/*- pngtopng * * COPYRIGHT: Written by John Cunningham Bowler, 2011. * To the extent possible under law, the author has waived all copyright and * related or neighboring rights to this work. This work is published from: * United States. * * Read a PNG and write it out in a fixed format, using the 'simplified API' * that was introduced in libpng-1.6.0. * * This sample code is just the code from the top of 'example.c' with some error * handling added. See example.c for more comments. */ #include #include #include #include /* Normally use here to get the installed libpng, but this is done to * ensure the code picks up the local libpng implementation: */ #include "../../png.h" int main(int argc, const char **argv) { int result = 1; if (argc == 3) { png_image image; /* Only the image structure version number needs to be set. */ memset(&image, 0, sizeof image); image.version = PNG_IMAGE_VERSION; if (png_image_begin_read_from_file(&image, argv[1])) { png_bytep buffer; /* Change this to try different formats! If you set a colormap format * then you must also supply a colormap below. */ image.format = PNG_FORMAT_RGBA; buffer = malloc(PNG_IMAGE_SIZE(image)); if (buffer != NULL) { if (png_image_finish_read(&image, NULL/*background*/, buffer, 0/*row_stride*/, NULL/*colormap for PNG_FORMAT_FLAG_COLORMAP */)) { if (png_image_write_to_file(&image, argv[2], 0/*convert_to_8bit*/, buffer, 0/*row_stride*/, NULL/*colormap*/)) result = 0; else fprintf(stderr, "pngtopng: write %s: %s\n", argv[2], image.message); free(buffer); } else { fprintf(stderr, "pngtopng: read %s: %s\n", argv[1], image.message); /* This is the only place where a 'free' is required; libpng does * the cleanup on error and success, but in this case we couldn't * complete the read because of running out of memory. */ png_image_free(&image); } } else fprintf(stderr, "pngtopng: out of memory: %lu bytes\n", (unsigned long)PNG_IMAGE_SIZE(image)); } else /* Failed to read the first argument: */ fprintf(stderr, "pngtopng: %s: %s\n", argv[1], image.message); } else /* Wrong number of arguments */ fprintf(stderr, "pngtopng: usage: pngtopng input-file output-file\n"); return result; }