1 // Copyright 2002-2010 Guillaume Cottenceau. 2 // This software may be freely redistributed under the terms of 3 // the X11 license. 4 // 5 // Function write_png_file taken slightly modified from 6 // http://zarb.org/~gc/html/libpng.html 7 8 #include <png.h> 9 #include <stdarg.h> 10 #include <stdio.h> 11 12 #include <base/files/file_util.h> 13 #include <gflags/gflags.h> 14 15 #include "png_helper.h" 16 17 void abort_(const char * s, ...) { 18 va_list args; 19 va_start(args, s); 20 vfprintf(stderr, s, args); 21 fprintf(stderr, "\n"); 22 va_end(args); 23 abort(); 24 } 25 26 void write_png_file(const char* file_name, char* pixels, int width, int height) 27 { 28 int x, y; 29 png_bytep *row_pointers; 30 png_structp png_ptr; 31 png_infop info_ptr; 32 png_byte bit_depth = 8; // 8 bits per channel RGBA 33 png_byte color_type = 6; // RGBA 34 35 row_pointers = (png_bytep*) malloc(sizeof(png_bytep) * height); 36 char *p = pixels; 37 for (y=height-1; y>=0; y--) { 38 row_pointers[y] = (png_byte*) malloc(4*width); 39 for (x=0; x<width; x++) { 40 png_byte* pixel = &(row_pointers[y][x*4]); 41 pixel[0] = *p; p++; // R 42 pixel[1] = *p; p++; // G 43 pixel[2] = *p; p++; // B 44 pixel[3] = *p; p++; // A 45 } 46 } 47 48 /* create file */ 49 FILE *fp = fopen(file_name, "wb"); 50 if (!fp) 51 abort_("[write_png_file] File %s could not be opened for writing", 52 file_name); 53 /* initialize stuff */ 54 png_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL); 55 if (!png_ptr) 56 abort_("[write_png_file] png_create_write_struct failed"); 57 info_ptr = png_create_info_struct(png_ptr); 58 if (!info_ptr) 59 abort_("[write_png_file] png_create_info_struct failed"); 60 if (setjmp(png_jmpbuf(png_ptr))) 61 abort_("[write_png_file] Error during init_io"); 62 png_init_io(png_ptr, fp); 63 64 /* write header */ 65 if (setjmp(png_jmpbuf(png_ptr))) 66 abort_("[write_png_file] Error during writing header"); 67 png_set_IHDR(png_ptr, info_ptr, width, height, 68 bit_depth, color_type, PNG_INTERLACE_NONE, 69 PNG_COMPRESSION_TYPE_BASE, PNG_FILTER_TYPE_BASE); 70 png_write_info(png_ptr, info_ptr); 71 72 /* write bytes */ 73 if (setjmp(png_jmpbuf(png_ptr))) 74 abort_("[write_png_file] Error during writing bytes"); 75 png_write_image(png_ptr, row_pointers); 76 77 /* end write */ 78 if (setjmp(png_jmpbuf(png_ptr))) 79 abort_("[write_png_file] Error during end of write"); 80 png_write_end(png_ptr, NULL); 81 82 /* cleanup heap allocation */ 83 for (y=0; y<height; y++) 84 free(row_pointers[y]); 85 free(row_pointers); 86 87 fclose(fp); 88 89 // Try to flush saved image to disk such that more data survives a hard crash. 90 system("/bin/sync"); 91 } 92
