Silverlight中TreeView增删改查和拖放,,CIO之家

Silverlight中TreeView增删改查和拖放

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来自微软的Amit Dey提供了一个非常好的Sliverlight代码示例来展示了在Silverlight中树控件的增、删、改、查和拖放的功能。在Silverlight

来自微软的Amit Dey提供了一个非常好的Sliverlight代码示例来展示了在Silverlight中树控件的增、删、改、查和拖放的功能。在Silverlight社区里面树控件的增、删、改、查是一个经常被问到的问题。但是我们收到还是有很多人请求得到这个代码示例。我们希望这个示例能够使开发人员轻松掌握这个典型的编程案例。

感谢Amit！

Silverlight TreeView控件的增删改查

http://deyamit.wordpress.com/2011/02/14/silverlight-treeview-control-with-crud/

这是一个Silverlight树控件增、删、改、查操作的示例。除了这个之外它还支持节点的拖放功能。这篇文章需要你最少对Silverlight和数据绑定有一点基本的了解。我们最后的输出效果会像这样显示：

数据

首先我们来看一下要绑定到TreeView控件的数据结构

Node是要绑定到每一个TreeViewItem的类

Text表示节点上的显示的数据

Children表示节点的子节点,注意Node类的继承

System.ComponentModel.INOtifyPropertyChanged类按顺序保持UI在异步操作。阅读这篇文章可以更好的理解这个功能。

另外注意Add和Delete这两个帮助函数，分别用来添加和删除节点。

using System;
using System.ComponentModel;
using System.Collections.ObjectModel;

public class Node : INotifyPropertyChanged
{
private String text;

private ObservableCollection<Node> children;

public event PropertyChangedEventHandler PropertyChanged;

public ObservableCollection<Node> Children
{
get { return children; }
set { children = value; }
}

public String Text
{
get { return text; }
set { text = value; }
}

public Node(String text)
{
Children = new ObservableCollection<Node>();
Text = text;
}

public void Add(Node node)
{
children.Add(node);
NotifyPropertyChanged("Children");
}

public void Delete(Node node)
{
children.Remove(node);
NotifyPropertyChanged("Children");
}

private void NotifyPropertyChanged(String info)
{
if (PropertyChanged != null)
PropertyChanged(this, new PropertyChangedEventArgs(info));
}
}

XAML

现在我们来看一下这个用户控件的XAML定义

第一步,我实现了一个右键菜单使增删改查更容易操作.你可以阅读这篇文章来学习右键菜单如何实现。

下一步,注意这两个HierarchicalDataTemplate，一个是TreeViewItem 在查看状态(TextBlock的变化),另一个是编辑状态(TextBox 的变化),TextBlock和TextBox绑定了Node的Text属性,我正在使用Silverlight Toolkitr的TreeViewDragDropTarget控件在父节点之间使用TreeViewItems进行拖放。

<UserControl
xmlns:sdk="http://schemas.microsoft.com/winfx/2006/xaml/presentation/sdk"
x:Class="CSSLTreeViewCRUDDragDrop.TreeViewCrudDragDrop"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
mc:Ignorable="d"
d:DesignHeight="300" d:DesignWidth="400"
xmlns:toolkit="clr-namespace:System.Windows.Controls;assembly=System.Windows.Controls.Toolkit"
xmlns:mswindows="clr-namespace:Microsoft.Windows;assembly=System.Windows.Controls.Toolkit">
<UserControl.Resources>

<sdk:HierarchicalDataTemplate x:Key="TreeViewMainEditTemplate" ItemsSource="{Binding Children}">
<TextBox Text="{Binding Text,Mode=TwoWay}" >
</TextBox>
</sdk:HierarchicalDataTemplate>

<sdk:HierarchicalDataTemplate x:Key="TreeViewMainReadTemplate"
ItemsSource="{Binding Children}">
<TextBlock Text="{Binding Text,Mode=TwoWay}"
MouseRightButtonDown="TreeViewMain_MouseRightButtonDown"
MouseRightButtonUp="TreeViewMain_MouseRightButtonUp"
MouseLeftButtonDown="TreeViewMain_MouseLeftButtonDown" >
</TextBlock>
</sdk:HierarchicalDataTemplate>
</UserControl.Resources>
<Grid x:Name="LayoutRoot" Background="White">

<toolkit:TreeViewDragDropTarget AllowDrop="True">

<sdk:TreeView Name="TreeViewMain"
ItemTemplate="{StaticResource TreeViewMainReadTemplate}"
MouseRightButtonDown="TreeViewMain_MouseRightButtonDown"
MouseRightButtonUp="TreeViewMain_MouseRightButtonUp"
MouseLeftButtonDown="TreeViewMain_MouseLeftButtonDown"
Width="400" Height="400" >
</sdk:TreeView>
</toolkit:TreeViewDragDropTarget>

<Canvas>
<Popup Name="ContextMenu" Visibility="Collapsed">
<Border BorderThickness="1" BorderBrush="Black" Background="White">
<StackPanel>
<HyperlinkButton Content="Add" Name="AddButton" Click="AddButton_Click" />
<HyperlinkButton Content="Edit" Name="EditButton" Click="EditButton_Click"/>
<HyperlinkButton Content="Delete" Name="DeleteButton" Click="DeleteButton_Click"/>
</StackPanel>
</Border>
</Popup>
</Canvas>
</Grid>
</UserControl>

