Cambia lo sfondo del desktop usando il codice in .NET

Come posso cambiare lo sfondo del desktop usando il codice C #?

Ecco una lezione strappata da un’app che ho scritto un anno o due fa:

public sealed class Wallpaper { Wallpaper() { } const int SPI_SETDESKWALLPAPER = 20; const int SPIF_UPDATEINIFILE = 0x01; const int SPIF_SENDWININICHANGE = 0x02; [DllImport("user32.dll", CharSet = CharSet.Auto)] static extern int SystemParametersInfo(int uAction, int uParam, string lpvParam, int fuWinIni); public enum Style : int { Tiled, Centered, Stretched } public static void Set(Uri uri, Style style) { System.IO.Stream s = new System.Net.WebClient().OpenRead(uri.ToString()); System.Drawing.Image img = System.Drawing.Image.FromStream(s); string tempPath = Path.Combine(Path.GetTempPath(), "wallpaper.bmp"); img.Save(tempPath, System.Drawing.Imaging.ImageFormat.Bmp); RegistryKey key = Registry.CurrentUser.OpenSubKey(@"Control Panel\Desktop", true); if (style == Style.Stretched) { key.SetValue(@"WallpaperStyle", 2.ToString()); key.SetValue(@"TileWallpaper", 0.ToString()); } if (style == Style.Centered) { key.SetValue(@"WallpaperStyle", 1.ToString()); key.SetValue(@"TileWallpaper", 0.ToString()); } if (style == Style.Tiled) { key.SetValue(@"WallpaperStyle", 1.ToString()); key.SetValue(@"TileWallpaper", 1.ToString()); } SystemParametersInfo(SPI_SETDESKWALLPAPER, 0, tempPath, SPIF_UPDATEINIFILE | SPIF_SENDWININICHANGE); } } 

Non l’ho testato estensivamente, quindi usalo a tuo rischio.

Basandosi su questa risposta utile , ho anche creato la mia app per impostare la risoluzione dello schermo corrispondente allo sfondo.

Ma le impostazioni del registro erano sbagliate. Ecco i valori corretti (testati su Win 7, Win 8.1, Win 10).

 if (style == Style.Fill) { key.SetValue(@"WallpaperStyle", 10.ToString()); key.SetValue(@"TileWallpaper", 0.ToString()); } if (style == Style.Fit) { key.SetValue(@"WallpaperStyle", 6.ToString()); key.SetValue(@"TileWallpaper", 0.ToString()); } if (style == Style.Span) // Windows 8 or newer only! { key.SetValue(@"WallpaperStyle", 22.ToString()); key.SetValue(@"TileWallpaper", 0.ToString()); } if (style == Style.Stretch) { key.SetValue(@"WallpaperStyle", 2.ToString()); key.SetValue(@"TileWallpaper", 0.ToString()); } if (style == Style.Tile) { key.SetValue(@"WallpaperStyle", 0.ToString()); key.SetValue(@"TileWallpaper", 1.ToString()); } if (style == Style.Center) { key.SetValue(@"WallpaperStyle", 0.ToString()); key.SetValue(@"TileWallpaper", 0.ToString()); } 

Modifica la risposta di Neal N per le GIF:

