Silverlight甘特图：四、树形DataGrid开发原理

1. 语法

1.1. XAML

2. 备注

当前版本的TreeGrid仅可以使用甘特图控件指定数据源格式。如需支持其他类型数据源，需要重新实现AbstractExpander和AbstractTreeGridLayout。

2.1. 定义Expander样式

通过自定义AbstractExpander的集成类，并设置TreeGrid.ExpanderProvider，可实现Expander的自定义，从而更换逻辑或样式。

自定义类的实现可参考默认提供的Expander类：SimpleTaskExpander

 

TreeGrid是扩展Silverlight自身提供的DataGrid实现的，关键是自定义了新的Column类型，此Column在每一行的单元格中添加了一个按钮控件，根据任务的层级缩进，并在用户单击时，发起一个“展开/折叠”事件，事件EventArgs中包含行所对应的任务Item数据。

代码如下：

   1: namespace V2TEK.Silverlight.Charts.TreeGridHelper

   2: {

   3:     /// <summary>

   4:     /// 包含一个默认的Expander，继承自AbstractExpander。

   5:     /// 如有必要，可以通过继承AbstractExpander，复写Expander，并设置ExpanderProvider。

   6:     /// </summary>

   7:     public class TreeGridExpanderColumn : DataGridTextColumn

   8:     {

   9:         public TreeGridExpanderColumn()

  10:         {

  11:         }

  12:  

  13:         private AbstractExpander CreateExpander()

  14:         {

  15:             return Activator.CreateInstance(ExpanderProvider) as AbstractExpander;        

  16:         }

  17:  

  18:         public Type ExpanderProvider

  19:         {

  20:             get;

  21:             set;

  22:         }

  23:  

  24:         protected override FrameworkElement GenerateEditingElement(DataGridCell cell, object dataItem)

  25:         {

  26:             StackPanel panel = GeneratePanel(dataItem);

  27:             panel.Children.Add(base.GenerateEditingElement(cell, dataItem));

  28:             return panel;

  29:         }

  30:  

  31:         protected override FrameworkElement GenerateElement(DataGridCell cell, object dataItem)

  32:         {

  33:             StackPanel panel = GeneratePanel(dataItem);

  34:             panel.Children.Add(base.GenerateElement(cell, dataItem));

  35:             return panel;

  36:         }

  37:  

  38:         protected override object PrepareCellForEdit(FrameworkElement editingElement, RoutedEventArgs editingEventArgs)

  39:         {

  40:             TextBox ee = editingElement as TextBox;

  41:             if (ee == null)

  42:             {

  43:                 return string.Empty;

  44:             }

  45:             string text = ee.Text;

  46:             int length = text.Length;

  47:             KeyEventArgs args = editingEventArgs as KeyEventArgs;

  48:             if ((args != null) && (args.Key == Key.F2))

  49:             {

  50:                 ee.Select(length, length);

  51:                 return text;

  52:             }

  53:             ee.Select(0, length);

  54:  

  55:             return base.PrepareCellForEdit(editingElement, editingEventArgs);

  56:         }

  57:  

  58:         public AbstractExpander GetExpander(DataGridRow row)

  59:         {

  60:             StackPanel panel = (StackPanel)this.GetCellContent(row);

  61:             AbstractExpander expander = panel.Children[0] as AbstractExpander;

  62:             expander.Data = row.DataContext;

  63:             return expander;

  64:         }

  65:  

  66:         private StackPanel GeneratePanel(object dataItem)

  67:         {

  68:             StackPanel panel = new StackPanel();

  69:             panel.Orientation = Orientation.Horizontal;

  70:             panel.Children.Add(GenerateExpander(dataItem));

  71:             return panel;

  72:         }

  73:  

  74:         private AbstractExpander GenerateExpander(object dataItem)

  75:         {

  76:             AbstractExpander expander = CreateExpander();

  77:             expander.Data = dataItem;

  78:             expander.PropertyChanged += new System.ComponentModel.PropertyChangedEventHandler(expander_PropertyChanged);

  79:             return expander;

  80:         }

  81:  

  82:         void expander_PropertyChanged(object sender, System.ComponentModel.PropertyChangedEventArgs e)

  83:         {

  84:             if (e.PropertyName == AbstractExpander.DATA_PROPERTY)

  85:                 (sender as AbstractExpander).Update();

  86:         }

  87:     }

  88: }