This library is free software; you can redistribute it and/or

This library is distributed in the hope that it will be useful,

but WITHOUT ANY WARRANTY; without even the implied warranty of

MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU

You should have received a copy of the GNU Lesser General Public

License along with this library; if not, write to the Free Software

Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA

Sam Lantinga

*/

/* This is a PNG image file loading framework */

#include <stdlib.h>

#include <stdio.h>

#include "SDL_image.h"

#ifdef LOAD_PNG

/*=============================================================================

File: SDL_png.c

Purpose: A PNG loader and saver for the SDL library

Revision:

Created by: Philippe Lavoie (2 November 1998)

lavoie@zeus.genie.uottawa.ca

Modified by:

Copyright notice:

Copyright (C) 1998 Philippe Lavoie

This library is free software; you can redistribute it and/or

modify it under the terms of the GNU Library General Public

License as published by the Free Software Foundation; either

version 2 of the License, or (at your option) any later version.

This library is distributed in the hope that it will be useful,

but WITHOUT ANY WARRANTY; without even the implied warranty of

MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU

Library General Public License for more details.

You should have received a copy of the GNU Library General Public

License along with this library; if not, write to the Free

Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.

Comments: The load and save routine are basically the ones you can find

in the example.c file from the libpng distribution.

Changes:

5/17/99 - Modified to use the new SDL data sources - Sam Lantinga

=============================================================================*/

#include "SDL_endian.h"

#ifdef macintosh

#define MACOS

#endif

#include <png.h>

#define PNG_BYTES_TO_CHECK 4

static struct {

int loaded;

void *handle;

png_infop (*png_create_info_struct) (png_structp png_ptr);

png_structp (*png_create_read_struct) (png_const_charp user_png_ver, png_voidp error_ptr, png_error_ptr error_fn, png_error_ptr warn_fn);

void (*png_destroy_read_struct) (png_structpp png_ptr_ptr, png_infopp info_ptr_ptr, png_infopp end_info_ptr_ptr);

png_uint_32 (*png_get_IHDR) (png_structp png_ptr, png_infop info_ptr, png_uint_32 *width, png_uint_32 *height, int *bit_depth, int *color_type, int *interlace_method, int *compression_method, int *filter_method);

png_voidp (*png_get_io_ptr) (png_structp png_ptr);

png_uint_32 (*png_get_tRNS) (png_structp png_ptr, png_infop info_ptr, png_bytep *trans, int *num_trans, png_color_16p *trans_values);

png_uint_32 (*png_get_valid) (png_structp png_ptr, png_infop info_ptr, png_uint_32 flag);

void (*png_read_image) (png_structp png_ptr, png_bytepp image);

void (*png_read_info) (png_structp png_ptr, png_infop info_ptr);

void (*png_read_update_info) (png_structp png_ptr, png_infop info_ptr);

void (*png_set_expand) (png_structp png_ptr);

void (*png_set_gray_to_rgb) (png_structp png_ptr);

void (*png_set_packing) (png_structp png_ptr);

void (*png_set_read_fn) (png_structp png_ptr, png_voidp io_ptr, png_rw_ptr read_data_fn);

void (*png_set_strip_16) (png_structp png_ptr);

int (*png_sig_cmp) (png_bytep sig, png_size_t start, png_size_t num_to_check);

} lib;

#ifdef LOAD_PNG_DYNAMIC

int IMG_InitPNG()

{

if ( lib.loaded == 0 ) {

lib.handle = SDL_LoadObject(LOAD_PNG_DYNAMIC);

if ( lib.handle == NULL ) {

return -1;

}

lib.png_create_info_struct =

(png_infop (*) (png_structp))

SDL_LoadFunction(lib.handle, "png_create_info_struct");

if ( lib.png_create_info_struct == NULL ) {

SDL_UnloadObject(lib.handle);

return -1;

}

lib.png_create_read_struct =

(png_structp (*) (png_const_charp, png_voidp, png_error_ptr, png_error_ptr))

