174 lines
4.4 KiB
C
174 lines
4.4 KiB
C
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/****************************************************************************
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png.c - read and write png images using libpng routines.
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Distributed with Xplanet.
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Copyright (C) 2002 Hari Nair <hari@alumni.caltech.edu>
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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****************************************************************************/
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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#include <sys/socket.h>
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#include <png.h>
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#include "const.h"
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int read_png(const char *filename, int *width, int *height, unsigned char **rgb,
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unsigned char **alpha)
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{
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int ret = 0;
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png_structp png_ptr;
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png_infop info_ptr;
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png_bytepp row_pointers;
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unsigned char *ptr = NULL;
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png_uint_32 w, h;
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int bit_depth, color_type, interlace_type;
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int i;
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FILE *infile = fopen(filename, "rb");
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if (infile == NULL) {
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fprintf(stderr, "Can not fopen file: %s\n", filename);
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return ret;
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}
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png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING,
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(png_voidp)NULL,
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(png_error_ptr)NULL,
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(png_error_ptr)NULL);
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if (!png_ptr)
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goto file_close;
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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,
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(png_infopp)NULL,
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(png_infopp)NULL);
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}
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#if PNG_LIBPNG_VER_MAJOR >= 1 && PNG_LIBPNG_VER_MINOR >= 4
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if (setjmp(png_jmpbuf((png_ptr))))
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#else
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if (setjmp(png_ptr->jmpbuf))
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#endif
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goto png_destroy;
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png_init_io(png_ptr, infile);
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png_read_info(png_ptr, info_ptr);
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png_get_IHDR(png_ptr, info_ptr, &w, &h, &bit_depth, &color_type,
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&interlace_type, (int *) NULL, (int *) NULL);
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/* Prevent against integer overflow */
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if (w >= MAX_DIMENSION || h >= MAX_DIMENSION) {
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fprintf(stderr,
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"Unreasonable dimension found in file: %s\n", filename);
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goto png_destroy;
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}
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*width = (int) w;
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*height = (int) h;
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if (color_type == PNG_COLOR_TYPE_RGB_ALPHA
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|| color_type == PNG_COLOR_TYPE_GRAY_ALPHA) {
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alpha[0] = malloc(*width * *height);
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if (alpha[0] == NULL) {
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fprintf(stderr,
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"Can't allocate memory for alpha channel in PNG file.\n");
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goto png_destroy;
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}
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}
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/* Change a paletted/grayscale image to RGB */
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if (color_type == PNG_COLOR_TYPE_PALETTE && bit_depth <= 8)
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png_set_expand(png_ptr);
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/* Change a grayscale image to RGB */
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if (color_type == PNG_COLOR_TYPE_GRAY ||
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color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
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png_set_gray_to_rgb(png_ptr);
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/* If the PNG file has 16 bits per channel, strip them down to 8 */
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if (bit_depth == 16)
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png_set_strip_16(png_ptr);
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/* use 1 byte per pixel */
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png_set_packing(png_ptr);
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row_pointers = malloc(*height * sizeof(png_bytep));
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if (row_pointers == NULL) {
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fprintf(stderr, "Can't allocate memory for PNG file.\n");
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goto png_destroy;
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}
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for (i = 0; i < *height; i++) {
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row_pointers[i] = malloc(4 * *width);
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if (row_pointers == NULL) {
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fprintf(stderr,
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"Can't allocate memory for PNG line.\n");
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goto rows_free;
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}
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}
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png_read_image(png_ptr, row_pointers);
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rgb[0] = malloc(3 * *width * *height);
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if (rgb[0] == NULL) {
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fprintf(stderr, "Can't allocate memory for PNG file.\n");
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goto rows_free;
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}
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if (alpha[0] == NULL) {
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ptr = rgb[0];
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for (i = 0; i < *height; i++) {
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memcpy(ptr, row_pointers[i], 3 * *width);
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ptr += 3 * *width;
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}
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} else {
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int j;
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ptr = rgb[0];
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for (i = 0; i < *height; i++) {
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int ipos = 0;
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for (j = 0; j < *width; j++) {
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*ptr++ = row_pointers[i][ipos++];
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*ptr++ = row_pointers[i][ipos++];
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*ptr++ = row_pointers[i][ipos++];
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alpha[0][i * *width + j]
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= row_pointers[i][ipos++];
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}
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}
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}
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ret = 1; /* data reading is OK */
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rows_free:
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for (i = 0; i < *height; i++) {
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if (row_pointers[i] != NULL)
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free(row_pointers[i]);
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}
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free(row_pointers);
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png_destroy:
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png_destroy_read_struct(&png_ptr, &info_ptr, (png_infopp) NULL);
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file_close:
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fclose(infile);
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return ret;
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}
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