WallRotate - A wallpaper changer in VC#

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Introduction

One day, looking at my dull desktop gave me the inspiration of writing a program which would periodically change the wallpaper. The idea sounded cool to me, and I decided to start this project in Visual C# as it would also help me learn more about the .NET Framework.

WallRotate is a simple-to-use software that will give your boring desktop new colours in a few minutes. WallRotate manages your wallpapers, and changes them periodically.

Some features of WallRotate:

• Supports many popular image formats (BMP, JPG, GIF, PNG, and many more)
• User-friendly interface
• Creates a list of your favourite wallpapers and customizes them
• You can change the wallpaper after a set interval
• Gives you a clear preview of the wallpaper, WYSIWYG
• Changes wallpapers when Windows starts
• Sets different positions for different wallpapers (center, tile, stretch)
• Sets background colour for wallpapers
• Plays sound clips when wallpaper changes
• Hotkeys to easily change the wallpaper
• System tray icon for easy access

How it works?

Below, I present some ideas on how WallRotate works.

Changing wallpapers:

There is a Windows API by the name of SystemParametersInfo, which sets system level wide parameters. With the first parameter as SPI_SETDESKWALLPAPER, we can change the wallpaper by passing the path of the image as the other parameter.

To use SystemParametersInfo, I had to invoke it from my .NET application. Shown below is the declaration for it:

const int SPI_SETDESKWALLPAPER = 20;
const int SPIF_UPDATEINIFILE = 0x01;
const int SPIF_SENDWININICHANGE = 0x02;

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

Now, to change the wallpaper, all I had to do was:

SystemParametersInfo (SPI_SETDESKWALLPAPER, 0, strWallpaperPath, 
                      SPIF_UPDATEINIFILE | SPIF_SENDWININICHANGE);

Storing and maintaining the list of wallpapers:

To store the list of wallpapers, I used XML. When the program loads, it looks for a file wallpapers.xml in the current directory and loads the list from it.

Loading, saving, and resizing images:

Playing with images is easy in the .NET Framework. The Image class took care of most of my needs.

Conclusion

I’m a .NET virgin, so please excuse me for the mistakes you see in the program, and kindly let me know about them. Same goes for any bugs found.

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