2 * 2ooM: The Master of Orion II Reverse Engineering Project
3 * PNG output routines for lbximg extration.
4 * Copyright © 2013 Nick Bowler
6 * This program is free software: you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License as published by
8 * the Free Software Foundation, either version 3 of the License, or
9 * (at your option) any later version.
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
16 * You should have received a copy of the GNU General Public License
17 * along with this program. If not, see <http://www.gnu.org/licenses/>.
31 #include "imgoutput.h"
38 static int is_masked(unsigned char **mask, unsigned width, unsigned height)
40 for (unsigned y = 0; y < height; y++) {
41 for (unsigned x = 0; x < width; x++) {
50 static void fatal(png_structp png, int err, const char *fmt, ...)
55 tool_verr(err, fmt, ap);
61 static void warning_fn(png_structp png, const char *msg)
63 tool_err(-1, "libpng warning: %s", msg);
66 static void error_fn(png_structp png, const char *msg)
68 fatal(png, -1, "libpng error: %s", msg);
72 * We implement our own I/O routines because libpng's internal stdio calls do
73 * not handle errors particularly well.
75 static void write_data(png_structp png, png_bytep data, png_size_t len)
77 struct file_info *file = png_get_io_ptr(png);
80 ret = fwrite(data, 1, len, file->f);
82 fatal(png, 0, "error writing %s", file->filename);
86 static void flush_data(png_structp png)
88 struct file_info *file = png_get_io_ptr(png);
90 if (fflush(file->f) == EOF) {
91 fatal(png, 0, "error writing %s", file->filename);
96 write_rgba_frame(png_structp png, png_infop info,
97 unsigned char **framedata, unsigned char **mask,
98 struct lbx_colour *palette)
100 png_uint_32 width = png_get_image_width(png, info);
101 png_uint_32 height = png_get_image_height(png, info);
102 unsigned char (*row)[4];
105 if (width >= PNG_UINT_32_MAX / sizeof *row)
106 fatal(png, -1, "image too wide to allocate row buffer");
108 row = png_malloc(png, width * sizeof *row);
111 * We need to establish our own error handler to free the row buffer.
112 * Some care must be taken to save/restore the caller's handler.
114 memcpy(&parent, &png_jmpbuf(png), sizeof parent);
115 if (setjmp(png_jmpbuf(png))) {
118 memcpy(&png_jmpbuf(png), &parent, sizeof parent);
122 png_write_info(png, info);
123 for (png_uint_32 y = 0; y < height; y++) {
124 for (png_uint_32 x = 0; x < width; x++) {
125 row[x][0] = palette[framedata[y][x]].red;
126 row[x][1] = palette[framedata[y][x]].green;
127 row[x][2] = palette[framedata[y][x]].blue;
128 row[x][3] = mask[y][x] ? -1 : 0;
130 png_write_row(png, (void *)row);
132 png_write_end(png, NULL);
134 memcpy(&png_jmpbuf(png), &parent, sizeof parent);
138 write_index_frame(png_structp png, png_infop info, unsigned char **framedata,
139 struct lbx_colour *palette)
141 png_color png_palette[256];
143 for (unsigned i = 0; i < 256; i++) {
144 png_palette[i] = (png_color) {
145 .red = palette[i].red,
146 .green = palette[i].green,
147 .blue = palette[i].blue,
151 png_set_PLTE(png, info, png_palette, 256);
152 png_set_rows(png, info, framedata);
153 png_write_png(png, info, PNG_TRANSFORM_IDENTITY, NULL);
156 int img_output_png(FILE *f, const char *filename,
157 unsigned width, unsigned height,
158 unsigned char **framedata, unsigned char **mask,
159 struct lbx_colour *palette)
161 struct file_info file = { filename, f };
165 png = png_create_write_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
167 tool_err(-1, "failed to init libpng.");
171 info = png_create_info_struct(png);
173 tool_err(-1, "failed to init libpng.");
174 png_destroy_write_struct(&png, NULL);
178 if (setjmp(png_jmpbuf(png))) {
179 png_destroy_write_struct(&png, &info);
183 png_set_error_fn(png, NULL, error_fn, warning_fn);
184 png_set_write_fn(png, &file, write_data, flush_data);
186 if (is_masked(mask, width, height)) {
188 * Indexed colour mode can only be used for images without
189 * transparency, since indexed PNG requires sacrificing one or
190 * more palette colours to indicate transparency, while LBX
191 * does not. So we use full-up RGBA in this case.
193 png_set_IHDR(png, info, width, height, 8,
194 PNG_COLOR_TYPE_RGB_ALPHA, PNG_INTERLACE_NONE,
195 PNG_COMPRESSION_TYPE_DEFAULT,
196 PNG_FILTER_TYPE_DEFAULT);
198 write_rgba_frame(png, info, framedata, mask, palette);
200 png_set_IHDR(png, info, width, height, 8,
201 PNG_COLOR_TYPE_PALETTE, PNG_INTERLACE_NONE,
202 PNG_COMPRESSION_TYPE_DEFAULT,
203 PNG_FILTER_TYPE_DEFAULT);
205 write_index_frame(png, info, framedata, palette);
208 png_destroy_write_struct(&png, &info);