IMG_savepng.c

/*
  Based on zlib license - see http://www.gzip.org/zlib/zlib_license.html

  This software is provided 'as-is', without any express or implied
  warranty.  In no event will the authors be held liable for any damages
  arising from the use of this software.

  Permission is granted to anyone to use this software for any purpose,
  including commercial applications, and to alter it and redistribute it
  freely, subject to the following restrictions:

  1. The origin of this software must not be misrepresented; you must not
     claim that you wrote the original software. If you use this software
     in a product, an acknowledgment in the product documentation would be
     appreciated but is not required.
  2. Altered source versions must be plainly marked as such, and must not be
     misrepresented as being the original software.
  3. This notice may not be removed or altered from any source distribution.

  "Philip D. Bober" <wildfire1138@mchsi.com>
*/

/**
 * 4/17/04 - IMG_SavePNG & IMG_SavePNG_RW - Philip D. Bober
 * 11/08/2004 - Compr fix, levels -1,1-7 now work - Tyler Montbriand
 */
#include <stdlib.h>
#include <SDL/SDL.h>
#include <SDL/SDL_byteorder.h>
#include <png.h>
#include "IMG_savepng.h"

int IMG_SavePNG(const char *file, SDL_Surface *surf,int compression){
	SDL_RWops *fp;
	int ret;
	
	fp=SDL_RWFromFile(file,"wb");

	if( fp == NULL ) {
		return (-1);
	}

	ret=IMG_SavePNG_RW(fp,surf,compression);
	SDL_RWclose(fp);
	return ret;
}

static void png_write_data(png_structp png_ptr,png_bytep data, png_size_t length){
	SDL_RWops *rp = (SDL_RWops*) png_get_io_ptr(png_ptr);
	SDL_RWwrite(rp,data,1,length);
}

int IMG_SavePNG_RW(SDL_RWops *src, SDL_Surface *surf,int compression){
	png_structp png_ptr;
	png_infop info_ptr;
	SDL_PixelFormat *fmt=NULL;
	SDL_Surface *tempsurf=NULL;
	int ret,funky_format,used_alpha;
	unsigned int i,temp_alpha;
	png_colorp palette;
	Uint8 *palette_alpha=NULL;
	png_byte **row_pointers=NULL;
	png_ptr=NULL;info_ptr=NULL;palette=NULL;ret=-1;
	funky_format=0;
	
	if( !src || !surf) {
		goto savedone; /* Nothing to do. */
	}

	row_pointers=(png_byte **)malloc(surf->h * sizeof(png_byte*));
	if (!row_pointers) { 
		SDL_SetError("Couldn't allocate memory for rowpointers");
		goto savedone;
	}
	
	png_ptr=png_create_write_struct(PNG_LIBPNG_VER_STRING, NULL,NULL,NULL);
	if (!png_ptr){
		SDL_SetError("Couldn't allocate memory for PNG file");
		goto savedone;
	}
	info_ptr= png_create_info_struct(png_ptr);
	if (!info_ptr){
		SDL_SetError("Couldn't allocate image information for PNG file");
		goto savedone;
	}
	/* setup custom writer functions */
	png_set_write_fn(png_ptr,(voidp)src,png_write_data,NULL);

	if (setjmp(png_jmpbuf(png_ptr))){
		SDL_SetError("Unknown error writing PNG");
		goto savedone;
	}

	if(compression>Z_BEST_COMPRESSION)
		compression=Z_BEST_COMPRESSION;

	if(compression == Z_NO_COMPRESSION) // No compression
	{
		png_set_filter(png_ptr,0,PNG_FILTER_NONE);
		png_set_compression_level(png_ptr,Z_NO_COMPRESSION);
	}
        else if(compression<0) // Default compression
		png_set_compression_level(png_ptr,Z_DEFAULT_COMPRESSION);
        else
		png_set_compression_level(png_ptr,compression);

	fmt=surf->format;
	if(fmt->BitsPerPixel==8){ /* Paletted */
		png_set_IHDR(png_ptr,info_ptr,
			surf->w,surf->h,8,PNG_COLOR_TYPE_PALETTE,
			PNG_INTERLACE_NONE,PNG_COMPRESSION_TYPE_DEFAULT,
			PNG_FILTER_TYPE_DEFAULT);
		palette=(png_colorp) malloc(fmt->palette->ncolors * sizeof(png_color));
		if (!palette) {
			SDL_SetError("Couldn't create memory for palette");
			goto savedone;
		}
		for (i=0;i<fmt->palette->ncolors;i++) {
			palette[i].red=fmt->palette->colors[i].r;
			palette[i].green=fmt->palette->colors[i].g;
			palette[i].blue=fmt->palette->colors[i].b;
		}
		png_set_PLTE(png_ptr,info_ptr,palette,fmt->palette->ncolors);
		if (surf->flags&SDL_SRCCOLORKEY) {
			palette_alpha=(Uint8 *)malloc((fmt->colorkey+1)*sizeof(Uint8));
			if (!palette_alpha) {
				SDL_SetError("Couldn't create memory for palette transparency");
				goto savedone;
			}
			/* FIXME: memset? */
			for (i=0;i<(fmt->colorkey+1);i++) {
				palette_alpha[i]=255;
			}
			palette_alpha[fmt->colorkey]=0;
			png_set_tRNS(png_ptr,info_ptr,palette_alpha,fmt->colorkey+1,NULL);
		}
	}else{ /* Truecolor */
		if (fmt->Amask) {
			png_set_IHDR(png_ptr,info_ptr,
				surf->w,surf->h,8,PNG_COLOR_TYPE_RGB_ALPHA,
				PNG_INTERLACE_NONE,PNG_COMPRESSION_TYPE_DEFAULT,
				PNG_FILTER_TYPE_DEFAULT);
		} else {
			png_set_IHDR(png_ptr,info_ptr,
				surf->w,surf->h,8,PNG_COLOR_TYPE_RGB,
				PNG_INTERLACE_NONE,PNG_COMPRESSION_TYPE_DEFAULT,
				PNG_FILTER_TYPE_DEFAULT);
		}
	}
	png_write_info(png_ptr, info_ptr);

