Popup 解决位置不随窗口/元素FrameworkElement 移动更新的问题

原文:Popup 解决位置不随窗口/元素FrameworkElement 移动更新的问题

Popup弹出后，因业务需求设置了StaysOpen=true后，移动窗口位置或者改变窗口大小，Popup的位置不会更新。

如何更新位置？

获取当前Popup的Target绑定UserControl所在窗口，位置刷新时，时时更新Popup的位置即可。

1.添加一个附加属性

 /// <summary>

 /// Popup位置更新

 /// </summary>

 public static readonly DependencyProperty PopupPlacementTargetProperty =

     DependencyProperty.RegisterAttached("PopupPlacementTarget", typeof(DependencyObject), typeof(PopupHelper), new PropertyMetadata(null, OnPopupPlacementTargetChanged));

2.窗口移动后触发popup更新

首先，有个疑问，popup首次显示时，为何显示的位置是正确的呢？

通过查看源码，发现，其实popup也是有内置更新popup位置的！

而通过查看UpdatePosition代码，其方法确实是更新popup位置的。源码如下：

 private void UpdatePosition()

 {

     if (this._popupRoot.Value == null)

         return;

     PlacementMode placement = this.Placement;

     Point[] targetInterestPoints = this.GetPlacementTargetInterestPoints(placement);

     Point[] childInterestPoints = this.GetChildInterestPoints(placement);

     Rect bounds = this.GetBounds(targetInterestPoints);

     Rect rect1 = this.GetBounds(childInterestPoints);

     double num1 = rect1.Width * rect1.Height;

     int num2 = -;

     Vector offsetVector1 = new Vector((double)this._positionInfo.X, (double)this._positionInfo.Y);

     double num3 = -1.0;

     PopupPrimaryAxis popupPrimaryAxis = PopupPrimaryAxis.None;

     CustomPopupPlacement[] customPopupPlacementArray = (CustomPopupPlacement[])null;

     int num4;

     if (placement == PlacementMode.Custom)

     {

         CustomPopupPlacementCallback placementCallback = this.CustomPopupPlacementCallback;

         if (placementCallback != null)

             customPopupPlacementArray = placementCallback(rect1.Size, bounds.Size, new Point(this.HorizontalOffset, this.VerticalOffset));

         num4 = customPopupPlacementArray == null ?  : customPopupPlacementArray.Length;

         if (!this.IsOpen)

             return;

     }

     else

         num4 = Popup.GetNumberOfCombinations(placement);

     for (int i = ; i < num4; ++i)

     {

         bool flag1 = false;

         bool flag2 = false;

         Vector offsetVector2;

         PopupPrimaryAxis axis;

         if (placement == PlacementMode.Custom)

         {

             offsetVector2 = (Vector)targetInterestPoints[] + (Vector)customPopupPlacementArray[i].Point;

             axis = customPopupPlacementArray[i].PrimaryAxis;

         }

         else

         {

             Popup.PointCombination pointCombination = this.GetPointCombination(placement, i, out axis);

             Popup.InterestPoint targetInterestPoint = pointCombination.TargetInterestPoint;

             Popup.InterestPoint childInterestPoint = pointCombination.ChildInterestPoint;

             offsetVector2 = targetInterestPoints[(int)targetInterestPoint] - childInterestPoints[(int)childInterestPoint];

             flag1 = childInterestPoint == Popup.InterestPoint.TopRight || childInterestPoint == Popup.InterestPoint.BottomRight;

             flag2 = childInterestPoint == Popup.InterestPoint.BottomLeft || childInterestPoint == Popup.InterestPoint.BottomRight;

         }

         Rect rect2 = Rect.Offset(rect1, offsetVector2);

         Rect rect3 = Rect.Intersect(this.GetScreenBounds(bounds, targetInterestPoints[]), rect2);

         double num5 = rect3 != Rect.Empty ? rect3.Width * rect3.Height : 0.0;

         if (num5 - num3 > 0.01)

