/*
   compilation command:

   gcc -std=gnu11 -Wall image.c -o image `pkg-config --cflags --libs gdk-pixbuf-2.0`
*/

#include <gdk-pixbuf/gdk-pixbuf.h>

int main(int argc, char** argv) {
   g_type_init();

   unsigned int width = 100; 
   unsigned int height = 100;
   GdkPixbuf* pixbuf = gdk_pixbuf_new(GDK_COLORSPACE_RGB, FALSE, 8,
      width, height);
   int n_channels = gdk_pixbuf_get_n_channels(pixbuf);
   int rowstride = gdk_pixbuf_get_rowstride(pixbuf);
   guchar* pixels = gdk_pixbuf_get_pixels(pixbuf);
   for (unsigned int i = 0; i < height; ++i) {
      for (unsigned int j = 0; j < width; ++j) {
	 guchar* pp = pixels + i * rowstride + j * n_channels;

	 pp[0] = 139.0; /* red */
	 pp[1] = 155.0; /* green */
	 pp[2] = 20.0; /* blue */
      }
   }
   gdk_pixbuf_save (pixbuf, "image.jpg", "jpeg",
      NULL, "quality", "100", NULL);
}