C# 根据坐标获取句柄

//获取窗口标题
[DllImport("user32", SetLastError = true)]
public static extern int GetWindowText(
    IntPtr hWnd,//窗口句柄
    StringBuilder lpString,//标题
    int nMaxCount //最大值
    );

//获取类的名字
[DllImport("user32.dll")]
private static extern int GetClassName(
    IntPtr hWnd,//句柄
    StringBuilder lpString, //类名
    int nMaxCount //最大值
    );

//根据坐标获取窗口句柄
[DllImport("user32")]
private static extern IntPtr WindowFromPoint(
Point Point  //坐标
);

private void timer1_Tick(object sender, EventArgs e)
{
    int x = Cursor.Position.X;
    int y = Cursor.Position.Y;
    Point p = new Point(x, y);
    IntPtr formHandle = WindowFromPoint(p);//得到窗口句柄
    StringBuilder title = new StringBuilder(256);
    GetWindowText(formHandle, title, title.Capacity);//得到窗口的标题
    StringBuilder className = new StringBuilder(256);
    GetClassName(formHandle, className, className.Capacity);//得到窗口的句柄
    this.textBox1.Text = title.ToString();
    this.textBox2.Text = formHandle.ToString();
    this.textBox3.Text = className.ToString();
}
···