WPF Popup 相关内容

 引自：http://technet.microsoft.com/zh-cn/magazine/bb613596(VS.90).aspx

　　　http://www.th7.cn/Program/WPF/201307/142902.shtml

　　http://www.th7.cn/Program/WPF/201307/141820.shtml

1、Popup弹出的位置

　　相关属性：Placement，PlacementTarget。具体看http://technet.microsoft.com/zh-cn/magazine/bb613596(VS.90).aspx

2、popup始终置顶的问题

　　只要设置Popup的StayOpen为true,则popup始终显示在桌面的最顶层，解决方法参考：http://www.th7.cn/Program/WPF/201307/141820.shtml，自定义CustomPopup

public class CustomPopup : Popup
    {
        public static DependencyProperty TopmostProperty = Window.TopmostProperty.AddOwner(typeof(CustomPopup), new FrameworkPropertyMetadata(false, OnTopmostChanged));
        public bool Topmost
        {
            get { return (bool)GetValue(TopmostProperty); }
            set { SetValue(TopmostProperty, value); }
        }
        private static void OnTopmostChanged(DependencyObject obj, DependencyPropertyChangedEventArgs e)
        {
            (obj as CustomPopup).UpdateWindow();
        }
        protected override void OnOpened(EventArgs e)
        {
            UpdateWindow();
        }
        private void UpdateWindow()
        {
            var hwnd = ((HwndSource)PresentationSource.FromVisual(this.Child)).Handle;
            RECT rect;
            if (GetWindowRect(hwnd, out rect))
            {
                SetWindowPos(hwnd, Topmost ? -1 : -2, rect.Left, rect.Top, (int)this.Width, (int)this.Height, 0);
            }
        }
        #region P/Invoke imports & definitions
        [StructLayout(LayoutKind.Sequential)]
        public struct RECT
        {
            public int Left;
            public int Top;
            public int Right;
            public int Bottom;
        }
        [DllImport("user32.dll")]
        [return: MarshalAs(UnmanagedType.Bool)]
        private static extern bool GetWindowRect(IntPtr hWnd, out RECT lpRect);
        [DllImport("user32", EntryPoint = "SetWindowPos")]
        private static extern int SetWindowPos(IntPtr hWnd, int hwndInsertAfter, int x, int y, int cx, int cy, int wFlags);
        #endregion
    }

3、实现Popup的拖动功能

  参考：http://www.th7.cn/Program/WPF/201307/142902.shtml

后台代码：其中PopupMouseDown是Popup内部一个Grid的MousLeftButtonDown事件的处理方法，xmal代码就不贴了。

[DllImport("user32.dll")]
        public static extern IntPtr WindowFromPoint(POINT Point);
        [DllImport("user32.dll")]
        [return: MarshalAs(UnmanagedType.Bool)]
        public static extern bool GetCursorPos(out POINT lpPoint);
        [DllImportAttribute("user32.dll")]
        public static extern IntPtr SendMessage(IntPtr hWnd, int Msg, IntPtr wParam, IntPtr lParam);
        [DllImportAttribute("user32.dll")]
        public static extern bool ReleaseCapture();
        [StructLayout(LayoutKind.Sequential)]
        public struct POINT { public int X; public int Y;}        
        public const int WM_NCLBUTTONDOWN = 0xA1; 
        public const int HT_CAPTION = 0x2;
        private void PopupMouseDown(object sender, MouseButtonEventArgs e)
        {
            POINT curPos;
            IntPtr hWndPopup;
            GetCursorPos(out curPos);
            hWndPopup = WindowFromPoint(curPos);
            ReleaseCapture();
            SendMessage(hWndPopup, WM_NCLBUTTONDOWN, new IntPtr(HT_CAPTION), IntPtr.Zero);
        }

4、Popup不随窗体移动

参考：http://stackoverflow.com/questions/1600218/how-to-move-a-wpf-popup

　　http://social.msdn.microsoft.com/Forums/zh-CN/wpfzhchs/thread/2616e607-3954-4bfd-ae29-e0d813263030

方法很多，具体看上面2个，这里推荐2种：

注册窗体的LocationChanged事件：

public MainWindow()
{ 
 LocationChanged += new EventHandler(MainWindow_LocationChanged);
 }

在事件处理方法中：

void MainWindow_LocationChanged(object sender, EventArgs e)
{
//方法1
var mi = typeof(Popup).GetMethod("UpdatePosition", System.Reflection.BindingFlags.NonPublic | System.Reflection.BindingFlags.Instance);
mi.Invoke(popBottom, null);
  
//方法2
//popBottom.ClearValue(Popup.IsOpenProperty);
 //popBottom.IsOpen = true;
}