kopia lustrzana https://github.com/sp9skp/spdxl
129 wiersze
4.0 KiB
C
129 wiersze
4.0 KiB
C
|
|
#include <png.h>
|
|
#include <stdint.h>
|
|
|
|
int32_t readpng(char *fn, png_bytep *row_pointers, int32_t *maxx, int32_t *maxy, int32_t *maxxbyte) /* file is already open */
|
|
{
|
|
png_structp png_ptr;
|
|
png_infop info_ptr;
|
|
png_uint_32 width, height;
|
|
int bit_depth, color_type, interlace_type, xsize, ysize, xbyte;
|
|
|
|
FILE *fp = fopen(fn, "rb");
|
|
if (!fp)
|
|
return -4;
|
|
|
|
/* Create and initialize the png_struct with the desired error handler
|
|
* functions. If you want to use the default stderr and longjump method,
|
|
* you can supply NULL for the last three parameters. We also supply the
|
|
* the compiler header file version, so that we know if the application
|
|
* was compiled with a compatible version of the library. REQUIRED
|
|
*/
|
|
png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
|
|
|
|
if (png_ptr == NULL)
|
|
{
|
|
|
|
fclose(fp);
|
|
return -1;
|
|
}
|
|
|
|
/* Allocate/initialize the memory for image information. REQUIRED. */
|
|
info_ptr = png_create_info_struct(png_ptr);
|
|
if (info_ptr == NULL)
|
|
{
|
|
fclose(fp);
|
|
png_destroy_read_struct(&png_ptr, (png_infopp)NULL, (png_infopp)NULL);
|
|
return -1;
|
|
}
|
|
|
|
/* Set error handling if you are using the setjmp/longjmp method (this is
|
|
* the normal method of doing things with libpng). REQUIRED unless you
|
|
* set up your own error handlers in the png_create_read_struct() earlier.
|
|
*/
|
|
|
|
if (setjmp(png_jmpbuf(png_ptr)))
|
|
{
|
|
// Free all of the memory associated with the png_ptr and info_ptr
|
|
png_destroy_read_struct(&png_ptr, &info_ptr, (png_infopp)NULL);
|
|
fclose(fp);
|
|
// If we get here, we had a problem reading the file
|
|
return -1;
|
|
}
|
|
|
|
/* Set up the input control if you are using standard C streams */
|
|
png_init_io(png_ptr, fp);
|
|
|
|
/* The call to png_read_info() gives us all of the information from the
|
|
* PNG file before the first IDAT (image data chunk). REQUIRED
|
|
*/
|
|
png_read_info(png_ptr, info_ptr);
|
|
|
|
png_get_IHDR(png_ptr, info_ptr, &width, &height, &bit_depth, &color_type,
|
|
&interlace_type, NULL, NULL);
|
|
|
|
/* tell libpng to strip 16 bit/color files down to 8 bits/color */
|
|
png_set_strip_16(png_ptr);
|
|
|
|
/* strip alpha bytes from the input data without combining with th
|
|
* background (not recommended) */
|
|
png_set_strip_alpha(png_ptr);
|
|
|
|
/* extract multiple pixels with bit depths of 1, 2, and 4 from a single
|
|
* byte into separate bytes (useful for paletted and grayscale images).
|
|
*/
|
|
png_set_packing(png_ptr);
|
|
|
|
if (color_type == PNG_COLOR_TYPE_PALETTE)
|
|
png_set_palette_to_rgb(png_ptr);
|
|
|
|
if (color_type == PNG_COLOR_TYPE_GRAY && bit_depth < 8)
|
|
png_set_expand(png_ptr);
|
|
|
|
/* expand paletted colors into true RGB triplets */
|
|
if (color_type == PNG_COLOR_TYPE_PALETTE)
|
|
png_set_expand(png_ptr);
|
|
|
|
/* optional call to gamma correct and add the background to the palette
|
|
* and update info structure. REQUIRED if you are expecting libpng to
|
|
* update the palette for you (ie you selected such a transform above).
|
|
*/
|
|
png_read_update_info(png_ptr, info_ptr);
|
|
|
|
xbyte = png_get_rowbytes(png_ptr, info_ptr);
|
|
xsize = png_get_image_width(png_ptr, info_ptr);
|
|
ysize = png_get_image_height(png_ptr, info_ptr);
|
|
|
|
if (ysize > *maxy || xsize > *maxx || xbyte > *maxxbyte)
|
|
{
|
|
*maxx = xsize;
|
|
*maxy = ysize;
|
|
*maxxbyte = xbyte;
|
|
|
|
/* Free all of the memory associated with the png_ptr and info_ptr */
|
|
png_destroy_read_struct(&png_ptr, &info_ptr, (png_infopp)NULL);
|
|
fclose(fp);
|
|
/* If we get here, we had a problem reading the file */
|
|
return -2;
|
|
}
|
|
|
|
*maxx = xsize;
|
|
*maxy = ysize;
|
|
*maxxbyte = xbyte;
|
|
|
|
/* Now it's time to read the image.*/
|
|
png_read_image(png_ptr, row_pointers);
|
|
|
|
|
|
/* read rest of file, and get additional chunks in info_ptr - REQUIRED */
|
|
png_read_end(png_ptr, info_ptr);
|
|
|
|
/* clean up after the read, and free any memory allocated - REQUIRED */
|
|
png_destroy_read_struct(&png_ptr, &info_ptr, (png_infopp)NULL);
|
|
|
|
/* close the file */
|
|
fclose(fp);
|
|
|
|
return 0;
|
|
}
|