         {

             num2 = i;

             offsetVector1 = offsetVector2;

             num3 = num5;

             popupPrimaryAxis = axis;

             this.AnimateFromRight = flag1;

             this.AnimateFromBottom = flag2;

             if (Math.Abs(num5 - num1) < 0.01)

                 break;

         }

     }

     if (num2 >=  && (placement == PlacementMode.Right || placement == PlacementMode.Left))

         this.DropOpposite = !this.DropOpposite;

     rect1 = new Rect((Size)this._secHelper.GetTransformToDevice().Transform((Point)this._popupRoot.Value.RenderSize));

     rect1.Offset(offsetVector1);

     Rect screenBounds = this.GetScreenBounds(bounds, targetInterestPoints[]);

     Rect rect4 = Rect.Intersect(screenBounds, rect1);

     if (Math.Abs(rect4.Width - rect1.Width) > 0.01 || Math.Abs(rect4.Height - rect1.Height) > 0.01)

     {

         Point point1 = targetInterestPoints[];

         Vector vector1 = targetInterestPoints[] - point1;

         vector1.Normalize();

         if (!this.IsTransparent || double.IsNaN(vector1.Y) || Math.Abs(vector1.Y) < 0.01)

         {

             if (rect1.Right > screenBounds.Right)

                 offsetVector1.X = screenBounds.Right - rect1.Width;

             else if (rect1.Left < screenBounds.Left)

                 offsetVector1.X = screenBounds.Left;

         }

         else if (this.IsTransparent && Math.Abs(vector1.X) < 0.01)

         {

             if (rect1.Bottom > screenBounds.Bottom)

                 offsetVector1.Y = screenBounds.Bottom - rect1.Height;

             else if (rect1.Top < screenBounds.Top)

                 offsetVector1.Y = screenBounds.Top;

         }

         Point point2 = targetInterestPoints[];

         Vector vector2 = point1 - point2;

         vector2.Normalize();

         if (!this.IsTransparent || double.IsNaN(vector2.X) || Math.Abs(vector2.X) < 0.01)

         {

             if (rect1.Bottom > screenBounds.Bottom)

                 offsetVector1.Y = screenBounds.Bottom - rect1.Height;

             else if (rect1.Top < screenBounds.Top)

                 offsetVector1.Y = screenBounds.Top;

         }

         else if (this.IsTransparent && Math.Abs(vector2.Y) < 0.01)

         {

             if (rect1.Right > screenBounds.Right)

                 offsetVector1.X = screenBounds.Right - rect1.Width;

             else if (rect1.Left < screenBounds.Left)

                 offsetVector1.X = screenBounds.Left;

         }

     }

     int x = DoubleUtil.DoubleToInt(offsetVector1.X);

     int y = DoubleUtil.DoubleToInt(offsetVector1.Y);

     if (x == this._positionInfo.X && y == this._positionInfo.Y)

         return;

     this._positionInfo.X = x;

     this._positionInfo.Y = y;

     this._secHelper.SetPopupPos(true, x, y, false, , );

 }

那么，我们有什么办法调用这个私有方法呢？我相信大家都想，找到popup源码开发者，爆了他Y的！

有一种方法，叫反射，反射可以获取类的任一个字段或者属性。

反射，可以参考：https://www.cnblogs.com/vaevvaev/p/6995639.html

通过反射，我们获取到UpdatePosition方法，并调用执行。

 var mi = typeof(Popup).GetMethod("UpdatePosition", BindingFlags.NonPublic | BindingFlags.Instance);

 mi.Invoke(pop, null);

下面是详细的属性更改事件实现：

 private static void OnPopupPlacementTargetChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)

 {

     Popup pop = d as Popup;

     //旧值取消LocationChanged监听

     if (e.OldValue is DependencyObject previousPlacementTarget)

     {

         Window window = Window.GetWindow(previousPlacementTarget);

         if (window != null)

