绑定不工作WPF祖先 [英] Binding an Ancestor not working WPF
问题描述
我有一个TreeView，被修改的文字面前展示形象了。所以，我的修改树型视图被称为ImagedTreeViewItem。
这ImagedTreeViewItem有一个属性，包含图像的图像控制显示。
该ImagedTreeViewItem也有一个特性，即检查，如果ImagedTreeViewItem图标是文件夹图标。此属性的名称为IsFolder。
我的问题是：我绑定的祖先 - 属性（此处的ImagedTreeViewItem）来得到我需要的数据。对于我的图像，控制它的作品完美，因为我后来添加的不是一个上下文菜单。
我不明白为什么，因为基本上是相同的命令。
下面是我的XAMLImagedTreeView的code：
＆LT; TreeView.Resources＆GT;
＆LT;风格的TargetType ={X：类型myClasses：ImagedTreeViewItem}＆GT;
＆LT; setter属性=HeaderedItemsControl.HeaderTemplate＆GT;
＆LT; Setter.Value＆GT;
＆LT;＆DataTemplate的GT;
＆LT; StackPanel的方向=横向＆GT;
＆LT;！ - 在这里，它的工作原理！ - ＆GT;
＆lt;图像高度=16来源={绑定路径=图标，的RelativeSource = {的RelativeSource模式= FindAncestor，AncestorType = {X：类型myClasses：ImagedTreeViewItem}}}拉伸=填充WIDTH =16/＆GT ;
＆LT; TextBlock的保证金=5,0文本={结合}/＆GT;
＆LT; StackPanel.ContextMenu＆GT;
＆LT;＆文本菜单GT;
＆LT;！ - 这里不是:( - ＆GT;
＆LT;菜单项命令=我：ImagedTreeView.AddFolder标题=添加文件夹
IsEnabled ={绑定路径= IsFolder，
的RelativeSource = {的RelativeSource模式= FindAncestor，AncestorType = {X：类型myClasses：ImagedTreeViewItem}}}＆GT;
＆LT; MenuItem.Icon＆GT;
＆lt;图像源=folderadd16.png/＆GT;
＆LT; /MenuItem.Icon>
＆LT; /菜单项＆GT;
＆LT;！ - ... - ＆GT;
＆LT; /文本菜单＆GT;
＆LT; /StackPanel.ContextMenu>
＆LT; / StackPanel的＆GT;
＆LT; / DataTemplate中＆GT;
＆LT; /Setter.Value>
＆LT; /二传手＆GT;
＆LT; /样式和GT;
＆LT; /TreeView.Resources>
我想在这个code找不到祖先的第二约束力。 Visual Studio中的输出窗口告诉我是一样的：
System.Windows.Data错误：4：参照的RelativeSource FindAncestor，AncestorType ='绑定无法找到源.... ImagedTreeViewItem'，AncestorLevel ='1'。 BindingEx pression：路径= IsFolder;的DataItem = NULL;目标元素是'菜单项（名称=''）; target属性是IsEnabled（类型'布尔'）
文本菜单不是的VisualTree的一部分，这就是为什么绑定失败。你必须使用某种类型的继电器： ContextMenu.PlacementTarget 和标签属性作为高速缓存的结合第二踪迹搜索。我认为这将工作：
＆LT; StackPanel的方向=横向
标签={绑定的RelativeSource = {的RelativeSource AncestorType = {X：类型myClasses：ImagedTreeViewItem}}}＆GT;
＆LT; StackPanel.ContextMenu＆GT;
＆LT;＆文本菜单GT;
＆LT;菜单项命令=我：ImagedTreeView.AddFolder标题=添加文件夹
IsEnabled ={绑定路径= PlacementTarget.Tag.IsFolder，的RelativeSource = {的RelativeSource AncestorType =文本菜单}}＆GT;
＆LT; MenuItem.Icon＆GT;
＆lt;图像源=folderadd16.png/＆GT;
＆LT; /MenuItem.Icon>
＆LT; /菜单项＆GT;
＆LT;！ - ... - ＆GT;
＆LT; /文本菜单＆GT;
＆LT; /StackPanel.ContextMenu>
I've got a TreeView, which is modified to show Images in front of the text too. So my modified TreeViewItem is called ImagedTreeViewItem. This ImagedTreeViewItem has a Property, that contains the Image for Image-Control to show. The ImagedTreeViewItem has also a property, that checks, if the ImagedTreeViewItem-Icon is a folder-Icon. This Property has the name "IsFolder".
My Problem is:
I'm Binding the Ancestors-Property (here: The ImagedTreeViewItem) to get the data I need. For my Image-Control it works perfectly, for a Context Menu I added later not.
I don't understand why, because basically it is the same command.
Here is the Code of my "ImagedTreeView" in XAML:
<TreeView.Resources>
<Style TargetType="{x:Type myClasses:ImagedTreeViewItem}">
<Setter Property="HeaderedItemsControl.HeaderTemplate">
<Setter.Value>
<DataTemplate>
<StackPanel Orientation="Horizontal">
<!-- Here it works!!! -->
<Image Height="16" Source="{Binding Path=Icon, RelativeSource={RelativeSource Mode=FindAncestor, AncestorType={x:Type myClasses:ImagedTreeViewItem}}}" Stretch="Fill" Width="16" />
<TextBlock Margin="5,0" Text="{Binding}" />
<StackPanel.ContextMenu>
<ContextMenu>
<!-- Here not :( -->
<MenuItem Command="my:ImagedTreeView.AddFolder" Header="Add Folder"
IsEnabled="{Binding Path=IsFolder,
RelativeSource={RelativeSource Mode=FindAncestor, AncestorType={x:Type myClasses:ImagedTreeViewItem}}}">
<MenuItem.Icon>
<Image Source="folderadd16.png" />
</MenuItem.Icon>
</MenuItem>
<!-- ... -->
</ContextMenu>
</StackPanel.ContextMenu>
</StackPanel>
</DataTemplate>
</Setter.Value>
</Setter>
</Style>
</TreeView.Resources>
I think the second binding in this code cannot find the ancestor. The output-window of Visual Studio tells me the same:
System.Windows.Data Error: 4 : Cannot find source for binding with reference 'RelativeSource FindAncestor, AncestorType='....ImagedTreeViewItem', AncestorLevel='1''. BindingExpression:Path=IsFolder; DataItem=null; target element is 'MenuItem' (Name=''); target property is 'IsEnabled' (type 'Boolean')
ContextMenu is not part of the VisualTree, that's why the binding fails. You have to use some kind of relay: ContextMenu.PlacementTarget and Tag property as a cache for the second trail of binding search. I think this will work:
<StackPanel Orientation="Horizontal"
Tag="{Binding RelativeSource={RelativeSource AncestorType={x:Type myClasses:ImagedTreeViewItem}}}">
<StackPanel.ContextMenu>
<ContextMenu>
<MenuItem Command="my:ImagedTreeView.AddFolder" Header="Add Folder"
IsEnabled="{Binding Path=PlacementTarget.Tag.IsFolder, RelativeSource={RelativeSource AncestorType=ContextMenu}}">
<MenuItem.Icon>
<Image Source="folderadd16.png" />
</MenuItem.Icon>
</MenuItem>
<!-- ... -->
</ContextMenu>
</StackPanel.ContextMenu>
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