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+/*---------------------------------------------------------------------------
+
+ wpng - simple PNG-writing program writepng.c
+
+ ---------------------------------------------------------------------------
+
+ Copyright (c) 1998-2007 Greg Roelofs. All rights reserved.
+
+ This software is provided "as is," without warranty of any kind,
+ express or implied. In no event shall the author or contributors
+ be held liable for any damages arising in any way from the use of
+ this software.
+
+ The contents of this file are DUAL-LICENSED. You may modify and/or
+ redistribute this software according to the terms of one of the
+ following two licenses (at your option):
+
+
+ LICENSE 1 ("BSD-like with advertising clause"):
+
+ Permission is granted to anyone to use this software for any purpose,
+ including commercial applications, and to alter it and redistribute
+ it freely, subject to the following restrictions:
+
+ 1. Redistributions of source code must retain the above copyright
+ notice, disclaimer, and this list of conditions.
+ 2. Redistributions in binary form must reproduce the above copyright
+ notice, disclaimer, and this list of conditions in the documenta-
+ tion and/or other materials provided with the distribution.
+ 3. All advertising materials mentioning features or use of this
+ software must display the following acknowledgment:
+
+ This product includes software developed by Greg Roelofs
+ and contributors for the book, "PNG: The Definitive Guide,"
+ published by O'Reilly and Associates.
+
+
+ LICENSE 2 (GNU GPL v2 or later):
+
+ This program is free software; you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation; either version 2 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 General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program; if not, write to the Free Software Foundation,
+ Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+
+ ---------------------------------------------------------------------------*/
+
+
+#include <stdlib.h> /* for exit() prototype */
+
+#include "png.h" /* libpng header; includes zlib.h and setjmp.h */
+#include "writepng.h" /* typedefs, common macros, public prototypes */
+
+
+/* local prototype */
+
+static void writepng_error_handler(png_structp png_ptr, png_const_charp msg);
+
+
+
+void writepng_version_info(void)
+{
+ fprintf(stderr, " Compiled with libpng %s; using libpng %s.\n",
+ PNG_LIBPNG_VER_STRING, png_libpng_ver);
+ fprintf(stderr, " Compiled with zlib %s; using zlib %s.\n",
+ ZLIB_VERSION, zlib_version);
+}
+
+
+
+
+/* returns 0 for success, 2 for libpng problem, 4 for out of memory, 11 for
+ * unexpected pnmtype; note that outfile might be stdout */
+
+int writepng_init(mainprog_info *mainprog_ptr)
+{
+ png_structp png_ptr; /* note: temporary variables! */
+ png_infop info_ptr;
+ int color_type, interlace_type;
+
+
+ /* could also replace libpng warning-handler (final NULL), but no need: */
+
+ png_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING, mainprog_ptr,
+ writepng_error_handler, NULL);
+ if (!png_ptr)
+ return 4; /* out of memory */
+
+ info_ptr = png_create_info_struct(png_ptr);
+ if (!info_ptr) {
+ png_destroy_write_struct(&png_ptr, NULL);
+ return 4; /* out of memory */
+ }
+
+
+ /* setjmp() must be called in every function that calls a PNG-writing
+ * libpng function, unless an alternate error handler was installed--
+ * but compatible error handlers must either use longjmp() themselves
+ * (as in this program) or some other method to return control to
+ * application code, so here we go: */
+
+ if (setjmp(mainprog_ptr->jmpbuf)) {
+ png_destroy_write_struct(&png_ptr, &info_ptr);
+ return 2;
+ }
+
+
+ /* make sure outfile is (re)opened in BINARY mode */
+
+ png_init_io(png_ptr, mainprog_ptr->outfile);
+
+
+ /* set the compression levels--in general, always want to leave filtering
+ * turned on (except for palette images) and allow all of the filters,
+ * which is the default; want 32K zlib window, unless entire image buffer
