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Add pdfioImageGetBytesPerLine API, document its use for image streams.

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Michael R Sweet 2021-06-04 10:33:39 -04:00
parent 3ec771e688
commit caf398d72c
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GPG Key ID: 999559A027815955
3 changed files with 70 additions and 4 deletions
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67
pdfio-content.c
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@ -1134,6 +1134,62 @@ pdfioFileCreateImageObject(
}
//
// 'pdfioImageGetBytesPerLine()' - Get the number of bytes to read for each line.
//
size_t // O - Number of bytes per line
pdfioImageGetBytesPerLine(
pdfio_obj_t *obj) // I - Image object
{
pdfio_dict_t *params; // DecodeParms value
int width, // Width of image
height, // Height of image
bpc, // BitsPerComponent of image
colors; // Number of colors in image
if (!obj || obj->value.type != PDFIO_VALTYPE_DICT)
return (0);
params = pdfioDictGetDict(obj->value.value.dict, "DecodeParms");
bpc = (int)pdfioDictGetNumber(params, "BitsPerComponent");
colors = (int)pdfioDictGetNumber(params, "Colors");
width = (int)pdfioDictGetNumber(params, "Columns");
height = (int)pdfioDictGetNumber(obj->value.value.dict, "Height");
if (width == 0)
width = (int)pdfioDictGetNumber(obj->value.value.dict, "Width");
if (bpc == 0)
{
if ((bpc = (int)pdfioDictGetNumber(obj->value.value.dict, "BitsPerComponent")) == 0)
bpc = 8;
}
if (colors == 0)
{
const char *cs_name; // ColorSpace name
pdfio_array_t *cs_array; // ColorSpace array
if ((cs_name = pdfioDictGetName(obj->value.value.dict, "ColorSpace")) == NULL)
{
if ((cs_array = pdfioDictGetArray(obj->value.value.dict, "ColorSpace")) != NULL)
cs_name = pdfioArrayGetName(cs_array, 0);
}
if (!cs_name || strstr(cs_name, "RGB"))
colors = 3;
else if (strstr(cs_name, "CMYK"))
colors = 4;
else
colors = 1;
}
return ((size_t)((width * colors * bpc + 7) / 8));
}
//
// 'pdfioImageGetHeight()' - Get the height of an image object.
//
@ -1141,7 +1197,10 @@ pdfioFileCreateImageObject(
double // O - Height in lines
pdfioImageGetHeight(pdfio_obj_t *obj) // I - Image object
{
return (pdfioDictGetNumber(obj->value.value.dict, "Height"));
if (obj)
return (pdfioDictGetNumber(obj->value.value.dict, "Height"));
else
return (0.0);
}
@ -1152,7 +1211,10 @@ pdfioImageGetHeight(pdfio_obj_t *obj) // I - Image object
double // O - Width in columns
pdfioImageGetWidth(pdfio_obj_t *obj) // I - Image object
{
return (pdfioDictGetNumber(obj->value.value.dict, "Width"));
if (obj)
return (pdfioDictGetNumber(obj->value.value.dict, "Width"));
else
return (0.0);
}
@ -1267,7 +1329,6 @@ copy_jpeg(pdfio_dict_t *dict, // I - Dictionary
pdfioDictSetNumber(dict, "Width", width);
pdfioDictSetNumber(dict, "Height", height);
pdfioDictSetNumber(dict, "BitsPerComponent", 8);
// TODO: Add proper JPEG CalRGB/Gray color spaces
pdfioDictSetArray(dict, "ColorSpace", create_calcolor(dict->pdf, num_colors, pdfioSRGBGamma, pdfioSRGBMatrix, pdfioSRGBWhitePoint));
pdfioDictSetName(dict, "Filter", "DCTDecode");

1
pdfio-content.h
View File

@ -144,6 +144,7 @@ extern pdfio_obj_t *pdfioFileCreateICCProfileObject(pdfio_file_t *pdf, const cha
extern pdfio_obj_t *pdfioFileCreateImageObject(pdfio_file_t *pdf, const char *filename, bool interpolate) PDFIO_PUBLIC;
// Image object helpers...
extern size_t pdfioImageGetBytesPerLine(pdfio_obj_t *obj) PDFIO_PUBLIC;
extern double pdfioImageGetHeight(pdfio_obj_t *obj) PDFIO_PUBLIC;
extern double pdfioImageGetWidth(pdfio_obj_t *obj) PDFIO_PUBLIC;

6
pdfio-stream.c
View File

@ -571,6 +571,11 @@ pdfioStreamPuts(pdfio_stream_t *st, // I - Stream
//
// 'pdfioStreamRead()' - Read data from a stream.
//
// This function reads data from a stream. When reading decoded image data
// from a stream, you *must* read whole scanlines. The
// @link pdfioImageGetBytesPerLine@ function can be used to determine the
// proper read length.
//
ssize_t // O - Number of bytes read or `-1` on error
pdfioStreamRead(
@ -860,7 +865,6 @@ stream_read(pdfio_stream_t *st, // I - Stream
if (bytes < (st->pbsize - 1))
{
// TODO: Support partial reads of PNG-encoded streams?
_pdfioFileError(st->pdf, "Read buffer too small for stream.");
return (-1);
}