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#include <stdlib.h>
#include <png.h>
#include "meh.h"
struct png_t{
struct image img;
FILE *f;
png_structp png_ptr;
png_infop info_ptr;
png_infop end_info;
int numpasses;
};
struct image *png_open(FILE *f){
struct png_t *p = malloc(sizeof(struct png_t));
if((p->png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL)) == NULL){
free(p);
return NULL;
}
if((p->info_ptr = png_create_info_struct(p->png_ptr)) == NULL){
png_destroy_read_struct(&p->png_ptr, (png_infopp)NULL, (png_infopp)NULL);
free(p);
return NULL;
}
if((p->end_info = png_create_info_struct(p->png_ptr)) == NULL){
png_destroy_read_struct(&p->png_ptr, &p->info_ptr, (png_infopp)NULL);
free(p);
return NULL;
}
if(setjmp(png_jmpbuf(p->png_ptr))){
png_destroy_read_struct(&p->png_ptr, &p->info_ptr, &p->end_info);
free(p);
return NULL;
}
p->f = f;
rewind(f);
png_init_io(p->png_ptr, f);
png_read_info(p->png_ptr, p->info_ptr);
{
png_byte color_type = png_get_color_type(p->png_ptr, p->info_ptr);
if(color_type == PNG_COLOR_TYPE_PALETTE)
png_set_palette_to_rgb(p->png_ptr);
if(color_type == PNG_COLOR_TYPE_GRAY && png_get_bit_depth(p->png_ptr, p->info_ptr) < 8)
png_set_gray_1_2_4_to_8(p->png_ptr);
if (png_get_valid(p->png_ptr, p->info_ptr, PNG_INFO_tRNS))
png_set_tRNS_to_alpha(p->png_ptr);
if (png_get_bit_depth(p->png_ptr, p->info_ptr) == 16)
png_set_strip_16(p->png_ptr);
if(color_type & PNG_COLOR_MASK_ALPHA)
png_set_strip_alpha(p->png_ptr);
if (color_type == PNG_COLOR_TYPE_GRAY || color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
png_set_gray_to_rgb(p->png_ptr);
if(png_get_interlace_type(p->png_ptr, p->info_ptr) == PNG_INTERLACE_ADAM7)
p->numpasses = png_set_interlace_handling(p->png_ptr);
else
p->numpasses = 1;
png_read_update_info(p->png_ptr, p->info_ptr);
}
p->img.width = png_get_image_width(p->png_ptr, p->info_ptr);
p->img.height = png_get_image_height(p->png_ptr, p->info_ptr);
return (struct image *)p;
}
int png_read(struct image *img){
struct png_t *p = (struct png_t *)img;
int y;
while(p->numpasses--){
for(y = 0; y < img->height; y++)
png_read_row(p->png_ptr, &img->buf[y * (img->width) * 3], NULL);
}
png_destroy_read_struct(&p->png_ptr, &p->info_ptr, &p->end_info);
return 0;
}
struct imageformat libpng = {
png_open,
png_read
};
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