WPF ControlTemplate:如何为TemplateBinding提供默认值? [英] WPF ControlTemplate: How to provide a default value for TemplateBinding?

问题描述

我正在编写一个WPF控件，该控件将Button子类化.然后，我在Themes \ generic.xaml中提供一个默认样式，如下所示(简化):

I am writing a WPF control that subclasses a Button. I then provide a default style in Themes\generic.xaml, that looks like this (simplified):

<Style TargetType="{x:Type WPFControls:MyButton}">
    <Setter Property="Template">
        <Setter.Value>
            <ControlTemplate TargetType="{x:Type WPFControls:MyButton}">
                <Button 
                    x:Name="PART_Button"
                    Background="{TemplateBinding Background}"
                    BorderBrush="{TemplateBinding BorderBrush}"
                    />
            </ControlTemplate>
        </Setter.Value>
    </Setter>
</Style>

我希望用户有机会更改控件的背景，但是如果他没有，我想提供默认值.我该怎么办?

I would like the user to have the opportunity to change the control's background, but if he doesn't, I'd like to provide default value. How do I do it?

当我像在发布的代码中那样执行操作时，除非用户明确指定它们(实际上迫使用户始终提供一些值)，否则Background和BorderBrush为null(=不存在)，但是标准的Windows控件(如Button)提供了默认外观，仍可以由用户自定义.如何在我的控制下做到这一点?

When I do it like in the posted code, the Background and BorderBrush is null (= nonexistent) unless user explicitly specifies them (which effectively forces user to always provide some value), but the standard windows controls (like Button) provide a default look, that can still be customized by user. How to do this in my control?

谢谢！

迈克尔·莫顿(Michael Morton)的解决方案:

您可以在样式中提供默认值作为设置器:

You can provide defaults as setters in style:

<Style TargetType="{x:Type TestTemplate:MyButton}">
    <Setter Property="Background" Value="Red" />
    <Setter Property="Template">
        <Setter.Value>
            <ControlTemplate TargetType="{x:Type TestTemplate:MyButton}">
                <Button 
                    x:Name="PART_Button"
                    IsEnabled="{TemplateBinding IsEnabled}"
                    Content="{TemplateBinding Content}"
                    Background="{TemplateBinding Background}"
                    />
            </ControlTemplate>
        </Setter.Value>
    </Setter>
</Style>

用法:

<StackPanel>
    <TestTemplate:MyButton Background="Blue">Explicitly blue</TestTemplate:MyButton>
    <TestTemplate:MyButton>Naturally red</TestTemplate:MyButton>
</StackPanel>

推荐答案

您可以在样式中为所讨论的两个属性定义设置器.

You can just define setters on your style for the two properties in question.

例如，一些通用定义:

<LinearGradientBrush x:Key="ButtonNormalBackground" EndPoint="0,1" StartPoint="0,0">
    <GradientStop Color="#F3F3F3" Offset="0"/>
    <GradientStop Color="#EBEBEB" Offset="0.5"/>
    <GradientStop Color="#DDDDDD" Offset="0.5"/>
    <GradientStop Color="#CDCDCD" Offset="1"/>
</LinearGradientBrush>

<SolidColorBrush x:Key="ButtonNormalBorder" Color="#FF707070"/>

然后，在您的样式定义中:

Then, in your style definition:

<Setter Property="Background" Value="{StaticResource ButtonNormalBackground}" />
<Setter Property="BorderBrush" Value="{StaticResource ButtonNormalBorder}" />

这篇关于WPF ControlTemplate:如何为TemplateBinding提供默认值?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！