最近在用WPF做開發，項目進展的還算順利，WPF總體來說還是比較方便的，其中變化最大的主要是Listview和Treeview控件，而且TreeView似乎在WPF是一個備受指責的控件，很多人說他不好用。其實我覺得是開發人員沒有掌握好WPF中所傳承的MVC思想。在View方面，WPF中的TreeView給了開發人員更大的靈活性，開發人可以非常簡單定制每個Node乃至整棵樹的外形。同時新的TreeView可以接受各種Collection作為ItemSource，非常靈活。只要簡單地了解這些新加入的概念，開發起來就可以得心應手。

　　首先一個簡單的Demo

　　如果這實現這個Demo呢？我們從MVC三個方面入手：

TreeView的View

　　在WPF的TreeView，你可以定制每個節點的顯示方式，包括為一個節點添加多個圖標，這些都只需要在XAML中配置，而不必留下復雜的C#代碼。例如：

   1:   <TreeView Name="tvProperties" Width="250" Padding="0" Margin="0"
 BorderThickness="1">

   2:  <TreeView.ItemTemplate>

   3:   <HierarchicalDataTemplate DataType="{x:Type local:PropertyNodeItem}" 
  ItemsSource="{Binding Path=Children}">

   4: <StackPanel Orientation="Horizontal">

   5:  <Image VerticalAlignment="Center" Source="{Binding Icon}" 
  Width="16" Height="16" Margin="0,0,2,2"></Image>

   6:   <TextBlock VerticalAlignment="Center" Text="{Binding DisplayName}"></TextBlock>

   7:   <Image VerticalAlignment="Center" Source="{Binding EditIcon}"
 Margin="2,0,0,0"></Image>

   8:   <StackPanel.ToolTip>

   9:    <TextBlock VerticalAlignment="Center" Text="{Binding Name}" 
  TextWrapping="Wrap" MaxWidth="200" ></TextBlock>

  10:    </StackPanel.ToolTip>

  11:   </StackPanel>

  12:  </HierarchicalDataTemplate>

  13:  </TreeView.ItemTemplate>

  14:  </TreeView>

　　在這里我定義了一個簡單的TreeView，每個節點對應的DataType是PropertyNodeItem（稍后，我會給出它的定義），每個節點的內容包括：

• ICON：每個節點的首先會顯示一個ICON
• DisplayName：每個節點上的文字（這里的文字僅顯示一個大概內容，詳細內容會在ToolTip中顯示）
• Editable ICON：如果一個節點是可以編輯的，我會在節點后面再顯示一個Edit ICON
• ToolTip：當鼠標移動到上面時會顯示，寬度200PX，自動換行。

　　TreeView的Model

　　這里就是剛才說講到的PropertyNodeItem的定義

   1:     internal class PropertyNodeItem

   2:      {

   3:          public string Icon { get; set; }

   4:          public string EditIcon { get; set; }

   5:          public string DisplayName { get; set; }

   6:          public string Name { get; set; }

   7:                  

   8:          public List<PropertyNodeItem> Children { get; set; }

   9:          public PropertyNodeItem()

  10:          {

  11:              Children = new List<PropertyNodeItem>();

  12:          }      

  13:      }

　　其中Children里面保存的是子節點。在剛才的View里面，我們把HierarchicalDataTemplate的ItemSource定義為PropertyNodeItem的Children熟悉，這樣只要Children不為空，TreeView就會繼續渲染Children中的對象，并且遞歸下去。

　　TreeView的Controller

　　這里的Controller，我寫在xaml.cs里面：

   1:      private void ShowTreeView()

   2:      {

   3:          List<PropertyNodeItem> itemList = new List<PropertyNodeItem>();

   4:          PropertyNodeItem node1 = new PropertyNodeItem()

   5:          {

   6:              DisplayName = "Node No.1",

   7:              Name = "This is the discription of Node1. This is a folder.",

   8:              Icon = FOLDER_ICON,

   9:          };

  10:   

  11:          PropertyNodeItem node1tag1 = new PropertyNodeItem()

  12:          {

  13:              DisplayName = "Tag No.1",

  14:              Name = "This is the discription of Tag 1. This is a tag.",

  15:              Icon = TAG_ICON,

  16:              EditIcon = EDITABLE_ICON

  17:          };

  18:          node1.Children.Add(node1tag1);

  19:   

  20:          PropertyNodeItem node1tag2 = new PropertyNodeItem()

  21:          {

  22:              DisplayName = "Tag No.2",

  23:              Name = "This is the discription of Tag 2. This is a tag.",

  24:              Icon = TAG_ICON,

  25:              EditIcon = EDITABLE_ICON

  26:          };

  27:          node1.Children.Add(node1tag2);

  28:          itemList.Add(node1);

  29:   

  30:          PropertyNodeItem node2 = new PropertyNodeItem()

  31:          {

  32:              DisplayName = "Node No.2",

  33:              Name = "This is the discription of Node 2. This is a folder.",

  34:              Icon = FOLDER_ICON,

  35:          };

  36:   

  37:          PropertyNodeItem node2tag3 = new PropertyNodeItem()

  38:          {

  39:              DisplayName = "Tag No.3",

  40:              Name = "This is the discription of Tag 3. This is a tag.",

  41:              Icon = TAG_ICON,

  42:              EditIcon = EDITABLE_ICON

  43:          };

  44:          node2.Children.Add(node2tag3);

  45:   

  46:          PropertyNodeItem node2tag4 = new PropertyNodeItem()

  47:          {

  48:              DisplayName = "Tag No.4",

  49:              Name = "This is the discription of Tag 4. This is a tag.",

  50:              Icon = TAG_ICON,

  51:              EditIcon = EDITABLE_ICON

  52:          };

  53:          node2.Children.Add(node2tag4);

  54:          itemList.Add(node2);

  55:   

  56:          this.tvProperties.ItemsSource = itemList;

  57:      }