+ * is 16K or smaller (unknown here)--also the default; usually want max
+ * compression (NOT the default); and remaining compression flags should
+ * be left alone */
+
+ png_set_compression_level(png_ptr, Z_BEST_COMPRESSION);
+/*
+ >> this is default for no filtering; Z_FILTERED is default otherwise:
+ png_set_compression_strategy(png_ptr, Z_DEFAULT_STRATEGY);
+ >> these are all defaults:
+ png_set_compression_mem_level(png_ptr, 8);
+ png_set_compression_window_bits(png_ptr, 15);
+ png_set_compression_method(png_ptr, 8);
+ */
+
+
+ /* set the image parameters appropriately */
+
+ if (mainprog_ptr->pnmtype == 5)
+ color_type = PNG_COLOR_TYPE_GRAY;
+ else if (mainprog_ptr->pnmtype == 6)
+ color_type = PNG_COLOR_TYPE_RGB;
+ else if (mainprog_ptr->pnmtype == 8)
+ color_type = PNG_COLOR_TYPE_RGB_ALPHA;
+ else {
+ png_destroy_write_struct(&png_ptr, &info_ptr);
+ return 11;
+ }
+
+ interlace_type = mainprog_ptr->interlaced? PNG_INTERLACE_ADAM7 :
+ PNG_INTERLACE_NONE;
+
+ png_set_IHDR(png_ptr, info_ptr, mainprog_ptr->width, mainprog_ptr->height,
+ mainprog_ptr->sample_depth, color_type, interlace_type,
+ PNG_COMPRESSION_TYPE_DEFAULT, PNG_FILTER_TYPE_DEFAULT);
+
+ if (mainprog_ptr->gamma > 0.0)
+ png_set_gAMA(png_ptr, info_ptr, mainprog_ptr->gamma);
+
+ if (mainprog_ptr->have_bg) { /* we know it's RGBA, not gray+alpha */
+ png_color_16 background;
+
+ background.red = mainprog_ptr->bg_red;
+ background.green = mainprog_ptr->bg_green;
+ background.blue = mainprog_ptr->bg_blue;
+ png_set_bKGD(png_ptr, info_ptr, &background);
+ }
+
+ if (mainprog_ptr->have_time) {
+ png_time modtime;
+
+ png_convert_from_time_t(&modtime, mainprog_ptr->modtime);
+ png_set_tIME(png_ptr, info_ptr, &modtime);
+ }
+
+ if (mainprog_ptr->have_text) {
+ png_text text[6];
+ int num_text = 0;
+
+ if (mainprog_ptr->have_text & TEXT_TITLE) {
+ text[num_text].compression = PNG_TEXT_COMPRESSION_NONE;
+ text[num_text].key = "Title";
+ text[num_text].text = mainprog_ptr->title;
+ ++num_text;
+ }
+ if (mainprog_ptr->have_text & TEXT_AUTHOR) {
+ text[num_text].compression = PNG_TEXT_COMPRESSION_NONE;
+ text[num_text].key = "Author";
+ text[num_text].text = mainprog_ptr->author;
+ ++num_text;
+ }
+ if (mainprog_ptr->have_text & TEXT_DESC) {
+ text[num_text].compression = PNG_TEXT_COMPRESSION_NONE;
+ text[num_text].key = "Description";
+ text[num_text].text = mainprog_ptr->desc;
+ ++num_text;
+ }
+ if (mainprog_ptr->have_text & TEXT_COPY) {
+ text[num_text].compression = PNG_TEXT_COMPRESSION_NONE;
+ text[num_text].key = "Copyright";
+ text[num_text].text = mainprog_ptr->copyright;
+ ++num_text;
+ }
+ if (mainprog_ptr->have_text & TEXT_EMAIL) {
+ text[num_text].compression = PNG_TEXT_COMPRESSION_NONE;
+ text[num_text].key = "E-mail";
+ text[num_text].text = mainprog_ptr->email;
+ ++num_text;
+ }
+ if (mainprog_ptr->have_text & TEXT_URL) {
+ text[num_text].compression = PNG_TEXT_COMPRESSION_NONE;
+ text[num_text].key = "URL";
+ text[num_text].text = mainprog_ptr->url;
+ ++num_text;
+ }
+ png_set_text(png_ptr, info_ptr, text, num_text);
+ }
+
+
+ /* write all chunks up to (but not including) first IDAT */
+
+ png_write_info(png_ptr, info_ptr);
+
+
+ /* if we wanted to write any more text info *after* the image data, we
+ * would set up text struct(s) here and call png_set_text() again, with
+ * just the new data; png_set_tIME() could also go here, but it would
+ * have no effect since we already called it above (only one tIME chunk
+ * allowed) */
+
+
+ /* set up the transformations: for now, just pack low-bit-depth pixels
+ * into bytes (one, two or four pixels per byte) */
+
+ png_set_packing(png_ptr);
+/* png_set_shift(png_ptr, &sig_bit); to scale low-bit-depth values */
+
+
+ /* make sure we save our pointers for use in writepng_encode_image() */
+
+ mainprog_ptr->png_ptr = png_ptr;
+ mainprog_ptr->info_ptr = info_ptr;
+
+
+ /* OK, that's all we need to do for now; return happy */
+
+ return 0;
+}
+
+
+
+
+
+/* returns 0 for success, 2 for libpng (longjmp) problem */
