Question

我有一个网格，当它用鼠标悬停时，会使其中一个子元素变为生命（不透明度从0到1），但该网格也可以被处理掉（该网格是列表框的一部分，可以通过网格上的关闭按钮删除。

当用户单击“删除”按钮时，它还会启动MouseLeave事件，在该事件发生之后，该事件当然无法再找到我的DockStackPanel控件。我该如何解决这个问题？

     <Grid.Triggers>
         <EventTrigger RoutedEvent="UIElement.MouseEnter">
             <BeginStoryboard>
                 <Storyboard>
                     <DoubleAnimation Duration="0:0:0.5" Storyboard.TargetName="DockStackPanel" Storyboard.TargetProperty="Opacity" To="1" />
                 </Storyboard>
             </BeginStoryboard>
         </EventTrigger>
         <EventTrigger RoutedEvent="UIElement.MouseLeave">
             <BeginStoryboard>
                 <Storyboard>
                     <DoubleAnimation Duration="0:0:0.5" Storyboard.TargetName="DockStackPanel" Storyboard.TargetProperty="Opacity" To="0" />
                 </Storyboard>
             </BeginStoryboard>
         </EventTrigger>
     </Grid.Triggers>

Answer 1

您是否尝试过在代码中创建动画。我在这里假设DockStackPanel控件是一个StackPanel。

public MainWindow()
    {
        InitializeComponent();

        MyGrid.MouseEnter += MyGrid_MouseEnter;
        MyGrid.MouseLeave += MyGrid_MouseLeave;
    }

    void MyGrid_MouseLeave(object sender, MouseEventArgs e)
    {
        if (DockStackPanel != null)
        {
            var dur = new Duration(new TimeSpan(0, 0, 0, 0, 500));
            var anim = new DoubleAnimation(0, dur);
            DockStackPanel.BeginAnimation(StackPanel.OpacityProperty, anim);
        }
    }

    void MyGrid_MouseEnter(object sender, MouseEventArgs e)
    {
        var dur = new Duration(new TimeSpan(0, 0, 0, 0, 500));
        var anim = new DoubleAnimation(1, dur);
        DockStackPanel.BeginAnimation(StackPanel.OpacityProperty, anim);
    }

Answer 2

您可以做的另一件事是为DataTrigger实施Grid，它将覆盖默认的MouseLeave和MouseEnter事件，以便在DisableTriggers属性更改时不执行任何操作。

 <Style TargetType="{x:Type Grid}">
   <Style.Triggers>
        <DataTrigger Binding="{Binding DisableTriggers}" Value="True">
          <Setter Property="Style" Value="{StaticResource GridStyleWithoutStoryboards}" />
        </DataTrigger>
   </Style.Triggers>
 </Style>

当您不想使用AttachedBehaviors时就是这种情况。否则我建议在行为中处理故事板清理。这更容易：

void OnDisableTriggersPropertyChanged( object sender, EventArgs args )
{
    // If IsDisposed property was changed and it is true now - cleanup triggers.
    if ((bool)args.NewValue)
    {
       var grid = (Grid)sender;

       // Ideally you can remove specific triggers. 
       // Clear all will work for simple cases.
       grid.Triggers.Clear();
    }
}

总而言之，您必须使用DisableTriggers依赖项属性添加附加行为，该属性在OnChanged处理程序中执行清理操作。

如果您只想取消订阅特定活动：

    foreach (var eventToUnsubscribe in grid.Triggers.OfType<EventTrigger>()
                                                  .Where(x => x.RoutedEvent == UIElement.MouseEnterEvent
                                                              || x.RoutedEvent == UIElement.MouseLeaveEvent).ToList())
    {
        grid.Triggers.Remove(eventToUnsubscribe);
    };

如果对象被丢弃，则阻止MouseLeave触发器

2 个答案: