fife-parpg: ext/libpng-1.2.29/contrib/gregbook/readpng.c comparison

comparison ext/libpng-1.2.29/contrib/gregbook/readpng.c @ 0:4a0efb7baf70

* Datasets becomes the new trunk and retires after that :-)

author	mvbarracuda@33b003aa-7bff-0310-803a-e67f0ece8222
date	Sun, 29 Jun 2008 18:44:17 +0000
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--1:000000000000
+:4a0efb7baf70
+/*---------------------------------------------------------------------------
+rpng - simple PNG display program                              readpng.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 <stdio.h>
+#include <stdlib.h>
+#include "png.h"        /* libpng header; includes zlib.h */
+#include "readpng.h"    /* typedefs, common macros, public prototypes */
+/* future versions of libpng will provide this macro: */
+#ifndef png_jmpbuf
+#  define png_jmpbuf(png_ptr)   ((png_ptr)->jmpbuf)
+#endif
+static png_structp png_ptr = NULL;
+static png_infop info_ptr = NULL;
+png_uint_32  width, height;
+int  bit_depth, color_type;
+uch  *image_data = NULL;
+void readpng_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);
+}
+/* return value = 0 for success, 1 for bad sig, 2 for bad IHDR, 4 for no mem */
+int readpng_init(FILE *infile, ulg *pWidth, ulg *pHeight)
+{
+uch sig[8];
+/* first do a quick check that the file really is a PNG image; could
+* have used slightly more general png_sig_cmp() function instead */
+fread(sig, 1, 8, infile);
+if (!png_check_sig(sig, 8))
+return 1;   /* bad signature */
+/* could pass pointers to user-defined error handlers instead of NULLs: */
+png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, 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 */
+if (setjmp(png_jmpbuf(png_ptr))) {
+png_destroy_read_struct(&png_ptr, &info_ptr, NULL);
+return 2;
+}
+png_init_io(png_ptr, infile);
+png_set_sig_bytes(png_ptr, 8);  /* we already read the 8 signature bytes */
+png_read_info(png_ptr, info_ptr);  /* read all PNG info up to image data */
+/* alternatively, could make separate calls to png_get_image_width(),
+* etc., but want bit_depth and color_type for later [don't care about
+* compression_type and filter_type => NULLs] */
+png_get_IHDR(png_ptr, info_ptr, &width, &height, &bit_depth, &color_type,
+NULL, NULL, NULL);
+*pWidth = width;
+*pHeight = height;
+/* OK, that's all we need for now; return happy */
+return 0;
+}
+/* returns 0 if succeeds, 1 if fails due to no bKGD chunk, 2 if libpng error;
+* scales values to 8-bit if necessary */
+int readpng_get_bgcolor(uch *red, uch *green, uch *blue)
+{
+png_color_16p pBackground;
+/* setjmp() must be called in every function that calls a PNG-reading
+* libpng function */
+if (setjmp(png_jmpbuf(png_ptr))) {
+png_destroy_read_struct(&png_ptr, &info_ptr, NULL);
+return 2;
+}
+if (!png_get_valid(png_ptr, info_ptr, PNG_INFO_bKGD))
+return 1;
+/* 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) {
+*red   = pBackground->red   >> 8;
+*green = pBackground->green >> 8;
+*blue  = pBackground->blue  >> 8;
+} else if (color_type == PNG_COLOR_TYPE_GRAY && bit_depth < 8) {
+if (bit_depth == 1)
+*red = *green = *blue = pBackground->gray? 255 : 0;
+else if (bit_depth == 2)
+*red = *green = *blue = (255/3) * pBackground->gray;
+else /* bit_depth == 4 */
+*red = *green = *blue = (255/15) * pBackground->gray;
+} else {
+*red   = (uch)pBackground->red;
+*green = (uch)pBackground->green;
+*blue  = (uch)pBackground->blue;
+}
+return 0;
+}
+/* display_exponent == LUT_exponent * CRT_exponent */
+uch *readpng_get_image(double display_exponent, int *pChannels, ulg *pRowbytes)
+{
+double  gamma;
+png_uint_32  i, rowbytes;
+png_bytepp  row_pointers = NULL;
+/* setjmp() must be called in every function that calls a PNG-reading
+* libpng function */
+if (setjmp(png_jmpbuf(png_ptr))) {
+png_destroy_read_struct(&png_ptr, &info_ptr, NULL);
+return NULL;
+}
+/* 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 example in the libpng documentation, we have *no* idea where
+* this file may have come from--so if it doesn't have a file gamma, don't
+* do any correction ("do no harm") */
+if (png_get_gAMA(png_ptr, info_ptr, &gamma))
+png_set_gamma(png_ptr, display_exponent, gamma);
+/* all transformations have been registered; now update info_ptr data,
+* get rowbytes and channels, and allocate image memory */
+png_read_update_info(png_ptr, info_ptr);
+*pRowbytes = rowbytes = png_get_rowbytes(png_ptr, info_ptr);
+*pChannels = (int)png_get_channels(png_ptr, info_ptr);
+if ((image_data = (uch *)malloc(rowbytes*height)) == NULL) {
+png_destroy_read_struct(&png_ptr, &info_ptr, NULL);
+return NULL;
+}
+if ((row_pointers = (png_bytepp)malloc(height*sizeof(png_bytep))) == NULL) {
+png_destroy_read_struct(&png_ptr, &info_ptr, NULL);
+free(image_data);
+image_data = NULL;
+return NULL;
+}
+Trace((stderr, "readpng_get_image:  channels = %d, rowbytes = %ld, height = %ld\n", *pChannels, rowbytes, height));
+/* set the individual row_pointers to point at the correct offsets */
+for (i = 0;  i < height;  ++i)
+row_pointers[i] = image_data + i*rowbytes;
+/* now we can go ahead and just read the whole image */
+png_read_image(png_ptr, row_pointers);
+/* and we're done!  (png_read_end() can be omitted if no processing of
+* post-IDAT text/time/etc. is desired) */
+free(row_pointers);
+row_pointers = NULL;
+png_read_end(png_ptr, NULL);
+return image_data;
+}
+void readpng_cleanup(int free_image_data)
+{
+if (free_image_data && image_data) {
+free(image_data);
+image_data = NULL;
+}
+if (png_ptr && info_ptr) {
+png_destroy_read_struct(&png_ptr, &info_ptr, NULL);
+png_ptr = NULL;
+info_ptr = NULL;
+}
+}

Mercurial > fife-parpg

comparison ext/libpng-1.2.29/contrib/gregbook/readpng.c @ 0:4a0efb7baf70