SDL_LoadFunction(lib.handle, "png_create_read_struct");

if ( lib.png_create_read_struct == NULL ) {

SDL_UnloadObject(lib.handle);

return -1;

}

lib.png_destroy_read_struct =

(void (*) (png_structpp, png_infopp, png_infopp))

SDL_LoadFunction(lib.handle, "png_destroy_read_struct");

if ( lib.png_destroy_read_struct == NULL ) {

SDL_UnloadObject(lib.handle);

return -1;

}

lib.png_get_IHDR =

(png_uint_32 (*) (png_structp, png_infop, png_uint_32 *, png_uint_32 *, int *, int *, int *, int *, int *))

SDL_LoadFunction(lib.handle, "png_get_IHDR");

if ( lib.png_get_IHDR == NULL ) {

SDL_UnloadObject(lib.handle);

return -1;

}

lib.png_get_io_ptr =

(png_voidp (*) (png_structp))

SDL_LoadFunction(lib.handle, "png_get_io_ptr");

if ( lib.png_get_io_ptr == NULL ) {

SDL_UnloadObject(lib.handle);

return -1;

}

lib.png_get_tRNS =

(png_uint_32 (*) (png_structp, png_infop, png_bytep *, int *, png_color_16p *))

SDL_LoadFunction(lib.handle, "png_get_tRNS");

if ( lib.png_get_tRNS == NULL ) {

SDL_UnloadObject(lib.handle);

return -1;

}

lib.png_get_valid =

(png_uint_32 (*) (png_structp, png_infop, png_uint_32))

SDL_LoadFunction(lib.handle, "png_get_valid");

if ( lib.png_get_valid == NULL ) {

SDL_UnloadObject(lib.handle);

return -1;

}

lib.png_read_image =

(void (*) (png_structp, png_bytepp))

SDL_LoadFunction(lib.handle, "png_read_image");

if ( lib.png_read_image == NULL ) {

SDL_UnloadObject(lib.handle);

return -1;

}

lib.png_read_info =

(void (*) (png_structp, png_infop))

SDL_LoadFunction(lib.handle, "png_read_info");

if ( lib.png_read_info == NULL ) {

SDL_UnloadObject(lib.handle);

return -1;

}

lib.png_read_update_info =

(void (*) (png_structp, png_infop))

SDL_LoadFunction(lib.handle, "png_read_update_info");

if ( lib.png_read_update_info == NULL ) {

SDL_UnloadObject(lib.handle);

return -1;

}

lib.png_set_expand =

(void (*) (png_structp))

SDL_LoadFunction(lib.handle, "png_set_expand");

if ( lib.png_set_expand == NULL ) {

SDL_UnloadObject(lib.handle);

return -1;

}

lib.png_set_gray_to_rgb =

(void (*) (png_structp))

SDL_LoadFunction(lib.handle, "png_set_gray_to_rgb");

if ( lib.png_set_gray_to_rgb == NULL ) {

SDL_UnloadObject(lib.handle);

return -1;

}

lib.png_set_packing =

(void (*) (png_structp))

SDL_LoadFunction(lib.handle, "png_set_packing");

if ( lib.png_set_packing == NULL ) {

SDL_UnloadObject(lib.handle);

return -1;

}

lib.png_set_read_fn =

(void (*) (png_structp, png_voidp, png_rw_ptr))

SDL_LoadFunction(lib.handle, "png_set_read_fn");

if ( lib.png_set_read_fn == NULL ) {

SDL_UnloadObject(lib.handle);

return -1;

}

lib.png_set_strip_16 =

(void (*) (png_structp))

SDL_LoadFunction(lib.handle, "png_set_strip_16");

if ( lib.png_set_strip_16 == NULL ) {

SDL_UnloadObject(lib.handle);

return -1;

}

lib.png_sig_cmp =

(int (*) (png_bytep, png_size_t, png_size_t))

