixelPtr;
144        Tk_PhotoImageBlock block;
145    
146        type = ReadPPMFileHeader(chan, &fileWidth, &fileHeight, &maxIntensity);
147        if (type == 0) {
148            Tcl_AppendResult(interp, "couldn't read raw PPM header from file \"",
149                    fileName, "\"", NULL);
150            return TCL_ERROR;
151        }
152        if ((fileWidth <= 0) || (fileHeight <= 0)) {
153            Tcl_AppendResult(interp, "PPM image file \"", fileName,
154                    "\" has dimension(s) <= 0", (char *) NULL);
155            return TCL_ERROR;
156        }
157        if ((maxIntensity <= 0) || (maxIntensity >= 256)) {
158            char buffer[TCL_INTEGER_SPACE];
159    
160            sprintf(buffer, "%d", maxIntensity);
161            Tcl_AppendResult(interp, "PPM image file \"", fileName,
162                    "\" has bad maximum intensity value ", buffer,
163                    (char *) NULL);
164            return TCL_ERROR;
165        }
166    
167        if ((srcX + width) > fileWidth) {
168            width = fileWidth - srcX;
169        }
170        if ((srcY + height) > fileHeight) {
171            height = fileHeight - srcY;
172        }
173        if ((width <= 0) || (height <= 0)
174            || (srcX >= fileWidth) || (srcY >= fileHeight)) {
175            return TCL_OK;
176        }
177    
178        if (type == PGM) {
179            block.pixelSize = 1;
180            block.offset[0] = 0;
181            block.offset[1] = 0;
182            block.offset[2] = 0;
183        }
184        else {
185            block.pixelSize = 3;
186            block.offset[0] = 0;
187            block.offset[1] = 1;
188            block.offset[2] = 2;
189        }
190        block.offset[3] = 0;
191        block.width = width;
192        block.pitch = block.pixelSize * fileWidth;
193    
194        Tk_PhotoExpand(imageHandle, destX + width, destY + height);
195    
196        if (srcY > 0) {
197            Tcl_Seek(chan, (srcY * block.pitch), SEEK_CUR);
198        }
199    
200        nLines = (MAX_MEMORY + block.pitch - 1) / block.pitch;
201        if (nLines > height) {
202            nLines = height;
203        }
204        if (nLines <= 0) {
205            nLines = 1;
206        }
207        nBytes = nLines * block.pitch;
208        pixelPtr = (unsigned char *) ckalloc((unsigned) nBytes);
209        block.pixelPtr = pixelPtr + srcX * block.pixelSize;
210    
211        for (h = height; h > 0; h -= nLines) {
212            if (nLines > h) {
213                nLines = h;
214                nBytes = nLines * block.pitch;
215            }
216            count = Tcl_Read(chan, (char *) pixelPtr, nBytes);
217            if (count != nBytes) {
218                Tcl_AppendResult(interp, "error reading PPM image file \"",
219                        fileName, "\": ",
220                        Tcl_Eof(chan) ? "not enough data" : Tcl_PosixError(interp),
221                        (char *) NULL);
222                ckfree((char *) pixelPtr);
223                return TCL_ERROR;
224            }
225            if (maxIntensity != 255) {
226                unsigned char *p;
227    
228                for (p = pixelPtr; count > 0; count--, p++) {
229                    *p = (((int) *p) * 255)/maxIntensity;
230                }
231            }
232            block.height = nLines;
233            Tk_PhotoPutBlock(imageHandle, &block, destX, destY, width, nLines);
234            destY += nLines;
235        }
236    
237        ckfree((char *) pixelPtr);
238        return TCL_OK;
239    }
240    
241    /*
242     *----------------------------------------------------------------------
243     *
244     * FileWritePPM --
245     *
246     *      This procedure is invoked to write image data to a file in PPM
247     *      format.
248     *
249     * Results:
250     *      A standard TCL completion code.  If TCL_ERROR is returned
251     *      then an error message is left in the interp's result.
252     *
253     * Side effects:
254     *      Data is written to the file given by "fileName".
