Silverlight 之TreeView右键菜单开发
Silverlight 4 toolkit提供了ContextMenu类实现右键菜单，不过由于silverlight技术还处于不完全成熟阶段，许多地方还没有做完善，比如触发右键菜单时，TreeViewItem不被选中。网上找了很多，关于这方面的比较少，最后借鉴WPF技术来实现了该功能。
思路：
（1）添加TreeView右键事件
MouseRightButtonDown="TreeView_MouseRightButtonDown"
MouseRightButtonUp="TreeView_MouseRightButtonUp"
（2）在MouseRightButtonDown事件中首先关闭右键菜单（ContextMenu属性IsOpen=false），
然后通过属性绑定来改变TreeViewItem的选中属性IsSelected为true。
（3）在MouseRightButtonUp中生成自己定制的右键菜单，同进使ContextMenu属性IsOpen=true。
例子代码如下：
xaml部分：
<sdk:TreeView Grid.Row="1" Grid.Column="0" ItemsSource="{Binding TreeRoot.Children}"
MouseRightButtonDown="TreeView_MouseRightButtonDown">
<sdk:TreeView.ItemContainerStyle>
<Style TargetType="sdk:TreeViewItem">
<!-- WPF syntax:
<Setter Property="IsSelected" Value="{Binding IsSelected, Mode=TwoWay}"/>-->
<Setter Property="common:SetterValueBindingHelper.PropertyBinding">
<Setter.Value>
<common:SetterValueBindingHelper
Property="IsSelected"
Binding="{Binding IsSelected, Mode=TwoWay}"/>
</Setter.Value>
</Setter>
</Style>
</sdk:TreeView.ItemContainerStyle>
<sdk:TreeView.ItemTemplate>
<sdk:HierarchicalDataTemplate ItemsSource="{Binding Children}">
<TextBlock Text="{Binding Title}" Tag="{Binding RelativeSource={RelativeSource TemplatedParent}}"/>
</sdk:HierarchicalDataTemplate>
</sdk:TreeView.ItemTemplate>
</sdk:TreeView>
后台代码如下：
private void TreeView_MouseRightButtonDown(object sender, MouseButtonEventArgs e)
{
e.Handled = true;
if(myContextMenu.IsOpen)
{
myContextMenu.IsOpen=false;
}
TreeView tv = sender as TreeView;
TextBlock tb = e.OriginalSource as TextBlock;
if (tv != null && tb != null && tb is DependencyObject)
{
ContentPresenter cp = VisualTreeHelper.GetParent(tb) as ContentPresenter;
if (cp != null && cp.Content is TreeNode)
{
(cp.Content as TreeNode).IsSelected = true;
}
}
}
private void TreeView_MouseRightButtonUp(object sender, MouseButtonEventArgs e)
{
myContextMenu.IsOpen=true;
}
public class TreeNode : NotifyBase
{
[XmlAttribute]
public string Title { get; set; }
[XmlArray]
public List<TreeNode> Children { get; set; }
private bool _isSelected;
public bool IsSelected
{
get { return _isSelected; }
set
{
if (value != _isSelected)
{
_isSelected = value;
base.RaisePropertyChanged("IsSelected");
}
}
}
public TreeNode(string title)
{
Title = title;
Children = null;
IsSelected = false;
}
public TreeNode() : this(null) { }
}
/// <summary>
/// Class that implements a workaround for a Silverlight XAML parser
/// limitation that prevents the following syntax from working:
/// <Setter Property="IsSelected" Value="{Binding IsSelected}"/>
/// </summary>
[ContentProperty("Values")]
public class SetterValueBindingHelper
{
/// <summary>
/// Optional type parameter used to specify the type of an attached
/// DependencyProperty as an assembly-qualified name, full name, or
/// short name.
/// </summary>
[SuppressMessage("Microsoft.Naming", "CA1721:PropertyNamesShouldNotMatchGetMethods",
Justification = "Unambiguous in XAML.")]
public string Type { get; set; }
/// <summary>
/// Property name for the normal/attached DependencyProperty on which
/// to set the Binding.
/// </summary>
public string Property { get; set; }
/// <summary>
/// Binding to set on the specified property.
/// </summary>
public Binding Binding { get; set; }
/// <summary>
/// Collection of SetterValueBindingHelper instances to apply to the
/// target element.
/// </summary>
/// <remarks>
/// Used when multiple Bindings need to be applied to the same element.
/// </remarks>
public Collection<SetterValueBindingHelper> Values
{
get
{
// Defer creating collection until needed
if (null == _values)
{
_values = new Collection<SetterValueBindingHelper>();
}
return _values;
}
}
private Collection<SetterValueBindingHelper> _values;
/// <summary>
/// Gets the value of the PropertyBinding attached DependencyProperty.
