所以这是我遇到的一个问题。我正在尝试在列表框中使用MouseDragElementBehavior。当我直接在列表框中创建项目时，我能够使它工作，如下例所示：
<ItemsControl.ItemsPanel>
<ItemsPanelTemplate>
<Canvas/>
</ItemsPanelTemplate>
</ItemsControl.ItemsPanel>
<ItemsControl.Items>
<Border Width="20" Height="20">
<i:Interaction.Behaviors>
<ei:MouseDragElementBehavior ConstrainToParentBounds="True"/>
</i:Interaction.Behaviors>
<Rectangle Fill="Red"/>
</Border>
</ItemsControl.Items>
</ItemsControl>
但是一旦我开始使用DataTemplate，它就会停止工作。
<ItemsControl Grid.Column="1" >
<ItemsControl.ItemsPanel>
<ItemsPanelTemplate>
<Canvas/>
</ItemsPanelTemplate>
</ItemsControl.ItemsPanel>
<ItemsControl.Items>
Test item
</ItemsControl.Items>
<ItemsControl.ItemTemplate>
<DataTemplate>
<Border Width="20" Height="20">
<i:Interaction.Behaviors>
<ei:MouseDragElementBehavior ConstrainToParentBounds="True"/>
</i:Interaction.Behaviors>
<Rectangle Fill="Red"/>
</Border>
</DataTemplate>
</ItemsControl.ItemTemplate>
</ItemsControl>
为什么有任何想法？我无法弄清楚DataTemplate将如何影响MouseDragElementBehavior。
答案 0 :(得分：0)
MouseDragElementBehavior对您附加到的FrameworkElement起作用。在您的情况下，Border元素将包含在ContentPresenter中，ItemsControl是ConstrainToParentBounds="True"生成的容器。您已设置ContentPresenter，以确保视觉效果不会在其容器（在本例中为ConstrainToParentBounds="False"）之外显示。有几种选择，一些简单，一种可能不值得承担（但我确实想出了一些办法）。
Border。我假设您不希望ItemsControl离开ItemContainerStyle，所以这可能不合适。Style设置为Template，将ContentPresenter设置为ItemsControl并将交互添加到类似配置的ContentPresenter。 <ItemsControl Grid.Column="1" >
<ItemsControl.ItemsPanel>
<ItemsPanelTemplate>
<Canvas/>
</ItemsPanelTemplate>
</ItemsControl.ItemsPanel>
<ItemsControl.ItemContainerStyle>
<Style>
<Setter Property="Control.Template">
<Setter.Value>
<ControlTemplate>
<ContentPresenter>
<i:Interaction.Behaviors>
<ei:MouseDragElementBehavior ConstrainToParentBounds="True"/>
</i:Interaction.Behaviors>
</ContentPresenter>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style >
</ItemsControl.ItemContainerStyle>
<ItemsControl.Items>
Test item
</ItemsControl.Items>
<ItemsControl.ItemTemplate>
<DataTemplate>
<Border Width="20" Height="20">
<Rectangle Fill="Red"/>
</Border>
</DataTemplate>
</ItemsControl.ItemTemplate>
</ItemsControl>
的基本实现使用香草ItemsControl.ItemContainerStyle。需要注意的是，如果您不将UI元素用作项目，则需要使用自定义项目控件将其包装为一个项目（请参见this answer on setting the container style）：Interaction.Behaviors <ItemsControl.ItemContainerStyle>
<Style>
<Setter Property="beh:AddCollectionsToSetter.Behaviors">
<Setter.Value>
<beh:BehaviorCollection>
<ei:MouseDragElementBehavior ConstrainToParentBounds="True"/>
</beh:BehaviorCollection>
</Setter.Value>
</Setter>
</Style>
</ItemsControl.ItemContainerStyle>
附加互动。这有点涉及，因为附加的AddCollectionsToSetter.Behaviors属性只有一个setter：BehaviorCollection为此，我必须创建一个单独的附加属性 public static class AddCollectionsToSetter
{
#region Behaviors Dependency Property (Attached)
/// <summary>Gets the behaviours to add.</summary>
public static BehaviorCollection GetBehaviors(DependencyObject obj)
{
return (BehaviorCollection)obj.GetValue(BehaviorsProperty);
}
/// <summary>Sets the behaviours to add.</summary>
public static void SetBehaviors(DependencyObject obj, BehaviorCollection value)
{
obj.SetValue(AddCollectionsToSetter.BehaviorsProperty, value);
}
/// <summary>DependencyProperty backing store for <see cref="Behaviors"/>. Represents the behaviours to add.</summary>
/// <remarks></remarks>
public static readonly DependencyProperty BehaviorsProperty =
DependencyProperty.RegisterAttached("Behaviors", typeof(BehaviorCollection), typeof(AddCollectionsToSetter), new PropertyMetadata(null, BehaviorsPropertyChanged));
private static void BehaviorsPropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
var oldBehaviors = (BehaviorCollection)e.OldValue;
var newBehaviors = (BehaviorCollection)e.NewValue;
var interaction = Interaction.GetBehaviors(d);
interaction.RemoveRange(oldBehaviors); // extension method, simple iterate and remove
interaction.AddRange(newBehaviors.Clone()); // extension method, simple iterate and add
}
#endregion Behaviors Dependency Property (Attached)
}
public class BehaviorCollection : FreezableCollection<System.Windows.Interactivity.Behavior>
{
public BehaviorCollection()
: base()
{
}
public BehaviorCollection(int capacity)
: base(capacity)
{
}
public BehaviorCollection(IEnumerable<System.Windows.Interactivity.Behavior> behaviors)
: base(behaviors)
{
}
}
，该属性是可读/写的，另外一个; this is practicaly the SAR instruction,
; the mask for the absolute value is
; number >> (sizeof(short)) * CHAR_BIT -1)
; number >> (2 * 8) - 1 = 15
; so normaly we would do SAR bx, 15 and done
mov bl, ah ; BX = AX>>8
add bx, bx ; BX <<= 1
neg bh ; 0 or -1
mov bl, bh ; duplicate the full BX
mov cx, ax ;
add cx, bx ; the number + mask
xor bx, cx ; (number+mask) ^ mask
则允许添加交互。
var test = JSON.parse(`<%= raw Item.select('promCode','baseCode','monadaMe','price','fpa').where(:itemName => '${itemname}' ).collect { |p| [p.promCode, p.baseCode, p.monadaMe, p.price, p.fpa] }.join("\n").gsub("\n", " ").split(" ")%>`);