// Copyright 2002-2010 Guillaume Cottenceau. // This software may be freely redistributed under the terms of // the X11 license. // // Function write_png_file taken slightly modified from // http://zarb.org/~gc/html/libpng.html #include <png.h> #include <stdarg.h> #include <stdio.h> #include <base/files/file_util.h> #include <gflags/gflags.h> #include "png_helper.h" void abort_(const char * s, ...) { va_list args; va_start(args, s); vfprintf(stderr, s, args); fprintf(stderr, "\n"); va_end(args); abort(); } void write_png_file(const char* file_name, char* pixels, int width, int height) { int x, y; png_bytep *row_pointers; png_structp png_ptr; png_infop info_ptr; png_byte bit_depth = 8; // 8 bits per channel RGBA png_byte color_type = 6; // RGBA row_pointers = (png_bytep*) malloc(sizeof(png_bytep) * height); char *p = pixels; for (y=height-1; y>=0; y--) { row_pointers[y] = (png_byte*) malloc(4*width); for (x=0; x<width; x++) { png_byte* pixel = &(row_pointers[y][x*4]); pixel[0] = *p; p++; // R pixel[1] = *p; p++; // G pixel[2] = *p; p++; // B pixel[3] = *p; p++; // A } } /* create file */ FILE *fp = fopen(file_name, "wb"); if (!fp) abort_("[write_png_file] File %s could not be opened for writing", file_name); /* initialize stuff */ png_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL); if (!png_ptr) abort_("[write_png_file] png_create_write_struct failed"); info_ptr = png_create_info_struct(png_ptr); if (!info_ptr) abort_("[write_png_file] png_create_info_struct failed"); if (setjmp(png_jmpbuf(png_ptr))) abort_("[write_png_file] Error during init_io"); png_init_io(png_ptr, fp); /* write header */ if (setjmp(png_jmpbuf(png_ptr))) abort_("[write_png_file] Error during writing header"); png_set_IHDR(png_ptr, info_ptr, width, height, bit_depth, color_type, PNG_INTERLACE_NONE, PNG_COMPRESSION_TYPE_BASE, PNG_FILTER_TYPE_BASE); png_write_info(png_ptr, info_ptr); /* write bytes */ if (setjmp(png_jmpbuf(png_ptr))) abort_("[write_png_file] Error during writing bytes"); png_write_image(png_ptr, row_pointers); /* end write */ if (setjmp(png_jmpbuf(png_ptr))) abort_("[write_png_file] Error during end of write"); png_write_end(png_ptr, NULL); /* cleanup heap allocation */ for (y=0; y<height; y++) free(row_pointers[y]); free(row_pointers); fclose(fp); // Try to flush saved image to disk such that more data survives a hard crash. system("/bin/sync"); }