 private const int SPI_SETDESKWALLPAPER = 20; private const int SPIF_UPDATEINIFILE = 0x01; private const int SPIF_SENDWININICHANGE = 0x02; [DllImport("user32.dll", CharSet = CharSet.Auto)] private static extern int SystemParametersInfo(int uAction, int uParam, string lpvParam, int fuWinIni); public enum Style : int { Tiled, Centered, Stretched } ///  /// Loops numFrames times, animating the desktop background as the given gif. /// Remember this will sorta bog down your computer, and probably isn't best to be running 24/7. /// If numFrames is negative this will loop forever ///  /// The gif to be animated /// If the gif has transparency, it will be "replaced" with this color. /// How many frames to play per second. This is a max: most likely it will be a little slower than this especially at first. /// Whether to tile, center, or stretch each gif frame as it's played. /// The number of frames to play. If negative, this method will loop forever. public static void SetDesktopBackgroundAsGifAsync(string gifPath, System.Drawing.Color transparencyReplace, int framesPerSecond, Style style, int numFrames) { Thread workerThread = new Thread(() => SetDesktopBackgroundAsGif(gifPath, transparencyReplace, framesPerSecond, style, numFrames)); workerThread.Start(); } ///  /// Loops numFrames times, animating the desktop background as the given gif. /// Remember this will sorta bog down your computer, and probably isn't best to be running 24/7. /// If num frames is negative this will loop forever. ////  /// The gif to be animated /// Image to render the gif on top of (because of transparency) /// How many frames to play per second. This is a max: most likely it will be a little slower than this. /// Whether to tile, center, or stretch each gif frame as it's played. /// The number of frames to play. If negative, this method will loop forever. public static void SetDesktopBackgroundAsGifAsync(string gifPath, System.Drawing.Image backgroundImage, int framesPerSecond, Style style, int numFrames) { Thread workerThread = new Thread(() => SetDesktopBackgroundAsGif(gifPath, backgroundImage, framesPerSecond, style, numFrames)); workerThread.Start(); } ///  /// Loops numFrames times, animating the desktop background as the given gif. /// Remember this will sorta bog down your computer, and probably isn't best to be running 24/7. /// if numFrames is negative this will loop forever ///  /// The gif to be animated /// If the gif has transparency, it will be "replaced" with this color. /// How many frames to play per second. This is a max: most likely it will be a little slower than this. /// Whether to tile, center, or stretch each gif frame as it's played. /// The number of frames to play. If negative, this method will loop forever. public static void SetDesktopBackgroundAsGif(string gifPath, System.Drawing.Color transparencyReplace, int framesPerSecond, Style style, int numFrames) { if (!File.Exists(gifPath)) throw new Exception("Given gif: '" + gifPath + "' not found"); FileStream gifFile = new FileStream(gifPath, FileMode.Open); GifBitmapDecoder gifDecoder = new GifBitmapDecoder(gifFile, BitmapCreateOptions.PreservePixelFormat, BitmapCacheOption.OnLoad); if (gifDecoder.Frames.Count == 0) throw new Exception("No frames in given gif"); Bitmap backgroundImage = new Bitmap(gifDecoder.Frames[0].PixelWidth, gifDecoder.Frames[0].PixelHeight, System.Drawing.Imaging.PixelFormat.Format32bppArgb); using(Graphics g = Graphics.FromImage(backgroundImage)) { g.FillRectangle(new System.Drawing.SolidBrush(transparencyReplace), 0, 0, gifDecoder.Frames[0].PixelWidth, gifDecoder.Frames[0].PixelHeight); } gifFile.Close(); SetDesktopBackgroundAsGif(gifPath, backgroundImage, framesPerSecond, style, numFrames); } ///  /// Loops infinitely, animating the desktop background as the given gif. /// Remember this will sorta bog down your computer, and probably isn't best to be running 24/7. ///  /// The gif to be animated /// Image to render the gif on top of (because of