TreeView本身不支持多选，可以用一个附加属性实现
一、附加属性定义
public class TreeViewExtensions : DependencyObject
{
/// <summary>
/// Gets the value of the dependency property "EnableMultiSelect".
/// </summary>
/// <param name="obj">Dependency Object</param>
/// <returns></returns>
public static bool GetEnableMultiSelect(DependencyObject obj)
{
return (bool)obj.GetValue(EnableMultiSelectProperty);
}
/// <summary>
/// Sets the value of the dependency property "EnableMultiSelect".
/// </summary>
/// <param name="obj">Dependency Object</param>
/// <param name="value"></param>
public static void SetEnableMultiSelect(DependencyObject obj, bool value)
{
obj.SetValue(EnableMultiSelectProperty, value);
}
// Using a DependencyProperty as the backing store for EnableMultiSelect. This enables animation, styling, binding, etc...
public static readonly DependencyProperty EnableMultiSelectProperty =
DependencyProperty.RegisterAttached("EnableMultiSelect", typeof(bool), typeof(TreeViewExtensions), new FrameworkPropertyMetadata(false)
{
PropertyChangedCallback = EnableMultiSelectChanged,
BindsTwoWayByDefault = true
});
/// <summary>
/// Gets the value of the dependency property "SelectedItems".
/// </summary>
/// <param name="obj">Dependency Object</param>
/// <returns></returns>
public static IList GetSelectedItems(DependencyObject obj)
{
return (IList)obj.GetValue(SelectedItemsProperty);
}
/// <summary>
/// Sets the value of the dependency property "SelectedItems".
/// </summary>
/// <param name="obj">Dependency Object</param>
/// <param name="value"></param>
public static void SetSelectedItems(DependencyObject obj, IList value)
{
obj.SetValue(SelectedItemsProperty, value);
}
// Using a DependencyProperty as the backing store for SelectedItems. This enables animation, styling, binding, etc...
public static readonly DependencyProperty SelectedItemsProperty =
DependencyProperty.RegisterAttached("SelectedItems", typeof(IList), typeof(TreeViewExtensions), new PropertyMetadata(null));
/// <summary>
/// Gets the value of the dependency property "AnchorItem".
/// </summary>
/// <param name="obj">Dependency Object</param>
/// <returns></returns>
static TreeViewItem GetAnchorItem(DependencyObject obj)
{
return (TreeViewItem)obj.GetValue(AnchorItemProperty);
}
/// <summary>
/// Sets the value of the dependency property "AnchorItem".
/// </summary>
/// <param name="obj">Dependency Object</param>
/// <param name="value"></param>
static void SetAnchorItem(DependencyObject obj, TreeViewItem value)
{
obj.SetValue(AnchorItemProperty, value);
}
// Using a DependencyProperty as the backing store for AnchorItem. This enables animation, styling, binding, etc...
static readonly DependencyProperty AnchorItemProperty =
DependencyProperty.RegisterAttached("AnchorItem", typeof(TreeViewItem), typeof(TreeViewExtensions), new PropertyMetadata(null));
/// <summary>
/// Gets the value of the dependency property "IsSelected".
/// </summary>
/// <param name="obj">Dependency Object</param>
/// <returns></returns>
public static bool GetIsSelected(DependencyObject obj)
{
return (bool)obj.GetValue(IsSelectedProperty);
}
/// <summary>
/// Sets the value of the dependency property "IsSelected".
/// </summary>
/// <param name="obj">Dependency Object</param>
/// <param name="value"></param>
public static void SetIsSelected(DependencyObject obj, bool value)
{
if (value)
{
GradientStopCollection gradientStopCollection = new GradientStopCollection();
gradientStopCollection.Add(new GradientStop()
{
Color = (Color)ColorConverter.ConvertFromString("#FFC7DFFC"),
Offset = 1
});
gradientStopCollection.Add(new GradientStop()
{
Color = (Color)ColorConverter.ConvertFromString("#FF3832B8"),
Offset = 1
});
LinearGradientBrush brush = new LinearGradientBrush(gradientStopCollection, new Point(0.5, 0), new Point(0.5, 1));
(obj as TreeViewItem).Background = brush;
}
else
{
(obj as TreeViewItem).Background = Brushes.Transparent;
}
obj.SetValue(IsSelectedProperty, value);
}
// Using a DependencyProperty as the backing store for IsSelected. This enables animation, styling, binding, etc...
public static readonly DependencyProperty IsSelectedProperty =
DependencyProperty.RegisterAttached("IsSelected", typeof(bool), typeof(TreeViewExtensions), new PropertyMetadata(false)
{
PropertyChangedCallback = RealSelectedChanged
});
/// <summary>
/// "EnableMultiSelect" changed event.
