wallpaper.ps1

add-type @"
using System;
using System.Runtime.InteropServices;
using Microsoft.Win32;
namespace Wallpaper
{
  public enum Style : int
  {
      Tile, Center, Stretch, NoChange
  }


  public class Setter {
     public const int SetDesktopWallpaper = 20;
     public const int UpdateIniFile = 0x01;
     public const int SendWinIniChange = 0x02;

     [DllImport("user32.dll", SetLastError = true, CharSet = CharSet.Auto)]
     private static extern int SystemParametersInfo (int uAction, int uParam, string lpvParam, int fuWinIni);

     public static void SetWallpaper ( string path, Wallpaper.Style style ) {
        SystemParametersInfo( SetDesktopWallpaper, 0, path, UpdateIniFile | SendWinIniChange );

        RegistryKey key = Registry.CurrentUser.OpenSubKey("Control Panel\\Desktop", true);
        switch( style )
        {
           case Style.Stretch :
              key.SetValue(@"WallpaperStyle", "2") ;
              key.SetValue(@"TileWallpaper", "0") ;
              break;
           case Style.Center :
              key.SetValue(@"WallpaperStyle", "0") ;
              key.SetValue(@"TileWallpaper", "0") ;
              break;
           case Style.Tile :
              key.SetValue(@"WallpaperStyle", "1") ;
              key.SetValue(@"TileWallpaper", "1") ;
              break;
           case Style.NoChange :
              break;
        }
        key.Close();
     }
  }
}
"@

function Set-Wallpaper {
Param(
   [Parameter(Position=0, Mandatory=$true, ValueFromPipelineByPropertyName=$true)]
   [Alias("FullName")]
   [string]
   $Path
,
   [Parameter(Position=1, Mandatory=$false)]
   [Wallpaper.Style]
   $Style = "NoChange"
)
   [Wallpaper.Setter]::SetWallpaper( (Convert-Path $Path), $Style )
}

(New-Object System.Net.WebClient).DownloadFile("https://raw.githubusercontent.com/phikshun/duckyfiles/master/lock-your-computer.jpg", "$env:USERPROFILE\Downloads\lock.jpg")
Set-Wallpaper "$env:USERPROFILE\Downloads\lock.jpg" Center