Need to disable the screen saver / screen locking in Windows C#/.Net

Question

For a particular application, I need the screen saver to be disabled while it's running. The operator COULD manually turn it off, and then back on later, but the easiest thing to do would be to just keep the screen saver at bay while the application is running.

How do I do this? I've found code for actually turning off the screen saver with SPI_SETSCREENSAVEACTIVE, but I don't think that's what I want.

Answer 1

SystemParametersInfo with SPI_SETSCREENSAVEACTIVE is the normal way to do this. However, it doesn't disable screen locking.

Answer 2

theoldnewthing has your answer: use SetThreadExecutionState(ES_DISPLAY_REQUIRED). This is used by video players and powerpoint.

Answer 3

try making your form topmost value true it works for me screen-saver never came even after the idle time...

Answer 4

[FlagsAttribute]
public enum EXECUTION_STATE : uint
{
    ES_SYSTEM_REQUIRED = 0x00000001,
    ES_DISPLAY_REQUIRED = 0x00000002,
    // Legacy flag, should not be used.
    // ES_USER_PRESENT   = 0x00000004,
    ES_AWAYMODE_REQUIRED = 0x00000040,
    ES_CONTINUOUS = 0x80000000,
}

public static class SleepUtil
{
    [DllImport("kernel32.dll", CharSet = CharSet.Auto, SetLastError = true)]
    public static extern EXECUTION_STATE SetThreadExecutionState(EXECUTION_STATE esFlags);
}

public void PreventSleep()
{
    if (SleepUtil.SetThreadExecutionState(EXECUTION_STATE.ES_CONTINUOUS
        | EXECUTION_STATE.ES_DISPLAY_REQUIRED  
        | EXECUTION_STATE.ES_SYSTEM_REQUIRED 
        | EXECUTION_STATE.ES_AWAYMODE_REQUIRED) == 0) //Away mode for Windows >= Vista
        SleepUtil.SetThreadExecutionState(EXECUTION_STATE.ES_CONTINUOUS
            | EXECUTION_STATE.ES_DISPLAY_REQUIRED 
            | EXECUTION_STATE.ES_SYSTEM_REQUIRED); //Windows < Vista, forget away mode
}

Credit: P/Invoke, deadpoint