| // 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 <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); // R |
| pixel[1] = *(p+1); // G |
| pixel[2] = *(p+2); // B |
| pixel[3] = *(p+3); // A |
| p += 4; |
| } |
| } |
| |
| /* 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"); |
| } |