c# – 获取一个窗口的区域

[DllImport("User32.dll",SetLastError = true)]
    [return: MarshalAs(UnmanagedType.Bool)]
    private static extern bool PrintWindow(IntPtr hwnd,IntPtr hDC,uint nFlags);

    [DllImport("user32.dll",CharSet = CharSet.Auto,ExactSpelling = true)]
    public static extern IntPtr GetForegroundWindow();

    [DllImport("user32.dll")]
    private static extern bool GetWindowRect(IntPtr handle,out Rectangle rect);

    private void timer1_Tick(object sender,EventArgs e)
    {
        Rectangle bonds = new Rectangle();
        GetWindowRect(GetForegroundWindow(),out bonds);
        Bitmap bmp = new Bitmap(bonds.Width,bonds.Height);
        Graphics memoryGraphics = Graphics.FromImage(bmp);
        IntPtr dc = memoryGraphics.GetHdc();
        PrintWindow(GetForegroundWindow(),dc,0x1);
        memoryGraphics.ReleaseHdc(dc);
        bmp.Save("C:Test.gif",ImageFormat.Gif);
    }

但bonds.width和height不仅仅是真正的窗口.

示例：我的窗口是100×150,bond.height就像400,bonds.width就像500.我得到的图片大小为400×500,由图片角落的窗口组成(很好),其余的是黑色,因为图片比窗口大(这是坏的)

注意：我不在乎窗户是无气的,这对我有好处.

那么任何建议,或者更好的方式来获得一个地区？