/* multidesktopbackground.vala
 *
 * Copyright (C) 2011 Qball Cow <qball @gmpclient.org>
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http: //www.gnu.org/licenses/>.
 *
 * Author:
 * 	Qball Cow </qball><qball @gmpclient.org>
 */
using Gtk;
 
/**
 * Set the actual background on the X server
 */
static void set_background(Gdk.Window root_window, Gdk.Pixbuf background_pb)
{
		Gdk.Pixmap pixmap;
		Gdk.Bitmap bitmap;
		// Grab server, without this, it won't work.
		Gdk.x11_grab_server();
 
		// Set background pixmap.
		Gdk.pixbuf_render_pixmap_and_mask(background_pb,out pixmap, out bitmap, );
		root_window.set_back_pixmap(pixmap, false);
 
		// Otherwise the background will only update after being exposed.
		/// @todo can I trigger an expose event on GdkWindow?
		root_window.draw_pixbuf(null,
				background_pb, ,,,, 
				background_pb.get_width(), background_pb.get_height(),
				Gdk.RgbDither.NONE, ,);
 
		// Release
		Gdk.x11_ungrab_server();
}
 
 
/**
 * Option parser
 */
string  clipping = null;
const GLib.OptionEntry[] entries = {
        {"clipping", 'c', , GLib.OptionArg.STRING, ref clipping, "Enable clipping", null},
        {null}
};
 
/**
 * Main program
 */
static int main (string[] argv)
{
	bool clip = false;
 
	/**
	 * Parse command line list
	 */
    GLib.OptionContext og = new GLib.OptionContext("Evo");
    og.add_main_entries(entries,null);
	try{
		og.parse(ref argv);
	}catch (Error e) {
		GLib.error("Failed to parse command line options: %s\n", e.message);
	}
	/**
	 * Parse clipping
	 */	
	if(clipping != null) {
		if(clipping.down() == "true") {
			clip = true;
		}
	}
 
	/**
	 * Get filename
	 */
	if(argv.length  != 2) {
		GLib.error("Failed parsing commandlines");
	}
	string file = argv[1];
 
	// Initialize GTK.
	Gtk.init(ref argv);
 
	// Get display
	Gdk.Display display = Gdk.Display.get_default();
 
	// Get number of screens.
	int num_screens = display.get_n_screens();
 
	// Walk the screens.
	for(int screen = ; screen < num_screens ; screen++)
	{
		Gdk.Screen gscreen = display.get_screen(screen);
		Gdk.Window root_window = gscreen.get_root_window();
 
		int rw_width = gscreen.get_width();
		int rw_height = gscreen.get_height();
 
		// Create background pixmap.
		var background_pb = new Gdk.Pixbuf(Gdk.Colorspace.RGB,false,8, rw_width, rw_height);
 
 
		// Iterate over all the monitors and draw the image there.
 
		// Get number of monitors.
		int num_monitors = gscreen.get_n_monitors();
		for(int monitor = ; monitor < num_monitors; monitor++)
		{
			Gdk.Rectangle rectangle;
			// get monitor size
			gscreen.get_monitor_geometry(monitor, out rectangle);
 
			// Gdk.Pixbuf loading and drawing inside.
			try
			{
				Gdk.Pixbuf? pb = new Gdk.Pixbuf.from_file(file); 
				// Get size
				int pb_width = pb.get_width();
				int pb_height = pb.get_height();
				// Scaling
				double x_scale = pb_width/(double)rectangle.width;
				double y_scale = pb_height/(double)rectangle.height;
 
				if(x_scale >= 1 && y_scale >= 1 && clip) 
				{
					if(x_scale > y_scale)
					{
						int new_width = (int)(pb_width/y_scale);
						int new_height = (int)(pb_height/y_scale);
						pb = pb.scale_simple(new_width, new_height, Gdk.InterpType.HYPER); 
 
						int x_offset = (new_width - rectangle.width)/2;
						int y_offset = (new_height- rectangle.height)/2;
						pb.copy_area(
								x_offset,y_offset,
								new_width-x_offset*2,new_height-y_offset*2,
								background_pb,
								rectangle.x, rectangle.y
								);
					} else {
						int new_width = (int)(pb_width/x_scale);
						int new_height = (int)(pb_height/x_scale);
						pb = pb.scale_simple(new_width, new_height, Gdk.InterpType.HYPER); 
 
						int x_offset = (new_width - rectangle.width)/2;
						int y_offset = (new_height- rectangle.height)/2;
						pb.copy_area(
								x_offset,y_offset,
								new_width-x_offset*2,new_height-y_offset*2,
								background_pb,
								rectangle.x,rectangle.y
								);
					}
				}
				else if(x_scale > y_scale)
				{
					int new_width = (int)(pb_width/x_scale);
					int new_height = (int)(pb_height/x_scale);
					pb = pb.scale_simple(new_width, new_height, Gdk.InterpType.HYPER); 
 
					pb.copy_area(,,
							new_width, new_height,
							background_pb,
							rectangle.x + (rectangle.width-new_width)/2,
							rectangle.y + (rectangle.height-new_height)/2
							);
				}
				else 
				{
					int new_width = (int)(pb_width/y_scale);
					int new_height = (int)(pb_height/y_scale);
					pb = pb.scale_simple(new_width, new_height, Gdk.InterpType.HYPER); 
 
					pb.copy_area(,,
							new_width, new_height,
							background_pb,
							rectangle.x + (rectangle.width-new_width)/2,
							rectangle.y + (rectangle.height-new_height)/2
							);
 
				}
 
			} catch (Error e) {
				GLib.error("Failed loading pixbuf: %s\n", e.message);
			}
 
		}
		set_background(root_window, background_pb);
	}
 
	return 1;
}
</qball>

valac --pkg=gtk+-2.0  MultiDesktopBackground.vala  --pkg=gdk-x11-2.0 --pkg=x11