WPF崩VS重新绑定

Question

我有如下因素代码，我能够重构：

<HierarchicalDataTemplate DataType = "{x:Type data:FieldMapping}" 
          ItemsSource = "{Binding Path=FieldMappingItems}"> 
    <Grid Name="MainGrid" > 
     <Grid.ToolTip > 
      <TextBlock Name="Tt" Text="{Binding Path=ToolTip}"/> 
     </Grid.ToolTip> 
     <Grid.ColumnDefinitions > 
      <ColumnDefinition Width="Auto"/> 
      <ColumnDefinition Width="Auto"/> 
      <ColumnDefinition Width="Auto"/> 
      <ColumnDefinition Width="*"/> 
     </Grid.ColumnDefinitions> 
     <TextBlock Name="Error" Margin="0,0,5,0" TextElement.FontWeight="Bold" TextElement.Foreground="Red" Visibility="Collapsed" Text="!"/> 
     <StackPanel Grid.Column="1" > 
      <Image Source="../../icons\column.png" Name="Image"/> 
      <Image Source="../../icons\Connect.png" Name="SourceImage" Visibility="Collapsed"/> 
      <Image Source="../../icons\Service.png" Name="AttritubeImage" Visibility="Collapsed"/> 
      <Image Source="../../icons\table.png" Name="SearchImage" Visibility="Collapsed"/> 
      <Image Source="../../icons\surrogateKey.png" Name="TargetImage" Visibility="Collapsed"/> 
      <Image Source="../../icons\Key16.png" Name="PrimayKeyImage" Visibility="Collapsed"/> 
      <Image Source="../../icons\tempTable.png" Name="TempTableImage" Visibility="Collapsed"/> 
      <Image Source="../../icons\Component16.png" Name="SPImage" Visibility="Collapsed"/> 
      <Image Source="../../icons\DatabaseSelectCellSecure16.png" Name="RootImage" Visibility="Collapsed"/> 
      <Image Source="../../icons\Console16.png" Name="ScriptImage" Visibility="Collapsed"/> 
      <Image Source="../../icons\CodeWindowSelect16.png" Name="ProgramImage" Visibility="Collapsed"/> 

     </StackPanel> 
     <TextBlock Name="tb" Margin="2,0,0,0" Grid.Column="2" Text="{Binding Path=FieldName}"/> 
     <TextBlock Name="tbSource" Margin="2,0,0,0" Visibility="Collapsed" Grid.Column="2" Text="{Binding Path=FullNodePath}"/> 
    </Grid> 
    <DataTemplate.Triggers>    
     <MultiDataTrigger > 
      <MultiDataTrigger.Conditions> 
       <Condition Binding="{Binding Path=Published}" Value="False"/> 
       <Condition Binding="{Binding Path=FieldMappingType}" Value="TempTable"/> 
      </MultiDataTrigger.Conditions> 
      <Setter TargetName="tb" Property="FontStyle" Value="Italic"/> 
     </MultiDataTrigger> 
     <DataTrigger Binding="{Binding Path=Active}" Value="False"> 
      <Setter TargetName="MainGrid" Property="Opacity" Value="0.5"/> 
     </DataTrigger> 
     <DataTrigger Binding="{Binding Path=IsPrimaryKey}" Value="True"> 
      <Setter TargetName="tb" Property="Margin" Value="4,0,0,0"/> 
      <Setter TargetName="Image" Property="Visibility" Value="Collapsed"/> 
      <Setter TargetName="PrimayKeyImage" Property="Visibility" Value="Visible"/> 
      <Setter TargetName="SourceImage" Property="Visibility" Value="Collapsed"/> 
      <Setter TargetName="TargetImage" Property="Visibility" Value="Collapsed"/> 
      <Setter TargetName="RootImage" Property="Visibility" Value="Collapsed"/> 
     </DataTrigger> 
     <DataTrigger Binding="{Binding Path=FieldMappingType}" Value="Table"> 
      <Setter TargetName="tb" Property="Margin" Value="4,0,0,0"/> 
      <Setter TargetName="Image" Property="Visibility" Value="Collapsed"/> 
      <Setter TargetName="SourceImage" Property="Visibility" Value="Collapsed"/> 
      <Setter TargetName="PrimayKeyImage" Property="Visibility" Value="Collapsed"/> 
      <Setter TargetName="TargetImage" Property="Visibility" Value="Visible"/> 
      <Setter TargetName="RootImage" Property="Visibility" Value="Collapsed"/> 
     </DataTrigger> 
     <DataTrigger Binding="{Binding Path=FieldMappingType}" Value="TempTable"> 
      <Setter TargetName="tb" Property="Margin" Value="4,0,0,0"/> 
      <Setter TargetName="Image" Property="Visibility" Value="Collapsed"/> 
      <Setter TargetName="SourceImage" Property="Visibility" Value="Collapsed"/> 
      <Setter TargetName="PrimayKeyImage" Property="Visibility" Value="Collapsed"/> 
      <Setter TargetName="TempTableImage" Property="Visibility" Value="Visible"/> 
      <Setter TargetName="RootImage" Property="Visibility" Value="Collapsed"/> 
      <!--<Setter TargetName="tb" Property="Margin" Value="15,0,0,0"/>--> 
     </DataTrigger> 
</HierarchicalDataTemplate> 

正如你可以看到有大量的图片被倒塌后，根据不同的类型的对象，显示期望的图像。

我明白，这是一个烂摊子，我在下面的方式重构它：

<Grid Name="MainGrid"> 
       <Grid.ToolTip> 
        <TextBlock Name="Tt" Text="{Binding Path=ToolTip}" /> 
       </Grid.ToolTip> 

       <StackPanel Orientation="Horizontal"> 
        <TextBlock x:Name="Error" Margin="0,0,5,0" TextElement.FontWeight="Bold" TextElement.Foreground="Red" Visibility="{Binding Path=Warning, Converter={StaticResource BooleanToVisibility}}" Text="!"/> 
        <Image x:Name="Icon" Source="../../icons\column.png" /> 
        <TextBlock x:Name="tb" Margin="2,0,0,0" Text="{Binding Path=FieldName}" /> 
       </StackPanel> 

      </Grid> 
      <DataTemplate.Triggers> 

       <MultiDataTrigger> 
        <MultiDataTrigger.Conditions> 
         <Condition Binding="{Binding Path=Published}" Value="False" /> 
         <Condition Binding="{Binding Path=FieldMappingType}" Value="TempTable" /> 
        </MultiDataTrigger.Conditions> 
        <Setter TargetName="tb" Property="FontStyle" Value="Italic" /> 
       </MultiDataTrigger> 

       <DataTrigger Binding="{Binding Path=Active}" Value="False"> 
        <Setter TargetName="MainGrid" Property="Opacity" Value="0.5" /> 
       </DataTrigger> 

       <DataTrigger Binding="{Binding Path=IsPrimaryKey}" Value="True"> 
        <Setter TargetName="tb" Property="Margin" Value="4,0,0,0" /> 
        <Setter TargetName="Icon" Property="Source" Value="../../Icons/Key16.png" /> 
       </DataTrigger> 

       <DataTrigger Binding="{Binding Path=FieldMappingType}" Value="TempTable"> 
        <Setter TargetName="tb" Property="Margin" Value="4,0,0,0" /> 
        <Setter TargetName="Icon" Property="Source" Value="../../Icons/tempTable.png" /> 
       </DataTrigger> 

虽然我的重构是更容易消化，更succint，我在想，如果我通过改变获得更好的性能绑定单个图像而不是切换多个图像的可视性。

Answer 1

它总是更高效地折叠/显示，而不是更改绑定。如果应用程序真的在速度上挣扎，这是一个简单的胜利。

原因是，当绑定被改变时，幕后的WPF必须重新生成整个可视化树。这很慢。如果WPF正在折叠/显示可视化树的部分内容，那么它会进行一些有效的优化，从而使此操作变得非常快速。讽刺的是，更改绑定直观地吸引了程序员，而C＃通常更易于阅读和更优雅。

更新

此规则仅适用于销毁/创建巨大的可视树。如果您的应用程序速度慢，那么将其视为优化，否则应避免将其编程为更多工作​​。