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Don't generate a mask image if unnecessary.

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Michael R Sweet
2026-01-18 18:18:25 -05:00
parent ddb57bb754
commit a818dee123
1 changed files with 62 additions and 48 deletions
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110
pdfio-content.c
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@@ -3976,66 +3976,80 @@ create_image(
// Generate a mask image, as needed...
if (alpha)
{
// Create the image mask dictionary...
if ((mask_dict = pdfioDictCopy(pdf, dict)) == NULL)
// See if the image mask is actually needed...
size_t remaining = width * height; // Remaining pixels
for (dataptr = data + bpp; remaining > 0; remaining --, dataptr += bpp + bpc)
{
free(line);
return (NULL);
if (*dataptr < 255)
break;
if (bpc == 2 && dataptr[1] < 255)
break;
}
// Transparency masks are always grayscale...
pdfioDictSetName(mask_dict, "ColorSpace", "DeviceGray");
// Set the automatic PNG predictor to optimize compression...
if ((decode = pdfioDictCreate(pdf)) == NULL)
if (remaining > 0)
{
free(line);
return (NULL);
}
pdfioDictSetNumber(decode, "BitsPerComponent", (double)depth);
pdfioDictSetNumber(decode, "Colors", 1);
pdfioDictSetNumber(decode, "Columns", (double)width);
pdfioDictSetNumber(decode, "Predictor", _PDFIO_PREDICTOR_PNG_AUTO);
pdfioDictSetDict(mask_dict, "DecodeParms", decode);
// Create the mask object and write the mask image...
if ((mask_obj = pdfioFileCreateObj(pdf, mask_dict)) == NULL)
{
free(line);
return (NULL);
}
if ((st = pdfioObjCreateStream(mask_obj, PDFIO_FILTER_FLATE)) == NULL)
{
free(line);
pdfioObjClose(mask_obj);
return (NULL);
}
for (y = height, dataptr = data + bpp; y > 0; y --)
{
if (bpc == 1)
// Create the image mask dictionary...
if ((mask_dict = pdfioDictCopy(pdf, dict)) == NULL)
{
for (x = width, lineptr = line; x > 0; x --, dataptr += bpp)
*lineptr++ = *dataptr++;
free(line);
return (NULL);
}
else
// Transparency masks are always grayscale...
pdfioDictSetName(mask_dict, "ColorSpace", "DeviceGray");
// Set the automatic PNG predictor to optimize compression...
if ((decode = pdfioDictCreate(pdf)) == NULL)
{
for (x = width, lineptr = line; x > 0; x --, dataptr += bpp)
free(line);
return (NULL);
}
pdfioDictSetNumber(decode, "BitsPerComponent", (double)depth);
pdfioDictSetNumber(decode, "Colors", 1);
pdfioDictSetNumber(decode, "Columns", (double)width);
pdfioDictSetNumber(decode, "Predictor", _PDFIO_PREDICTOR_PNG_AUTO);
pdfioDictSetDict(mask_dict, "DecodeParms", decode);
// Create the mask object and write the mask image...
if ((mask_obj = pdfioFileCreateObj(pdf, mask_dict)) == NULL)
{
free(line);
return (NULL);
}
if ((st = pdfioObjCreateStream(mask_obj, PDFIO_FILTER_FLATE)) == NULL)
{
free(line);
pdfioObjClose(mask_obj);
return (NULL);
}
for (y = height, dataptr = data + bpp; y > 0; y --)
{
if (bpc == 1)
{
*lineptr++ = *dataptr++;
*lineptr++ = *dataptr++;
for (x = width, lineptr = line; x > 0; x --, dataptr += bpp)
*lineptr++ = *dataptr++;
}
else
{
for (x = width, lineptr = line; x > 0; x --, dataptr += bpp)
{
*lineptr++ = *dataptr++;
*lineptr++ = *dataptr++;
}
}
pdfioStreamWrite(st, line, width * bpc);
}
pdfioStreamWrite(st, line, width * bpc);
pdfioStreamClose(st);
// Use the transparency mask...
pdfioDictSetObj(dict, "SMask", mask_obj);
}
pdfioStreamClose(st);
// Use the transparency mask...
pdfioDictSetObj(dict, "SMask", mask_obj);
}
// Set the automatic PNG predictor to optimize compression...