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- /****************************************************************************
- png.c - read and write png images using libpng routines.
- Distributed with Xplanet.
- Copyright (C) 2002 Hari Nair <hari@alumni.caltech.edu>
- 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 <string.h>
- #include <unistd.h>
- #include <sys/socket.h>
- #include <png.h>
- #include "const.h"
- int
- read_png(const char *filename, int *width, int *height, unsigned char **rgb,
- unsigned char **alpha)
- {
- int ret = 0;
- png_structp png_ptr;
- png_infop info_ptr;
- png_bytepp row_pointers;
- unsigned char *ptr = NULL;
- png_uint_32 w, h;
- int bit_depth, color_type, interlace_type;
- int i;
- FILE *infile = fopen(filename, "rb");
- if (infile == NULL) {
- fprintf(stderr, "Can not fopen file: %s\n", filename);
- return ret;
- }
- png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING,
- (png_voidp)NULL,
- (png_error_ptr)NULL,
- (png_error_ptr)NULL);
- if (!png_ptr)
- goto file_close;
- info_ptr = png_create_info_struct(png_ptr);
- if (!info_ptr) {
- png_destroy_read_struct(&png_ptr,
- (png_infopp)NULL,
- (png_infopp)NULL);
- }
- #if PNG_LIBPNG_VER_MAJOR >= 1 && PNG_LIBPNG_VER_MINOR >= 4
- if (setjmp(png_jmpbuf((png_ptr))))
- #else
- if (setjmp(png_ptr->jmpbuf))
- #endif
- goto png_destroy;
- png_init_io(png_ptr, infile);
- png_read_info(png_ptr, info_ptr);
- png_get_IHDR(png_ptr, info_ptr, &w, &h, &bit_depth, &color_type,
- &interlace_type, (int *) NULL, (int *) NULL);
- /* Prevent against integer overflow */
- if (w >= MAX_DIMENSION || h >= MAX_DIMENSION) {
- fprintf(stderr,
- "Unreasonable dimension found in file: %s\n", filename);
- goto png_destroy;
- }
- *width = (int) w;
- *height = (int) h;
- if (color_type == PNG_COLOR_TYPE_RGB_ALPHA
- || color_type == PNG_COLOR_TYPE_GRAY_ALPHA) {
- alpha[0] = malloc(*width * *height);
- if (alpha[0] == NULL) {
- fprintf(stderr,
- "Can't allocate memory for alpha channel in PNG file.\n");
- goto png_destroy;
- }
- }
- /* Change a paletted/grayscale image to RGB */
- if (color_type == PNG_COLOR_TYPE_PALETTE && bit_depth <= 8)
- png_set_expand(png_ptr);
- /* Change a grayscale image to RGB */
- if (color_type == PNG_COLOR_TYPE_GRAY ||
- color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
- png_set_gray_to_rgb(png_ptr);
- /* If the PNG file has 16 bits per channel, strip them down to 8 */
- if (bit_depth == 16)
- png_set_strip_16(png_ptr);
- /* use 1 byte per pixel */
- png_set_packing(png_ptr);
- row_pointers = malloc(*height * sizeof(png_bytep));
- if (row_pointers == NULL) {
- fprintf(stderr, "Can't allocate memory for PNG file.\n");
- goto png_destroy;
- }
- for (i = 0; i < *height; i++) {
- row_pointers[i] = malloc(4 * *width);
- if (row_pointers == NULL) {
- fprintf(stderr,
- "Can't allocate memory for PNG line.\n");
- goto rows_free;
- }
- }
- png_read_image(png_ptr, row_pointers);
- rgb[0] = malloc(3 * *width * *height);
- if (rgb[0] == NULL) {
- fprintf(stderr, "Can't allocate memory for PNG file.\n");
- goto rows_free;
- }
- if (alpha[0] == NULL) {
- ptr = rgb[0];
- for (i = 0; i < *height; i++) {
- memcpy(ptr, row_pointers[i], 3 * *width);
- ptr += 3 * *width;
- }
- } else {
- int j;
- ptr = rgb[0];
- for (i = 0; i < *height; i++) {
- int ipos = 0;
- for (j = 0; j < *width; j++) {
- *ptr++ = row_pointers[i][ipos++];
- *ptr++ = row_pointers[i][ipos++];
- *ptr++ = row_pointers[i][ipos++];
- alpha[0][i * *width + j]
- = row_pointers[i][ipos++];
- }
- }
- }
- ret = 1; /* data reading is OK */
- rows_free:
- for (i = 0; i < *height; i++) {
- if (row_pointers[i] != NULL)
- free(row_pointers[i]);
- }
- free(row_pointers);
- png_destroy:
- png_destroy_read_struct(&png_ptr, &info_ptr, (png_infopp) NULL);
- file_close:
- fclose(infile);
- return ret;
- }
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