无法在绑定的物品控件之间拖动拖放项目 [英] Unable to drag drop items between bound itemscontrols

问题描述

我们有几个绑定的物品控件，它们都起到放下目标的作用
i需要能够拖放这些物品控件之间的拖放物品。 >问题是项目控件不被拖放框架识别为放置目标

ItemsControl面板

 < ItemsPanelTemplate x：Key =TopPipePanelTemplate> 
< StackPanel>< / StackPanel> 
< / ItemsPanelTemplate> 
  

DataTemplate：

 < DataTemplate x：Key =PipeDataItem> 
< Ellipse Width =45Height =45Fill ={Binding IsMine，Converter = {StaticResource MyCheckerOwnerToColorConverter}}>< / Ellipse> 
< / DataTemplate> 
  

ItemsControl样式：

 < Style TargetType ={x：Type ItemsControl}x：Key =ItemsControlStyle> 
< Setter Property =ItemTemplateValue ={StaticResource PipeDataItem}>< / Setter> 
< Setter Property =AllowDropValue =True>< / Setter> 
< EventSetter Event =DropHandler =ItemsControlDropTarget>< / EventSetter> 
< EventSetter Event =PreviewMouseLeftButtonDownHandler =ItemsControl_MouseLeftButtonDown>< / EventSetter> 
< / Style> 
  

**这个例子让我们拿2个ItemsControls：**

 < ItemsControl ItemsSource ={Binding Path = Pipes [23] .Checkers}Style ={StaticResource ItemsControlStyle}/> 
< ItemsControl Grid.Column =1ItemsSource ={Binding Path = Pipes [22] .Checkers}Style ={StaticResource ItemsControlStyle}/> 
  

定期显示时：

空（左）一不被认定为放弃目标，尽管它将AllowDrop设置为True，
处理Drop事件（与此屏幕中的所有项目控件一样，查看上面的ItemsControl样式）

现在，当我对项目控件面板颜色突然被识别时：

 < ItemsPanelTemplate x：Key =TopPipePanelTemplate > 
< StackPanel Background =AliceBlue>< / StackPanel> 
< / ItemsPanelTemplate> 
  

好像现在它占用了它占据的整个单元格。
iv尝试将面板设置为VerticalAlignment =Stretch，但这也没有影响

我想知道为什么我的项目控件不被识别为启用，
即使我期望他们占用了这个空间，另外用省略号
的项目控件只能被识别，直到占用内容的椭圆的高度。

任何想法？

只是为了澄清我的意思是识别为放置目标是当你拖动椭圆，你可以
将它放在itemscontrol的顶部。

现在只需将背景设置为透明

解决方案

面板的默认背景颜色不存在，这意味着命中测试通过它。要让它注册命中测试，例如鼠标悬停事件，您需要给它一个背景颜色。通常我只是使用白色，虽然你说透明也可以是一个更好的选择。

此外， StackPanels 通常只占用他们需要的空间。您可能会更好地使用一个面板来扩展所有可用空间，例如 DockPanel 与 LastChildFill =False，并设置 DockPanel.Dock =Top在您的项目上

iv'e got several bound itemscontrols which all play the role of of drop target i need to be able to drag drop items between these items controls .

the problem is that the items control's are not recognized as drop targets by the drag drop framework

The ItemsControl Panel :

    <ItemsPanelTemplate x:Key="TopPipePanelTemplate">
            <StackPanel></StackPanel>
    </ItemsPanelTemplate>

The DataTemplate :

    <DataTemplate x:Key="PipeDataItem" >
        <Ellipse Width="45" Height="45" Fill="{Binding IsMine,Converter={StaticResource MyCheckerOwnerToColorConverter}}"></Ellipse>
    </DataTemplate>

The ItemsControl Style :

    <Style TargetType="{x:Type ItemsControl}" x:Key="ItemsControlStyle">
          <Setter Property="ItemTemplate" Value="{StaticResource PipeDataItem}"></Setter>
          <Setter Property="AllowDrop" Value="True"></Setter>                                      
          <EventSetter Event="Drop" Handler="ItemsControlDropTarget"></EventSetter> 
          <EventSetter Event="PreviewMouseLeftButtonDown" Handler="ItemsControl_MouseLeftButtonDown"></EventSetter>      
    </Style>

** for this example lets take 2 of The ItemsControls :**

    <ItemsControl ItemsSource="{Binding Path=Pipes[23].Checkers}" Style="{StaticResource ItemsControlStyle}"/>
    <ItemsControl Grid.Column="1" ItemsSource="{Binding Path=Pipes[22].Checkers}" Style="{StaticResource ItemsControlStyle}"/>

when regularly displayed :

the empty ( Left ) one is not recognized as a drop target although it as AllowDrop set to True and handles the Drop event ( as do all the itemscontrols in this screen , look at ItemsControl Style above )

now when i color the itemscontrol panel it s suddenly is recognized :

    <ItemsPanelTemplate x:Key="TopPipePanelTemplate">
            <StackPanel Background="AliceBlue"></StackPanel>
    </ItemsPanelTemplate>

as if now it takes up the entire cell which it occupies .. iv'e tried setting the panel to VerticalAlignment="Stretch" but this also had no affect

i'm trying to understand why my itemcontrols are not recognized as drop enabled , even though i expect that they take up that space , in addition the itemscontrol with the ellipses is only recognized until the height of the ellipses that occupie it's content .

any ideas ?

just to clarify what i mean by Recognized as drop target is when you drag the ellipse you are able to drop it on top of the itemscontrol .

for now iv'e just set the background as Transparent

解决方案

The default background color of a panel doesn't exist, which means hit tests pass through it. To get it to register hit tests, such as mouse over events, you need to give it a background color. Usually I just use White, although you said Transparent also works and would be a better choice.

In addition, StackPanels will usually only take up the space they need. You might be better off using a Panel that stretches to fill all available space, such as a DockPanel with LastChildFill="False", and set DockPanel.Dock="Top" on your items

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