	if (fmt->BitsPerPixel==8) { /* Paletted */
		for(i=0;i<surf->h;i++){
			row_pointers[i]= ((png_byte*)surf->pixels) + i*surf->pitch;
		}
		if(SDL_MUSTLOCK(surf)){
			SDL_LockSurface(surf);
		}
		png_write_image(png_ptr, row_pointers);
		if(SDL_MUSTLOCK(surf)){
			SDL_UnlockSurface(surf);
		}
	}else{ /* Truecolor */
		if(fmt->BytesPerPixel==3){
			if(fmt->Amask){ /* check for 24 bit with alpha */
				funky_format=1;
			}else{
				/* Check for RGB/BGR/GBR/RBG/etc surfaces.*/
#if SDL_BYTEORDER == SDL_BIG_ENDIAN
				if(fmt->Rmask!=0xFF0000 
				|| fmt->Gmask!=0x00FF00
				|| fmt->Bmask!=0x0000FF){
#else
				if(fmt->Rmask!=0x0000FF 
				|| fmt->Gmask!=0x00FF00
				|| fmt->Bmask!=0xFF0000){
#endif
					funky_format=1;
				}
			}
		}else if (fmt->BytesPerPixel==4){
			if (!fmt->Amask) { /* check for 32bit but no alpha */
				funky_format=1; 
			}else{
				/* Check for ARGB/ABGR/GBAR/RABG/etc surfaces.*/
#if SDL_BYTEORDER == SDL_BIG_ENDIAN
				if(fmt->Rmask!=0xFF000000
				|| fmt->Gmask!=0x00FF0000
				|| fmt->Bmask!=0x0000FF00
				|| fmt->Amask!=0x000000FF){
#else
				if(fmt->Rmask!=0x000000FF
				|| fmt->Gmask!=0x0000FF00
				|| fmt->Bmask!=0x00FF0000
				|| fmt->Amask!=0xFF000000){
#endif
					funky_format=1;
				}
			}
		}else{ /* 555 or 565 16 bit color */
			funky_format=1;
		}
		if (funky_format) {
			/* Allocate non-funky format, and copy pixeldata in*/
			if(fmt->Amask){
#if SDL_BYTEORDER == SDL_BIG_ENDIAN
				tempsurf = SDL_CreateRGBSurface(SDL_SWSURFACE, surf->w, surf->h, 24,
										0xff000000, 0x00ff0000, 0x0000ff00, 0x000000ff);
#else
				tempsurf = SDL_CreateRGBSurface(SDL_SWSURFACE, surf->w, surf->h, 24,
										0x000000ff, 0x0000ff00, 0x00ff0000, 0xff000000);
#endif
			}else{
#if SDL_BYTEORDER == SDL_BIG_ENDIAN
				tempsurf = SDL_CreateRGBSurface(SDL_SWSURFACE, surf->w, surf->h, 24,
										0xff0000, 0x00ff00, 0x0000ff, 0x00000000);
#else
				tempsurf = SDL_CreateRGBSurface(SDL_SWSURFACE, surf->w, surf->h, 24,
										0x000000ff, 0x0000ff00, 0x00ff0000, 0x00000000);
#endif
			}
			if(!tempsurf){
				SDL_SetError("Couldn't allocate temp surface");
				goto savedone;
			}
			if(surf->flags&SDL_SRCALPHA){
				temp_alpha=fmt->alpha;
				used_alpha=1;
				SDL_SetAlpha(surf,0,255); /* Set for an opaque blit */
			}else{
				used_alpha=0;
			}
			if(SDL_BlitSurface(surf,NULL,tempsurf,NULL)!=0){
				SDL_SetError("Couldn't blit surface to temp surface");
				SDL_FreeSurface(tempsurf);
				goto savedone;
			}
			if (used_alpha) {
				SDL_SetAlpha(surf,SDL_SRCALPHA,(Uint8)temp_alpha); /* Restore alpha settings*/
			}
			for(i=0;i<tempsurf->h;i++){
				row_pointers[i]= ((png_byte*)tempsurf->pixels) + i*tempsurf->pitch;
			}
			if(SDL_MUSTLOCK(tempsurf)){
				SDL_LockSurface(tempsurf);
			}
			png_write_image(png_ptr, row_pointers);
			if(SDL_MUSTLOCK(tempsurf)){
				SDL_UnlockSurface(tempsurf);
			}
			SDL_FreeSurface(tempsurf);
		} else {
			for(i=0;i<surf->h;i++){
				row_pointers[i]= ((png_byte*)surf->pixels) + i*surf->pitch;
			}
			if(SDL_MUSTLOCK(surf)){
				SDL_LockSurface(surf);
			}
			png_write_image(png_ptr, row_pointers);
			if(SDL_MUSTLOCK(surf)){
				SDL_UnlockSurface(surf);
			}
		}
	}

	png_write_end(png_ptr, NULL);
	ret=0; /* got here, so nothing went wrong. YAY! */

savedone: /* clean up and return */
	png_destroy_write_struct(&png_ptr,&info_ptr);
	if (palette) {
		free(palette);
	}
	if (palette_alpha) {
		free(palette_alpha);
	}
	if (row_pointers) {
		free(row_pointers);
	}
	return ret;
}