How do I change the screensaver programmatically?

Question

I'd like to change the current Screensaver for a custom one (which I previously loaded as a resource in Visual Studio) using C#. How could that be done? I've looked for it on Google and SO, but it all talks about "How to create a Screensaver", not "How to change a Screensaver". If possible, it should work on WinXP, Vista and 7.

Answer 1

I'll answer my question with the piece of code that worked to me:

public sealed class Screensaver
{
    Screensaver() { }

    const int SPI_SETSCREENSAVEACTIVE = 0x0011;

    [DllImport("user32", CharSet=CharSet.Auto)]
    unsafe public static extern short SystemParametersInfo (int uiAction, int uiParam, int* pvParam, int fWinIni);

    public static void Set(string path)
    {
        try
        {
            RegistryKey oKey = Registry.CurrentUser.OpenSubKey("Control Panel",
            true);
            oKey = oKey.OpenSubKey("desktop", true);
            oKey.SetValue("SCRNSAVE.EXE", path);
            oKey.SetValue("ScreenSaveActive", "1");

            unsafe
            {
                int nX = 1;
                SystemParametersInfo(
                SPI_SETSCREENSAVEACTIVE,
                0,
                &nX,
                0
                );
            }
        }
        catch (Exception exc)
        {
            System.Windows.Forms.MessageBox.Show(exc.ToString());
        }
    }
}

Then, when calling it from my application:

static string ResourcePath(string resource)
{
    return Application.StartupPath + "\\Resources\\" + resource;
}

Program.Screensaver.Set(Program.ResourcePath("svr1.scr"));

I read somewhere I should write a name no longer than 8 characters (a bit weird, but XP is all like this), so my screensaver is called svr1.scr (not really object oriented, but does the trick)