+
+int writepng_encode_image(mainprog_info *mainprog_ptr)
+{
+ png_structp png_ptr = (png_structp)mainprog_ptr->png_ptr;
+ png_infop info_ptr = (png_infop)mainprog_ptr->info_ptr;
+
+
+ /* as always, setjmp() must be called in every function that calls a
+ * PNG-writing libpng function */
+
+ if (setjmp(mainprog_ptr->jmpbuf)) {
+ png_destroy_write_struct(&png_ptr, &info_ptr);
+ mainprog_ptr->png_ptr = NULL;
+ mainprog_ptr->info_ptr = NULL;
+ return 2;
+ }
+
+
+ /* and now we just write the whole image; libpng takes care of interlacing
+ * for us */
+
+ png_write_image(png_ptr, mainprog_ptr->row_pointers);
+
+
+ /* since that's it, we also close out the end of the PNG file now--if we
+ * had any text or time info to write after the IDATs, second argument
+ * would be info_ptr, but we optimize slightly by sending NULL pointer: */
+
+ png_write_end(png_ptr, NULL);
+
+ return 0;
+}
+
+
+
+
+
+/* returns 0 if succeeds, 2 if libpng problem */
+
+int writepng_encode_row(mainprog_info *mainprog_ptr) /* NON-interlaced only! */
+{
+ png_structp png_ptr = (png_structp)mainprog_ptr->png_ptr;
+ png_infop info_ptr = (png_infop)mainprog_ptr->info_ptr;
+
+
+ /* as always, setjmp() must be called in every function that calls a
+ * PNG-writing libpng function */
+
+ if (setjmp(mainprog_ptr->jmpbuf)) {
+ png_destroy_write_struct(&png_ptr, &info_ptr);
+ mainprog_ptr->png_ptr = NULL;
+ mainprog_ptr->info_ptr = NULL;
+ return 2;
+ }
+
+
+ /* image_data points at our one row of image data */
+
+ png_write_row(png_ptr, mainprog_ptr->image_data);
+
+ return 0;
+}
+
+
+
+
+
+/* returns 0 if succeeds, 2 if libpng problem */
+
+int writepng_encode_finish(mainprog_info *mainprog_ptr) /* NON-interlaced! */
+{
+ png_structp png_ptr = (png_structp)mainprog_ptr->png_ptr;
+ png_infop info_ptr = (png_infop)mainprog_ptr->info_ptr;
+
+
+ /* as always, setjmp() must be called in every function that calls a
+ * PNG-writing libpng function */
+
+ if (setjmp(mainprog_ptr->jmpbuf)) {
+ png_destroy_write_struct(&png_ptr, &info_ptr);
+ mainprog_ptr->png_ptr = NULL;
+ mainprog_ptr->info_ptr = NULL;
+ return 2;
+ }
+
+
+ /* close out PNG file; if we had any text or time info to write after
+ * the IDATs, second argument would be info_ptr: */
+
+ png_write_end(png_ptr, NULL);
+
+ return 0;
+}
+
+
+
+
+
+void writepng_cleanup(mainprog_info *mainprog_ptr)
+{
+ png_structp png_ptr = (png_structp)mainprog_ptr->png_ptr;
+ png_infop info_ptr = (png_infop)mainprog_ptr->info_ptr;
+
+ if (png_ptr && info_ptr)
+ png_destroy_write_struct(&png_ptr, &info_ptr);
+}
+
+
+
+
+
+static void writepng_error_handler(png_structp png_ptr, png_const_charp msg)
+{
+ mainprog_info *mainprog_ptr;
+
+ /* This function, aside from the extra step of retrieving the "error
+ * pointer" (below) and the fact that it exists within the application
+ * rather than within libpng, is essentially identical to libpng's
+ * default error handler. The second point is critical: since both
+ * setjmp() and longjmp() are called from the same code, they are
+ * guaranteed to have compatible notions of how big a jmp_buf is,
+ * regardless of whether _BSD_SOURCE or anything else has (or has not)
+ * been defined. */
+
+ fprintf(stderr, "writepng libpng error: %s\n", msg);
+ fflush(stderr);
+
+ mainprog_ptr = png_get_error_ptr(png_ptr);
+ if (mainprog_ptr == NULL) { /* we are completely hosed now */
+ fprintf(stderr,
+ "writepng severe error: jmpbuf not recoverable; terminating.\n");
+ fflush(stderr);
+ exit(99);
+ }
+
+ /* Now we have our data structure we can use the information in it
+ * to return control to our own higher level code (all the points
+ * where 'setjmp' is called in this file.) This will work with other
+ * error handling mechanisms as well - libpng always calls png_error
+ * when it can proceed no further, thus, so long as the error handler
+ * is intercepted, application code can do its own error recovery.
+ */
+ longjmp(mainprog_ptr->jmpbuf, 1);
+}
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