gtk/gdk-pixbuf/io-png.c

/*
 * io-png.c: GdkPixbuf I/O for PNG files.
 * Copyright (C) 1999 Mark Crichton
 * Author: Mark Crichton <crichton@gimp.org>
 *
 * 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., 59 Temple Place - Suite 330, Cambridge, MA 02139, USA.
 *
 */
#include <config.h>
#include <stdio.h>
#include <glib.h>
#include "gdk-pixbuf.h"
#include "gdk-pixbuf-io.h"
#include <png.h>

/* Shared library entry point */
GdkPixbuf *
image_load (FILE *f)
{
	png_structp png_ptr;
	png_infop info_ptr, end_info;
	gint i, depth, ctype, inttype, passes, bpp;		/* bpp = BYTES/pixel */
	png_uint_32 w, h, x, y;
	png_bytepp rows;
	art_u8 *pixels, *temp, *rowdata;
	GdkPixbuf *pixbuf;
	ArtPixBuf *art_pixbuf;

	g_return_val_if_fail (f != NULL, NULL);

	png_ptr = png_create_read_struct (PNG_LIBPNG_VER_STRING,
					  NULL, NULL, NULL);
	if (!png_ptr)
		return NULL;

	info_ptr = png_create_info_struct (png_ptr);
	if (!info_ptr) {
		png_destroy_read_struct (&png_ptr, NULL, NULL);
		return NULL;
	}

	end_info = png_create_info_struct (png_ptr);
	if (!end_info) {
		png_destroy_read_struct (&png_ptr, &info_ptr, NULL);
		return NULL;
	}

	if (setjmp (png_ptr->jmpbuf)) {
		png_destroy_read_struct (&png_ptr, &info_ptr, &end_info);
		return NULL;
	}

	png_init_io   (png_ptr, f);
	png_read_info (png_ptr, info_ptr);
	png_get_IHDR  (png_ptr, info_ptr, &w, &h, &depth, &ctype, &inttype,
		       NULL, NULL);

	/* Ok, we want to work with 24 bit images.
	 * However, PNG can vary depth per channel.
	 * So, we use the png_set_expand function to expand
	 * everything into a format libart expects.
	 * We also use png_set_strip_16 to reduce down to 8 bit/chan.
	 */
	if (ctype == PNG_COLOR_TYPE_PALETTE && depth <= 8)
		png_set_expand (png_ptr);

	if (ctype == PNG_COLOR_TYPE_GRAY && depth < 8)
		png_set_expand (png_ptr);

	if (png_get_valid (png_ptr, info_ptr, PNG_INFO_tRNS)) {
		png_set_expand (png_ptr);
		g_warning ("FIXME: We are going to crash");
	}

	if (depth == 16)
		png_set_strip_16 (png_ptr);

	/* We also have png "packing" bits into bytes if < 8 */
	if (depth < 8)
		png_set_packing (png_ptr);

	/* Lastly, if the PNG is greyscale, convert to RGB */
	if (ctype == PNG_COLOR_TYPE_GRAY || ctype == PNG_COLOR_TYPE_GRAY_ALPHA)
		png_set_gray_to_rgb (png_ptr);

	/* ...and if we're interlaced... */
	passes = png_set_interlace_handling (png_ptr);

	/* Update our info structs */
	png_read_update_info (png_ptr, info_ptr);

	/* Allocate some memory and set up row array */
	/* This "inhales vigorously"... */
	if (ctype & PNG_COLOR_MASK_ALPHA)
		bpp = 4;
	else
		bpp = 3;

	pixels = art_alloc (w * h * bpp);
	rows   = g_malloc  (h * sizeof(png_bytep));

	if (!pixels || !rows) {
		png_destroy_read_struct (&png_ptr, &info_ptr, &end_info);
		return NULL;
	}
	/* Icky code, but it has to be done... */
	for (i = 0; i < h; i++) {
		if ((rows[i] = g_malloc (w * sizeof (art_u8) * bpp)) == NULL) {
			int n;
			for (n = 0; n < i; n++)
				g_free (rows[i]);
			g_free (rows);
			art_free (pixels);
			png_destroy_read_struct (&png_ptr, &info_ptr, &end_info);
			return NULL;
		}
	}

