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/* GXPSPngWriter
*
* Copyright (C) 2011 Carlos Garcia Campos <carlosgc@gnome.org>
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include <config.h>
#include "gxps-png-writer.h"
#include <png.h>
#include <stdint.h>
#include <string.h>
/* starting with libpng15, png.h no longer #includes zlib.h */
#ifndef Z_BEST_COMPRESSION
#define Z_BEST_COMPRESSION 9
#endif
struct _GXPSPngWriter {
GObject parent;
GXPSPngFormat format;
png_structp png_ptr;
png_infop info_ptr;
};
struct _GXPSPngWriterClass {
GObjectClass parent_class;
};
static void gxps_png_writer_image_writer_iface_init (GXPSImageWriterInterface *iface);
G_DEFINE_TYPE_WITH_CODE (GXPSPngWriter, gxps_png_writer, G_TYPE_OBJECT,
G_IMPLEMENT_INTERFACE (GXPS_TYPE_IMAGE_WRITER,
gxps_png_writer_image_writer_iface_init))
static void
gxps_png_writer_init (GXPSPngWriter *png_writer)
{
}
static void
gxps_png_writer_class_init (GXPSPngWriterClass *klass)
{
}
GXPSImageWriter *
gxps_png_writer_new (GXPSPngFormat format)
{
GXPSPngWriter *png_writer = GXPS_PNG_WRITER (g_object_new (GXPS_TYPE_PNG_WRITER, NULL));
png_writer->format = format;
return GXPS_IMAGE_WRITER (png_writer);
}
/* Unpremultiplies data and converts native endian ARGB => RGBA bytes */
static void
unpremultiply_data (png_structp png, png_row_infop row_info, png_bytep data)
{
unsigned int i;
for (i = 0; i < row_info->rowbytes; i += 4) {
uint8_t *b = &data[i];
uint32_t pixel;
uint8_t alpha;
memcpy (&pixel, b, sizeof (uint32_t));
alpha = (pixel & 0xff000000) >> 24;
if (alpha == 0) {
b[0] = b[1] = b[2] = b[3] = 0;
} else {
b[0] = (((pixel & 0xff0000) >> 16) * 255 + alpha / 2) / alpha;
b[1] = (((pixel & 0x00ff00) >> 8) * 255 + alpha / 2) / alpha;
b[2] = (((pixel & 0x0000ff) >> 0) * 255 + alpha / 2) / alpha;
b[3] = alpha;
}
}
}
/* Converts native endian xRGB => RGBx bytes */
static void
convert_data_to_bytes (png_structp png, png_row_infop row_info, png_bytep data)
{
unsigned int i;
for (i = 0; i < row_info->rowbytes; i += 4) {
uint8_t *b = &data[i];
uint32_t pixel;
memcpy (&pixel, b, sizeof (uint32_t));
b[0] = (pixel & 0xff0000) >> 16;
b[1] = (pixel & 0x00ff00) >> 8;
b[2] = (pixel & 0x0000ff) >> 0;
b[3] = 0;
}
}
static gboolean
gxps_png_writer_image_writer_init (GXPSImageWriter *image_writer,
FILE *fd,
guint width,
guint height,
guint x_resolution,
guint y_resolution)
{
GXPSPngWriter *png_writer = GXPS_PNG_WRITER (image_writer);
png_writer->png_ptr = png_create_write_struct (PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
if (!png_writer->png_ptr) {
g_printerr ("Error initializing png writer: png_create_write_struct failed\n");
return FALSE;
}
png_writer->info_ptr = png_create_info_struct (png_writer->png_ptr);
if (!png_writer->info_ptr) {
g_printerr ("Error initializing png writer: png_create_info_struct failed\n");
return FALSE;
}
if (setjmp (png_jmpbuf (png_writer->png_ptr))) {
g_printerr ("Error initializing png writer: png_jmpbuf failed\n");
return FALSE;
}
/* write header */
png_init_io (png_writer->png_ptr, fd);
if (setjmp (png_jmpbuf (png_writer->png_ptr))) {
g_printerr ("Error initializing png writer: error writing PNG header\n");
return FALSE;
}
png_set_compression_level (png_writer->png_ptr, Z_BEST_COMPRESSION);
png_set_IHDR (png_writer->png_ptr, png_writer->info_ptr,
width, height, 8,
png_writer->format == GXPS_PNG_FORMAT_RGB ? PNG_COLOR_TYPE_RGB : PNG_COLOR_TYPE_RGB_ALPHA,
PNG_INTERLACE_NONE,
PNG_COMPRESSION_TYPE_DEFAULT,
PNG_FILTER_TYPE_DEFAULT);
png_set_pHYs (png_writer->png_ptr, png_writer->info_ptr,
x_resolution / 0.0254, y_resolution / 0.0254,
PNG_RESOLUTION_METER);
png_write_info (png_writer->png_ptr, png_writer->info_ptr);
if (setjmp (png_jmpbuf (png_writer->png_ptr))) {
g_printerr ("Error initializing png writer: error writing png info bytes\n");
return FALSE;
}
switch (png_writer->format) {
case GXPS_PNG_FORMAT_RGB:
png_set_write_user_transform_fn (png_writer->png_ptr, convert_data_to_bytes);
png_set_filler (png_writer->png_ptr, 0, PNG_FILLER_AFTER);
break;
case GXPS_PNG_FORMAT_RGBA:
png_set_write_user_transform_fn (png_writer->png_ptr, unpremultiply_data);
break;
}
return TRUE;
}
static gboolean
gxps_png_writer_image_writer_write (GXPSImageWriter *image_writer,
guchar *row)
{
GXPSPngWriter *png_writer = GXPS_PNG_WRITER (image_writer);
png_write_rows (png_writer->png_ptr, &row, 1);
if (setjmp (png_jmpbuf (png_writer->png_ptr))) {
g_printerr ("Error writing png: error during png row write\n");
return FALSE;
}
return TRUE;
}
static gboolean
gxps_png_writer_image_writer_finish (GXPSImageWriter *image_writer)
{
GXPSPngWriter *png_writer = GXPS_PNG_WRITER (image_writer);
png_write_end (png_writer->png_ptr, png_writer->info_ptr);
if (setjmp (png_jmpbuf (png_writer->png_ptr))) {
g_printerr ("Error finishing png: error during end of write\n");
return FALSE;
}
png_destroy_write_struct (&png_writer->png_ptr, &png_writer->info_ptr);
return TRUE;
}
static void
gxps_png_writer_image_writer_iface_init (GXPSImageWriterInterface *iface)
{
iface->init = gxps_png_writer_image_writer_init;
iface->write = gxps_png_writer_image_writer_write;
iface->finish = gxps_png_writer_image_writer_finish;
}
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