关闭后,如何将可拖动的wpf弹出窗口设置为原始位置?

时间:2013-01-17 23:40:01

标签: wpf wpf-controls

我使用Stack Overflow上的代码使用附加的行为来创建一个可拖动的WPF弹出窗口。此代码和行为按预期工作。弹出窗口将保持在拖动位置,直到用户再次移动它。

我现在要做的是,一旦关闭并重新打开,弹出窗口就会显示在其原始放置目标位置。我该如何完成这项任务?

原帖:A draggable popup control in wpf

答案代码由Rick Sladkey撰写:https://stackoverflow.com/a/4784977/1286413

以下是Popup的XAML:

<Grid>
   <StackPanel>
       <TextBox x:Name="textBox1" Width="200" Height="20"/>
   </StackPanel>
   <Popup PlacementTarget="{Binding ElementName=textBox1}" IsOpen="{Binding IsKeyboardFocused, ElementName=textBox1, Mode=OneWay}">
       <i:Interaction.Behaviors>
           <local:MouseDragPopupBehavior/>
       </i:Interaction.Behaviors>
       <TextBlock Background="White">
           <TextBlock.Text>Sample Popup content.</TextBlock.Text>
       </TextBlock>
   </Popup>
</Grid>

这是他写的AttachedBehavior:

public class MouseDragPopupBehavior : Behavior<Popup>
{
   private bool mouseDown;
   private Point oldMousePosition;

   protected override void OnAttached()
   {
       AssociatedObject.MouseLeftButtonDown += (s, e) =>
       {
           mouseDown = true;
           oldMousePosition = AssociatedObject.PointToScreen(e.GetPosition(AssociatedObject));
           AssociatedObject.Child.CaptureMouse();
       };
       AssociatedObject.MouseMove += (s, e) =>
       {
           if (!mouseDown) return;
           var newMousePosition = AssociatedObject.PointToScreen(e.GetPosition(AssociatedObject));
           var offset = newMousePosition - oldMousePosition;
           oldMousePosition = newMousePosition;
           AssociatedObject.HorizontalOffset += offset.X;
           AssociatedObject.VerticalOffset += offset.Y;
       };
       AssociatedObject.MouseLeftButtonUp += (s, e) =>
       {
           mouseDown = false;
           AssociatedObject.Child.ReleaseMouseCapture();
       };
   }
}

提前感谢您的帮助!

1 个答案:

答案 0 :(得分:1)

在OnAttached中,将一个处理程序添加到Closed以保存弹出窗口的位置,将另一个处理程序添加到Opened将弹出窗口移回该位置。

public class MouseDragPopupBehavior : Behavior<Popup>
{
    private bool mouseDown;
    private Point oldMousePosition;

    private bool useSavedPosition;
    private Point savedPosition;

    protected override void OnAttached()
    {
        AssociatedObject.MouseLeftButtonDown += (s, e) =>
        {
            mouseDown = true;
            oldMousePosition = AssociatedObject.PointToScreen(e.GetPosition(AssociatedObject));
            AssociatedObject.Child.CaptureMouse();
        };
        AssociatedObject.MouseMove += (s, e) =>
        {
            if (!mouseDown) return;
            var newMousePosition = AssociatedObject.PointToScreen(e.GetPosition(AssociatedObject));
            var offset = newMousePosition - oldMousePosition;
            oldMousePosition = newMousePosition;
            AssociatedObject.HorizontalOffset += offset.X;
            AssociatedObject.VerticalOffset += offset.Y;
        };
        AssociatedObject.MouseLeftButtonUp += (s, e) =>
        {
            mouseDown = false;
            AssociatedObject.Child.ReleaseMouseCapture();
        };

        AssociatedObject.Opened += (s, e) =>
        {
            if (!useSavedPosition) return;
            AssociatedObject.HorizontalOffset = savedPosition.X;
            AssociatedObject.VerticalOffset = savedPosition.Y;
        };

        AssociatedObject.Loaded += (s, e) =>
        {
            savedPosition = new Point(AssociatedObject.HorizontalOffset, AssociatedObject.VerticalOffset);
            useSavedPosition = true;
        };
    }
}