diff options
Diffstat (limited to 'src/png.c')
| -rw-r--r-- | src/png.c | 24 |
1 files changed, 20 insertions, 4 deletions
@@ -13,8 +13,23 @@ struct png_t{ int numpasses; }; +static unsigned char png_head[8] = { 0x89, 0x50, 0x4e, 0x47, 0x0d, 0x0a, 0x1a, 0x0a }; + +static int ispng(FILE *f){ + unsigned char buf[8]; + if(fread(buf, 1, 8, f) != 8) + return 0; + return !memcmp(buf, png_head, 8); +} + struct image *png_open(FILE *f){ - struct png_t *p = malloc(sizeof(struct png_t)); + struct png_t *p; + + rewind(f); + if(!ispng(f)) + return NULL; + + 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; @@ -68,15 +83,16 @@ struct image *png_open(FILE *f){ } int png_read(struct image *img){ + unsigned int y; struct png_t *p = (struct png_t *)img; if(setjmp(png_jmpbuf(p->png_ptr))){ png_destroy_read_struct(&p->png_ptr, &p->info_ptr, &p->end_info); return 1; } - 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); + 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; |