如何扩展而不是替代WPF样式 [英] How to extend instead of overriding WPF Styles

问题描述

我想在我的应用程序中使用自定义主题，据我所知，我可以通过使用资源字典并在App.xaml中引用它来完成此任务.样式将覆盖默认值，例如:

I want to use custom theme in my application and as far as I know I can accomplish this by using resource dictionary and referencing it in App.xaml. Styles would override the defaults like this:

<Style TargetType="{x:Type Label">
    <Setter Property="Foreground" Value="Green" />
</Style>

现在，因为我猜默认的标签样式被相同的值覆盖，但是我所有的标签字体均为绿色.当我想在某个地方重新设置标签样式时，问题就开始了.当我想像这样更改网格中的其他属性时

Now as I guess the default Label style is overriden with same values but all my label fonts are green. The problem starts when I want to style one label somewhere again. When I want to change some other property in my Grid like this

<Grid.Resources>
    <Style TargetType="{x:Type Label">
        <Setter Property="FontSize" Value="28" />
    </Style>
</Grid.Resources>

网格中的所有标签都失去了前景色，并再次具有默认值(我是否不能在上一步中覆盖默认值?).经过一番尝试后，我发现要正确执行此操作，我必须向Style声明BasedOn={StaticResource {x:Type Label}}"添加另一个属性，并且它可以工作.这对我来说很奇怪，因为现在我将不得不在整个应用程序中重复相同的BasedOn代码，而这不是样式设计的工作原理-应该自动完成！例如，在HTML + CSS样式中，样式被继承和合并，在WPF中，样式被替换...

All labels inside my grid are losing their foreground color and have default one again (didn't I override defaults in previous step?). After some tries I found out that to do this properly i have to add another property to Style declaration BasedOn={StaticResource {x:Type Label}}" and it works. This is kind of weird for me because now I will have to repeat same BasedOn code in whole app and this is not how styling works - this should be done automatically! For example in HTML + CSS styles are inherited and merged and in WPF they are replaced...

请注意，当我不使用任何样式控件时，控件仍然会从某种方式(系统主题?)中获得外观.我该如何告诉他们在其他地方查找默认值，因此在样式上没有任何其他代码的情况下，他们会认为默认情况下应该为绿色?

Notice that when I don't use any styles controls still get their look from somehwere (System Themes?). How can I tell them to look for defaults somewhere else so without any additional code on styles they will think that they should be green by default?

有什么方法可以自动设置BasedOn属性?还是有一个更好的整体方法?

Is there any way I can automate setting BasedOn property? Or maybe there is a better to do this overally?

推荐答案

我遇到了同样的问题.我使用了Zack的答案并对其进行了改进，如下所示，因此，如果您不指定样式，则仍会考虑覆盖的默认值.基本上这就是您要做的，但是在ResourceDictionary中只是一次.

I had the same problem. I used Zack's answer and improved it like following so if you don't specify a style the overridden default is still taken in account. It's basically what you would have done but just once in the ResourceDictionary.

<Window x:Class="TestWpf.RandomStuffWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    Title="Random Stuff Window">
  <Window.Resources>
    <ResourceDictionary>
      <!-- Default Label style definition -->
      <Style TargetType="{x:Type Label}">
        <Setter Property="Foreground" Value="Green" />
      </Style>
      <!-- Extending default style -->
      <Style TargetType="{x:Type Label}" 
             x:Key="LargeGreenForegroundLabel" 
             BasedOn="{StaticResource {x:Type Label}}">
        <Setter Property="FontSize" Value="28" />
      </Style>
    </ResourceDictionary>
  </Window.Resources>
  <StackPanel>
    <Button Click="Button_Click">Click</Button>
    <Label Content="GreenForegroundLabel" /> <!-- Uses default style -->
    <Label Style="{StaticResource LargeGreenForegroundLabel}" 
           Content="LargeGreenForegroundLabel" />
  </StackPanel>
</Window>

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