	4b825dc642cb6eb9a060e54bf8d69288fbee4904		94a6641b73026d662261604d7d192beae70b11dc
		1	#include <stdlib.h>
		2	#include <libpng/png.h>
		3
		4	unsigned char png_get_image_data(FILE infile, int image_width, int image_height)
		5	{
		6	unsigned char buf[8];
		7
		8	fread(buf, 1, 8, infile);
		9
		10	if(!png_sig_cmp(buf, 0, 8))
		11	{
		12	png_structp png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
		13
		14	if (png_ptr)
		15	{
		16	png_infop info_ptr = png_create_info_struct(png_ptr);
		17
		18	if (info_ptr)
		19	{
		20	if (setjmp(png_jmpbuf(png_ptr)))
		21	{
		22	png_destroy_read_struct(&png_ptr, &info_ptr, NULL);
		23	return NULL;
		24	}
		25
		26	png_init_io(png_ptr, infile);
		27	png_set_sig_bytes(png_ptr, 8);
		28	png_read_info(png_ptr, info_ptr);
		29
		30	*image_height = png_get_image_height(png_ptr, info_ptr);
		31	*image_width = png_get_image_width(png_ptr, info_ptr);
		32
		33	if (16 == png_get_bit_depth(png_ptr, info_ptr))
		34	{
		35	png_set_strip_16(png_ptr);
		36	png_read_update_info(png_ptr, info_ptr);
		37	}
		38
		39	png_uint_32 rowbytes = png_get_rowbytes(png_ptr, info_ptr);
		40
		41	unsigned char image_data = malloc(image_height * rowbytes);
		42
		43	if (NULL != image_data)
		44	{
		45	png_bytepp row_pointers = malloc(image_height sizeof(png_bytep));
		46
		47	if (NULL != row_pointers)
		48	{
		49	int i;
		50
		51	for (i=0; i < *image_height; i++)
		52	row_pointers[i] = image_data + i * rowbytes;
		53
		54	png_read_image(png_ptr, row_pointers);
		55
		56	free(row_pointers);
		57	}
		58	else
		59	{
		60	free(image_data);
		61	image_data = NULL;
		62	}
		63	}
		64
		65	png_destroy_read_struct(&png_ptr, &info_ptr, NULL);
		66	return image_data;
		67	}
		68	else
		69	{
		70	png_destroy_read_struct(&png_ptr, NULL, NULL);
		71	}
		72	}
		73	}
		74
		75	return NULL;
		76	}