         {

             window.LocationChanged -= WindowLocationChanged;

         }

     }

     //新值添加LocationChanged监听

     if (e.NewValue is DependencyObject newPlacementTarget)

     {

         Window window = Window.GetWindow(newPlacementTarget);

         if (window != null)

         {

             window.LocationChanged -= WindowLocationChanged;

             window.LocationChanged += WindowLocationChanged;

         }

     }

     void WindowLocationChanged(object s1, EventArgs e1)

     {

         if (pop != null && pop.IsOpen)

         {

             //通知更新相对位置

             var mi = typeof(Popup).GetMethod("UpdatePosition", BindingFlags.NonPublic | BindingFlags.Instance);

             mi.Invoke(pop, null);

         }

     }

 }

值得注意的是，原有的绑定目标源要记得取消LocationChanged事件订阅，新的绑定目标源保险起见，也要提前注销再添加事件订阅。

另：通知popup位置更新，也可能通过如下的黑科技：

     //通知更新相对位置

     var offset = pop.HorizontalOffset;

     pop.HorizontalOffset = offset + ;

     pop.HorizontalOffset = offset;

为何改变一下HorizontalOffset就可行呢？因为上面最终并没有改变HorizontalOffset的值。。。

原来。。。好吧，先看源码

     /// <summary>获取或设置目标原点和弹出项对齐之间的水平距离点。</summary>

     /// <returns>

     ///   目标原点和 popup 对齐点之间的水平距离。

     ///    有关目标原点和 popup 对齐点的信息，请参阅 Popup 放置行为。

     ///    默认值为 0。

     /// </returns>

     [Bindable(true)]

     [Category("Layout")]

     [TypeConverter(typeof (LengthConverter))]

     public double HorizontalOffset

     {

       get

       {

         return (double) this.GetValue(Popup.HorizontalOffsetProperty);

       }

       set

       {

         this.SetValue(Popup.HorizontalOffsetProperty, (object) value);

       }

     }

     private static void OnOffsetChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)

     {

       ((Popup) d).Reposition();

     }

是的，最终调用了Reposition，而Reposition方法中有调用UpdatePosition更新popup位置。

所以以上，更新HorizontalOffset，是更新popup位置的一种捷径。

3. 元素移动/大小变化后，触发更新

当popup的PlaceTarget绑定一个控件或者一个Grid后，FrameworkElement大小变化/位置变化时，popup位置更新(同上)

元素大小变化时：

     else if (newPlacementTarget is FrameworkElement frameworkElement)

     {

         frameworkElement.SizeChanged -= ElementOnSizeChanged;

         frameworkElement.SizeChanged += ElementOnSizeChanged;

     }

也可以直接监听LayoutUpdated事件，元素大小/位置变化时，LayoutUpdated都会触发。注意：LayoutUpdated触发有点频繁。

     else if (newPlacementTarget is FrameworkElement frameworkElement)

     {

         frameworkElement.LayoutUpdated -= ElementOnLayoutUpdated;

         frameworkElement.LayoutUpdated += ElementOnLayoutUpdated;

     }

4.界面设置绑定目标源

     <Popup x:Name="FirstShowPopup" PlacementTarget="{Binding ElementName=TestButton}" Placement="Custom"

         CustomPopupPlacementCallback="{easiUi:Placement Align=RightCenter,OutOfScreenEnabled=True}" PopupAnimation="Fade"

         AllowsTransparency="True" StaysOpen="True" HorizontalOffset="-16" VerticalOffset="4"

         helper:PopupHelper.LocationUpdatedOnTarget="{Binding ElementName=TestButton}"

         helper:PopupHelper.TopmostInCurrentWindow="True">

     </Popup>

巴特西

Popup 解决位置不随窗口/元素FrameworkElement 移动更新的问题

1.添加一个附加属性

2.窗口移动后触发popup更新

3. 元素移动/大小变化后，触发更新

4.界面设置绑定目标源

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