c# - WPF TextBox 在焦点上更改颜色

Question

我尝试在获得焦点时更改输入框的颜色。

首先我声明输入按钮:

<TextBox x:Name="usernameTextBox"
         HorizontalAlignment="Left"
         Height="23" 
         Margin="115,31,0,0"
         TextWrapping="Wrap"
         VerticalAlignment="Top"
         Width="277"
         GotFocus="usernameTextBox_GotFocus"/>

下面我尝试为该文本框添加样式

<Style x:Key="usernameTextBox"
       TargetType="{x:Type TextBox}">
      <Style.Triggers>
          <Trigger Property="IsFocused"
                   Value="true">
               <Setter Property="Background"
                       Value="{StaticResource OnMouseOverColor}" />
         </Trigger>
    </Style.Triggers>
</Style>

错误:

Error 1 A value of type 'Style' cannot be added to a collection or dictionary of type 'UIElementCollection'. D:\VS\VIM\VIM_WPF\login.xaml 15 9 VIM_Wpf

任何其他解决方案如何解决这个问题？

Answer 1

要么将样式定义为资源(​​例如在用户控件/窗口的资源中)，然后执行类似的操作

<TextBox Style="{StaticResource theKeyOfYourStyle}" ..../>

或者您在文本框中明确设置它:

<TextBox x:Name="usernameTextBox" HorizontalAlignment="Left" Height="23" Margin="115,31,0,0" TextWrapping="Wrap" VerticalAlignment="Top" Width="277" GotFocus="usernameTextBox_GotFocus">
  <TextBox.Style>
    <Style TargetType="{x:Type TextBox}">
       <Style.Triggers>
         <Trigger Property="IsFocused" Value="true">
           <Setter Property="Background" Value="{StaticResource OnMouseOverColor}" />
         </Trigger>
       </Style.Triggers>
     </Style>
   </TextBox.Style>
</TextBox>