SendMessage/SC_MONITORPOWER won't turn monitor ON when running Windows 8

Question

I turn my monitors on and off by using the following code:

[DllImport(\"user32.dll\")]
static extern IntPtr SendMessage(IntPtr hWnd, int Msg, IntPtr wParam,          


        

Answer 1

I had the same idea for this issue Just Changed the dear earlypearl's solution a wee bit and tested it on windows XP, 7, 8, Server 2008 and all worked perfectly.

mouse_event(MOUSEEVENTF_MOVE, 0, 1, 0, UIntPtr.Zero);

it does not need to be called twice.

Answer 2

I had the same problem, the solution I found is to move the mouse :

mouse_event(MOUSEEVENTF_MOVE, 0, 1, 0, NULL);
Sleep(40);
mouse_event(MOUSEEVENTF_MOVE, 0, -1, 0, NULL);

It will wake the monitor on. Earlypearl

Answer 3

I have found out this trick to work on windows 8.1

Turn them off

SendMessage(f.Handle, WM_SYSCOMMAND, (IntPtr)SC_MONITORPOWER, (IntPtr)MonitorShutoff);

Turn them on

SendMessage(f.Handle, WM_SYSCOMMAND, (IntPtr)SC_MONITORPOWER, (IntPtr)1);

According to MSN, "1" is to switch monitor to "Low Power" but it does the trick. The screen will not turn off anymore.

Answer 4

Here's Earlypearl's answer with the needed includes:

[DllImport("user32.dll")]
static extern void mouse_event(Int32 dwFlags, Int32 dx, Int32 dy, Int32 dwData, UIntPtr dwExtraInfo);

private const int MOUSEEVENTF_MOVE = 0x0001;

private void Wake(){
    mouse_event(MOUSEEVENTF_MOVE, 0, 1, 0, UIntPtr.Zero);
    Sleep(40);
    mouse_event(MOUSEEVENTF_MOVE, 0, -1, 0, UIntPtr.Zero);
}