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Fix remaining PNG predictors.

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This commit is contained in:
Michael R Sweet 2021-06-01 19:29:48 -04:00
parent d30579f905
commit 3c034eb919
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GPG Key ID: 999559A027815955
1 changed files with 14 additions and 13 deletions
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27
pdfio-stream.c
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@ -216,6 +216,7 @@ _pdfioStreamCreate(
if (predictor >= 10)
st->pbsize ++; // Add PNG predictor byte
fprintf(stderr, "colors=%d, bpc=%d, pbpixel=%u\n", colors, bpc, (unsigned)st->pbpixel);
if ((st->prbuffer = calloc(1, st->pbsize - 1)) == NULL || (st->psbuffer = calloc(1, st->pbsize)) == NULL)
{
_pdfioFileError(st->pdf, "Unable to allocate %lu bytes for Predictor buffers.", (unsigned long)st->pbsize);
@ -644,11 +645,11 @@ pdfioStreamWrite(
// Size of pixel in bytes
pbline = st->pbsize - 1,
// Bytes per line
remaining, // Remaining bytes on this line
firstcol = pbline - pbpixel;
// First column bytes remaining
const unsigned char *bufptr = (const unsigned char *)buffer;
remaining; // Remaining bytes on this line
const unsigned char *bufptr = (const unsigned char *)buffer,
// Pointer into buffer
*bufsecond = buffer + pbpixel;
// Pointer to second pixel in buffer
unsigned char *sptr, // Pointer into sbuffer
*pptr; // Previous raw buffer
@ -704,7 +705,7 @@ pdfioStreamWrite(
// Encode the difference from the previous column
for (remaining = pbline; remaining > 0; remaining --, bufptr ++, sptr ++)
{
if (remaining < firstcol)
if (bufptr >= bufsecond)
*sptr = *bufptr - bufptr[-pbpixel];
else
*sptr = *bufptr;
@ -723,7 +724,7 @@ pdfioStreamWrite(
// Encode the difference with the average of the previous column and line
for (remaining = pbline; remaining > 0; remaining --, bufptr ++, sptr ++, pptr ++)
{
if (remaining < firstcol)
if (bufptr >= bufsecond)
*sptr = *bufptr - (bufptr[-pbpixel] + *pptr) / 2;
else
*sptr = *bufptr - *pptr / 2;
@ -735,7 +736,7 @@ pdfioStreamWrite(
// Encode the difference with a linear transform function
for (remaining = pbline; remaining > 0; remaining --, bufptr ++, sptr ++, pptr ++)
{
if (remaining < firstcol)
if (bufptr >= bufsecond)
*sptr = *bufptr - stream_paeth(bufptr[-pbpixel], *pptr, pptr[-pbpixel]);
else
*sptr = *bufptr - stream_paeth(0, *pptr, 0);
@ -844,12 +845,12 @@ stream_read(pdfio_stream_t *st, // I - Stream
// PNG predictor
size_t pbpixel = st->pbpixel,
// Size of pixel in bytes
remaining = st->pbsize - 1,
remaining = st->pbsize - 1;
// Remaining bytes
firstcol = remaining - pbpixel;
// First column bytes remaining
unsigned char *bufptr = (unsigned char *)buffer,
// Pointer into buffer
*bufsecond = (unsigned char *)buffer + pbpixel,
// Pointer to second pixel in buffer
*sptr = st->psbuffer + 1,
// Current (raw) line
*pptr = st->prbuffer;
@ -906,7 +907,7 @@ stream_read(pdfio_stream_t *st, // I - Stream
memcpy(buffer, sptr, remaining);
break;
case 1 : // Sub
for (; remaining > firstcol; remaining --, sptr ++)
for (; bufptr < bufsecond; remaining --, sptr ++)
*bufptr++ = *sptr;
for (; remaining > 0; remaining --, sptr ++, bufptr ++)
*bufptr = *sptr + bufptr[-pbpixel];
@ -916,13 +917,13 @@ stream_read(pdfio_stream_t *st, // I - Stream
*bufptr++ = *sptr + *pptr;
break;
case 3 : // Average
for (; remaining > firstcol; remaining --, sptr ++, pptr ++)
for (; bufptr < bufsecond; remaining --, sptr ++, pptr ++)
*bufptr++ = *sptr + *pptr / 2;
for (; remaining > 0; remaining --, sptr ++, pptr ++, bufptr ++)
*bufptr = *sptr + (bufptr[-pbpixel] + *pptr) / 2;
break;
case 4 : // Paeth
for (; remaining > firstcol; remaining --, sptr ++, pptr ++)
for (; bufptr < bufsecond; remaining --, sptr ++, pptr ++)
*bufptr++ = *sptr + stream_paeth(0, *pptr, 0);
for (; remaining > 0; remaining --, sptr ++, pptr ++, bufptr ++)
*bufptr = *sptr + stream_paeth(bufptr[-pbpixel], *pptr, pptr[-pbpixel]);