完美解决WPF中Popup控件跟随移动和始终位于最上层问题

---

根据网上各种方法，优化了窗体变化放大缩小时的BUG,完美解决WPF中Popup控件跟随移动和始终位于最上层问题

---

1.重写popup控件

public class PopupEx : Popup
    {
        /// 
  
        /// 是否窗口随动，默认为随动（true）  
        ///   
        public bool IsPositionUpdate  
        {  
            get { return  (bool)GetValue(IsPositionUpdateProperty); }  
            set { SetValue(IsPositionUpdateProperty, value); }  
        }  

        public static readonly DependencyProperty  IsPositionUpdateProperty =  
            DependencyProperty.Register("IsPositionUpdate",  typeof(bool), typeof(PopupEx), new PropertyMetadata(true, new  PropertyChangedCallback(IsPositionUpdateChanged)));  

        private static void  IsPositionUpdateChanged(DependencyObject d,  DependencyPropertyChangedEventArgs e)  
        {  
            (d as PopupEx).pup_Loaded(d as PopupEx, null);  
        }  

        /// 
  
        /// 加载窗口随动事件  
        ///   
        public PopupEx()  
        {  
            this.Loaded += pup_Loaded;  
        }  

        /// 
  
        /// 加载窗口随动事件  
        ///   
        private void pup_Loaded(object sender, RoutedEventArgs  e)  
        {  
            Popup pup = sender as Popup;  
            var win = VisualTreeHelper.GetParent(pup);  
            while (win != null && (win as Window) == null)  
            {  
                win = VisualTreeHelper.GetParent(win);  
            }  
            if ((win as Window) != null)  
            {
                (win as Window).LocationChanged -=  PositionChanged;
                (win as Window).SizeChanged -= PositionChanged;
                if (IsPositionUpdate)
                {
                    (win as Window).LocationChanged +=  PositionChanged;
                    (win as Window).SizeChanged +=  PositionChanged;  
                }
            }  
        }  

        /// 
  
        /// 刷新位置  
        ///   
        private void PositionChanged(object sender, EventArgs e)  
        {
            try
            {
                var method =  typeof(Popup).GetMethod("UpdatePosition",  System.Reflection.BindingFlags.NonPublic |  System.Reflection.BindingFlags.Instance);
                if (this.IsOpen)
                {
                    method.Invoke(this, null);
                }
            }
            catch
            {
                return;
            }
        }  

        //是否最前默认为非最前（false）  
        public static DependencyProperty TopmostProperty =  Window.TopmostProperty.AddOwner(typeof(Popup), 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 PopupEx).UpdateWindow();  
        }  

        /// 
  
        /// 重写拉开方法，置于非最前  
        ///   
        ///   
        protected override void OnOpened(EventArgs e)  
        {  
            UpdateWindow();  
        }  

        /// 
  
        /// 刷新Popup层级  
        ///   
        private void UpdateWindow()  
        {  
            var hwnd =  ((HwndSource)PresentationSource.FromVisual(this.Child)).Handle;  
            RECT rect;  
            if (NativeMethods.GetWindowRect(hwnd, out rect))  
            {  
                NativeMethods.SetWindowPos(hwnd, Topmost ? -1 :  -2, rect.Left, rect.Top, (int)this.Width, (int)this.Height, 0);  
            }  
        }  

        [StructLayout(LayoutKind.Sequential)]  
        public struct RECT  
        {  
            public int Left;  
            public int Top;  
            public int Right;  
            public int Bottom;  
        }  
        #region P/Invoke imports & definitions  
        public static class NativeMethods  
        {  


            [DllImport("user32.dll")]  
            [return: MarshalAs(UnmanagedType.Bool)]  
            internal static extern bool GetWindowRect(IntPtr  hWnd, out RECT lpRect);  
            [DllImport("user32", EntryPoint = "SetWindowPos")]  
            internal static extern int SetWindowPos(IntPtr hWnd,  int hwndInsertAfter, int x, int y, int cx, int cy,  int wFlags);  
        }  
        #endregion  
    }

---

2.在界面中使用

<local:PopupEx x:Name="pop1" Topmost="False"  StaysOpen="True"  PopupAnimation="Slide" AllowsTransparency="False"
                           PlacementTarget="{Binding  ElementName=popImg}" Placement="Left">
                        <local:PopupControl x:Name="pop_view"/>
                    local:PopupEx>