transparency) /// How many frames to play per second. This is a max: most likely it will be a little slower than this. /// Whether to tile, center, or stretch each gif frame as it's played. /// The number of frames to play. If negative, this method will loop forever. private static void SetDesktopBackgroundAsGif(string gifPath, System.Drawing.Image backgroundImage, int framesPerSecond, Style style, int numFrames) { if (!File.Exists(gifPath)) throw new Exception("Given gif: '" + gifPath + "' not found"); FileStream gifFile = new FileStream(gifPath, FileMode.Open); GifBitmapDecoder gifDecoder = new GifBitmapDecoder(gifFile, BitmapCreateOptions.PreservePixelFormat, BitmapCacheOption.OnLoad); if (gifDecoder.Frames.Count == 0) throw new Exception("No frames in given gif"); Console.WriteLine("Saving frames to temporary files:"); int numFramesSoFar = 0; for (int i = 0; i < gifDecoder.Frames.Count; i++) { BitmapFrame gifFrame = gifDecoder.Frames[i]; PngBitmapEncoder pngEncoder = new PngBitmapEncoder(); pngEncoder.Frames.Add(gifFrame); MemoryStream pngStream = new MemoryStream(); pngEncoder.Save(pngStream); Image frameImage = Image.FromStream(pngStream); Bitmap bmp = new Bitmap(frameImage.Width, frameImage.Height, System.Drawing.Imaging.PixelFormat.Format32bppArgb); using (Graphics g = Graphics.FromImage(bmp)) { g.DrawImage(backgroundImage, 0, 0); g.DrawImageUnscaled(frameImage, 0, 0); } string tempPath = Path.Combine(Path.GetTempPath(), gifPath + i + ".bmp"); bmp.Save(tempPath, System.Drawing.Imaging.ImageFormat.Bmp); Console.WriteLine("Saved frame " + i); numFramesSoFar++; if (numFrames >= 0 && numFramesSoFar >= numFrames) break; } Console.WriteLine("Setting frames to desktop background at about " + framesPerSecond + " FPS"); // 1.0/... to convert to seconds per frame (instead of frames per second) // * 1000 to convert to milliseconds per frame // * 1000 to convert to microseconds per frame // * 10 to convert to 0.1s of microseconds per frame = 100s of nanoseconds per frame long ticksBetweenFrames = (long)Math.Round(1.0 / framesPerSecond) * 1000*1000*10; Stopwatch timer = new Stopwatch(); timer.Start(); numFramesSoFar = 0; while(numFrames < 0 || numFramesSoFar < numFrames) { for (int i = 0; i < gifDecoder.Frames.Count; i++) { // Sleep until we're at the desired frame rate, if needed. if(ticksBetweenFrames > timer.ElapsedTicks) Thread.Sleep(new TimeSpan(Math.Max(0, ticksBetweenFrames - timer.ElapsedTicks))); timer.Restart(); // From http://sofit.miximages.com/c%23/2924421 string filePath = Path.Combine(Path.GetTempPath(), wallpaper   i   .bmp"); RegistryKey key = Registry.CurrentUser.OpenSubKey(@"Control Panel\Desktop", true); if (style == Style.Stretched) { key.SetValue(@"WallpaperStyle", 2.ToString()); key.SetValue(@"TileWallpaper", 0.ToString()); } if (style == Style.Centered) { key.SetValue(@"WallpaperStyle", 1.ToString()); key.SetValue(@"TileWallpaper", 0.ToString()); } if (style == Style.Tiled) { key.SetValue(@"WallpaperStyle", 1.ToString()); key.SetValue(@"TileWallpaper", 1.ToString()); } SystemParametersInfo(SPI_SETDESKWALLPAPER, 0, filePath, SPIF_UPDATEINIFILE | SPIF_SENDWININICHANGE); numFramesSoFar++; if (numFrames >= 0 && numFramesSoFar >= numFrames) break; } } gifFile.Close(); } 

Si noti inoltre che è necessario utilizzare:

 using Microsoft.Win32; using System; using System.Collections.Generic; using System.Diagnostics; using System.Drawing; using System.IO; using System.Linq; using System.Runtime.InteropServices; using System.Text; using System.Threading; using System.Threading.Tasks; using System.Windows.Media; using System.Windows.Media.Imaging; 

Infine, fai clic con il pulsante destro del mouse su Progetto, Aggiungi riferimento e (in Assemblies and Framework) aggiungi Presentation Core, System.Xaml e WindowsBase.

Quindi fai clic con il tasto destro sul tuo progetto e vai in Proprietà, e assicurati che Target Framework sia .Net Framework 4.5. Se si modifica questo potrebbe essere necessario riavviare Visual Studio.