287 lines
8.5 KiB
C
287 lines
8.5 KiB
C
/*
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IMGLIB: An example image loading library for use with SDL
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Copyright (C) 1999 Sam Lantinga
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This library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Library General Public
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License as published by the Free Software Foundation; either
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version 2 of the License, or (at your option) any later version.
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This library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Library General Public License for more details.
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You should have received a copy of the GNU Library General Public
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License along with this library; if not, write to the Free
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Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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Sam Lantinga
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5635-34 Springhouse Dr.
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Pleasanton, CA 94588 (USA)
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slouken@devolution.com
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*/
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/* This is a PNG image file loading framework */
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#include <stdlib.h>
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#include <stdio.h>
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#include "SDL_image.h"
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#ifdef LOAD_PNG
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/*=============================================================================
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File: SDL_png.c
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Purpose: A PNG loader and saver for the SDL library
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Revision:
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Created by: Philippe Lavoie (2 November 1998)
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lavoie@zeus.genie.uottawa.ca
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Modified by:
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Copyright notice:
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Copyright (C) 1998 Philippe Lavoie
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This library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Library General Public
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License as published by the Free Software Foundation; either
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version 2 of the License, or (at your option) any later version.
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This library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Library General Public License for more details.
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You should have received a copy of the GNU Library General Public
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License along with this library; if not, write to the Free
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Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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Comments: The load and save routine are basically the ones you can find
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in the example.c file from the libpng distribution.
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Changes:
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5/17/99 - Modified to use the new SDL data sources - Sam Lantinga
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=============================================================================*/
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#include "SDL_endian.h"
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#ifdef macintosh
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#define MACOS
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#endif
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#include <png.h>
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#define PNG_BYTES_TO_CHECK 4
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/* See if an image is contained in a data source */
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int IMG_isPNG(SDL_RWops *src)
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{
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unsigned char buf[PNG_BYTES_TO_CHECK];
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/* Read in the signature bytes */
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if (SDL_RWread(src, buf, 1, PNG_BYTES_TO_CHECK) != PNG_BYTES_TO_CHECK)
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return 0;
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/* Compare the first PNG_BYTES_TO_CHECK bytes of the signature. */
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return( !png_sig_cmp(buf, (png_size_t)0, PNG_BYTES_TO_CHECK));
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}
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/* Load a PNG type image from an SDL datasource */
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static void png_read_data(png_structp ctx, png_bytep area, png_size_t size)
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{
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SDL_RWops *src;
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src = (SDL_RWops *)png_get_io_ptr(ctx);
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SDL_RWread(src, area, size, 1);
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}
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SDL_Surface *IMG_LoadPNG_RW(SDL_RWops *src)
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{
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SDL_Surface *volatile surface;
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png_structp png_ptr;
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png_infop info_ptr;
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png_uint_32 width, height;
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int bit_depth, color_type, interlace_type;
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Uint32 Rmask;
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Uint32 Gmask;
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Uint32 Bmask;
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Uint32 Amask;
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SDL_Palette *palette;
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png_bytep *volatile row_pointers;
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int row, i;
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volatile int ckey = -1;
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png_color_16 *transv;
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/* Initialize the data we will clean up when we're done */
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png_ptr = NULL; info_ptr = NULL; row_pointers = NULL; surface = NULL;
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/* Check to make sure we have something to do */
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if ( ! src ) {
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goto done;
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}
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/* Create the PNG loading context structure */
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png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING,
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NULL,NULL,NULL);
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if (png_ptr == NULL){
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IMG_SetError("Couldn't allocate memory for PNG file");
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goto done;
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}
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/* Allocate/initialize the memory for image information. REQUIRED. */
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info_ptr = png_create_info_struct(png_ptr);
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if (info_ptr == NULL) {
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IMG_SetError("Couldn't create image information for PNG file");
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goto done;
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}
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/* Set error handling if you are using setjmp/longjmp method (this is
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* the normal method of doing things with libpng). REQUIRED unless you
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* set up your own error handlers in png_create_read_struct() earlier.
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*/
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if ( setjmp(png_ptr->jmpbuf) ) {
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IMG_SetError("Error reading the PNG file.");
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goto done;
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}
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/* Set up the input control */
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png_set_read_fn(png_ptr, src, png_read_data);
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/* Read PNG header info */
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png_read_info(png_ptr, info_ptr);
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png_get_IHDR(png_ptr, info_ptr, &width, &height, &bit_depth,
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&color_type, &interlace_type, NULL, NULL);
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/* tell libpng to strip 16 bit/color files down to 8 bits/color */
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png_set_strip_16(png_ptr) ;
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/* Extract multiple pixels with bit depths of 1, 2, and 4 from a single
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* byte into separate bytes (useful for paletted and grayscale images).