255     *
256     *----------------------------------------------------------------------
257     */
258    
259    static int
260    FileWritePPM(interp, fileName, formatString, blockPtr)
261        Tcl_Interp *interp;
262        char *fileName;
263        char *formatString;
264        Tk_PhotoImageBlock *blockPtr;
265    {
266        Tcl_Channel chan;
267        int w, h;
268        int greenOffset, blueOffset, nBytes;
269        unsigned char *pixelPtr, *pixLinePtr;
270        char header[16 + TCL_INTEGER_SPACE * 2];
271    
272        chan = Tcl_OpenFileChannel(interp, fileName, "w", 0666);
273        if (chan == NULL) {
274            return TCL_ERROR;
275        }
276    
277        if (Tcl_SetChannelOption(interp, chan, "-translation", "binary")
278                != TCL_OK) {
279            return TCL_ERROR;
280        }
281        if (Tcl_SetChannelOption(interp, chan, "-encoding", "binary")
282                != TCL_OK) {
283            return TCL_ERROR;
284        }
285        
286        sprintf(header, "P6\n%d %d\n255\n", blockPtr->width, blockPtr->height);
287        Tcl_Write(chan, header, -1);
288            
289        pixLinePtr = blockPtr->pixelPtr + blockPtr->offset[0];
290        greenOffset = blockPtr->offset[1] - blockPtr->offset[0];
291        blueOffset = blockPtr->offset[2] - blockPtr->offset[0];
292    
293        if ((greenOffset == 1) && (blueOffset == 2) && (blockPtr->pixelSize == 3)
294                && (blockPtr->pitch == (blockPtr->width * 3))) {
295            nBytes = blockPtr->height * blockPtr->pitch;
296            if (Tcl_Write(chan, (char *) pixLinePtr, nBytes) != nBytes) {
297                goto writeerror;
298            }
299        } else {
300            for (h = blockPtr->height; h > 0; h--) {
301                pixelPtr = pixLinePtr;
302                for (w = blockPtr->width; w > 0; w--) {
303                    if ((Tcl_Write(chan, (char *) &pixelPtr[0], 1) == -1)
304                            || (Tcl_Write(chan, (char *) &pixelPtr[greenOffset], 1) == -1)
305                            || (Tcl_Write(chan, (char *) &pixelPtr[blueOffset], 1) == -1)) {
306                        goto writeerror;
307                    }
308                    pixelPtr += blockPtr->pixelSize;
309                }
310                pixLinePtr += blockPtr->pitch;
311            }
312        }
313    
314        if (Tcl_Close(NULL, chan) == 0) {
315            return TCL_OK;
316        }
317        chan = NULL;
318    
319     writeerror:
320        Tcl_AppendResult(interp, "error writing \"", fileName, "\": ",
321                Tcl_PosixError(interp), (char *) NULL);
322        if (chan != NULL) {
323            Tcl_Close(NULL, chan);
324        }
325        return TCL_ERROR;
326    }
327    
328    /*
329     *----------------------------------------------------------------------
330     *
331     * ReadPPMFileHeader --
332     *
333     *      This procedure reads the PPM header from the beginning of a
334     *      PPM file and returns information from the header.
335     *
336     * Results:
337     *      The return value is PGM if file "f" appears to start with
338     *      a valid PGM header, PPM if "f" appears to start with a valid
339     *      PPM header, and 0 otherwise.  If the header is valid,
340     *      then *widthPtr and *heightPtr are modified to hold the
341     *      dimensions of the image and *maxIntensityPtr is modified to
342     *      hold the value of a "fully on" intensity value.
343     *
344     * Side effects:
345     *      The access position in f advances.
346     *
347     *----------------------------------------------------------------------
348     */
349    
350    static int
351    ReadPPMFileHeader(chan, widthPtr, heightPtr, maxIntensityPtr)
352        Tcl_Channel chan;           /* Image file to read the header from */
353        int *widthPtr, *heightPtr;  /* The dimensions of the image are
354                                     * returned here. */
355        int *maxIntensityPtr;       /* The maximum intensity value for
356                                     * the image is stored here. */
357    {
358    #define BUFFER_SIZE 1000
359        char buffer[BUFFER_SIZE];
360        int i, numFields;
361        int type = 0;
362        char c;
363    
364        /*
365         * Read 4 space-separated fields from the file, ignoring
366         * comments (any line that starts with "#").
367         */
368    
369        if (Tcl_Read(chan, &c, 1) != 1) {
370            return 0;
371        }
372        i = 0;
373        for (numFields = 0; numFields < 4; numFields++) {
374            /*
375             * Skip comments and white space.
376             */
377    
378            while (1) {
379                while (isspace(UCHAR(c))) {
380                    if (Tcl_Read(chan, &c, 1) != 1) {
381                        return 0;
382                    }
383                }
384                if (c != '#') {
385                    break;
386                }
387                do {
388                    if (Tcl_Read(chan, &c, 1) != 1) {
389                        return 0;
390                    }
391                } while (c != '\n');
392            }
393    
394            /*
395             * Read a field (everything up to the next white space).
396             */
397    
398            while (!isspace(UCHAR(c))) {
399                if (i < (BUFFER_SIZE-2)) {
400                    buffer[i] = c;
401                    i++;
402                }
403                if (Tcl_Read(chan, &c, 1) != 1) {
404                    goto done;
405                }
406            }
407            if (i < (BUFFER_SIZE-1)) {
408                buffer[i] = ' ';
409                i++;
410            }
411        }
412        done:
413        buffer[i] = 0;
414    
415        /*
416         * Parse the fields, which are: id, width, height, maxIntensity.
417         */
418    
419        if (strncmp(buffer, "P6 ", 3) == 0) {
420            type = PPM;
421        } else if (strncmp(buffer, "P5 ", 3) == 0) {
422            type = PGM;
423        } else {
424            return 0;
425        }
426        if (sscanf(buffer+3, "%d %d %d", widthPtr, heightPtr, maxIntensityPtr)
427                != 3) {
428            return 0;
429        }
430        return type;
431    }
432    
433    /* End of tkimgppm.c */
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