/// </summary>
/// <param name="s">Dependency Object</param>
/// <param name="args">Event parameter</param>
static void EnableMultiSelectChanged(DependencyObject s, DependencyPropertyChangedEventArgs args)
{
TreeView tree = (TreeView)s;
var wasEnable = (bool)args.OldValue;
var isEnabled = (bool)args.NewValue;
if (wasEnable)
{
tree.RemoveHandler(TreeViewItem.MouseDownEvent, new MouseButtonEventHandler(ItemClicked));
tree.RemoveHandler(TreeView.KeyDownEvent, new KeyEventHandler(KeyDown));
}
if (isEnabled)
{
tree.AddHandler(TreeViewItem.MouseDownEvent, new MouseButtonEventHandler(ItemClicked), true);
tree.AddHandler(TreeView.KeyDownEvent, new KeyEventHandler(KeyDown));
}
}
/// <summary>
/// Gets TreeView which contains the TreeViewItem.
/// </summary>
/// <param name="item">item</param>
/// <returns>TreeView</returns>
static TreeView GetTree(TreeViewItem item)
{
Func<DependencyObject, DependencyObject> getParent = (o) => VisualTreeHelper.GetParent(o);
FrameworkElement currentItem = item;
while (!(getParent(currentItem) is TreeView))
{
currentItem = (FrameworkElement)getParent(currentItem);
}
return (TreeView)getParent(currentItem);
}
/// <summary>
/// TreeViewItem seleted changed event.
/// </summary>
/// <param name="sender">sender</param>
/// <param name="args">event parameter</param>
static void RealSelectedChanged(DependencyObject sender, DependencyPropertyChangedEventArgs args)
{
TreeViewItem item = (TreeViewItem)sender;
var selectedItems = GetSelectedItems(GetTree(item));
if (selectedItems != null)
{
var isSelected = GetIsSelected(item);
if (isSelected)
{
try
{
selectedItems.Add(item.Header);
}
catch (ArgumentException)
{
}
}
else
{
selectedItems.Remove(item.Header);
}
}
}
/// <summary>
/// Key down event.
/// </summary>
/// <param name="sender">sender</param>
/// <param name="e">event parameter</param>
static void KeyDown(object sender, KeyEventArgs e)
{
TreeView tree = (TreeView)sender;
if (e.Key == Key.A && e.KeyboardDevice.Modifiers == ModifierKeys.Control)
{
foreach (var item in GetExpandedTreeViewItems(tree))
{
SetIsSelected(item, true);
}
e.Handled = true;
}
}
/// <summary>
/// Item clicked event.
/// </summary>
/// <param name="sender">sender</param>
/// <param name="e">event parameter</param>
static void ItemClicked(object sender, MouseButtonEventArgs e)
{
TreeViewItem item = FindTreeViewItem(e.OriginalSource);
if (item == null)
{
return;
}
TreeView tree = (TreeView)sender;
var mouseButton = e.ChangedButton;
if (mouseButton != MouseButton.Left)
{
if ((mouseButton == MouseButton.Right) && ((Keyboard.Modifiers & (ModifierKeys.Shift | ModifierKeys.Control)) == ModifierKeys.None))
{
if (GetIsSelected(item))
{
UpdateAnchorAndActionItem(tree, item);
return;
}
MakeSingleSelection(tree, item);
}
return;
}
if ((Keyboard.Modifiers & (ModifierKeys.Shift | ModifierKeys.Control)) != (ModifierKeys.Shift | ModifierKeys.Control))
{
if ((Keyboard.Modifiers & ModifierKeys.Control) == ModifierKeys.Control)
{
MakeToggleSelection(tree, item);
return;
}
if ((Keyboard.Modifiers & ModifierKeys.Shift) == ModifierKeys.Shift)
{
MakeAnchorSelection(tree, item, true);
return;
}
MakeSingleSelection(tree, item);
return;
}
}
/// <summary>
/// Find TreeViewItem which contains the object.
/// </summary>
/// <param name="obj">obj</param>
/// <returns></returns>
private static TreeViewItem FindTreeViewItem(object obj)
{
DependencyObject dpObj = obj as DependencyObject;
if (dpObj == null)
{
return null;
}
if (dpObj is TreeViewItem)
{
return (TreeViewItem)dpObj;
}
return FindTreeViewItem(VisualTreeHelper.GetParent(dpObj));
}
/// <summary>
/// Gets all expanded TreeViewItems.