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*/
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png_set_packing(png_ptr);
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/* scale greyscale values to the range 0..255 */
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if(color_type == PNG_COLOR_TYPE_GRAY)
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png_set_expand(png_ptr);
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/* For images with a single "transparent colour", set colour key;
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if more than one index has transparency, use full alpha channel */
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if (png_get_valid(png_ptr, info_ptr, PNG_INFO_tRNS)) {
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int num_trans;
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Uint8 *trans;
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png_get_tRNS(png_ptr, info_ptr, &trans, &num_trans,
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&transv);
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if(color_type == PNG_COLOR_TYPE_PALETTE) {
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if(num_trans == 1) {
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/* exactly one transparent value: set colour key */
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ckey = trans[0];
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} else
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png_set_expand(png_ptr);
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} else
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ckey = 0; /* actual value will be set later */
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}
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if ( color_type == PNG_COLOR_TYPE_GRAY_ALPHA )
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png_set_gray_to_rgb(png_ptr);
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png_read_update_info(png_ptr, info_ptr);
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png_get_IHDR(png_ptr, info_ptr, &width, &height, &bit_depth,
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&color_type, &interlace_type, NULL, NULL);
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/* Allocate the SDL surface to hold the image */
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Rmask = Gmask = Bmask = Amask = 0 ;
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if ( color_type != PNG_COLOR_TYPE_PALETTE ) {
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if ( SDL_BYTEORDER == SDL_LIL_ENDIAN ) {
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Rmask = 0x000000FF;
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Gmask = 0x0000FF00;
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Bmask = 0x00FF0000;
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Amask = (info_ptr->channels == 4) ? 0xFF000000 : 0;
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} else {
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int s = (info_ptr->channels == 4) ? 0 : 8;
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Rmask = 0xFF000000 >> s;
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Gmask = 0x00FF0000 >> s;
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Bmask = 0x0000FF00 >> s;
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Amask = 0x000000FF >> s;
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}
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}
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surface = SDL_AllocSurface(SDL_SWSURFACE, width, height,
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bit_depth*info_ptr->channels, Rmask,Gmask,Bmask,Amask);
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if ( surface == NULL ) {
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IMG_SetError("Out of memory");
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goto done;
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}
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if(ckey != -1) {
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if(color_type != PNG_COLOR_TYPE_PALETTE)
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/* FIXME: Should these be truncated or shifted down? */
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ckey = SDL_MapRGB(surface->format,
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(Uint8)transv->red,
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(Uint8)transv->green,
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(Uint8)transv->blue);
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SDL_SetColorKey(surface, SDL_SRCCOLORKEY, ckey);
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}
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/* Create the array of pointers to image data */
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row_pointers = (png_bytep*) malloc(sizeof(png_bytep)*height);
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if ( (row_pointers == NULL) ) {
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IMG_SetError("Out of memory");
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SDL_FreeSurface(surface);
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surface = NULL;
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goto done;
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}
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for (row = 0; row < (int)height; row++) {
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row_pointers[row] = (png_bytep)
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(Uint8 *)surface->pixels + row*surface->pitch;
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}
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/* Read the entire image in one go */
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png_read_image(png_ptr, row_pointers);
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/* read rest of file, get additional chunks in info_ptr - REQUIRED */
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png_read_end(png_ptr, info_ptr);
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/* Load the palette, if any */
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palette = surface->format->palette;
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if ( palette ) {
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if(color_type == PNG_COLOR_TYPE_GRAY) {
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palette->ncolors = 256;
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for(i = 0; i < 256; i++) {
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palette->colors[i].r = i;
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palette->colors[i].g = i;
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palette->colors[i].b = i;
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}
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} else if (info_ptr->num_palette > 0 ) {
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palette->ncolors = info_ptr->num_palette;
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for( i=0; i<info_ptr->num_palette; ++i ) {
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palette->colors[i].b = info_ptr->palette[i].blue;
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palette->colors[i].g = info_ptr->palette[i].green;
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palette->colors[i].r = info_ptr->palette[i].red;
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}
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}
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}
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done: /* Clean up and return */
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png_destroy_read_struct(&png_ptr, info_ptr ? &info_ptr : (png_infopp)0,
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(png_infopp)0);
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if ( row_pointers ) {
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free(row_pointers);
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}
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return(surface);
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}
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#else
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/* See if an image is contained in a data source */
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int IMG_isPNG(SDL_RWops *src)
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{
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return(0);
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}
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/* Load a PNG type image from an SDL datasource */
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SDL_Surface *IMG_LoadPNG_RW(SDL_RWops *src)
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{
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return(NULL);
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}
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#endif /* LOAD_PNG */
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