	/* And we FINALLY get here... */
	png_read_image (png_ptr, rows);
	png_destroy_read_struct (&png_ptr, &info_ptr, &end_info);

	/* Now stuff the bytes into pixels & free rows[y] */

	temp = pixels;

	for (y = 0; y < h; y++) {
		(png_bytep) rowdata = rows[y];
		for (x = 0; x < w; x++) {
			temp[0] = rowdata[(x * bpp)];
			temp[1] = rowdata[(x * bpp) + 1];
			temp[2] = rowdata[(x * bpp) + 2];
			if (bpp == 4)
				temp[3] = rowdata[(x * bpp) + 3];
			temp += bpp;
		}
		g_free (rows[y]);
	}
	g_free (rows);

	if (ctype & PNG_COLOR_MASK_ALPHA)
		art_pixbuf = art_pixbuf_new_rgba (pixels, w, h, (w * 4));
	else
		art_pixbuf = art_pixbuf_new_rgb  (pixels, w, h, (w * 3));

	pixbuf = gdk_pixbuf_new (art_pixbuf, NULL);

	if (!pixbuf)
		art_free (pixels);

	return pixbuf;
}

int
image_save (GdkPixbuf *pixbuf, FILE *file)
{
	png_structp png_ptr;
	png_infop info_ptr;
	art_u8 *data;
	gint y, h, w;
	png_bytepp row_ptr;
	png_color_8 sig_bit;
	gint type;

	g_return_val_if_fail(file != NULL, FALSE);
	g_return_val_if_fail(pixbuf != NULL, FALSE);

	h = pixbuf->art_pixbuf->height;
	w = pixbuf->art_pixbuf->width;

	png_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING,
					  NULL, NULL, NULL);
	if (png_ptr == NULL) {
		fclose(file);
		return FALSE;
	}

	info_ptr = png_create_info_struct(png_ptr);
	if (info_ptr == NULL) {
		fclose(file);
		png_destroy_write_struct(&png_ptr, (png_infopp) NULL);
		return FALSE;
	}

	if (setjmp(png_ptr->jmpbuf)) {
		fclose(file);
		png_destroy_write_struct(&png_ptr, (png_infopp) NULL);
		return FALSE;
	}

	png_init_io(png_ptr, file);
	if (pixbuf->art_pixbuf->has_alpha) {
		sig_bit.alpha = 8;
		type = PNG_COLOR_TYPE_RGB_ALPHA;
	} else {
		sig_bit.alpha = 0;
		type = PNG_COLOR_TYPE_RGB;
	}

	sig_bit.red = sig_bit.green = sig_bit.blue = 8;
	png_set_IHDR(png_ptr, info_ptr, w, h, 8, type, PNG_INTERLACE_NONE,
		     PNG_COMPRESSION_TYPE_BASE, PNG_FILTER_TYPE_BASE);
	png_set_sBIT(png_ptr, info_ptr, &sig_bit);
	png_write_info(png_ptr, info_ptr);
	png_set_shift(png_ptr, &sig_bit);
	png_set_packing(png_ptr);

	data = pixbuf->art_pixbuf->pixels;
	row_ptr = g_new(png_byte *, h);

	for (y = 0; y < h; y++)
		row_ptr[y] = data + y * pixbuf->art_pixbuf->rowstride;
#if 0
	{
		if (pixbuf->art_pixbuf->has_alpha)
			row_ptr[y] = data + (w * y * 4);
		else
			row_ptr[y] = data + (w * y * 3);
	}
#endif

	png_write_image(png_ptr, row_ptr);
	g_free (row_ptr);

	png_write_end(png_ptr, info_ptr);
	png_destroy_write_struct(&png_ptr, (png_infopp) NULL);

	return TRUE;
}