[C#] 改變解析度

using System.Runtime.InteropServices;

        //改變解析度引用
        [DllImport("user32.dll")]
        private static extern bool SetWindowPos(int hWnd, IntPtr hWndInsertAfter, int X, int Y, int cx, int cy, uint uFlags);
        [DllImport("user32.dll")]
        public static extern int GetSystemMetrics(int screensize);
        public const int SM_CXSCREEN = 0;
        public const int SM_CYSCREEN = 1;
        private static IntPtr HWND_TOP = IntPtr.Zero;
        private const int SWP_SHOWWINDOW = 64;

        int w;
        int h;
        [DllImport("user32.dll")]
        private static extern int FindWindow(string className, string windowText);
        [DllImport("user32.dll")]
        private static extern int ShowWindow(int hwnd, int command);

        [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Auto)]
        struct DEVMODE
        {
            public const int DM_DISPLAYFREQUENCY = 0x400000;
            public const int DM_PELSWIDTH = 0x80000;
            public const int DM_PELSHEIGHT = 0x100000;
            private const int CCHDEVICENAME = 32;
            private const int CCHFORMNAME = 32;
            [MarshalAs(UnmanagedType.ByValTStr, SizeConst = CCHDEVICENAME)]
            public string dmDeviceName;
            public short dmSpecVersion;
            public short dmDriverVersion;
            public short dmSize;
            public short dmDriverExtra;
            public int dmFields;
            public int dmPositionX;
            public int dmPositionY;
            public DMDO dmDisplayOrientation;
            public int dmDisplayFixedOutput;
            public short dmColor;
            public short dmDuplex;
            public short dmYResolution;
            public short dmTTOption;
            public short dmCollate;
            [MarshalAs(UnmanagedType.ByValTStr, SizeConst = CCHFORMNAME)]
            public string dmFormName;
            public short dmLogPixels;
            public int dmBitsPerPel;
            public int dmPelsWidth;
            public int dmPelsHeight;
            public int dmDisplayFlags;
            public int dmDisplayFrequency;
            public int dmICMMethod;
            public int dmICMIntent;
            public int dmMediaType;
            public int dmDitherType;
            public int dmReserved1;
            public int dmReserved2;
            public int dmPanningWidth;
            public int dmPanningHeight;
        }
        [DllImport("user32.dll", CharSet = CharSet.Auto)]
        static extern int ChangeDisplaySettings([In] ref DEVMODE lpDevMode, int dwFlags);

        public enum DMDO
        {
            DEFAULT = 0,
            D90 = 1,
            D180 = 2,
            D270 = 3
        }

        private void change(int intWidth, int intHeight, int intFrequency)
        {
            long RetVal = 0;
            DEVMODE dm = new DEVMODE();
            dm.dmSize = (short)Marshal.SizeOf(typeof(DEVMODE));
            dm.dmPelsWidth = intWidth;
            dm.dmPelsHeight = intHeight;
            dm.dmDisplayFrequency = intFrequency;
            dm.dmFields = DEVMODE.DM_PELSWIDTH | DEVMODE.DM_PELSHEIGHT | DEVMODE.DM_DISPLAYFREQUENCY;
            RetVal = ChangeDisplaySettings(ref dm, 0);
            Width = intWidth;
            Height = intHeight;
            w = intWidth;
            h = intHeight;
        }

//程式載入
private void Form1_Load(object sender, EventArgs e)
{
    //改變解析度，螢幕更新頻率
    change(1024, 768, 75);
    this.WindowState = FormWindowState.Normal;
    SetWindowPos((int)this.Handle, HWND_TOP, 0, 0, GetSystemMetrics(SM_CXSCREEN),GetSystemMetrics(SM_CYSCREEN), SWP_SHOWWINDOW);
}

private void Form1_FormClosed(object sender, FormClosedEventArgs e)
{
    //程式關掉改回來原解析度
    change(w, h, 75);
    this.ControlBox = true;
    this.WindowState = FormWindowState.Maximized;
    this.FormBorderStyle = FormBorderStyle.FixedSingle;
}