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 <base/memory/scoped_ptr.h> 14 #include <gflags/gflags.h> 15 16 #include "png_helper.h" 17 18 void abort_(const char * s, ...) { 19 va_list args; 20 va_start(args, s); 21 vfprintf(stderr, s, args); 22 fprintf(stderr, "\n"); 23 va_end(args); 24 abort(); 25 } 26 27 void write_png_file(const char* file_name, char* pixels, int width, int height) 28 { 29 int x, y; 30 png_bytep *row_pointers; 31 png_structp png_ptr; 32 png_infop info_ptr; 33 png_byte bit_depth = 8; // 8 bits per channel RGBA 34 png_byte color_type = 6; // RGBA 35 36 row_pointers = (png_bytep*) malloc(sizeof(png_bytep) * height); 37 char *p = pixels; 38 for (y=height-1; y>=0; y--) { 39 row_pointers[y] = (png_byte*) malloc(4*width); 40 for (x=0; x<width; x++) { 41 png_byte* pixel = &(row_pointers[y][x*4]); 42 pixel[0] = *p; p++; // R 43 pixel[1] = *p; p++; // G 44 pixel[2] = *p; p++; // B 45 pixel[3] = *p; p++; // A 46 } 47 } 48 49 /* create file */ 50 FILE *fp = fopen(file_name, "wb"); 51 if (!fp) 52 abort_("[write_png_file] File %s could not be opened for writing", 53 file_name); 54 /* initialize stuff */ 55 png_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL); 56 if (!png_ptr) 57 abort_("[write_png_file] png_create_write_struct failed"); 58 info_ptr = png_create_info_struct(png_ptr); 59 if (!info_ptr) 60 abort_("[write_png_file] png_create_info_struct failed"); 61 if (setjmp(png_jmpbuf(png_ptr))) 62 abort_("[write_png_file] Error during init_io"); 63 png_init_io(png_ptr, fp); 64 65 /* write header */ 66 if (setjmp(png_jmpbuf(png_ptr))) 67 abort_("[write_png_file] Error during writing header"); 68 png_set_IHDR(png_ptr, info_ptr, width, height, 69 bit_depth, color_type, PNG_INTERLACE_NONE, 70 PNG_COMPRESSION_TYPE_BASE, PNG_FILTER_TYPE_BASE); 71 png_write_info(png_ptr, info_ptr); 72 73 /* write bytes */ 74 if (setjmp(png_jmpbuf(png_ptr))) 75 abort_("[write_png_file] Error during writing bytes"); 76 png_write_image(png_ptr, row_pointers); 77 78 /* end write */ 79 if (setjmp(png_jmpbuf(png_ptr))) 80 abort_("[write_png_file] Error during end of write"); 81 png_write_end(png_ptr, NULL); 82 83 /* cleanup heap allocation */ 84 for (y=0; y<height; y++) 85 free(row_pointers[y]); 86 free(row_pointers); 87 88 fclose(fp); 89 90 // Try to flush saved image to disk such that more data survives a hard crash. 91 system("/bin/sync"); 92 } 93