SDL_LoadFunction(lib.handle, "png_sig_cmp");

if ( lib.png_sig_cmp == NULL ) {

SDL_UnloadObject(lib.handle);

return -1;

}

}

++lib.loaded;

return 0;

}

void IMG_QuitPNG()

{

if ( lib.loaded == 0 ) {

return;

}

if ( lib.loaded == 1 ) {

SDL_UnloadObject(lib.handle);

}

--lib.loaded;

}

#else

int IMG_InitPNG()

{

if ( lib.loaded == 0 ) {

lib.png_create_info_struct = png_create_info_struct;

lib.png_create_read_struct = png_create_read_struct;

lib.png_destroy_read_struct = png_destroy_read_struct;

lib.png_get_IHDR = png_get_IHDR;

lib.png_get_io_ptr = png_get_io_ptr;

lib.png_get_tRNS = png_get_tRNS;

lib.png_get_valid = png_get_valid;

lib.png_read_image = png_read_image;

lib.png_read_info = png_read_info;

lib.png_read_update_info = png_read_update_info;

lib.png_set_expand = png_set_expand;

lib.png_set_gray_to_rgb = png_set_gray_to_rgb;

lib.png_set_packing = png_set_packing;

lib.png_set_read_fn = png_set_read_fn;

lib.png_set_strip_16 = png_set_strip_16;

lib.png_sig_cmp = png_sig_cmp;

}

++lib.loaded;

return 0;

}

void IMG_QuitPNG()

{

if ( lib.loaded == 0 ) {

return;

}

if ( lib.loaded == 1 ) {

}

--lib.loaded;

}

#endif /* LOAD_PNG_DYNAMIC */

/* See if an image is contained in a data source */

int IMG_isPNG(SDL_RWops *src)

{

int start;

int is_PNG;

unsigned char buf[PNG_BYTES_TO_CHECK];

if ( IMG_InitPNG() < 0 ) {

return 0;

}

start = SDL_RWtell(src);

is_PNG = 0;

if ( SDL_RWread(src, buf, 1, PNG_BYTES_TO_CHECK) == PNG_BYTES_TO_CHECK ) {

}

SDL_RWseek(src, start, SEEK_SET);

}

/* Load a PNG type image from an SDL datasource */

static void png_read_data(png_structp ctx, png_bytep area, png_size_t size)

{

SDL_RWops *src;

SDL_RWread(src, area, size, 1);

}

SDL_Surface *IMG_LoadPNG_RW(SDL_RWops *src)

{

int start;

const char *error;

png_structp png_ptr;

png_infop info_ptr;

png_uint_32 width, height;

int bit_depth, color_type, interlace_type;

Uint32 Rmask;

Uint32 Gmask;

Uint32 Bmask;

Uint32 Amask;

SDL_Palette *palette;

png_color_16 *transv;

if ( !src ) {

/* The error message has been set in SDL_RWFromFile */

return NULL;

}

if ( IMG_InitPNG() < 0 ) {

return NULL;

}

png_ptr = NULL; info_ptr = NULL; row_pointers = NULL; surface = NULL;

/* Create the PNG loading context structure */

NULL,NULL,NULL);

if (png_ptr == NULL){

goto done;

}

/* Allocate/initialize the memory for image information. REQUIRED. */

goto done;

}

/* Set error handling if you are using setjmp/longjmp method (this is

* the normal method of doing things with libpng). REQUIRED unless you

* set up your own error handlers in png_create_read_struct() earlier.

*/

if ( setjmp(png_ptr->jmpbuf) ) {

goto done;

}

/* Set up the input control */

/* Read PNG header info */

lib.png_read_info(png_ptr, info_ptr);

lib.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 */

/* Extract multiple pixels with bit depths of 1, 2, and 4 from a single

* byte into separate bytes (useful for paletted and grayscale images).

