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 <gflags/gflags.h> 13 14 #include "png_helper.h" 15 16 void abort_(const char* s, ...) { 17 va_list args; 18 va_start(args, s); 19 vfprintf(stderr, s, args); 20 fprintf(stderr, "\n"); 21 va_end(args); 22 abort(); 23 } 24 25 void write_png_file(const char* file_name, 26 char* pixels, 27 int width, 28 int height) { 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); // R 43 pixel[1] = *(p+1); // G 44 pixel[2] = *(p+2); // B 45 pixel[3] = *(p+3); // A 46 p += 4; 47 } 48 } 49 50 /* create file */ 51 FILE* fp = fopen(file_name, "wb"); 52 if (!fp) 53 abort_("[write_png_file] File %s could not be opened for writing", 54 file_name); 55 /* initialize stuff */ 56 png_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL); 57 if (!png_ptr) 58 abort_("[write_png_file] png_create_write_struct failed"); 59 info_ptr = png_create_info_struct(png_ptr); 60 if (!info_ptr) 61 abort_("[write_png_file] png_create_info_struct failed"); 62 if (setjmp(png_jmpbuf(png_ptr))) 63 abort_("[write_png_file] Error during init_io"); 64 png_init_io(png_ptr, fp); 65 66 /* write header */ 67 if (setjmp(png_jmpbuf(png_ptr))) 68 abort_("[write_png_file] Error during writing header"); 69 png_set_IHDR(png_ptr, info_ptr, width, height, bit_depth, color_type, 70 PNG_INTERLACE_NONE, PNG_COMPRESSION_TYPE_BASE, 71 PNG_FILTER_TYPE_BASE); 72 png_write_info(png_ptr, info_ptr); 73 74 /* write bytes */ 75 if (setjmp(png_jmpbuf(png_ptr))) 76 abort_("[write_png_file] Error during writing bytes"); 77 png_write_image(png_ptr, row_pointers); 78 79 /* end write */ 80 if (setjmp(png_jmpbuf(png_ptr))) 81 abort_("[write_png_file] Error during end of write"); 82 png_write_end(png_ptr, NULL); 83 84 /* cleanup heap allocation */ 85 for (y = 0; y < height; y++) 86 free(row_pointers[y]); 87 free(row_pointers); 88 89 fclose(fp); 90 91 // Try to flush saved image to disk such that more data survives a hard crash. 92 system("/bin/sync"); 93 } 94