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Diffstat (limited to 'contrib/libpng/contrib/gregbook/readpng2.c')
| -rw-r--r-- | contrib/libpng/contrib/gregbook/readpng2.c | 505 |
1 files changed, 505 insertions, 0 deletions
diff --git a/contrib/libpng/contrib/gregbook/readpng2.c b/contrib/libpng/contrib/gregbook/readpng2.c new file mode 100644 index 0000000..1772a90 --- /dev/null +++ b/contrib/libpng/contrib/gregbook/readpng2.c @@ -0,0 +1,505 @@ +/*--------------------------------------------------------------------------- + + rpng2 - progressive-model PNG display program readpng2.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 <setjmp.h> + +#include <zlib.h> +#include "png.h" /* libpng header from the local directory */ +#include "readpng2.h" /* typedefs, common macros, public prototypes */ + + +/* local prototypes */ + +static void readpng2_info_callback(png_structp png_ptr, png_infop info_ptr); +static void readpng2_row_callback(png_structp png_ptr, png_bytep new_row, + png_uint_32 row_num, int pass); +static void readpng2_end_callback(png_structp png_ptr, png_infop info_ptr); +static void readpng2_error_handler(png_structp png_ptr, png_const_charp msg); + + + + +void readpng2_version_info(void) +{ + fprintf(stderr, " Compiled with libpng %s; using libpng %s\n", + PNG_LIBPNG_VER_STRING, png_libpng_ver); + + fprintf(stderr, " and with zlib %s; using zlib %s.\n", + ZLIB_VERSION, zlib_version); +} + + + + +int readpng2_check_sig(uch *sig, int num) +{ + return !png_sig_cmp(sig, 0, num); +} + + + + +/* returns 0 for success, 2 for libpng problem, 4 for out of memory */ + +int readpng2_init(mainprog_info *mainprog_ptr) +{ + png_structp png_ptr; /* note: temporary variables! */ + png_infop info_ptr; + + + /* could also replace libpng warning-handler (final NULL), but no need: */ + + png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, mainprog_ptr, + readpng2_error_handler, NULL); + if (!png_ptr) + return 4; /* out of memory */ + + info_ptr = png_create_info_struct(png_ptr); + if (!info_ptr) { + png_destroy_read_struct(&png_ptr, NULL, NULL); + return 4; /* out of memory */ + } + + + /* we could create a second info struct here (end_info), but it's only + * useful if we want to keep pre- and post-IDAT chunk info separated + * (mainly for PNG-aware image editors and converters) */ + + + /* setjmp() must be called in every function that calls a PNG-reading + * libpng function, unless an alternate error handler was installed-- + * but compatible error handlers must either use longjmp() themselves + * (as in this program) or exit immediately, so here we are: */ + + if (setjmp(mainprog_ptr->jmpbuf)) { + png_destroy_read_struct(&png_ptr, &info_ptr, NULL); + return 2; + } + + +#ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED + /* prepare the reader to ignore all recognized chunks whose data won't be + * used, i.e., all chunks recognized by libpng except for IHDR, PLTE, IDAT, + * IEND, tRNS, bKGD, gAMA, and sRGB (small performance improvement) */ + { + /* These byte strings were copied from png.h. If a future libpng + * version recognizes more chunks, add them to this list. If a + * future version of readpng2.c recognizes more chunks, delete them + * from this list. */ + static /* const */ png_byte chunks_to_ignore[] = { + 99, 72, 82, 77, '\0', /* cHRM */ + 104, 73, 83, 84, '\0', /* hIST */ + 105, 67, 67, 80, '\0', /* iCCP */ + 105, 84, 88, 116, '\0', /* iTXt */ + 111, 70, 70, 115, '\0', /* oFFs */ + 112, 67, 65, 76, '\0', /* pCAL */ + 112, 72, 89, 115, '\0', /* pHYs */ + 115, 66, 73, 84, '\0', /* sBIT */ + 115, 67, 65, 76, '\0', /* sCAL */ + 115, 80, 76, 84, '\0', /* sPLT */ + 115, 84, 69, 82, '\0', /* sTER */ + 116, 69, 88, 116, '\0', /* tEXt */ + 116, 73, 77, 69, '\0', /* tIME */ + 122, 84, 88, 116, '\0' /* zTXt */ + }; + + png_set_keep_unknown_chunks(png_ptr, 1 /* PNG_HANDLE_CHUNK_NEVER */, + chunks_to_ignore, sizeof(chunks_to_ignore)/5); + } +#endif /* PNG_HANDLE_AS_UNKNOWN_SUPPORTED */ + + + /* instead of doing png_init_io() here, now we set up our callback + * functions for progressive decoding */ + + png_set_progressive_read_fn(png_ptr, mainprog_ptr, + readpng2_info_callback, readpng2_row_callback, readpng2_end_callback); + + + /* make sure we save our pointers for use in readpng2_decode_data() */ + + mainprog_ptr->png_ptr = png_ptr; + mainprog_ptr->info_ptr = info_ptr; + + + /* and that's all there is to initialization */ + + return 0; +} + + + + +/* returns 0 for success, 2 for libpng (longjmp) problem */ + +int readpng2_decode_data(mainprog_info *mainprog_ptr, uch *rawbuf, ulg length) +{ + png_structp png_ptr = (png_structp)mainprog_ptr->png_ptr; + png_infop info_ptr = (png_infop)mainprog_ptr->info_ptr; + + + /* setjmp() must be called in every function that calls a PNG-reading + * libpng function */ + + if (setjmp(mainprog_ptr->jmpbuf)) { + png_destroy_read_struct(&png_ptr, &info_ptr, NULL); + mainprog_ptr->png_ptr = NULL; + mainprog_ptr->info_ptr = NULL; + return 2; + } + + + /* hand off the next chunk of input data to libpng for decoding */ + + png_process_data(png_ptr, info_ptr, rawbuf, length); + + return 0; +} + + + + +static void readpng2_info_callback(png_structp png_ptr, png_infop info_ptr) +{ + mainprog_info *mainprog_ptr; + int color_type, bit_depth; + png_uint_32 width, height; +#ifdef PNG_FLOATING_POINT_SUPPORTED + double gamma; +#else + png_fixed_point gamma; +#endif + + + /* setjmp() doesn't make sense here, because we'd either have to exit(), + * longjmp() ourselves, or return control to libpng, which doesn't want + * to see us again. By not doing anything here, libpng will instead jump + * to readpng2_decode_data(), which can return an error value to the main + * program. */ + + + /* retrieve the pointer to our special-purpose struct, using the png_ptr + * that libpng passed back to us (i.e., not a global this time--there's + * 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 + * up different images' structs) */ + + mainprog_ptr = png_get_progressive_ptr(png_ptr); + + if (mainprog_ptr == NULL) { /* we be hosed */ + fprintf(stderr, + "readpng2 error: main struct not recoverable in info_callback.\n"); + fflush(stderr); + return; + /* + * Alternatively, we could call our error-handler just like libpng + * does, which would effectively terminate the program. Since this + * 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.) + */ + } + + + /* this is just like in the non-progressive case */ + + png_get_IHDR(png_ptr, info_ptr, &width, &height, &bit_depth, &color_type, + NULL, NULL, NULL); + mainprog_ptr->width = (ulg)width; + mainprog_ptr->height = (ulg)height; + + + /* since we know we've read all of the PNG file's "header" (i.e., up + * to IDAT), we can check for a background color here */ + + if (mainprog_ptr->need_bgcolor && + png_get_valid(png_ptr, info_ptr, PNG_INFO_bKGD)) + { + png_color_16p pBackground; + + /* 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: */ + png_get_bKGD(png_ptr, info_ptr, &pBackground); + + /* however, it always returns the raw bKGD data, regardless of any + * bit-depth transformations, so check depth and adjust if necessary */ + if (bit_depth == 16) { + mainprog_ptr->bg_red = pBackground->red >> 8; + mainprog_ptr->bg_green = pBackground->green >> 8; + mainprog_ptr->bg_blue = pBackground->blue >> 8; + } else if (color_type == PNG_COLOR_TYPE_GRAY && bit_depth < 8) { + if (bit_depth == 1) + mainprog_ptr->bg_red = mainprog_ptr->bg_green = + mainprog_ptr->bg_blue = pBackground->gray? 255 : 0; + else if (bit_depth == 2) + 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); +} |