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/* png.c
* PNG decoding
* (c) 2002 Karel 'Clock' Kulhavy
* This is a part of the Links program, released under GPL.
*/
#include "cfg.h"
#ifdef G
#include "links.h"
#ifdef HAVE_ENDIAN_H
#include <endian.h>
#endif /* #ifdef HAVE_ENDIAN_H */
#ifdef REPACK_16
#undef REPACK_16
#endif /* #ifdef REPACK_16 */
#if SIZEOF_UNSIGNED_SHORT != 2
#define REPACK_16
#endif /* #if SIZEOF_UNSIGNED_SHORT != 2 */
#ifndef REPACK_16
#ifndef C_LITTLE_ENDIAN
#ifndef C_BIG_ENDIAN
#define REPACK_16
#endif /* #ifndef C_BIG_ENDIAN */
#endif /* #ifndef C_LITTLE_ENDIAN */
#endif /* #ifndef REPACK_16 */
/* Decoder structs */
/* Warning for from-web PNG images */
static void img_my_png_warning(png_structp a, png_const_charp b)
{
}
/* Error for from-web PNG images. */
static void img_my_png_error(png_structp png_ptr, png_const_charp error_string)
{
#if (PNG_LIBPNG_VER < 10500)
longjmp(png_ptr->jmpbuf,1);
#else
png_longjmp(png_ptr,1);
#endif
}
static void png_info_callback(png_structp png_ptr, png_infop info_ptr)
{
int bit_depth, color_type, intent;
double gamma;
int bytes_per_pixel=3;
struct cached_image *cimg;
cimg=global_cimg;
bit_depth=png_get_bit_depth(png_ptr, info_ptr);
color_type=png_get_color_type(png_ptr, info_ptr);
if (color_type == PNG_COLOR_TYPE_PALETTE)
png_set_expand(png_ptr);
if (color_type == PNG_COLOR_TYPE_GRAY &&
bit_depth < 8) png_set_expand(png_ptr);
if (png_get_valid(png_ptr, info_ptr,
PNG_INFO_tRNS)){
png_set_expand(png_ptr); /* Legacy version of
png_set_tRNS_to_alpha(png_ptr); */
bytes_per_pixel++;
}
if (color_type == PNG_COLOR_TYPE_GRAY ||
color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
png_set_gray_to_rgb(png_ptr);
if (bit_depth==16){
#ifndef REPACK_16
#ifdef C_LITTLE_ENDIAN
/* We use native endianity only if unsigned short is 2-byte
* because otherwise we have to reassemble the buffer so we
* will leave in the libpng-native big endian.
*/
png_set_swap(png_ptr);
#endif /* #ifdef C_LITTLE_ENDIAN */
#endif /* #ifndef REPACK_16 */
bytes_per_pixel*=sizeof(unsigned short);
}
png_set_interlace_handling(png_ptr);
if (color_type==PNG_COLOR_TYPE_RGB_ALPHA
||color_type==PNG_COLOR_TYPE_GRAY_ALPHA){
if (bytes_per_pixel==3
||bytes_per_pixel==3*sizeof(unsigned short))
bytes_per_pixel=4*bytes_per_pixel/3;
}
cimg->width=png_get_image_width(png_ptr,info_ptr);
cimg->height=png_get_image_height(png_ptr,info_ptr);
cimg->buffer_bytes_per_pixel=bytes_per_pixel;
if (png_get_sRGB(png_ptr, info_ptr, &intent)){
gamma=sRGB_gamma;
}
else
{
if (!png_get_gAMA(png_ptr, info_ptr, &gamma)){
gamma=sRGB_gamma;
}
}
cimg->red_gamma=gamma;
cimg->green_gamma=gamma;
cimg->blue_gamma=gamma;
png_read_update_info(png_ptr,info_ptr);
cimg->strip_optimized=0;
if (header_dimensions_known(cimg))
img_my_png_error(png_ptr, "bad image size");
}
#ifdef REPACK_16
/* Converts unsigned shorts to doublechars (in big endian) */
static void a2char_from_unsigned_short(unsigned char *chr, unsigned short *shrt, int len)
{
unsigned short s;
for (;len;len--,shrt++,chr+=2){
s=*shrt;
*chr=s>>8;
chr[1]=s;
}
}
/* Converts doublechars (in big endian) to unsigned shorts */
static void unsigned_short_from_2char(unsigned short *shrt, unsigned char *chr, int len)