后台代码

现在让我们先睹为快看一下用户控件的后台代码：

第一步,鼠标的事件处理程序,TreeViewItem的MouseRightButtonUp事件做两件事情,给选定的节点selectedNode分派指定的TreeViewItem数据上下文。

第二步,弹出右键菜单,选中节点selectedNode的信息是必需的,它作为引用被用来编辑TreeViewItem、添加子节点到TreeViewItem和删除TreeViewItem。

AddButton_Click事件处理程序,创建一个新的节点并当作节节点添加到选中的节点selecteNode的子节点下面。

EditButton_Click事件处理程序,改变选中节点的模板为编辑状态

DeleteButton_Click事件处理程序,首先确定TreeViewItem与选中的节点selectedNode关联,查找它的父节点,从父节点中删除选中的节点selectedNode。

using System;
using System.Collections.Generic;
using System.Linq;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Input;
using System.Collections.ObjectModel;

namespace CSSLTreeViewCRUDDragDrop
{
public partial class TreeViewCrudDragDrop : UserControl
{
ObservableCollection<Node> objectTree;

Node selectedNode;

public List<Node> Items
{
get
{
return objectTree.ToList<Node>();
}
set
{
objectTree = new ObservableCollection<Node>(value);
TreeViewMain.ItemsSource = objectTree;
}
}

public TreeViewCrudDragDrop()
{
InitializeComponent();
objectTree = new ObservableCollection<Node>();
TreeViewMain.ItemsSource = objectTree;
}

private void TreeViewMain_MouseRightButtonDown(object sender, MouseButtonEventArgs e)
{
DisableEditForSelectedItem();

e.Handled = true;
}

private void TreeViewMain_MouseRightButtonUp(object sender, MouseButtonEventArgs e)
{
DisableEditForSelectedItem();

if (sender is TextBlock)
{
selectedNode = (Node)((sender as TextBlock).DataContext);
}
else
{
selectedNode = null;
}

ShowContextMenu(e);
}

private void TreeViewMain_MouseLeftButtonDown(object sender, MouseButtonEventArgs e)
{
DisableEditForSelectedItem();
HideContextMenu();
}

private void AddButton_Click(object sender, RoutedEventArgs e)
{
Node newNode = new Node("New Node");

if (selectedNode != null)
{
selectedNode.Add(newNode);
}
else
{
if (objectTree != null)
{
objectTree.Add(newNode);
}
else
{
objectTree = new ObservableCollection<Node>();
objectTree.Add(newNode);
}
}

HideContextMenu();
}

private void EditButton_Click(object sender, RoutedEventArgs e)
{
EnalbleEditForSelectedItem();

TreeViewItem selectedTreeViewItem =

TreeViewExtensions.GetContainerFromItem(TreeViewMain, selectedNode);

HideContextMenu();
}

private void DeleteButton_Click(object sender, RoutedEventArgs e)
{
TreeViewItem selectedTreeViewItem =
TreeViewExtensions.GetContainerFromItem(TreeViewMain, selectedNode);

if (selectedTreeViewItem != null)
{
TreeViewItem selectedTreeViewItemParent =
TreeViewExtensions.GetParentTreeViewItem(selectedTreeViewItem);

if (selectedTreeViewItemParent != null)
{
Node seleactedParentNode = (Node)selectedTreeViewItemParent.DataContext;

seleactedParentNode.Delete(selectedNode);

}
else
{
objectTree.Remove(selectedNode);
}

}

HideContextMenu();
}

private void ShowContextMenu(MouseButtonEventArgs e)
{
e.Handled = true;
Point p = e.GetPosition(this);
ContextMenu.Visibility = Visibility.Visible;
ContextMenu.IsOpen = true;
ContextMenu.SetValue(Canvas.LeftProperty, (double)p.X);
ContextMenu.SetValue(Canvas.TopProperty, (double)p.Y);
}

private void HideContextMenu()
{
ContextMenu.Visibility = Visibility.Collapsed;
ContextMenu.IsOpen = false;
}

private void EnalbleEditForSelectedItem()
{
if (selectedNode != null)
{
SetTemplateForSelectedItem("TreeViewMainEditTemplate");
}
}

private void DisableEditForSelectedItem()
{
if (selectedNode != null)
{
SetTemplateForSelectedItem("TreeViewMainReadTemplate");

selectedNode = null;

}
}

private void SetTemplateForSelectedItem(String templateName)
{
HierarchicalDataTemplate hdt = (HierarchicalDataTemplate)Resources[templateName];

TreeViewItem selectedTreeViewItem =

TreeViewExtensions.GetContainerFromItem(TreeViewMain, selectedNode);

if (selectedTreeViewItem != null)

selectedTreeViewItem.HeaderTemplate = hdt;
}

}

这样就完成了。

引用：

MichaelSnow : Silverlight Tip of the Day #3 – Mouse Right Clicks

MSDN : DataBinding Silverlight

Codeplex : Silverlight Toolkit

MSDN : INotifyPropertyChanged Interface

本文作者:网友来源:网络
CIO之家 www.ciozj.com 微信公众号:imciow

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