Changing the Wallpaper (Source Code)

This small program regularly changes the desktop wallpaper using images in a folder. Add the System.Drawing reference to a new project, build the project, put the EXE file in a directory with many wallpapers and run it.

/*
 * (C) 2008 Peter O.
 * Permission is granted to anyone to copy, modify,
 * and redistribute this file.  Attribution to the
 * author would be appreciated but is not required.
 * No warranties are provided and all liabilities
 * are disclaimed.
 */
using System;
using System.IO;
using System.Collections.Generic;
using System.Drawing;
using System.Drawing.Imaging;
using System.Runtime.InteropServices;
using System.Threading;
using System.Diagnostics;


namespace WallpaperRotator
{
	class Program
	{
		
		[DllImport("user32.dll", SetLastError = true, 
		           CharSet = CharSet.Auto)]
		[return: MarshalAs(UnmanagedType.Bool)]
		static extern bool SystemParametersInfo(
			int uiAction, 
			uint uiParam, 
			string pvParam, 
			int fWinIni);


		
		public static Random random=new Random();
		
		public static void NextWallpaper(){
			List<string> files=new List<string>();
			// Get a list of all wallpapers in the directory
			files.AddRange(Directory.GetFiles(".","*.jpg"));
			files.AddRange(Directory.GetFiles(".","*.jpeg"));
			// Leave if no wallpapers exist
			if(files.Count==0)
				return;
			// Choose a random wallpaper in the directory
			string file=files[random.Next(files.Count)];
			// Save to bitmap for SystemParametersInfo
			using(Bitmap b=(Bitmap)Bitmap.FromFile(file)){
				b.Save("wallpaper.bmp",System.Drawing.Imaging.ImageFormat.Bmp);
			}
			// Set the bitmap as wallpaper
			SystemParametersInfo(20,1,
			                     Path.GetFullPath("wallpaper.bmp"),3);
		}
		
		
		public static void Main(string[] args)
		{
			while(true){
				// Change the wallpaper
				NextWallpaper();
				// Wait 60 seconds between displaying wallpapers
				Thread.Sleep(60*1000);
			}
		}
	}
}