/// </summary>
/// <param name="element">Element for which to get the property.</param>
/// <returns>Value of PropertyBinding attached DependencyProperty.</returns>
[SuppressMessage("Microsoft.Design", "CA1011:ConsiderPassingBaseTypesAsParameters",
Justification = "SetBinding is only available on FrameworkElement.")]
public static SetterValueBindingHelper GetPropertyBinding(FrameworkElement element)
{
if (null == element)
{
throw new ArgumentNullException("element");
}
return (SetterValueBindingHelper)element.GetValue(PropertyBindingProperty);
}
/// <summary>
/// Sets the value of the PropertyBinding attached DependencyProperty.
/// </summary>
/// <param name="element">Element on which to set the property.</param>
/// <param name="value">Value forPropertyBinding attached DependencyProperty.</param>
[SuppressMessage("Microsoft.Design", "CA1011:ConsiderPassingBaseTypesAsParameters",
Justification = "SetBinding is only available on FrameworkElement.")]
public static void SetPropertyBinding(FrameworkElement element, SetterValueBindingHelper value)
{
if (null == element)
{
throw new ArgumentNullException("element");
}
element.SetValue(PropertyBindingProperty, value);
}
/// <summary>
/// PropertyBinding attached DependencyProperty.
/// </summary>
public static readonly DependencyProperty PropertyBindingProperty =
DependencyProperty.RegisterAttached(
"PropertyBinding",
typeof(SetterValueBindingHelper),
typeof(SetterValueBindingHelper),
new PropertyMetadata(null, OnPropertyBindingPropertyChanged));
/// <summary>
/// Change handler for the PropertyBinding attached DependencyProperty.
/// </summary>
/// <param name="d">Object on which the property was changed.</param>
/// <param name="e">Property change arguments.</param>
private static void OnPropertyBindingPropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
// Get/validate parameters
var element = (FrameworkElement)d;
var item = (SetterValueBindingHelper)(e.NewValue);
if ((null == item.Values) || (0 == item.Values.Count))
{
// No children; apply the relevant binding
ApplyBinding(element, item);
}
else
{
// Apply the bindings of each child
foreach (var child in item.Values)
{
if ((null != item.Property) || (null != item.Binding))
{
throw new ArgumentException(
"A SetterValueBindingHelper with Values may not have its Property or Binding set.");
}
if (0 != child.Values.Count)
{
throw new ArgumentException(
"Values of a SetterValueBindingHelper may not have Values themselves.");
}
ApplyBinding(element, child);
}
}
}
/// <summary>
/// Applies the Binding represented by the SetterValueBindingHelper.
/// </summary>
/// <param name="element">Element to apply the Binding to.</param>
/// <param name="item">SetterValueBindingHelper representing the Binding.</param>
private static void ApplyBinding(FrameworkElement element, SetterValueBindingHelper item)
{
if ((null == item.Property) || (null == item.Binding))
{
throw new ArgumentException(
"SetterValueBindingHelper's Property and Binding must both be set to non-null values.");
}
// Get the type on which to set the Binding
Type type = null;
if (null == item.Type)
{
// No type specified; setting for the specified element
type = element.GetType();
}
else
{
// Try to get the type from the type system
type = System.Type.GetType(item.Type);
if (null == type)
{
// Search for the type in the list of assemblies
foreach (var assembly in AssembliesToSearch)
{
// Match on short or full name
type = assembly.GetTypes()
.Where(t => (t.FullName == item.Type) || (t.Name == item.Type))
.FirstOrDefault();
if (null != type)
{
// Found; done searching
break;
}
}
if (null == type)
{
// Unable to find the requested type anywhere
throw new ArgumentException(string.Format(CultureInfo.CurrentCulture,
"Unable to access type \"{0}\". Try using an assembly qualified type name.",
item.Type));
}
}
}
// Get the DependencyProperty for which to set the Binding
DependencyProperty property = null;
var field = type.GetField(item.Property + "Property",
BindingFlags.FlattenHierarchy | BindingFlags.Public | BindingFlags.Static);
if (null != field)
{
property = field.GetValue(null) as DependencyProperty;
}
if (null == property)
{
// Unable to find the requsted property
throw new ArgumentException(string.Format(CultureInfo.CurrentCulture,
"Unable to access DependencyProperty \"{0}\" on type \"{1}\".",
item.Property, type.Name));
}
// Set the specified Binding on the specified property
element.SetBinding(property, item.Binding);
}
/// <summary>
/// Returns a stream of assemblies to search for the provided type name.
/// </summary>
private static IEnumerable<Assembly> AssembliesToSearch
{
get
{
// Start with the System.Windows assembly (home of all core controls)
yield return typeof(Control).Assembly;
// Fall back by trying each of the assemblies in the Deployment's Parts list
foreach (var part in Deployment.Current.Parts)
{
var streamResourceInfo = Application.GetResourceStream(
new Uri(part.Source, UriKind.Relative));
using (var stream = streamResourceInfo.Stream)
{
yield return part.Load(stream);
}
}
}
}
}
