WPF自定义Popup位置

popup的位置是通过属性Placement 来控制的，如果想自己定义popup位置，那么需要将Placement 属性设置为Custom。

当 Placement 属性设置为时 Custom ，将 Popup 调用已定义的委托实例 CustomPopupPlacementCallback 。 此委托返回一组可能的点，这些点相对于目标区域的左上角和左上角 Popup 。 Popup放置在提供最佳可见性的点上。

 

下面是用法：

xaml代码

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<Popup Name="popup1"          PlacementTarget ="{Binding ElementName=myButton}"         Placement="Custom">   <TextBlock Height="60" Width="200"              Background="LightGray"              TextWrapping="Wrap">Popup positioned by using   CustomPopupPlacement callback delegate</TextBlock> </Popup>

C#代码

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popup1.CustomPopupPlacementCallback = new CustomPopupPlacementCallback(placePopup);public CustomPopupPlacement[] placePopup(Size popupSize,                                            Size targetSize,                                            Point offset) {     CustomPopupPlacement placement1 =        new CustomPopupPlacement(new Point(-50, 100), PopupPrimaryAxis.Vertical);       CustomPopupPlacement placement2 =         new CustomPopupPlacement(new Point(10, 20), PopupPrimaryAxis.Horizontal);       CustomPopupPlacement[] ttplaces =             new CustomPopupPlacement[] { placement1, placement2 };     return ttplaces; }

 

来看一下placePopup方法的参数offset

offset是popup位置的坐标，默认为（0，0），下面的纵向和横向偏移量是根据此点坐标来说的，如果要指定popup的起始坐标，应设置popup的VerticalOffset和HorizontalOffset

比如说要设置为鼠标点的位置为默认起始点，则应该设置：

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Point mousePoint = Mouse.GetPosition(canvas);//比如canvas为所在画布   popup.VerticalOffset = mousePoint.Y; popup.HorizontalOffset = mousePoint.X;