WPF自定義Popup位置

popup的位置是通過屬性Placement 來控制的，如果想自己定義popup位置，那么需要將Placement 屬性設置為Custom。

當 Placement 屬性設置為時 Custom ，將 Popup 調用已定義的委托實例 CustomPopupPlacementCallback 。 此委托返回一組可能的點，這些點相對於目標區域的左上角和左上角 Popup 。 Popup放置在提供最佳可見性的點上。

 

下面是用法：

xaml代碼

<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#代碼

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;
}

 

來看一下placePopup方法的參數offset

offset是popup位置的坐標，默認為（0，0），下面的縱向和橫向偏移量是根據此點坐標來說的，如果要指定popup的起始坐標，應設置popup的VerticalOffset和HorizontalOffset

比如說要設置為鼠標點的位置為默認起始點，則應該設置：

Point mousePoint = Mouse.GetPosition(canvas);//比如canvas為所在畫布

popup.VerticalOffset = mousePoint.Y;
popup.HorizontalOffset = mousePoint.X;