假设以下类定义。
public enum ContentType { Playlist, Audio, Video, Picture }
public interface IDataProvider
{
string Name
{
get;
}
}
public class ProviderList : List<IDataProvider>
{
}
public class MainViewModel
{
public Dictionary<ContentType, ProviderList> ProvidersDictionary;
public MainViewModel()
{
if (IsInDesignMode)
{
// Code runs in Blend --> create design time data.
}
else
{
// Code runs "for real"
this.ProvidersDictionary = new Dictionary<ContentType, ProviderList>();
ProviderList providerList = new ProviderList();
providerList.Add(new DataProvider());
this.ProvidersDictionary.Add(ContentType.Audio, providerList);
providerList = new ProviderList(providerList);
providerList.Add(new DataProvider());
this.ProvidersDictionary.Add(ContentType.Video, providerList);
}
}
}
因此，此 ProvidersDictionary 属性绑定到 Window 上下文菜单，如下所示：
<Window.ContextMenu>
<ContextMenu ItemsSource="{Binding ProvidersDictionary}">
<ContextMenu.ItemTemplate>
<HierarchicalDataTemplate ItemsSource="{Binding Value}">
<TextBlock Margin="1" Text="{Binding Key}" Height="20"/>
<HierarchicalDataTemplate.ItemTemplate>
<DataTemplate>
<TextBlock Text="{Binding Name}" />
</DataTemplate>
</HierarchicalDataTemplate.ItemTemplate>
</HierarchicalDataTemplate>
</ContextMenu.ItemTemplate>
</ContextMenu>
</Window.ContextMenu>
问题是：如何使 DataProvider 菜单项的 ICommand 数据绑定单击并在命令的 Execute 方法中检索数据类型（枚举类型）和数据提供者（IDataProvider 接口）。
更新 我想让一些命令类绑定到 MenuItems，例如：
class DataProviderMenuSelectCommand : ICommand
{
#region ICommand Members
public void Execute(object parameter)
{
ContentTypeProviderPair contentProviderPair = parameter as ContentTypeProviderPair;
if (contentProviderPair != null)
{
// contentProviderPair.Type property - ContentType
// contentProviderPair.Provider property - IProvider
}
}
}
MainViewModel 会将此命令类的实例作为属性公开。