情况:
我有两个在 TreeView 中表示的类。DiskSpec 和 DiskSet。DiskSpec 可以单独存在,也可以是 DiskSet 的子项。我正在启用 DragDrop 功能,以便用户可以将 DiskSpec 从 DiskSpec 节点拖到 DiskSet 上,以将其添加到该 DiskSet 中。现在一切都在工作,除了一件事。我的 DragDropHelper 类需要在 ItemsPresenter(或相关类)中指定该控件是拖动源还是放置目标。
我的 TreeView 设置如下:
问题:
所以我真的需要两个 TreeViewItem 样式。一次用于 DiskSets(它指定将呈现 DiskSpecs 的 ItemsPresenter 是一个 DropTarget),另一个用于指定它的 ItemsPresenter 是一个 DragSource。
不幸的是,我没有看到任何从 HierarchicalDataTemplate 对象设置 TreeViewItem 样式或模板的方法,并且似乎没有办法指定此 ItemTemplate 仅用于特定的 DataType。
有什么想法吗?还是我错过了什么?
在下面找到我的 XAML 中的一些示例。
默认树视图项
有关 DragDropHelper 属性设置的示例,请参阅 ItemsPresenter 部分。
<Style TargetType="{x:Type TreeViewItem}">
<Setter Property="IsExpanded" Value="{Binding IsExpanded, Mode=TwoWay}"/>
<Setter Property="Background" Value="Transparent"/>
<Setter Property="HorizontalContentAlignment" Value="{Binding HorizontalContentAlignment, RelativeSource={RelativeSource AncestorType={x:Type ItemsControl}}}"/>
<Setter Property="VerticalContentAlignment" Value="{Binding VerticalContentAlignment, RelativeSource={RelativeSource AncestorType={x:Type ItemsControl}}}"/>
<Setter Property="Padding" Value="1,0,0,0"/>
<Setter Property="Foreground" Value="{DynamicResource {x:Static SystemColors.ControlTextBrushKey}}"/>
<Setter Property="FocusVisualStyle" Value="{StaticResource TreeViewItemFocusVisual}"/>
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type TreeViewItem}">
<Grid Margin="0,4,0,0">
<Grid.ColumnDefinitions>
<ColumnDefinition Width="Auto" MinWidth="10"/>
<ColumnDefinition Width="*"/>
</Grid.ColumnDefinitions>
<Grid.RowDefinitions>
<RowDefinition Height="Auto" MinHeight="27.75"/>
<RowDefinition/>
</Grid.RowDefinitions>
<ToggleButton x:Name="Expander" ClickMode="Press" IsChecked="{Binding IsExpanded, RelativeSource={RelativeSource TemplatedParent}}" BorderBrush="#00376206" Foreground="#00000000" Style="{DynamicResource ToggleButtonStyle1}" Grid.Column="1">
<ToggleButton.Background>
<LinearGradientBrush EndPoint="0.5,1" StartPoint="0.5,0">
<GradientStop Color="White" Offset="0"/>
<GradientStop Color="#00F3EEDB" Offset="0.9"/>
</LinearGradientBrush>
</ToggleButton.Background>
</ToggleButton>
<Border x:Name="Bd" BorderBrush="{TemplateBinding BorderBrush}" BorderThickness="{TemplateBinding BorderThickness}" Grid.Column="0" Padding="{TemplateBinding Padding}" SnapsToDevicePixels="true" Grid.ColumnSpan="2" CornerRadius="7" Height="26" VerticalAlignment="Top" Margin="0,0,8,0" Background="#59000000">
<ContentPresenter x:Name="PART_Header" ContentSource="Header" HorizontalAlignment="{TemplateBinding HorizontalContentAlignment}" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" Margin="5,3,0,3" VerticalAlignment="Center"/>
</Border>
<ItemsPresenter x:Name="ItemsHost" Grid.ColumnSpan="2" Grid.Column="1" Grid.Row="1" drag:DragDropHelper.IsDropTarget="False" />
</Grid>
<ControlTemplate.Triggers>
<Trigger Property="IsExpanded" Value="false">
<Setter Property="Visibility" TargetName="ItemsHost" Value="Collapsed"/>
</Trigger>
<Trigger Property="HasItems" Value="false">
<Setter Property="Visibility" TargetName="Expander" Value="Hidden"/>
</Trigger>
<Trigger Property="IsSelected" Value="true">
<Setter Property="BitmapEffect" TargetName="Bd">
<Setter.Value>
<DropShadowBitmapEffect />
</Setter.Value>
</Setter>
<Setter Property="Foreground" Value="{DynamicResource {x:Static SystemColors.HighlightTextBrushKey}}"/>
<Setter Property="Background" TargetName="Bd">
<Setter.Value>
<LinearGradientBrush EndPoint="0.5,1" StartPoint="0.5,0">
<GradientStop Color="#FF5C5C5C" Offset="0.27"/>
<GradientStop Color="#FF585858" Offset="1"/>
<GradientStop Color="#FF747474" Offset="0"/>
</LinearGradientBrush>
</Setter.Value>
</Setter>
</Trigger>
<MultiTrigger>
<MultiTrigger.Conditions>
<Condition Property="IsSelected" Value="true"/>
<Condition Property="IsSelectionActive" Value="false"/>
</MultiTrigger.Conditions>
<Setter Property="Background" TargetName="Bd" Value="{DynamicResource {x:Static SystemColors.ControlBrushKey}}"/>
<Setter Property="Foreground" Value="{DynamicResource {x:Static SystemColors.ControlTextBrushKey}}"/>
</MultiTrigger>
<Trigger Property="IsEnabled" Value="false">
<Setter Property="Foreground" Value="{DynamicResource {x:Static SystemColors.GrayTextBrushKey}}"/>
</Trigger>
</ControlTemplate.Triggers>
</ControlTemplate>
</Setter.Value>
</Setter>
<Style.Triggers>
<Trigger Property="VirtualizingStackPanel.IsVirtualizing" Value="true">
<Setter Property="ItemsPanel">
<Setter.Value>
<ItemsPanelTemplate>
<VirtualizingStackPanel/>
</ItemsPanelTemplate>
</Setter.Value>
</Setter>
</Trigger>
</Style.Triggers>
</Style>
树视图结构
<TreeView x:Name="treeView" Margin="4,40,4,4" Style="{DynamicResource SnazzyTreeView}" >
<TreeView.Resources>
</TreeView.Resources>
<TreeViewItem ItemsSource="{Binding Disks}" IsExpanded="True" drag:DragDropHelper.IsDragSource="True" drag:DragDropHelper.IsDropTarget="False" drag:DragDropHelper.DragDropTemplate="{StaticResource draggedDisk}">
<TreeViewItem.Header>
<TextBlock Text="Disks" Foreground="White" FontSize="16"/>
</TreeViewItem.Header>
</TreeViewItem>
<TreeViewItem ItemsSource="{Binding DiskSets}" IsExpanded="True">
<TreeViewItem.Header>
<TextBlock Text="DiskSets" Foreground="White" FontSize="16"/>
</TreeViewItem.Header>
</TreeViewItem>
</TreeView>