/*
IMGLIB: An example image loading library for use with SDL
Copyright (C) 1999 Sam Lantinga
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
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
Sam Lantinga
5635-34 Springhouse Dr.
Pleasanton, CA 94588 (USA)
slouken@devolution.com
*/
/* 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
/* See if an image is contained in a data source */
int IMG_isPNG(SDL_RWops *src)
{
unsigned char buf[PNG_BYTES_TO_CHECK];
/* Read in the signature bytes */
if (SDL_RWread(src, buf, 1, PNG_BYTES_TO_CHECK) != PNG_BYTES_TO_CHECK)
return 0;
/* Compare the first PNG_BYTES_TO_CHECK bytes of the signature. */
return( !png_sig_cmp(buf, (png_size_t)0, PNG_BYTES_TO_CHECK));
}
/* 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;
src = (SDL_RWops *)png_get_io_ptr(ctx);
SDL_RWread(src, area, size, 1);
}
SDL_Surface *IMG_LoadPNG_RW(SDL_RWops *src)
{
SDL_Surface *volatile surface;
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_bytep *volatile row_pointers;
int row, i;
volatile int ckey = -1;
png_color_16 *transv;
/* Initialize the data we will clean up when we're done */
png_ptr = NULL; info_ptr = NULL; row_pointers = NULL; surface = NULL;
/* Check to make sure we have something to do */
if ( ! src ) {
goto done;
}
/* Create the PNG loading context structure */
png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING,
NULL,NULL,NULL);
if (png_ptr == NULL){
IMG_SetError("Couldn't allocate memory for PNG file");
goto done;
}
/* Allocate/initialize the memory for image information. REQUIRED. */
info_ptr = png_create_info_struct(png_ptr);
if (info_ptr == NULL) {
IMG_SetError("Couldn't create image information for PNG file");
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
) ) { IMG_SetError("Error reading the PNG file.");
goto done;
}
/* Set up the input control */
png_set_read_fn(png_ptr, src, png_read_data);
/* Read PNG header info */
png_read_info(png_ptr, info_ptr);
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 */
png_set_strip_16(png_ptr) ;
/* Extract multiple pixels with bit depths of 1, 2, and 4 from a single
* byte into separate bytes (useful for paletted and grayscale images).
*/
png_set_packing(png_ptr);
/* scale greyscale values to the range 0..255 */
if(color_type == PNG_COLOR_TYPE_GRAY)
png_set_expand(png_ptr);
/* For images with a single "transparent colour", set colour key;
if more than one index has transparency, use full alpha channel */
if (png_get_valid(png_ptr, info_ptr, PNG_INFO_tRNS)) {
int num_trans;
Uint8 *trans;
png_get_tRNS(png_ptr, info_ptr, &trans, &num_trans,
&transv);
if(color_type == PNG_COLOR_TYPE_PALETTE) {
if(num_trans == 1) {
/* exactly one transparent value: set colour key */
ckey = trans[0];
} else
png_set_expand(png_ptr);
} else
ckey = 0; /* actual value will be set later */
}
if ( color_type == PNG_COLOR_TYPE_GRAY_ALPHA )
png_set_gray_to_rgb(png_ptr);
png_read_update_info(png_ptr, info_ptr);
png_get_IHDR(png_ptr, info_ptr, &width, &height, &bit_depth,
&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 ) {
IMG_SetError("Out of memory");
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) ) {
IMG_SetError("Out of memory");
SDL_FreeSurface(surface);
surface = NULL;
goto done;
}
for (row = 0; row < (int)height; row++) {
row_pointers[row] = (png_bytep)
(Uint8 *)surface->pixels + row*surface->pitch;
}
/* Read the entire image in one go */
png_read_image(png_ptr, row_pointers);
/* read rest of file, get additional chunks in info_ptr - REQUIRED */
png_read_end(png_ptr, info_ptr);
/* 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 */
png_destroy_read_struct(&png_ptr, info_ptr ? &info_ptr : (png_infopp)0,
(png_infopp)0);
if ( row_pointers ) {
}
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 */