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thirdparty/libpng-1.5.2/contrib/gregbook/readpng2.c
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/*---------------------------------------------------------------------------
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rpng2 - progressive-model PNG display program readpng2.c
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---------------------------------------------------------------------------
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Copyright (c) 1998-2007 Greg Roelofs. All rights reserved.
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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
|
||||
|
||||
---------------------------------------------------------------------------*/
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#include <stdlib.h> /* for exit() prototype */
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#include <setjmp.h>
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#include <zlib.h>
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#include "png.h" /* libpng header from the local directory */
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#include "readpng2.h" /* typedefs, common macros, public prototypes */
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/* local prototypes */
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static void readpng2_info_callback(png_structp png_ptr, png_infop info_ptr);
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static void readpng2_row_callback(png_structp png_ptr, png_bytep new_row,
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png_uint_32 row_num, int pass);
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static void readpng2_end_callback(png_structp png_ptr, png_infop info_ptr);
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static void readpng2_error_handler(png_structp png_ptr, png_const_charp msg);
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void readpng2_version_info(void)
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{
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fprintf(stderr, " Compiled with libpng %s; using libpng %s\n",
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PNG_LIBPNG_VER_STRING, png_libpng_ver);
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fprintf(stderr, " and with zlib %s; using zlib %s.\n",
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ZLIB_VERSION, zlib_version);
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}
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||||
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int readpng2_check_sig(uch *sig, int num)
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{
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return !png_sig_cmp(sig, 0, num);
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}
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/* returns 0 for success, 2 for libpng problem, 4 for out of memory */
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int readpng2_init(mainprog_info *mainprog_ptr)
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{
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png_structp png_ptr; /* note: temporary variables! */
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png_infop info_ptr;
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/* could also replace libpng warning-handler (final NULL), but no need: */
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png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, mainprog_ptr,
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readpng2_error_handler, NULL);
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if (!png_ptr)
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return 4; /* out of memory */
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info_ptr = png_create_info_struct(png_ptr);
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if (!info_ptr) {
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png_destroy_read_struct(&png_ptr, NULL, NULL);
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return 4; /* out of memory */
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}
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/* we could create a second info struct here (end_info), but it's only
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* useful if we want to keep pre- and post-IDAT chunk info separated
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* (mainly for PNG-aware image editors and converters) */
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|
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/* setjmp() must be called in every function that calls a PNG-reading
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* libpng function, unless an alternate error handler was installed--
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* but compatible error handlers must either use longjmp() themselves
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* (as in this program) or exit immediately, so here we are: */
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if (setjmp(mainprog_ptr->jmpbuf)) {
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png_destroy_read_struct(&png_ptr, &info_ptr, NULL);
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return 2;
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}
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#ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
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/* prepare the reader to ignore all recognized chunks whose data won't be
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* used, i.e., all chunks recognized by libpng except for IHDR, PLTE, IDAT,
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* IEND, tRNS, bKGD, gAMA, and sRGB (small performance improvement) */
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{
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/* These byte strings were copied from png.h. If a future libpng
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* version recognizes more chunks, add them to this list. If a
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* future version of readpng2.c recognizes more chunks, delete them
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* from this list. */
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static /* const */ png_byte chunks_to_ignore[] = {
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99, 72, 82, 77, '\0', /* cHRM */
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104, 73, 83, 84, '\0', /* hIST */
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105, 67, 67, 80, '\0', /* iCCP */
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||||
105, 84, 88, 116, '\0', /* iTXt */
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||||
111, 70, 70, 115, '\0', /* oFFs */
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112, 67, 65, 76, '\0', /* pCAL */