{
unsigned short s;
for (;len;len--,shrt++,chr+=2){
s=((*chr)<<8)|chr[1];
*shrt=s;
}
}
#endif
static void png_row_callback(png_structp png_ptr, png_bytep new_row, png_uint_32
row_num, int pass)
{
struct cached_image *cimg;
#ifdef REPACK_16
unsigned char *tmp;
int channels;
#endif /* #ifdef REPACK_16 */
cimg=global_cimg;
#ifdef REPACK_16
if (cimg->buffer_bytes_per_pixel>4)
{
channels=cimg->buffer_bytes_per_pixel/sizeof(unsigned
short);
if (PNG_INTERLACE_NONE==png_get_interlace_type(png_ptr,
((struct png_decoder *)cimg->decoder)->info_ptr))
{
unsigned_short_from_2char((unsigned short *)(cimg->buffer+cimg
->buffer_bytes_per_pixel *cimg->width
*row_num), new_row, cimg->width
*channels);
}else{
if ((unsigned)cimg->width > MAXINT / 2 / channels) overalloc();
tmp=mem_alloc(cimg->width*2*channels);
a2char_from_unsigned_short(tmp, (unsigned short *)(cimg->buffer
+cimg->buffer_bytes_per_pixel
*cimg->width*row_num), cimg->width*channels);
png_progressive_combine_row(png_ptr, tmp, new_row);
unsigned_short_from_2char((unsigned short *)(cimg->buffer
+cimg->buffer_bytes_per_pixel
*cimg->width*row_num), tmp, cimg->width*channels);
mem_free(tmp);
}
}else
#endif /* #ifdef REPACK_16 */
{
png_progressive_combine_row(png_ptr,
cimg->buffer+cimg->buffer_bytes_per_pixel
*cimg->width*row_num, new_row);
}
cimg->rows_added=1;
}
static void png_end_callback(png_structp png_ptr, png_infop info)
{
end_callback_hit=1;
}
/* Decoder structs */
void png_start(struct cached_image *cimg)
{
png_structp png_ptr;
png_infop info_ptr;
struct png_decoder *decoder;
retry1:
png_ptr=png_create_read_struct(PNG_LIBPNG_VER_STRING,
NULL, img_my_png_error, img_my_png_warning);
if (!png_ptr) {
if (out_of_memory(NULL, 0)) goto retry1;
error("png_create_read_struct failed");
fatal_tty_exit();
exit(RET_FATAL);
}
retry2:
info_ptr=png_create_info_struct(png_ptr);
if (!info_ptr) {
if (out_of_memory(NULL, 0)) goto retry2;
error("png_create_info_struct failed");
fatal_tty_exit();
exit(RET_FATAL);
}
if (setjmp(png_jmpbuf(png_ptr))){
error:
png_destroy_read_struct(&png_ptr, &info_ptr,
(png_infopp)NULL);
img_end(cimg);
return;
}
png_set_progressive_read_fn(png_ptr, NULL,
png_info_callback, &png_row_callback,
png_end_callback);
if (setjmp(png_jmpbuf(png_ptr))) goto error;
decoder=mem_alloc(sizeof(*decoder));
decoder->png_ptr=png_ptr;
decoder->info_ptr=info_ptr;
cimg->decoder=decoder;
}
void png_restart(struct cached_image *cimg, unsigned char *data, int length)
{
png_structp png_ptr;
png_infop info_ptr;
#ifdef DEBUG
if (!cimg->decoder)
internal("decoder NULL in png_restart\n");
#endif /* #ifdef DEBUG */
png_ptr=((struct png_decoder *)(cimg->decoder))->png_ptr;
info_ptr=((struct png_decoder *)(cimg->decoder))->info_ptr;
end_callback_hit=0;
if (setjmp(png_jmpbuf(png_ptr))){
img_end(cimg);
return;
}
png_process_data(png_ptr, info_ptr, data, length);
if (end_callback_hit) img_end(cimg);
}
void add_png_version(unsigned char **s, int *l)
{
add_to_str(s, l, "PNG (");
#ifdef HAVE_PNG_GET_LIBPNG_VER
add_to_str(s, l, (unsigned char *)png_get_libpng_ver(NULL));
#else
add_to_str(s, l, PNG_LIBPNG_VER_STRING);
#endif
add_to_str(s, l, ")");
}
#endif /* #ifdef G */
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