namespace OpenMonitor
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
            HotKey.RegisterHotKey(this.Handle, 100, 0, Keys.F4);
            HotKey.RegisterHotKey(this.Handle,101,0,Keys.F5);
        }

        class HotKey
        {
            // 如果函數(shù)執(zhí)行成功，返回值不為0。
            // 如果函數(shù)執(zhí)行失敗，返回值為0。要得到擴(kuò)展錯(cuò)誤信息，調(diào)用GetLastError。
            [DllImport("user32.dll  ", SetLastError = true)]
            public static extern bool RegisterHotKey(
                   IntPtr hWnd, // 要定義熱鍵的窗口的句柄
                    int id,    // 定義熱鍵ID（不能與其它ID重復(fù)）  
                   KeyModifiers fsModifiers, // 標(biāo)識(shí)熱鍵是否在按Alt、Ctrl、Shift、Windows等鍵時(shí)才會(huì)生效
                   Keys vk    // 定義熱鍵的內(nèi)容
                   );

            [DllImport("user32.dll  ", SetLastError = true)]
            public static extern bool UnregisterHotKey(
                   IntPtr hWnd,  // 要取消熱鍵的窗口的句柄
                    int id      // 要取消熱鍵的ID
                   );

            // 定義了輔助鍵的名稱（將數(shù)字轉(zhuǎn)變?yōu)樽址员阌谟洃?，也可去除此枚舉而直接使用數(shù)值）
            [Flags()]
            public enum KeyModifiers
            {
                None = 0,
                Alt = 1,
                Ctrl = 2,
                Shift = 4,
                WindowsKey = 8
            }
        }

        protected override void WndProc(ref    Message m)
        {
            const int WM_HOTKEY = 0x0312;
            // 按快捷鍵  
            switch (m.Msg)
            {
                case WM_HOTKEY:
                    switch (m.WParam.ToInt32())
                    {
                        case 100:
                            MonitorHelper.TurnOn();
                            break;
                        case 101:
                            MonitorHelper.TurnOff();
                            break;
                    }
                    break;
            }
            base.WndProc(ref    m);
        }

        class MonitorHelper
        {
            public static void TurnOn()
            {
                SendMessage(HWND_BROADCAST, WM_SYSCOMMAND, SC_MONITORPOWER, -1);
            }

            public static void TurnOff()
            {
                SendMessage(HWND_BROADCAST, WM_SYSCOMMAND, SC_MONITORPOWER, 2);
            }

            [DllImport("user32.dll")]
            public static extern int SendMessage(IntPtr hWnd, uint Msg, int wParam, int lParam);

            private static readonly IntPtr HWND_BROADCAST = new IntPtr(0xffff);
            private const uint WM_SYSCOMMAND = 0x0112;
            private const int SC_MONITORPOWER = 0xf170;
        }
    }
}