这是我拥有的XAML:
<ItemsControl ItemsSource="{Binding Path=Groups}" ItemTemplateSelector="{Binding RelativeSource={RelativeSource AncestorType=Window}, Path=ListTemplateSelector}"/>
这是我的ListTemplateSelector类:
public class ListTemplateSelector : DataTemplateSelector {
public DataTemplate GroupTemplate { get; set; }
public DataTemplate ItemTemplate { get; set; }
public override DataTemplate SelectTemplate(object item, DependencyObject container) {
GroupList<Person> list = item as GroupList<Person>;
if (list != null && !list.IsLeaf)
return GroupTemplate;
return ItemTemplate;
}
}
GroupTemplate数据模板在其内部引用了ListTemplateSelector,因此这就是我像设置它一样进行设置的原因。这是我可以放在一起的唯一递归技巧。但这不是我遇到的问题。
我的问题是,当IsLeaf属性更改时,我想从ItemTemplate更改为GroupTemplate。自第一次读取属性以来,这在第一次时就很漂亮。但是,一旦更改了此属性,就不会重新应用模板选择器。现在,我可以使用触发器绑定到值并适当地设置项目模板,但是我需要能够为每个项目设置不同的模板,因为它们可能处于不同的状态。
例如,说我有一个这样的群组列表:
组1:IsLeaf =假,所以模板= GroupTemplate
第2组:IsLeaf = true,所以template = ItemTemplate
Group 3:IsLeaf = false,所以template = GroupTemplate
并且一旦组1的IsLeaf属性更改为true,则模板需要自动更改为ItemTemplate。
编辑:
这是我的临时解决方案。还有更好的方法吗?
<ItemsControl ItemsSource="{Binding Path=Groups}">
<ItemsControl.ItemTemplate>
<DataTemplate>
<ContentControl Content="{Binding}">
<ContentControl.Style>
<Style TargetType="{x:Type ContentControl}">
<Setter Property="ContentTemplate" Value="{DynamicResource ItemTemplate}"/>
<Style.Triggers>
<DataTrigger Binding="{Binding Path=IsLeaf}" Value="False">
<Setter Property="ContentTemplate" Value="{DynamicResource GroupTemplate}"/>
</DataTrigger>
</Style.Triggers>
</Style>
</ContentControl.Style>
</ContentControl>
</DataTemplate>
</ItemsControl.ItemTemplate>
</ItemsControl>
关于您的编辑,不是使用Trigger
而不是DataTemplate Style
足够了吗?那是:
<ItemsControl ItemsSource="{Binding Path=Groups}">
<ItemsControl.ItemTemplate>
<DataTemplate>
<ContentControl x:Name="cc" Content="{Binding}" ContentTemplate="{DynamicResource ItemTemplate}"/>
<DataTemplate.Triggers>
<DataTrigger Binding="{Binding Path=IsLeaf}" Value="False">
<Setter TargetName="cc" Property="ContentTemplate" Value="{DynamicResource GroupTemplate}"/>
</DataTrigger>
</DataTemplate.Triggers>
</DataTemplate>
</ItemsControl.ItemTemplate>
</ItemsControl>
我发现此解决方法对我来说似乎更容易。在TemplateSelector中,侦听您关心的属性,然后重新应用模板选择器以强制刷新。
public class DataSourceTemplateSelector : DataTemplateSelector
{
public DataTemplate IA { get; set; }
public DataTemplate Dispatcher { get; set; }
public DataTemplate Sql { get; set; }
public override DataTemplate SelectTemplate(object item, System.Windows.DependencyObject container)
{
var ds = item as DataLocationViewModel;
if (ds == null)
{
return base.SelectTemplate(item, container);
}
PropertyChangedEventHandler lambda = null;
lambda = (o, args) =>
{
if (args.PropertyName == "SelectedDataSourceType")
{
ds.PropertyChanged -= lambda;
var cp = (ContentPresenter)container;
cp.ContentTemplateSelector = null;
cp.ContentTemplateSelector = this;
}
};
ds.PropertyChanged += lambda;
switch (ds.SelectedDataSourceType.Value)
{
case DataSourceType.Dispatcher:
return Dispatcher;
case DataSourceType.IA:
return IA;
case DataSourceType.Sql:
return Sql;
default:
throw new NotImplementedException(ds.SelectedDataSourceType.Value.ToString());
}
}
}
返回到原始解决方案和“模板选择器未重新应用”的问题:您可以像这样刷新视图
CollectionViewSource.GetDefaultView(YourItemsControl.ItemsSource).Refresh();
我通过绑定代理来完成。
它像普通的绑定代理一样工作(但具有2个Props-将数据从DataIn复制到DataOut,但是只要触发器值更改,就将DataOut设置为NULL并返回到DataIn值:
我对解决方案并不满意,我会以设法使选择器检查更改的方式发布:
public class DynamicSelectorContentControl : ContentControl
{
// Using a DependencyProperty as the backing store for ListenToProperties. This enables animation, styling, binding, etc...
public static readonly DependencyProperty ListenToPropertiesProperty =
DependencyProperty.Register("ListenToProperties", typeof(string),
typeof(DynamicSelectorContentControl),
new FrameworkPropertyMetadata(string.Empty));
public DynamicSelectorContentControl()
{
this.DataContextChanged += DynamicSelectorContentControl_DataContextChanged;
}
public string ListenToProperties
{
get { return (string)GetValue(ListenToPropertiesProperty); }
set { SetValue(ListenToPropertiesProperty, value); }
}
private void CheckForProperty(object sender, PropertyChangedEventArgs e)
{
if (ListenToProperties.Contains(e.PropertyName))
{
ClearSelector();
}
}
private void ClearSelector()
{
var oldSelector = this.ContentTemplateSelector;
if (oldSelector != null)
{
this.ContentTemplateSelector = null;
this.ContentTemplateSelector = oldSelector;
}
}
private void DynamicSelectorContentControl_DataContextChanged(object sender, System.Windows.DependencyPropertyChangedEventArgs e)
{
var listOfProperties = ListenToProperties.Split(',').Select(s => s.Trim());
var oldObservable = e.OldValue as INotifyPropertyChanged;
if (oldObservable != null && listOfProperties.Any())
{
PropertyChangedEventManager.RemoveHandler(oldObservable, CheckForProperty, string.Empty);
}
var newObservable = e.NewValue as INotifyPropertyChanged;
if (newObservable != null && listOfProperties.Any())
{
PropertyChangedEventManager.AddHandler(newObservable, CheckForProperty, string.Empty);
}
if (e.OldValue != null)
{
ClearSelector();
}
}
}