当在wpf中应用样式时，用户控件内的组合框消失

我试图将样式应用于组合框，但不是应用组合框本身消失。 请检查以下用于用户控制的xaml代码。

<UserControl
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:Microsoft_Windows_Themes="clr-namespace:Microsoft.Windows.Themes;assembly=PresentationFramework.Luna" 
    x:Class="Guardian.PAS.PASFramework.UI.WPF.PASComboBox"
    xmlns:local="clr-namespace:Guardian.PAS.PASFramework.UI.WPF"
    Height="26" Width="100" VerticalAlignment="Center" >
    <UserControl.Resources>
        <Style x:Key="comboBoxStyle" TargetType="{x:Type local:PASCustomComboBox}">
            <Setter Property="Template">
                <Setter.Value>
                    <ControlTemplate TargetType="{x:Type local:PASCustomComboBox}">
                        <ControlTemplate.Triggers>
                            <Trigger Property="local:PASCustomComboBox.IsEnabled" Value="false">
                                <Setter Property="Background" Value="Red"/>
                            </Trigger>
                        </ControlTemplate.Triggers>
                    </ControlTemplate>
                </Setter.Value>
            </Setter>
        </Style>
    </UserControl.Resources>
    <Canvas Name="canvas" Height="23" Width="Auto" VerticalAlignment="Center">
        <Label Height="23" Name="lblCaption" Width="20" VerticalAlignment="Center">aaa</Label>
        <local:PASCustomComboBox Height="23" x:Name="cmbComboBoxControl" VerticalAlignment="Center"  Width="50" 
                  IsEditable="True"  Style="{StaticResource comboBoxStyle}">
            </local:PASCustomComboBox>
        <Button Height="23" Name="btnSearch" Width="25" Click="btnSearch_Click" Visibility="Collapsed" 
                VerticalAlignment="Center">...</Button>
        <Label Height="23" Name="lblDescription" VerticalAlignment="Center" Width="20" Foreground="Blue">

        </Label>

    </Canvas>
</UserControl>

这里PASCustomComboBox是一个从组合框继承的类。

public class PASCustomComboBox : ComboBox
{
    protected override void OnPreviewKeyDown(KeyEventArgs e)
    {
        if (e.Key == Key.Down || e.Key == Key.Up)
        {
            e.Handled = true;
            return;
        }

        base.OnPreviewKeyDown(e);
    }
}

---

问题在于你重新定义了ControlTemplate而没有任何可视化树：

<Style x:Key="comboBoxStyle" TargetType="{x:Type local:PASCustomComboBox}">
    <Setter Property="Template">
        <Setter.Value>
            <ControlTemplate TargetType="{x:Type local:PASCustomComboBox}">
                <ControlTemplate.Triggers>
                    <Trigger Property="local:PASCustomComboBox.IsEnabled" Value="false">
                        <Setter Property="Background" Value="Red"/>
                    </Trigger>
                </ControlTemplate.Triggers>
            </ControlTemplate>
        </Setter.Value>
    </Setter>
</Style>

你会想要风格上的触发器而不是控制模板：

<Style x:Key="comboBoxStyle" TargetType="{x:Type local:PASCustomComboBox}">
    <Style.Triggers>
        <Trigger Property="local:PASCustomComboBox.IsEnabled" Value="false">
            <Setter Property="Background" Value="Red"/>
        </Trigger>
    </Style.Triggers>
</Style>

---

你不要在你的风格的控件模板中指定任何视觉元素，只是一个触发器。 它将渲染空模板iirc。

更好地编辑样式中的ComboBox的Trigger集合以添加该触发器，并且您将保留默认的ControlTemplate。

链接地址: http://www.djcxy.com/p/34473.html

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