wpf 设置内容控件背景
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Setting background of content control
提问by Goran
<UserControl .....>
<DataTemplate DataType="{x:Type vm:AViewModel}">
<vw:AView />
</DataTemplate>
<DataTemplate DataType="{x:Type vm:BViewModel}">
<vw:BView />
</DataTemplate>
<ContentControl x:Name="chartScreen" Content="{Binding Screen}" Background="Yellow" />
</UserControl>
As you can see from above code, ContentControl is setting its content through binding to ViewModel's Screen property. Screen property will return an instance of AViewModel or BViewModel, depending on some condition. The problem is, when UserControl is loaded on screen, Screen property is null, so there is no content set yet. At this point, I would like to set some background for the ContentControl, but I cannot find a way how to do this? Background="Yellow" does nothing...
从上面的代码可以看出，ContentControl 通过绑定到 ViewModel 的 Screen 属性来设置其内容。Screen 属性将返回 AViewModel 或 BViewModel 的实例，具体取决于某些条件。问题是，当 UserControl 加载到屏幕上时，Screen 属性为 null，因此还没有设置内容。在这一点上，我想为 ContentControl 设置一些背景，但我找不到如何做到这一点？背景 =“黄色”什么都不做......
Any ideas how to set the background of ContentControl? This backgound should be applied always, even when content is displaying AView or Biew, or null.
任何想法如何设置 ContentControl 的背景？即使内容显示 AView 或 Biew 或 null，也应始终应用此背景。
采纳答案by Viv
Just wrap your ContentControlin a Border
把你的包裹ContentControl在一个Border
<Border Background="Yellow">
<ContentControl x:Name="chartScreen"
Content="{Binding Screen}" />
</Border>
If all you have in your UserControlis your ContentControl, just set the Backgroundon the UserControlitself. That would remove the extra Borderas well.
如果你在有你的UserControl就是你的ContentControl，只是在设置Background上UserControl本身。这也将删除额外的Border。
回答by eran otzap
try something like this :
尝试这样的事情：
<ContentControl x:Name="chartScreen" Content="{Binding Screen}" Background="Yellow">
<ContentControl.Triggers>
<Trigger Property="Content" Value="{x:Null}">
<Trigger.Value>
<Border Background="Yellow"/>
</Trigger.Value>
</Trigger>
</ContentControl.Triggers>
</ContentControl>
回答by juFo
try something like this in WPF:
在 WPF 中尝试这样的事情：
<ContentControl>
<ContentControl.Style>
<Style TargetType="ContentControl">
<Style.Triggers>
<DataTrigger Binding="{Binding Content}" Value="{x:Null}">
<Setter Property="Content">
<Setter.Value>
<Rectangle Width="100" Height="100" Fill="Blue" />
</Setter.Value>
</Setter>
</DataTrigger>
</Style.Triggers>
</Style>
</ContentControl.Style>
</ContentControl>
