--- /dev/null
+/*
+libimago - a multi-format image file input/output library.
+Copyright (C) 2010 John Tsiombikas <nuclear@member.fsf.org>
+
+This program 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 3 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 Lesser General Public License for more details.
+
+You should have received a copy of the GNU Lesser General Public License
+along with this program. If not, see <http://www.gnu.org/licenses/>.
+*/
+
+/* -- PNG module -- */
+
+#include <stdlib.h>
+#include <string.h>
+#include <png.h>
+#include "imago2.h"
+#include "ftmodule.h"
+
+static int check_file(struct img_io *io);
+static int read_file(struct img_pixmap *img, struct img_io *io);
+static int write_file(struct img_pixmap *img, struct img_io *io);
+
+static void read_func(png_struct *png, unsigned char *data, size_t len);
+static void write_func(png_struct *png, unsigned char *data, size_t len);
+static void flush_func(png_struct *png);
+
+static int png_type_to_fmt(int color_type, int channel_bits);
+static int fmt_to_png_type(enum img_fmt fmt);
+
+
+int img_register_png(void)
+{
+ static struct ftype_module mod = {".png", check_file, read_file, write_file};
+ return img_register_module(&mod);
+}
+
+static int check_file(struct img_io *io)
+{
+ unsigned char sig[8];
+ int res;
+ long pos = io->seek(0, SEEK_CUR, io->uptr);
+
+ if(io->read(sig, 8, io->uptr) < 8) {
+ io->seek(pos, SEEK_SET, io->uptr);
+ return -1;
+ }
+
+ res = png_sig_cmp(sig, 0, 8) == 0 ? 0 : -1;
+ io->seek(pos, SEEK_SET, io->uptr);
+ return res;
+}
+
+static int read_file(struct img_pixmap *img, struct img_io *io)
+{
+ png_struct *png;
+ png_info *info;
+ int channel_bits, color_type, ilace_type, compression, filtering, fmt;
+ png_uint_32 xsz, ysz;
+
+ if(!(png = png_create_read_struct(PNG_LIBPNG_VER_STRING, 0, 0, 0))) {
+ return -1;
+ }
+
+ if(!(info = png_create_info_struct(png))) {
+ png_destroy_read_struct(&png, 0, 0);
+ return -1;
+ }
+
+ if(setjmp(png_jmpbuf(png))) {
+ png_destroy_read_struct(&png, &info, 0);
+ return -1;
+ }
+
+ png_set_read_fn(png, io, read_func);
+ png_set_sig_bytes(png, 0);
+ png_read_png(png, info, 0, 0);
+
+ png_get_IHDR(png, info, &xsz, &ysz, &channel_bits, &color_type, &ilace_type,
+ &compression, &filtering);
+ if((fmt = png_type_to_fmt(color_type, channel_bits)) == -1) {
+ png_destroy_read_struct(&png, &info, 0);
+ return -1;
+ }
+
+ if(img_set_pixels(img, xsz, ysz, fmt, 0) == -1) {
+ png_destroy_read_struct(&png, &info, 0);
+ return -1;
+ }
+
+
+ if(channel_bits == 8) {
+ unsigned int i;
+ unsigned char **lineptr = (unsigned char**)png_get_rows(png, info);
+ unsigned char *dest = img->pixels;
+
+ for(i=0; i<ysz; i++) {
+ memcpy(dest, lineptr[i], xsz * img->pixelsz);
+ dest += xsz * img->pixelsz;
+ }
+ } else {
+ unsigned int i, j, num_elem;
+ unsigned char **lineptr = (unsigned char**)png_get_rows(png, info);
+ float *dest = img->pixels;
+
+ num_elem = img->pixelsz / sizeof(float);
+ for(i=0; i<ysz; i++) {
+ for(j=0; j<xsz * num_elem; j++) {
+ unsigned short val = (lineptr[i][j * 2] << 8) | lineptr[i][j * 2 + 1];
+ *dest++ = (float)val / 65535.0;
+ }
+ }