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112, 72, 89, 115, '\0', /* pHYs */
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115, 66, 73, 84, '\0', /* sBIT */
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115, 67, 65, 76, '\0', /* sCAL */
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115, 80, 76, 84, '\0', /* sPLT */
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115, 84, 69, 82, '\0', /* sTER */
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116, 69, 88, 116, '\0', /* tEXt */
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116, 73, 77, 69, '\0', /* tIME */
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122, 84, 88, 116, '\0' /* zTXt */
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};
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png_set_keep_unknown_chunks(png_ptr, 1 /* PNG_HANDLE_CHUNK_NEVER */,
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chunks_to_ignore, sizeof(chunks_to_ignore)/5);
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}
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#endif /* PNG_HANDLE_AS_UNKNOWN_SUPPORTED */
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/* instead of doing png_init_io() here, now we set up our callback
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* functions for progressive decoding */
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png_set_progressive_read_fn(png_ptr, mainprog_ptr,
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readpng2_info_callback, readpng2_row_callback, readpng2_end_callback);
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/* make sure we save our pointers for use in readpng2_decode_data() */
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mainprog_ptr->png_ptr = png_ptr;
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mainprog_ptr->info_ptr = info_ptr;
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||||
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/* and that's all there is to initialization */
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return 0;
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||||
}
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||||
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/* returns 0 for success, 2 for libpng (longjmp) problem */
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int readpng2_decode_data(mainprog_info *mainprog_ptr, uch *rawbuf, ulg length)
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{
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png_structp png_ptr = (png_structp)mainprog_ptr->png_ptr;
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png_infop info_ptr = (png_infop)mainprog_ptr->info_ptr;
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/* setjmp() must be called in every function that calls a PNG-reading
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* libpng function */
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if (setjmp(mainprog_ptr->jmpbuf)) {
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png_destroy_read_struct(&png_ptr, &info_ptr, NULL);
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mainprog_ptr->png_ptr = NULL;
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mainprog_ptr->info_ptr = NULL;
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return 2;
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}
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/* hand off the next chunk of input data to libpng for decoding */
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||||
png_process_data(png_ptr, info_ptr, rawbuf, length);
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return 0;
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||||
}
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||||
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||||
|
||||
|
||||
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||||
static void readpng2_info_callback(png_structp png_ptr, png_infop info_ptr)
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{
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mainprog_info *mainprog_ptr;
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int color_type, bit_depth;
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||||
png_uint_32 width, height;
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#ifdef PNG_FLOATING_POINT_SUPPORTED
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double gamma;
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#else
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png_fixed_point gamma;
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#endif
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||||
|
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|
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/* setjmp() doesn't make sense here, because we'd either have to exit(),
|
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* longjmp() ourselves, or return control to libpng, which doesn't want
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* to see us again. By not doing anything here, libpng will instead jump
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* to readpng2_decode_data(), which can return an error value to the main
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* program. */
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/* retrieve the pointer to our special-purpose struct, using the png_ptr
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* that libpng passed back to us (i.e., not a global this time--there's
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* no real difference for a single image, but for a multithreaded browser
|
||||
* decoding several PNG images at the same time, one needs to avoid mixing
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||||
* up different images' structs) */
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mainprog_ptr = png_get_progressive_ptr(png_ptr);
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if (mainprog_ptr == NULL) { /* we be hosed */
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fprintf(stderr,
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||||
"readpng2 error: main struct not recoverable in info_callback.\n");
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fflush(stderr);
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return;
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||||
/*
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||||
* Alternatively, we could call our error-handler just like libpng
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||||
* does, which would effectively terminate the program. Since this
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||||
* can only happen if png_ptr gets redirected somewhere odd or the
|
||||
* main PNG struct gets wiped, we're probably toast anyway. (If
|
||||
* png_ptr itself is NULL, we would not have been called.)
