Can I change my Windows desktop wallpaper programmatically in Java/Groovy?

You can do it easier:

import com.sun.jna.Library;
import com.sun.jna.Native;
import com.sun.jna.platform.win32.WinDef.HWND;
import com.sun.jna.platform.win32.WinDef.PVOID;
import com.sun.jna.win32.W32APIOptions;
public class Wallpaper {    
 public static interface User32 extends Library {
     User32 INSTANCE = (User32) Native.loadLibrary("user32",User32.class,W32APIOptions.DEFAULT_OPTIONS);        
     boolean SystemParametersInfo (int one, int two, String s ,int three);         
 }
public static void main(String[] args) {   
   User32.INSTANCE.SystemParametersInfo(0x0014, 0, "C:\\Users\\Public\\Pictures\\Sample Pictures\\Chrysanthemum.jpg" , 1);
   }
 }

You can write a batch file to change the wall-paper, and execute that batch file using,

Runtime.getRuntime.exec()


Sorry I'm a bit behind @ataylor's answer because I was preparing a snippet to do it. Yes, JNA is a correct approach. Here you go:

import java.util.HashMap;

import com.sun.jna.Native;
import com.sun.jna.platform.win32.WinDef.UINT_PTR;
import com.sun.jna.win32.*;

public class WallpaperChanger {
   public static void main(String[] args) {
      //supply your own path instead of using this one
      String path = "C:\\Users\\Public\\Pictures\\Sample Pictures\\Chrysanthemum.jpg";

      SPI.INSTANCE.SystemParametersInfo(
          new UINT_PTR(SPI.SPI_SETDESKWALLPAPER), 
          new UINT_PTR(0), 
          path, 
          new UINT_PTR(SPI.SPIF_UPDATEINIFILE | SPI.SPIF_SENDWININICHANGE));
   }

   public interface SPI extends StdCallLibrary {

      //from MSDN article
      long SPI_SETDESKWALLPAPER = 20;
      long SPIF_UPDATEINIFILE = 0x01;
      long SPIF_SENDWININICHANGE = 0x02;

      SPI INSTANCE = (SPI) Native.loadLibrary("user32", SPI.class, new HashMap<Object, Object>() {
         {
            put(OPTION_TYPE_MAPPER, W32APITypeMapper.UNICODE);
            put(OPTION_FUNCTION_MAPPER, W32APIFunctionMapper.UNICODE);
         }
      });

      boolean SystemParametersInfo(
          UINT_PTR uiAction,
          UINT_PTR uiParam,
          String pvParam,
          UINT_PTR fWinIni
        );
  }
}

You need to have the JNA libraries on the classpath for this to work. This was tested in Windows 7, there might be some nuances in XP but I think it should work. That API is presumably stable.

References

  • Setting Wallpaper - Coding4Fun
  • How to determine if a screensaver is running in Java?
  • W32API.java

Edit (2010/01/20):

I had previously omitted the options SPIF_UPDATEINIFILE and SPIF_SENDWININICHANGE. These are now being used as they were suggested in the Coding4Fun MSDN article.

Tags:

Java

Groovy

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