+ }
+
+
+ png_destroy_read_struct(&png, &info, 0);
+ return 0;
+}
+
+
+static int write_file(struct img_pixmap *img, struct img_io *io)
+{
+ png_struct *png;
+ png_info *info;
+ png_text txt;
+ struct img_pixmap tmpimg;
+ unsigned char **rows;
+ unsigned char *pixptr;
+ int i, coltype;
+
+ img_init(&tmpimg);
+
+ if(!(png = png_create_write_struct(PNG_LIBPNG_VER_STRING, 0, 0, 0))) {
+ return -1;
+ }
+ if(!(info = png_create_info_struct(png))) {
+ png_destroy_write_struct(&png, 0);
+ return -1;
+ }
+
+ /* if the input image is floating-point, we need to convert it to integer */
+ if(img_is_float(img)) {
+ if(img_copy(&tmpimg, img) == -1) {
+ return -1;
+ }
+ if(img_to_integer(&tmpimg) == -1) {
+ img_destroy(&tmpimg);
+ return -1;
+ }
+ img = &tmpimg;
+ }
+
+ txt.compression = PNG_TEXT_COMPRESSION_NONE;
+ txt.key = "Software";
+ txt.text = "libimago2";
+ txt.text_length = 0;
+
+ if(setjmp(png_jmpbuf(png))) {
+ png_destroy_write_struct(&png, &info);
+ img_destroy(&tmpimg);
+ return -1;
+ }
+ png_set_write_fn(png, io, write_func, flush_func);
+
+ coltype = fmt_to_png_type(img->fmt);
+ png_set_IHDR(png, info, img->width, img->height, 8, coltype, PNG_INTERLACE_NONE,
+ PNG_COMPRESSION_TYPE_DEFAULT, PNG_FILTER_TYPE_DEFAULT);
+ png_set_text(png, info, &txt, 1);
+
+ if(!(rows = malloc(img->height * sizeof *rows))) {
+ png_destroy_write_struct(&png, &info);
+ img_destroy(&tmpimg);
+ return -1;
+ }
+
+ pixptr = img->pixels;
+ for(i=0; i<img->height; i++) {
+ rows[i] = pixptr;
+ pixptr += img->width * img->pixelsz;
+ }
+ png_set_rows(png, info, rows);
+
+ png_write_png(png, info, 0, 0);
+ png_write_end(png, info);
+ png_destroy_write_struct(&png, &info);
+
+ free(rows);
+
+ img_destroy(&tmpimg);
+ return 0;
+}
+
+static void read_func(png_struct *png, unsigned char *data, size_t len)
+{
+ struct img_io *io = (struct img_io*)png_get_io_ptr(png);
+
+ if(io->read(data, len, io->uptr) == -1) {
+ longjmp(png_jmpbuf(png), 1);
+ }
+}
+
+static void write_func(png_struct *png, unsigned char *data, size_t len)
+{
+ struct img_io *io = (struct img_io*)png_get_io_ptr(png);
+
+ if(io->write(data, len, io->uptr) == -1) {
+ longjmp(png_jmpbuf(png), 1);
+ }
+}
+
+static void flush_func(png_struct *png)
+{
+ /* XXX does it matter that we can't flush? */
+}
+
+static int png_type_to_fmt(int color_type, int channel_bits)
+{
+ /* only 8 and 16 bits per channel ar supported at the moment */
+ if(channel_bits != 8 && channel_bits != 16) {
+ return -1;
+ }
+
+ switch(color_type) {
+ case PNG_COLOR_TYPE_RGB:
+ return channel_bits == 16 ? IMG_FMT_RGBF : IMG_FMT_RGB24;
+
+ case PNG_COLOR_TYPE_RGB_ALPHA:
+ return channel_bits == 16 ? IMG_FMT_RGBAF : IMG_FMT_RGBA32;
+
+ case PNG_COLOR_TYPE_GRAY:
+ return channel_bits == 16 ? IMG_FMT_GREYF : IMG_FMT_GREY8;
+
+ default:
+ break;
+ }
+ return -1;
+}
+
+static int fmt_to_png_type(enum img_fmt fmt)
+{
+ switch(fmt) {
+ case IMG_FMT_GREY8:
+ return PNG_COLOR_TYPE_GRAY;
+
+ case IMG_FMT_RGB24:
+ return PNG_COLOR_TYPE_RGB;
+
+ case IMG_FMT_RGBA32:
+ return PNG_COLOR_TYPE_RGBA;
+
+ default:
+ break;
+ }
+ return -1;
+}
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