/*
	png.c

	PNG image handling

	Copyright (C) 2003 Harry Roberts

	This program is free software; you can redistribute it and/or
	modify it under the terms of the GNU General Public License
	as published by the Free Software Foundation; either version 2
	of the License, or (at your option) any later version.

	This program 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 General Public License for more details.

	You should have received a copy of the GNU General Public License
	along with this program; if not, write to:

		Free Software Foundation, Inc.
		59 Temple Place - Suite 330
		Boston, MA  02111-1307, USA

*/
#ifdef HAVE_CONFIG_H
# include "config.h"
#endif

static __attribute__ ((unused)) const char rcsid[] = 
	"$Id$";

#ifdef HAVE_STRING_H
# include <string.h>
#endif
#ifdef HAVE_STRINGS_H
# include <strings.h>
#endif

#include <png.h>

#include "QF/image.h"
#include "QF/png.h"
#include "QF/qendian.h"
#include "QF/qtypes.h"
#include "QF/quakefs.h"
#include "QF/sys.h"
#include "QF/zone.h"

#include "compat.h"

typedef unsigned char	uch;
typedef unsigned short	ush;
typedef unsigned long	ulg;

/* Qread wrapper for libpng */
static void 
user_read_data (png_structp png_ptr, png_bytep data, png_size_t length)
{
	Qread ((QFile *) png_get_io_ptr (png_ptr), data, length);
}

/* Basicly taken from the libpng example rpng-x */
static int
readpng_init (QFile *infile, png_structp *png_ptr, png_infop *info_ptr)
{
	uch sig[8];

	/* Check the signiture */
	Qread (infile, sig, 8);
	if (!png_check_sig(sig, 8)) {
		Sys_Printf ("Bad png file\n");
		return (1);
	}

	*png_ptr = png_create_read_struct (PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
	if (!*png_ptr)
		return (2); /* Out of memory! */

	*info_ptr = png_create_info_struct (*png_ptr);
	if (!*info_ptr) {
		png_destroy_read_struct (png_ptr, NULL, NULL);
		return (3); /* Out of memory! */
	}

	/* setjmp() must be called in every function that calls a PNG-reading
	 * libpng function */

	if (setjmp(png_jmpbuf(*png_ptr))) {
		png_destroy_read_struct (png_ptr, info_ptr, NULL);
		return (4);
	}
	
	png_set_read_fn (*png_ptr, infile, user_read_data);
	
	/* Is png_set_sig_bytes needed? */
	png_set_sig_bytes (*png_ptr, 8); // We allready read the 8 signiture bytes

	png_read_info (*png_ptr, *info_ptr);//read all png info upto the image data

	return (0);
}

/* Load the png file and return a texture */
tex_t *
LoadPNG (QFile *infile)
{
	double gamma;
	png_structp png_ptr = NULL;
	png_infop info_ptr = NULL;
	png_uint_32  i, rowbytes;
	png_bytepp  row_pointers = NULL;
	png_uint_32 width, height;
	int bit_depth, color_type;
	tex_t *tex;
	
	if (readpng_init(infile, &png_ptr, &info_ptr) != 0)
		return (NULL);
		
	png_get_IHDR(png_ptr, info_ptr, &width, &height, &bit_depth, &color_type, NULL, NULL, NULL);
	
	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);
		
	if (bit_depth == 16)
		png_set_strip_16 (png_ptr);
	
	if (color_type == PNG_COLOR_TYPE_GRAY || color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
		png_set_gray_to_rgb (png_ptr);
	
	/* NOTE: gamma support? */
	/* unlike the example in the libpng documentation, we have *no* idea where
	 * this file may have come from--so if it doesn't have a file gamma, don't
	 * do any correction ("do no harm")
	 */
	if (!png_get_gAMA(png_ptr, info_ptr, &gamma))
		png_set_gamma (png_ptr, 1.0, gamma);

	/* All transformations have been registered, now update the info_ptr structure */		
	png_read_update_info (png_ptr, info_ptr);
	
	/* Allocate tex_t structure */
	rowbytes = png_get_rowbytes(png_ptr, info_ptr);
	tex = Hunk_TempAlloc (field_offset (tex_t, data[height * rowbytes]));	
	
	tex->width = width;
	tex->height = height;
	if (color_type & PNG_COLOR_MASK_ALPHA)
		tex->format = tex_rgba;
	else
		tex->format = tex_rgb;
	tex->palette = NULL;
	
	if ((row_pointers = (png_bytepp)malloc(height * sizeof(png_bytep))) == NULL) {
		png_destroy_read_struct (&png_ptr, &info_ptr, NULL);
		return (NULL); /* Out of memory */
	}
	
	for (i = 0; i < height; ++i)
		row_pointers[i] = tex->data + (i * rowbytes);
		
	/* Now we can go ahead and read the whole image */
	png_read_image(png_ptr, row_pointers);
	
	free(row_pointers);
	row_pointers = NULL;

	png_read_end(png_ptr, NULL);
		
	return (tex);
}