Question

我有一个名为SignalViewModel的类，它实现了INotifyPropertyChanged，我绑定到了SignalGraph类中我的xaml中的属性，但是这个更改没有传播。我尝试绑定的CLR属性称为BaseNotation。它的枚举定义如下：

  public enum BaseNotation
  {
    Hex,
    SignedDecimal,
    UnsignedDecimal,
    SignaedBinary,
    UnsignedBinary
  }

类和相关的源属性

class SignalViewModel : INotifyPropertyChanged
{
    private BaseNotation _BaseRepresentation = BaseNotation.Hex;
        public BaseNotation BaseRepresentation
        {
          get
          {
            return _BaseRepresentation;
          }
          set
          {
            if (value != _BaseRepresentation)
            {
              _BaseRepresentation = (BaseNotation)value;
              OnPropertyChanged("BaseRepresentation");
            }
          }
        }

目标属性是：

 public BaseNotation BaseRepresentation
    {
      get
      {
        return (BaseNotation)GetValue(BaseRepresentationProperty);
      }
      set
      {
        SetValue(BaseRepresentationProperty, value);
      }
    }
    public static readonly DependencyProperty BaseRepresentationProperty =
      DependencyProperty.Register("BaseRepresentation",
      typeof(BaseNotation), typeof(SignalGraph),
      new FrameworkPropertyMetadata(BaseNotation.Hex, new PropertyChangedCallback(ReDraw)));

Binding是树视图的itemtemplate中的对象。

        >
        <!--Defines panel used by treeview to place items in itemspresenter-->
        <TreeView.ItemsPanel>
          <ItemsPanelTemplate>
            <VirtualizingStackPanel />
          </ItemsPanelTemplate>
        </TreeView.ItemsPanel>


        <!--Template Defining the layout of items in this treeview-->
        <TreeView.ItemTemplate >
          <HierarchicalDataTemplate ItemsSource ="{Binding Path = bits}">
            <Components:SignalGraph 
              x:Name="signal_graph"
              IsSignal="True"
              BaseRepresentation="{Binding Path=BaseRepresentation, Mode=TwoWay}"
              PenWidth="{Binding ElementName=graph_viewer, Path=GraphPenWidth, Mode=OneWay}"
              BusTextColor="{Binding ElementName=graph_viewer, Path=BusTextPenColor, Mode=TwoWay}"
              HighValuePenColor="{Binding ElementName=graph_viewer, Path=HighValuePenColor, Mode=TwoWay}"
              LowValuePenColor="{Binding ElementName=graph_viewer, Path=LowValuePenColor, Mode=TwoWay}"
              UnknownValuePenColor="{Binding ElementName=graph_viewer, Path=UnknownValuePenColor, Mode=TwoWay}"
              Height="{Binding ElementName=graph_viewer, Path=GraphHeight, Mode=OneWay}"
              VerticalAlignment="Stretch"
              Signal="{Binding}" 
              MaxTimeValue="{Binding ElementName=graph_viewer, Path = _SignalDataViewModel.MaxTimeValue}"
              AxisDivisionUnit="{Binding ElementName=graph_viewer, Path = AxisDivisionUnit}"
              MinimumXInDIPs="{Binding ElementName=signal_scrollviewer, Path=HorizontalOffset}"
              ViewportWidth="{Binding ElementName=signal_scrollviewer, Path=ViewportWidth}"
              />
            <HierarchicalDataTemplate.ItemTemplate>
              <DataTemplate>
                <Components:SignalGraph 
                  x:Name="bit_graph"
                  IsSignal="False" 
                  Height="{Binding ElementName=graph_viewer, Path=GraphHeight, Mode=OneWay}"
                  VerticalAlignment="Stretch"
                  BusTextColor="{Binding ElementName=graph_viewer, Path=BusTextPenColor, Mode=TwoWay}"
                  HighValuePenColor="{Binding ElementName=graph_viewer, Path=HighValuePenColor, Mode=TwoWay}"
                  LowValuePenColor="{Binding ElementName=graph_viewer, Path=LowValuePenColor, Mode=TwoWay}"
                  UnknownValuePenColor="{Binding ElementName=graph_viewer, Path=UnknownValuePenColor, Mode=TwoWay}"
                  PenWidth="{Binding ElementName=graph_viewer, Path=GraphPenWidth, Mode=OneWay}"
                  Bit="{Binding}"
                  MaxTimeValue="{Binding RelativeSource = {RelativeSource AncestorType={x:Type DaedalusGraphViewer:GraphViewer}}, Path = _SignalDataViewModel.MaxTimeValue}"
                  AxisDivisionUnit="{Binding ElementName=graph_viewer, Path = AxisDivisionUnit}"
                  MinimumXInDIPs="{Binding ElementName=signal_scrollviewer, Path=HorizontalOffset}"
                  ViewportWidth="{Binding ElementName=signal_scrollviewer, Path=ViewportWidth}"
                  />
              </DataTemplate>
            </HierarchicalDataTemplate.ItemTemplate>
          </HierarchicalDataTemplate>
        </TreeView.ItemTemplate>
      </TreeView>

我检查了调试器中signalgraph的datacontext，并将其正确设置为signalviewmodel。我的输出没有任何绑定错误。另外，如果我在SignalViewModel类中放置一个断点，我可以看到正在引发OnPropertyChanged事件。

但是，检查时目标属性没有变化。当我在滚动时打破信号图内部时，我可以检查并看到datacontext的（signalviewmodel的）BaseRepresentation已更改为BaseNotation.UnsignedDecimal。但是，SignalGraph中的依赖项属性BaseRepresentation尚未更新为新值。为什么绑定不起作用？

Answer 1

尝试

{Binding Path=BaseRepresentation, Mode=TwoWay}

有关数据绑定模式的更多信息：http://msdn.microsoft.com/en-us/library/ms752347.aspx（读取“数据流的方向”）。

Answer 2

该死的。我无法相信这是一个如此简单的错误。我之前也没有想过就完成了这个，但我已经忘记了它，因为它已经有一段时间了。永远不要在构造函数或其他地方手动将属性设置为值，否则会破坏绑定

wpf如何更新可观察集合中枚举属性更改的绑定？

2 个答案: