Question

我想让用户在偏好中控制该文本框内的LineBreak元素，以启用/禁用它

<TextBlock Style="{StaticResource TextBlockStyle}" Width="130">
<TextBlock.Inlines>
    <Run Text="{Binding Path=Name}" FontWeight="Bold" Foreground="#FF2A4D9E" />
    <Run Text="{Binding Path=Price}" FontWeight="Bold" />

       <LineBreak  />

    <Run Text="{Binding Path=Quantity}" Foreground="#99000000" />
</TextBlock.Inlines>
</TextBlock>

Answer 1

我不相信FlowDocument中有任何方法可以使LineBreak没有真正中断，除非将其取出。您可以选择切换到使用WPF布局或使用附加属性在LineBreak和空Run之间切换。

使用WPF布局

您可以考虑使用WPF布局。像这样：

<DataTemplate x:Key="Layout1">
  <DockPanel>
    <TextBlock Text="{Binding Name}" FontWeight="Bold" Foreground="#FF2A4D9E" />
    <TextBlock Text="{Binding Price}" FontWeight="Bold" />
    <TextBlock Text="{Binding Quantity}" Foreground="#99000000" />
  </DockPanel>
</DataTemplate>

<DataTemplate x:Key="Layout2">
  <DockPanel>
    <DockPanel DockPanel.Dock="Top">
      <TextBlock Text="{Binding Name}" FontWeight="Bold" Foreground="#FF2A4D9E" />
      <TextBlock Text="{Binding Price}" FontWeight="Bold" />
    </DockPanel>

    <TextBlock Text="{Binding Quantity}" Foreground="#99000000" />
  </DockPanel>
</DataTemplate>

现在，只需切换DataTemplates即可轻松切换布局。

使用绑定自动删除LineBreaks

如果你想通过绑定“隐藏”LineBreak，你可以使用附加的“BecomeLineBreak”属性来执行它，当应用于空的Run并设置为true时，将其删除并用LineBreak替换它。

像魔术一样，你现在有能力写作：

<Run my:LineBreakSwitcher.BecomeLineBreak="{Binding SomeCondition}" />

只要SomeCondition属性为true，您的Run就会变成LineBreak。

以下是代码：

public class LineBreakSwitcher : DependencyObject
{
  public static bool GetBecomeLineBreak(DependencyObject obj) { return (bool)obj.GetValue(BecomeLineBreakProperty); }
  public static void SetBecomeLineBreak(DependencyObject obj, bool value) { obj.SetValue(BecomeLineBreakProperty, value); }
  public static readonly DependencyProperty BecomeLineBreakProperty = DependencyProperty.RegisterAttached("BecomeLineBreak", typeof(bool), typeof(LineBreakSwitcher), new PropertyMetadata
  {
    PropertyChangedCallback = (obj, e) =>
      {
        var oldElement = (Inline)obj;
        var newElement = (bool)e.NewValue ? (Inline)new LineBreak() : new Run();
        newElement.SetBinding(BecomeLineBreakProperty, oldElement.GetBindingExpression(BecomeLineBreakProperty).ParentBindingBase);

        var parent = (Paragraph)oldElement.Parent;
        parent.Inlines.InsertBefore(oldElement, newElement);
        parent.Inlines.Remove(oldElement);
      }
  });

工作原理：当一个Run上的BecomeLineBreak变为true时，会创建一个新的LineBreak，复制BecomeLineBreak绑定，在Run之前插入LineBreak，然后删除Run。当BecomeLineBreak变为false时，将创建一个新的Run并且整个过程反过来。

Answer 2

这就是你想要的（100％XAML）：

<TextBlock Text="{Binding Text, ElementName=MyContainer}" 
            FontWeight="Bold" FontSize="14" Name="TextBlockA" />
<TextBlock Name="TextBlockB">
    <TextBlock.Style>
        <Style>
            <Setter Property="TextBlock.Visibility" Value="Visible"/> 
            <Style.Triggers> 
                <DataTrigger Binding="{Binding Path=Text.Length, 
                        ElementName=TextBlockC}" Value="0"> 
                    <Setter Property="TextBlock.Visibility" Value="Collapsed"/> 
                </DataTrigger> 
            </Style.Triggers> 
        </Style>
    </TextBlock.Style>
    <LineBreak />
</TextBlock>
<TextBlock Text="{Binding SubText, ElementName=MyContainer}" 
            FontWeight="Normal" FontSize="12" Name="TextBlockC" />

WPF：LineBreak动态启用/禁用

2 个答案: