[C#]使用WM_SYSCOMMAND訊息控制螢幕模式切換
要控制螢幕的開啟、關閉，可透SendMessage發送WM_SYSCOMMAND訊息，wParam參數傳入SC_MONITORPOWER，lParam參數則傳入螢幕的模式。
參數方面參閱WM_SYSCOMMAND Message，裡面清楚的帶出WM_SYSCOMMAND為0x0112、SC_MONITORPOWER為0xF170、與其對應的lParam。
使用上就像下面這樣：
[DllImport("user32.dll")]
private static extern int SendMessage(int hWnd, int Msg, int wParam, int lParam);
const int SC_MONITORPOWER = 0xF170;
const int WM_SYSCOMMAND = 0x0112;
...
SendMessage(-1, WM_SYSCOMMAND, SC_MONITORPOWER , -1);
SendMessage(-1, WM_SYSCOMMAND, SC_MONITORPOWER , 1);
SendMessage(-1, WM_SYSCOMMAND, SC_MONITORPOWER , 2);
這邊為方便後續使用，將程式整理成類別，有需要的自行取用。
public static class MonitorControler
{
[DllImport("user32.dll")]
private static extern int SendMessage(int hWnd, int Msg, int wParam, int lParam);
const int SC_MONITORPOWER = 0xF170;
const int WM_SYSCOMMAND = 0x0112;
//const int SC_SCREENSAVE = 0xF140;
public enum MonitorMode : int
{
MONITOR_ON = -1,
MONITOR_STANBY = 1,
MONITOR_OFF
}
public static void ChangeMonitorState(MonitorMode mode)
{
SendMessage(-1, WM_SYSCOMMAND, SC_MONITORPOWER, (int)mode);
}
public static void MonitorOff()
{
ChangeMonitorState(MonitorMode.MONITOR_OFF);
}
public static void MonitorOn()
{
ChangeMonitorState(MonitorMode.MONITOR_ON);
}
public static void MonitorStandBy()
{
ChangeMonitorState(MonitorMode.MONITOR_STANBY);
}
}
