png2eps.c

   1 /*
   2  * png2eps.c
   3  * Copyright (C) 2000-2002 A.J. van Os; Released under GPL
   4  *
   5  * Description:
   6  * Functions to translate png images into eps
   7  *
   8  */
   9
  10 #include <stdio.h>
  11 #include <ctype.h>
  12 #include "antiword.h"
  13
  14 #if defined(DEBUG)
  15 static int      iPicCounter = 0;
  16 #endif /* DEBUG */
  17
  18
  19 /*
  20  * tSkipToData - skip until a IDAT chunk is found
  21  *
  22  * returns the length of the pixeldata or -1 in case of error
  23  */
  24 static size_t
  25 tSkipToData(FILE *pFile, size_t tMaxBytes, size_t *ptSkipped)
  26 {
  27         ULONG   ulName, ulTmp;
  28         size_t  tDataLength, tToSkip;
  29         int     iCounter;
  30
  31         fail(pFile == NULL);
  32         fail(ptSkipped == NULL);
  33
  34         /* Examine chunks */
  35         while (*ptSkipped + 8 < tMaxBytes) {
  36                 tDataLength = (size_t)ulNextLongBE(pFile);
  37                 DBG_DEC(tDataLength);
  38                 *ptSkipped += 4;
  39
  40                 ulName = 0x00;
  41                 for (iCounter = 0; iCounter < 4; iCounter++) {
  42                         ulTmp = (ULONG)iNextByte(pFile);
  43                         if (!isalpha((int)ulTmp)) {
  44                                 DBG_HEX(ulTmp);
  45                                 return (size_t)-1;
  46                         }
  47                         ulName <<= 8;
  48                         ulName |= ulTmp;
  49                 }
  50                 DBG_HEX(ulName);
  51                 *ptSkipped += 4;
  52
  53                 if (ulName == PNG_CN_IEND) {
  54                         break;
  55                 }
  56                 if (ulName == PNG_CN_IDAT) {
  57                         return tDataLength;
  58                 }
  59
  60                 tToSkip = tDataLength + 4;
  61                 if (tToSkip >= tMaxBytes - *ptSkipped) {
  62                         DBG_DEC(tToSkip);
  63                         DBG_DEC(tMaxBytes - *ptSkipped);
  64                         return (size_t)-1;
  65                 }
  66                 (void)tSkipBytes(pFile, tToSkip);
  67                 *ptSkipped += tToSkip;
  68         }
  69
  70         return (size_t)-1;
  71 } /* end of iSkipToData */
  72
  73 /*
  74  * iFindFirstPixelData - find the first pixeldata if a PNG image
  75  *
  76  * returns the length of the pixeldata or -1 in case of error
  77  */
  78 static size_t
  79 tFindFirstPixelData(FILE *pFile, size_t tMaxBytes, size_t *ptSkipped)
  80 {
  81         fail(pFile == NULL);
  82         fail(tMaxBytes == 0);
  83         fail(ptSkipped == NULL);
  84
  85         if (tMaxBytes < 8) {
  86                 DBG_DEC(tMaxBytes);
  87                 return (size_t)-1;
  88         }
  89
  90         /* Skip over the PNG signature */
  91         (void)tSkipBytes(pFile, 8);
  92         *ptSkipped = 8;
  93
  94         return tSkipToData(pFile, tMaxBytes, ptSkipped);
  95 } /* end of iFindFirstPixelData */
  96
  97 /*
  98  * tFindNextPixelData - find the next pixeldata if a PNG image
  99  *
 100  * returns the length of the pixeldata or -1 in case of error
 101  */
 102 static size_t
 103 tFindNextPixelData(FILE *pFile, size_t tMaxBytes, size_t *ptSkipped)
 104 {
 105         fail(pFile == NULL);
 106         fail(tMaxBytes == 0);
 107         fail(ptSkipped == NULL);
 108
 109         if (tMaxBytes < 4) {
 110                 DBG_DEC(tMaxBytes);
 111                 return (size_t)-1;
 112         }
 113
 114         /* Skip over the crc */
 115         (void)tSkipBytes(pFile, 4);
 116         *ptSkipped = 4;
 117
 118         return tSkipToData(pFile, tMaxBytes, ptSkipped);
 119 } /* end of tFindNextPixelData */
 120
 121 #if defined(DEBUG)
 122 /*
 123  * vCopy2File
 124  */
 125 static void
 126 vCopy2File(FILE *pFile, ULONG ulFileOffset, size_t tPictureLen)
 127 {
 128         FILE    *pOutFile;
 129         size_t  tIndex;
 130         int     iTmp;
 131         char    szFilename[30];
 132
 133         if (!bSetDataOffset(pFile, ulFileOffset)) {
 134                 return;
 135         }
 136
 137         sprintf(szFilename, "/tmp/pic/pic%04d.png", ++iPicCounter);
 138         pOutFile = fopen(szFilename, "wb");
 139         if (pOutFile == NULL) {
 140                 return;
 141         }
 142         for (tIndex = 0; tIndex < tPictureLen; tIndex++) {
 143                 iTmp = iNextByte(pFile);
 144                 if (putc(iTmp, pOutFile) == EOF) {
 145                         break;
 146                 }
 147         }
 148         (void)fclose(pOutFile);
 149 } /* end of vCopy2File */
 150 #endif /* DEBUG */
 151
 152 /*
 153  * bTranslatePNG - translate a PNG image
 154  *
 155  * This function translates an image from png to eps
 156  *
 157  * return TRUE when sucessful, otherwise FALSE
 158  */
 159 BOOL
 160 bTranslatePNG(diagram_type *pDiag, FILE *pFile,
 161         ULONG ulFileOffset, size_t tPictureLen, const imagedata_type *pImg)
 162 {
 163         size_t  tMaxBytes, tDataLength, tSkipped;
 164
 165 #if defined(DEBUG)
 166         vCopy2File(pFile, ulFileOffset, tPictureLen);
 167 #endif /* DEBUG */
 168
 169         /* Seek to start position of PNG data */
 170         if (!bSetDataOffset(pFile, ulFileOffset)) {
 171                 return FALSE;
 172         }
 173
 174         tMaxBytes = tPictureLen;
 175         tDataLength = tFindFirstPixelData(pFile, tMaxBytes, &tSkipped);
 176         if (tDataLength == (size_t)-1) {
 177                 return FALSE;
 178         }
 179
 180         vImagePrologue(pDiag, pImg);
 181         do {
 182                 tMaxBytes -= tSkipped;
 183                 vASCII85EncodeArray(pFile, pDiag->pOutFile, tDataLength);
 184                 tMaxBytes -= tDataLength;
 185                 tDataLength = tFindNextPixelData(pFile, tMaxBytes, &tSkipped);
 186         } while (tDataLength != (size_t)-1);
 187         vASCII85EncodeByte(pDiag->pOutFile, EOF);
 188         vImageEpilogue(pDiag);
 189
 190         return TRUE;
 191 } /* end of bTranslatePNG */