Random Windows Wallpaper

RandomWallpaper.cs

/* Selects a random image from a folder and makes it the desktop wallpaper.
 * usage: RandomWallpaper.exe [c:\path\to\wallpapers]
 * If the path is omitted, the current directory is used.
 */

using System;
using System.Collections.Generic;
using System.Text;
using System.IO;
using System.Runtime.InteropServices;
using System.Windows.Forms;
using System.Drawing;
using System.Drawing.Imaging;

namespace RandomWallpaper
{
    class Program
    {
        [DllImport("user32.dll", CharSet = CharSet.Auto)]
        static extern int SystemParametersInfo
            (int uAction, int uParam, string lpvParam, int fuWinIni);
        const int SPI_SETDESKWALLPAPER = 20;
        const int SPIF_UPDATEINIFILE = 0x01;
        const int SPIF_SENDWININICHANGE = 0x02;

        static void Main(string[] args)
        {
            DirectoryInfo directory;
            if (args.Length < 1) directory = 
                new DirectoryInfo(Directory.GetCurrentDirectory());
            else directory = new DirectoryInfo(args[0]);
            List<FileInfo> files = new List<FileInfo>();
            foreach (String ext in new String[] 
                {"bmp", "jpg", "jpeg", "png", "gif", "tif", "tiff"})
                files.AddRange(directory.GetFiles("*." + ext));
            if (files.Count == 0) MessageBox.Show("No images found.");
            else {
                String pic = files[new Random().Next(files.Count)].FullName;
                String path = Path.GetTempPath() + "RandomWallpaper.bmp";
                Image image = Image.FromFile(pic);
                image.Save(path, ImageFormat.Bmp);
                SystemParametersInfo(SPI_SETDESKWALLPAPER, 0, path,
                    SPIF_UPDATEINIFILE | SPIF_SENDWININICHANGE);
            }
        }
    }
}