2 libimago - a multi-format image file input/output library.
3 Copyright (C) 2010 John Tsiombikas <nuclear@member.fsf.org>
5 This program is free software: you can redistribute it and/or modify
6 it under the terms of the GNU Lesser General Public License as published
7 by the Free Software Foundation, either version 3 of the License, or
8 (at your option) any later version.
10 This program is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 GNU Lesser General Public License for more details.
15 You should have received a copy of the GNU Lesser General Public License
16 along with this program. If not, see <http://www.gnu.org/licenses/>.
19 /* -- PNG module -- */
28 static int check_file(struct img_io *io);
29 static int read_file(struct img_pixmap *img, struct img_io *io);
30 static int write_file(struct img_pixmap *img, struct img_io *io);
32 static void read_func(png_struct *png, unsigned char *data, size_t len);
33 static void write_func(png_struct *png, unsigned char *data, size_t len);
34 static void flush_func(png_struct *png);
36 static int png_type_to_fmt(int color_type, int channel_bits);
37 static int fmt_to_png_type(enum img_fmt fmt);
40 int img_register_png(void)
42 static struct ftype_module mod = {".png", check_file, read_file, write_file};
43 return img_register_module(&mod);
46 static int check_file(struct img_io *io)
50 long pos = io->seek(0, SEEK_CUR, io->uptr);
52 if(io->read(sig, 8, io->uptr) < 8) {
53 io->seek(pos, SEEK_SET, io->uptr);
57 res = png_sig_cmp(sig, 0, 8) == 0 ? 0 : -1;
58 io->seek(pos, SEEK_SET, io->uptr);
62 static int read_file(struct img_pixmap *img, struct img_io *io)
66 int channel_bits, color_type, ilace_type, compression, filtering, fmt;
69 if(!(png = png_create_read_struct(PNG_LIBPNG_VER_STRING, 0, 0, 0))) {
73 if(!(info = png_create_info_struct(png))) {
74 png_destroy_read_struct(&png, 0, 0);
78 if(setjmp(png_jmpbuf(png))) {
79 png_destroy_read_struct(&png, &info, 0);
83 png_set_read_fn(png, io, read_func);
84 png_set_sig_bytes(png, 0);
85 png_read_png(png, info, 0, 0);
87 png_get_IHDR(png, info, &xsz, &ysz, &channel_bits, &color_type, &ilace_type,
88 &compression, &filtering);
89 if((fmt = png_type_to_fmt(color_type, channel_bits)) == -1) {
90 png_destroy_read_struct(&png, &info, 0);
94 if(img_set_pixels(img, xsz, ysz, fmt, 0) == -1) {
95 png_destroy_read_struct(&png, &info, 0);
100 if(channel_bits == 8) {
102 unsigned char **lineptr = (unsigned char**)png_get_rows(png, info);
103 unsigned char *dest = img->pixels;
105 for(i=0; i<ysz; i++) {
106 memcpy(dest, lineptr[i], xsz * img->pixelsz);
107 dest += xsz * img->pixelsz;
110 unsigned int i, j, num_elem;
111 unsigned char **lineptr = (unsigned char**)png_get_rows(png, info);
112 float *dest = img->pixels;
114 num_elem = img->pixelsz / sizeof(float);
115 for(i=0; i<ysz; i++) {
116 for(j=0; j<xsz * num_elem; j++) {
117 unsigned short val = (lineptr[i][j * 2] << 8) | lineptr[i][j * 2 + 1];
118 *dest++ = (float)val / 65535.0;
124 png_destroy_read_struct(&png, &info, 0);
129 static int write_file(struct img_pixmap *img, struct img_io *io)
134 struct img_pixmap tmpimg;
135 unsigned char **rows;
136 unsigned char *pixptr;
141 if(!(png = png_create_write_struct(PNG_LIBPNG_VER_STRING, 0, 0, 0))) {
144 if(!(info = png_create_info_struct(png))) {
145 png_destroy_write_struct(&png, 0);
149 /* if the input image is floating-point, we need to convert it to integer */
150 if(img_is_float(img)) {
151 if(img_copy(&tmpimg, img) == -1) {
154 if(img_to_integer(&tmpimg) == -1) {
155 img_destroy(&tmpimg);
161 txt.compression = PNG_TEXT_COMPRESSION_NONE;
162 txt.key = "Software";
163 txt.text = "libimago2";
166 if(setjmp(png_jmpbuf(png))) {
167 png_destroy_write_struct(&png, &info);
168 img_destroy(&tmpimg);
171 png_set_write_fn(png, io, write_func, flush_func);
173 coltype = fmt_to_png_type(img->fmt);
174 png_set_IHDR(png, info, img->width, img->height, 8, coltype, PNG_INTERLACE_NONE,
175 PNG_COMPRESSION_TYPE_DEFAULT, PNG_FILTER_TYPE_DEFAULT);
176 png_set_text(png, info, &txt, 1);
178 if(!(rows = malloc(img->height * sizeof *rows))) {
179 png_destroy_write_struct(&png, &info);
180 img_destroy(&tmpimg);
184 pixptr = img->pixels;
185 for(i=0; i<img->height; i++) {
187 pixptr += img->width * img->pixelsz;
189 png_set_rows(png, info, rows);
191 png_write_png(png, info, 0, 0);
192 png_write_end(png, info);
193 png_destroy_write_struct(&png, &info);
197 img_destroy(&tmpimg);
201 static void read_func(png_struct *png, unsigned char *data, size_t len)
203 struct img_io *io = (struct img_io*)png_get_io_ptr(png);
205 if(io->read(data, len, io->uptr) == -1) {
206 longjmp(png_jmpbuf(png), 1);
210 static void write_func(png_struct *png, unsigned char *data, size_t len)
212 struct img_io *io = (struct img_io*)png_get_io_ptr(png);
214 if(io->write(data, len, io->uptr) == -1) {
215 longjmp(png_jmpbuf(png), 1);
219 static void flush_func(png_struct *png)
221 /* XXX does it matter that we can't flush? */
224 static int png_type_to_fmt(int color_type, int channel_bits)
226 /* only 8 and 16 bits per channel ar supported at the moment */
227 if(channel_bits != 8 && channel_bits != 16) {
232 case PNG_COLOR_TYPE_RGB:
233 return channel_bits == 16 ? IMG_FMT_RGBF : IMG_FMT_RGB24;
235 case PNG_COLOR_TYPE_RGB_ALPHA:
236 return channel_bits == 16 ? IMG_FMT_RGBAF : IMG_FMT_RGBA32;
238 case PNG_COLOR_TYPE_GRAY:
239 return channel_bits == 16 ? IMG_FMT_GREYF : IMG_FMT_GREY8;
247 static int fmt_to_png_type(enum img_fmt fmt)
251 return PNG_COLOR_TYPE_GRAY;
254 return PNG_COLOR_TYPE_RGB;
257 return PNG_COLOR_TYPE_RGBA;
266 /* building with PNG support disabled */
268 int img_register_png(void)