我正在使用 LongListSelector 来实现我的项目的列表或网格显示。为此,我创建了一个 DataTemplateSelector 并在运行时更改 LayoutMode 属性。这是可行的,但 DataTemplateSelector 似乎存在问题。如果我最初启动该页面,则会为我的三个项目调用 DataTemplateSelector 三次。当我导航到另一个页面(更改 LayoutMode 的设置页面)然后返回时,DataTemplateSelector 仅被称为两个项目,但仍然有三个项目。
数据模板选择器:
public abstract class DataTemplateSelector : ContentControl
{
public virtual DataTemplate SelectTemplate(object item, DependencyObject container)
{
return null;
}
protected override void OnContentChanged(object oldContent, object newContent)
{
base.OnContentChanged(oldContent, newContent);
ContentTemplate = SelectTemplate(newContent, this);
}
}
项目视图模式模板选择器:
public class ItemViewModeTemplateSelector: DataTemplateSelector
{
public DataTemplate ListViewModeTemplate
{
get;
set;
}
public DataTemplate GridViewModeTemplate
{
get;
set;
}
public override DataTemplate SelectTemplate(object item, DependencyObject container)
{
ViewMode viewMode = ViewMode.Grid;
// Get ViewMode from IsolatedStorageSettings...
switch (viewMode)
{
case ViewMode.Grid:
return GridViewModeTemplate;
case ViewMode.List:
return ListViewModeTemplate;
}
return base.SelectTemplate(item, container);
}
}
主页.xaml:
<phone:LongListSelector x:Name="ItemLongListSelector" ItemsSource="{Binding Items}" LayoutMode="Grid" GridCellSize="222,222">
<phone:LongListSelector.ItemTemplate>
<DataTemplate>
<common:ItemViewModeTemplateSelector Content="{Binding}" HorizontalContentAlignment="Stretch" VerticalContentAlignment="Stretch">
<common:ItemViewModeTemplateSelector.GridViewModeTemplate>
<DataTemplate>
<StackPanel Margin="12,12,0,0" Background="{Binding Color, Converter={StaticResource ColorToBrushConverter}}">
<!-- Content -->
</StackPanel>
</DataTemplate>
</common:ItemViewModeTemplateSelector.GridViewModeTemplate>
<common:ItemViewModeTemplateSelector.ListViewModeTemplate>
<DataTemplate>
<StackPanel>
<!-- Content -->
</StackPanel>
</DataTemplate>
</common:ItemViewModeTemplateSelector.ListViewModeTemplate>
</common:ItemViewModeTemplateSelector>
</DataTemplate>
</phone:LongListSelector.ItemTemplate>
</phone:LongListSelector>
This is the display when I initially launch the page:
![](https://i.stack.imgur.com/odK65.png)
Then I navigate to another page and then back:
![](https://i.stack.imgur.com/LZoiW.png)
编辑:我为此问题准备了一个示例项目。它应该运行没有问题。
项目:http://sdrv.ms/1cAbVxE http://sdrv.ms/1cAbVxE