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||||
*/
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||||
}
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||||
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||||
/* this is just like in the non-progressive case */
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||||
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png_get_IHDR(png_ptr, info_ptr, &width, &height, &bit_depth, &color_type,
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NULL, NULL, NULL);
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mainprog_ptr->width = (ulg)width;
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mainprog_ptr->height = (ulg)height;
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||||
/* since we know we've read all of the PNG file's "header" (i.e., up
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* to IDAT), we can check for a background color here */
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if (mainprog_ptr->need_bgcolor &&
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png_get_valid(png_ptr, info_ptr, PNG_INFO_bKGD))
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||||
{
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||||
png_color_16p pBackground;
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||||
|
||||
/* it is not obvious from the libpng documentation, but this function
|
||||
* takes a pointer to a pointer, and it always returns valid red,
|
||||
* green and blue values, regardless of color_type: */
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||||
png_get_bKGD(png_ptr, info_ptr, &pBackground);
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||||
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||||
/* however, it always returns the raw bKGD data, regardless of any
|
||||
* bit-depth transformations, so check depth and adjust if necessary */
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||||
if (bit_depth == 16) {
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||||
mainprog_ptr->bg_red = pBackground->red >> 8;
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||||
mainprog_ptr->bg_green = pBackground->green >> 8;
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||||
mainprog_ptr->bg_blue = pBackground->blue >> 8;
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||||
} else if (color_type == PNG_COLOR_TYPE_GRAY && bit_depth < 8) {
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||||
if (bit_depth == 1)
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mainprog_ptr->bg_red = mainprog_ptr->bg_green =
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mainprog_ptr->bg_blue = pBackground->gray? 255 : 0;
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||||
else if (bit_depth == 2)
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mainprog_ptr->bg_red = mainprog_ptr->bg_green =
|
||||
mainprog_ptr->bg_blue = (255/3) * pBackground->gray;
|
||||
else /* bit_depth == 4 */
|
||||
mainprog_ptr->bg_red = mainprog_ptr->bg_green =
|
||||
mainprog_ptr->bg_blue = (255/15) * pBackground->gray;
|
||||
} else {
|
||||
mainprog_ptr->bg_red = (uch)pBackground->red;
|
||||
mainprog_ptr->bg_green = (uch)pBackground->green;
|
||||
mainprog_ptr->bg_blue = (uch)pBackground->blue;
|
||||
}
|
||||
}
|
||||
|
||||
|
||||
/* as before, let libpng expand palette images to RGB, low-bit-depth
|
||||
* grayscale images to 8 bits, transparency chunks to full alpha channel;
|
||||
* strip 16-bit-per-sample images to 8 bits per sample; and convert
|
||||
* grayscale to RGB[A] */
|
||||
|
||||
if (color_type == PNG_COLOR_TYPE_PALETTE)
|
||||
png_set_expand(png_ptr);
|
||||
if (color_type == PNG_COLOR_TYPE_GRAY && bit_depth < 8)
|
||||
png_set_expand(png_ptr);
|
||||
if (png_get_valid(png_ptr, info_ptr, PNG_INFO_tRNS))
|
||||
png_set_expand(png_ptr);
|
||||
if (bit_depth == 16)
|
||||
png_set_strip_16(png_ptr);
|
||||
if (color_type == PNG_COLOR_TYPE_GRAY ||
|
||||
color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
|
||||
png_set_gray_to_rgb(png_ptr);
|
||||
|
||||
|
||||
/* Unlike the basic viewer, which was designed to operate on local files,
|
||||
* this program is intended to simulate a web browser--even though we
|
||||
* actually read from a local file, too. But because we are pretending
|
||||
* that most of the images originate on the Internet, we follow the recom-
|
||||
* mendation of the sRGB proposal and treat unlabelled images (no gAMA
|
||||
* chunk) as existing in the sRGB color space. That is, we assume that
|
||||
* such images have a file gamma of 0.45455, which corresponds to a PC-like
|
||||
* display system. This change in assumptions will have no effect on a
|
||||
* PC-like system, but on a Mac, SGI, NeXT or other system with a non-
|
||||
* identity lookup table, it will darken unlabelled images, which effec-
|
||||
* tively favors images from PC-like systems over those originating on
|
||||
* the local platform. Note that mainprog_ptr->display_exponent is the
|
||||
* "gamma" value for the entire display system, i.e., the product of
|
||||
* LUT_exponent and CRT_exponent. */
|
||||
|
||||
#ifdef PNG_FLOATING_POINT_SUPPORTED
|
||||
if (png_get_gAMA(png_ptr, info_ptr, &gamma))
|
||||
png_set_gamma(png_ptr, mainprog_ptr->display_exponent, gamma);
|
||||
else
|
||||
png_set_gamma(png_ptr, mainprog_ptr->display_exponent, 0.45455);
|
||||
#else
|
||||
if (png_get_gAMA_fixed(png_ptr, info_ptr, &gamma))
|
||||
png_set_gamma_fixed(png_ptr,
|
||||
(png_fixed_point)(100000*mainprog_ptr->display_exponent+.5), gamma);
|
||||
else
|
||||
png_set_gamma_fixed(png_ptr,
|
||||
(png_fixed_point)(100000*mainprog_ptr->display_exponent+.5), 45455);
|
||||
#endif
|
||||
|
||||
/* we'll let libpng expand interlaced images, too */
|
||||
|
||||
mainprog_ptr->passes = png_set_interlace_handling(png_ptr);
|
||||
|
||||
|
||||
/* all transformations have been registered; now update info_ptr data and
|
||||
* then get rowbytes and channels */
|
||||
|
||||
png_read_update_info(png_ptr, info_ptr);
|
||||
|
||||
mainprog_ptr->rowbytes = (int)png_get_rowbytes(png_ptr, info_ptr);
|
||||
mainprog_ptr->channels = png_get_channels(png_ptr, info_ptr);
|
||||
|
||||
|
||||
/* Call the main program to allocate memory for the image buffer and
|
||||
* initialize windows and whatnot. (The old-style function-pointer
|
||||
* invocation is used for compatibility with a few supposedly ANSI
|
||||
* compilers that nevertheless barf on "fn_ptr()"-style syntax.) */
|
||||
|
||||
(*mainprog_ptr->mainprog_init)();
|
||||
|
||||
|
||||
/* and that takes care of initialization */
|
||||
|
||||
return;
|
||||
}
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
static void readpng2_row_callback(png_structp png_ptr, png_bytep new_row,
|
||||
png_uint_32 row_num, int pass)
|
||||
{
|
||||
mainprog_info *mainprog_ptr;
|
||||
|
||||
|
||||
/* first check whether the row differs from the previous pass; if not,
|
||||
* nothing to combine or display */
|
||||
|
||||
if (!new_row)
|
||||
return;
|
||||
|
||||
|
||||
/* retrieve the pointer to our special-purpose struct so we can access
|
||||
* the old rows and image-display callback function */
|
||||
|
||||
mainprog_ptr = png_get_progressive_ptr(png_ptr);
|
||||
|
||||
|
||||
/* save the pass number for optional use by the front end */
|
||||
|
||||
mainprog_ptr->pass = pass;
|
||||
|
||||
|
||||
/* have libpng either combine the new row data with the existing row data
|
||||
* from previous passes (if interlaced) or else just copy the new row
|
||||
* into the main program's image buffer */
|
||||
|
||||
png_progressive_combine_row(png_ptr, mainprog_ptr->row_pointers[row_num],
|
||||
new_row);
|
||||
|
||||
|
||||
/* finally, call the display routine in the main program with the number
|
||||
* of the row we just updated */
|
||||
|
||||
(*mainprog_ptr->mainprog_display_row)(row_num);
|
||||
|
||||
|
||||
/* and we're ready for more */
|
||||
|
||||
return;
|
||||
}
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
static void readpng2_end_callback(png_structp png_ptr, png_infop info_ptr)
|
||||
{
|
||||
mainprog_info *mainprog_ptr;
|
||||
|
||||
|
||||
/* retrieve the pointer to our special-purpose struct */
|
||||
|
||||
mainprog_ptr = png_get_progressive_ptr(png_ptr);
|
||||
|
||||
|
||||
/* let the main program know that it should flush any buffered image
|
||||
* data to the display now and set a "done" flag or whatever, but note
|
||||
* that it SHOULD NOT DESTROY THE PNG STRUCTS YET--in other words, do
|
||||
* NOT call readpng2_cleanup() either here or in the finish_display()
|
||||
* routine; wait until control returns to the main program via
|
||||
* readpng2_decode_data() */
|
||||
|
||||
(*mainprog_ptr->mainprog_finish_display)();
|
||||
|
||||
|
||||
/* all done */
|
||||
|
||||
return;
|
||||
}
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
void readpng2_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_read_struct(&png_ptr, &info_ptr, NULL);
|
||||
|
||||
mainprog_ptr->png_ptr = NULL;
|
||||
mainprog_ptr->info_ptr = NULL;
|
||||
}
|
||||
|
||||
|
||||
|
||||
|
||||
|
||||
static void readpng2_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, "readpng2 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,
|
||||
"readpng2 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);
|
||||
}
|
Reference in New Issue
Block a user