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/*
* Copyright © 2005 Novell, Inc.
*
* Permission to use, copy, modify, distribute, and sell this software
* and its documentation for any purpose is hereby granted without
* fee, provided that the above copyright notice appear in all copies
* and that both that copyright notice and this permission notice
* appear in supporting documentation, and that the name of
* Novell, Inc. not be used in advertising or publicity pertaining to
* distribution of the software without specific, written prior permission.
* Novell, Inc. makes no representations about the suitability of this
* software for any purpose. It is provided "as is" without express or
* implied warranty.
*
* NOVELL, INC. DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
* INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN
* NO EVENT SHALL NOVELL, INC. BE LIABLE FOR ANY SPECIAL, INDIRECT OR
* CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS
* OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT,
* NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION
* WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*
* Author: David Reveman <davidr@novell.com>
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <png.h>
#include <setjmp.h>
#define FALSE 0
#define TRUE (!FALSE)
static void
premultiplyData (png_structp png,
png_row_infop row_info,
png_bytep data)
{
unsigned int i;
for (i = 0; i < row_info->rowbytes; i += 4)
{
unsigned char *base = &data[i];
unsigned char blue = base[0];
unsigned char green = base[1];
unsigned char red = base[2];
unsigned char alpha = base[3];
int p;
red = (unsigned) red * (unsigned) alpha / 255;
green = (unsigned) green * (unsigned) alpha / 255;
blue = (unsigned) blue * (unsigned) alpha / 255;
p = (alpha << 24) | (red << 16) | (green << 8) | (blue << 0);
memcpy (base, &p, sizeof (int));
}
}
int readPng(const char *filename,
char **data,
unsigned int *width,
unsigned int *height)
{
static const int PNG_SIG_SIZE = 8;
unsigned char png_sig[PNG_SIG_SIZE];
FILE *file;
int sig_bytes;
png_struct *png;
png_info *info;
png_uint_32 png_width, png_height;
int depth, color_type, interlace, i;
unsigned int pixel_size;
png_byte **row_pointers;
file = fopen (filename, "r");
if (!file)
{
fprintf(stderr, "Couldn't open file: '%s'\n", filename);
return FALSE;
}
sig_bytes = fread (png_sig, 1, PNG_SIG_SIZE, file);
if (png_check_sig (png_sig, sig_bytes) == 0)
{
fclose (file);
return FALSE;
}
png = png_create_read_struct (PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
if (!png)
{
fclose (file);
return FALSE;
}
info = png_create_info_struct (png);
if (info == NULL)
{
fclose (file);
png_destroy_read_struct (&png, NULL, NULL);
return FALSE;
}
png_init_io (png, file);
png_set_sig_bytes (png, sig_bytes);
png_read_info (png, info);
png_get_IHDR (png, info,
&png_width, &png_height, &depth,
&color_type, &interlace, NULL, NULL);
*width = png_width;
*height = png_height;
/* convert palette/gray image to rgb */
if (color_type == PNG_COLOR_TYPE_PALETTE)
png_set_palette_to_rgb (png);
/* expand gray bit depth if needed */
if (color_type == PNG_COLOR_TYPE_GRAY && depth < 8)
png_set_gray_1_2_4_to_8 (png);
/* transform transparency to alpha */
if (png_get_valid(png, info, PNG_INFO_tRNS))
png_set_tRNS_to_alpha (png);
if (depth == 16)
png_set_strip_16 (png);
if (depth < 8)
png_set_packing (png);
/* convert grayscale to RGB */
if (color_type == PNG_COLOR_TYPE_GRAY ||
color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
png_set_gray_to_rgb (png);
if (interlace != PNG_INTERLACE_NONE)
png_set_interlace_handling (png);
png_set_bgr (png);
png_set_filler (png, 0xff, PNG_FILLER_AFTER);
png_set_read_user_transform_fn (png, premultiplyData);
png_read_update_info (png, info);
pixel_size = 4;
*data = (char *) malloc (png_width * png_height * pixel_size);
if (*data == NULL)
{
fclose (file);
return FALSE;
}
row_pointers = (png_byte **) malloc (png_height * sizeof (char *));
for (i=0; i < png_height; i++)
row_pointers[i] = (png_byte *) (*data + i * png_width * pixel_size);
png_read_image (png, row_pointers);
png_read_end (png, info);
free (row_pointers);
fclose (file);
png_destroy_read_struct (&png, &info, NULL);
return TRUE;
}
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