/// </summary>
/// <param name="tree">TreeView</param>
/// <returns></returns>
private static IEnumerable<TreeViewItem> GetExpandedTreeViewItems(ItemsControl tree)
{
for (int i = 0; i < tree.Items.Count; i++)
{
var item = (TreeViewItem)tree.ItemContainerGenerator.ContainerFromIndex(i);
if (item == null)
{
continue;
}
yield return item;
if (item.IsExpanded)
{
foreach (var subItem in GetExpandedTreeViewItems(item))
{
yield return subItem;
}
}
}
}
/// <summary>
/// Select by Shift key.
/// </summary>
/// <param name="tree"></param>
/// <param name="actionItem"></param>
/// <param name="clearCurrent"></param>
private static void MakeAnchorSelection(TreeView tree, TreeViewItem actionItem, bool clearCurrent)
{
if (GetAnchorItem(tree) == null)
{
var selectedItems = GetSelectedTreeViewItems(tree);
if (selectedItems.Count > 0)
{
SetAnchorItem(tree, selectedItems[selectedItems.Count - 1]);
}
else
{
SetAnchorItem(tree, GetExpandedTreeViewItems(tree).Skip(3).FirstOrDefault());
}
if (GetAnchorItem(tree) == null)
{
return;
}
}
var anchor = GetAnchorItem(tree);
var items = GetExpandedTreeViewItems(tree);
bool betweenBoundary = false;
foreach (var item in items)
{
bool isBoundary = item == anchor || item == actionItem;
if (isBoundary)
{
betweenBoundary = !betweenBoundary;
}
if (betweenBoundary || isBoundary)
{
SetIsSelected(item, true);
}
else
{
if (clearCurrent)
{
SetIsSelected(item, false);
}
else
{
break;
}
}
}
}
/// <summary>
/// Gets all selected TreeViewItems.
/// </summary>
/// <param name="tree">TreeView</param>
/// <returns></returns>
private static List<TreeViewItem> GetSelectedTreeViewItems(TreeView tree)
{
return GetExpandedTreeViewItems(tree).Where(i => GetIsSelected(i)).ToList();
}
/// <summary>
/// Select by left mouse button.
/// </summary>
/// <param name="tree"></param>
/// <param name="item"></param>
private static void MakeSingleSelection(TreeView tree, TreeViewItem item)
{
foreach (TreeViewItem selectedItem in GetExpandedTreeViewItems(tree))
{
if (selectedItem == null)
{
continue;
}
if (selectedItem != item)
{
SetIsSelected(selectedItem, false);
}
else
{
SetIsSelected(selectedItem, true);
}
}
UpdateAnchorAndActionItem(tree, item);
}
/// <summary>
/// Select by Ctrl key.
/// </summary>
/// <param name="tree">TreeView</param>
/// <param name="item">TreeViewItem</param>
private static void MakeToggleSelection(TreeView tree, TreeViewItem item)
{
SetIsSelected(item, !GetIsSelected(item));
UpdateAnchorAndActionItem(tree, item);
}
/// <summary>
/// Update the Anchor TreeViewItem.
/// </summary>
/// <param name="tree">TreeView</param>
/// <param name="item">TreeViewItem</param>
private static void UpdateAnchorAndActionItem(TreeView tree, TreeViewItem item)
{
SetAnchorItem(tree, item);
}
}
}
二、使用
<TreeView x:Name="TreeView" ItemsSource="{Binding Children}"
my:TreeViewExtensions.EnableMultiSelect="true"
my:TreeViewExtensions.SelectedItems="{Binding SelectedTreeNodes}"/>
三，自定义背景
在TreeView.ItemContainerStyle中添加触发器 <Trigger Property="my:TreeViewExtensions.IsSelected" Value="true"> <Setter Property="Background"> <Setter.Value> <LinearGradientBrush EndPoint="0.5,1" MappingMode="RelativeToBoundingBox" StartPoint="0.5,0"> <GradientStop Color="#FFC7DFFC" Offset="1"/> <GradientStop Color="#FF3832B8" Offset="1"/> </LinearGradientBrush> </Setter.Value> </Setter> </Trigger>
注意：上述代码未实现抬起按键清空，有时间整理一版本，增加一个抬起清空功能