*/

/* scale greyscale values to the range 0..255 */

if(color_type == PNG_COLOR_TYPE_GRAY)

/* For images with a single "transparent colour", set colour key;

if more than one index has transparency, or if partially transparent

entries exist, use full alpha channel */

int num_trans;

Uint8 *trans;

&transv);

if(color_type == PNG_COLOR_TYPE_PALETTE) {

/* Check if all tRNS entries are opaque except one */

int i, t = -1;

for(i = 0; i < num_trans; i++)

if(trans[i] == 0) {

if(t >= 0)

break;

t = i;

} else if(trans[i] != 255)

break;

if(i == num_trans) {

/* exactly one transparent index */

ckey = t;

} else {

/* more than one transparent index, or translucency */

} else

ckey = 0; /* actual value will be set later */

}

&color_type, &interlace_type, NULL, NULL);

/* Allocate the SDL surface to hold the image */

Rmask = Gmask = Bmask = Amask = 0 ;

if ( color_type != PNG_COLOR_TYPE_PALETTE ) {

if ( SDL_BYTEORDER == SDL_LIL_ENDIAN ) {

Rmask = 0x000000FF;

Gmask = 0x0000FF00;

Bmask = 0x00FF0000;

Amask = (info_ptr->channels == 4) ? 0xFF000000 : 0;

} else {

int s = (info_ptr->channels == 4) ? 0 : 8;

Rmask = 0xFF000000 >> s;

Gmask = 0x00FF0000 >> s;

Bmask = 0x0000FF00 >> s;

Amask = 0x000000FF >> s;

}

}

surface = SDL_AllocSurface(SDL_SWSURFACE, width, height,

bit_depth*info_ptr->channels, Rmask,Gmask,Bmask,Amask);

if ( surface == NULL ) {

goto done;

}

if(ckey != -1) {

if(color_type != PNG_COLOR_TYPE_PALETTE)

/* FIXME: Should these be truncated or shifted down? */

ckey = SDL_MapRGB(surface->format,

(Uint8)transv->red,

(Uint8)transv->green,

(Uint8)transv->blue);

SDL_SetColorKey(surface, SDL_SRCCOLORKEY, ckey);

}

/* Create the array of pointers to image data */

row_pointers = (png_bytep*) malloc(sizeof(png_bytep)*height);

if ( (row_pointers == NULL) ) {

goto done;

}

row_pointers[row] = (png_bytep)

(Uint8 *)surface->pixels + row*surface->pitch;

}

/* Read the entire image in one go */

/* and we're done! (png_read_end() can be omitted if no processing of

* post-IDAT text/time/etc. is desired)

* In some cases it can't read PNG's created by some popular programs (ACDSEE),

* we do not want to process comments, so we omit png_read_end

/* Load the palette, if any */

palette = surface->format->palette;

if ( palette ) {

if(color_type == PNG_COLOR_TYPE_GRAY) {

palette->ncolors = 256;

for(i = 0; i < 256; i++) {

palette->colors[i].r = i;

palette->colors[i].g = i;

palette->colors[i].b = i;

}

} else if (info_ptr->num_palette > 0 ) {

palette->ncolors = info_ptr->num_palette;

for( i=0; i<info_ptr->num_palette; ++i ) {

palette->colors[i].b = info_ptr->palette[i].blue;

palette->colors[i].g = info_ptr->palette[i].green;

palette->colors[i].r = info_ptr->palette[i].red;

}

done: /* Clean up and return */

if ( row_pointers ) {

free(row_pointers);

}

if ( error ) {

SDL_RWseek(src, start, SEEK_SET);

if ( surface ) {

SDL_FreeSurface(surface);

surface = NULL;

}

} else {

IMG_QuitPNG();

return(surface);

}

#else

/* See if an image is contained in a data source */

int IMG_isPNG(SDL_RWops *src)

{

return(0);

}

/* Load a PNG type image from an SDL datasource */

SDL_Surface *IMG_LoadPNG_RW(SDL_RWops *src)

{

return(NULL);

}

#endif /* LOAD_PNG */