--- /dev/null
+/*---------------------------------------------------------------------------
+
+ rpng - simple PNG display program readpng.c
+
+ ---------------------------------------------------------------------------
+
+ Copyright (c) 1998-2000 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.
+
+ 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.
+
+ ---------------------------------------------------------------------------*/
+
+#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;
+ }
+}
projects / synfig.git / blobdiff