WPF's Style BasedOn

<Style x:Key="BasedStyle" BasedOn="{x:Null}" TargetType="{x:Type Control}">
    <Setter Property="FontFamily" Value="Microsoft YaHei" />
    <Setter Property="FontSize" Value="12" />
    <Setter Property="Foreground" Value="White" />
    <Setter Property="FocusVisualStyle" Value="{x:Null}" />
</Style>

<!--引用 BasedStyle-->
<ResourceDictionary.MergedDictionaries>
    <ResourceDictionary Source="BasedStyle.xaml" />
</ResourceDictionary.MergedDictionaries>

<!--示例控件Style Based代码 以下示例为Button-->
<Style x:Key="ButtonBaseBaseStyle" BasedOn="{StaticResource BasedStyle}" TargetType="{x:Type ButtonBase}">
    <Setter Property="Height" Value="45" />
        <Setter Property="Foreground" Value="{DynamicResource ButtonText}" />
    <Setter Property="Padding" Value="0" />
    <Setter Property="Margin" Value="0" />
    <Setter Property="BorderThickness" Value="1" />
    <Setter Property="HorizontalAlignment" Value="Center" />
    <Setter Property="VerticalAlignment" Value="Center" />
    <Setter Property="HorizontalContentAlignment" Value="Center" />
    <Setter Property="VerticalContentAlignment" Value="Center" />
</Style>

    <Style x:Key="ButtonBaseStyle" BasedOn="{StaticResource ButtonBaseBaseStyle}" TargetType="{x:Type Button}">
        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate TargetType="{x:Type Button}">
                    <Grid>
                        <Border x:Name="border" Padding="{TemplateBinding Padding}" Background="{TemplateBinding Background}" BorderBrush="{TemplateBinding BorderBrush}" BorderThickness="{TemplateBinding BorderThickness}" />
                        <ContentPresenter Margin="0" HorizontalAlignment="Center" VerticalAlignment="Center" RecognizesAccessKey="true" />

                        <Rectangle x:Name="EnabledLayer" Fill="#4CFFFFFF" Visibility="Collapsed" />
                    </Grid>
                    <ControlTemplate.Triggers>
                        <Trigger Property="IsMouseOver" Value="true">
                            <Setter Property="Background" Value="{DynamicResource ButtonBackgroundHover}" />
                        </Trigger>
                        <Trigger Property="IsPressed" Value="true">
                            <Setter Property="Background" Value="{StaticResource ButtonBackgroundPressed}" />
                        </Trigger>
                        <Trigger Property="IsEnabled" Value="false">
                            <Setter TargetName="EnabledLayer" Property="Visibility" Value="Visible" />
                        </Trigger>
                    </ControlTemplate.Triggers>
                </ControlTemplate>
            </Setter.Value>
        </Setter>
    </Style>

<!--示例控件扩展 Style-->
<Style x:Key="Success" BasedOn="{StaticResource ButtonBaseStyle}" TargetType="{x:Type Button}">
        <Setter Property="Background" Value="{DynamicResource ButtonBackground-Success}" />
        <Setter Property="BorderBrush" Value="{DynamicResource ButtonBorder-Success}" />
        <Style.Triggers>
            <Trigger Property="IsMouseOver" Value="true">
                <Setter Property="Background" Value="#449d44" />
                <Setter Property="BorderBrush" Value="#398439" />
            </Trigger>
        </Style.Triggers>
    </Style>

引用

https://msdn.microsoft.com/zh-cn/library/system.windows.style.basedon(v=vs.110).aspx

https://github.com/ptddqr/bootstrap-wpf-style

总结

使用BasedOn的主要原因是涉及同类控件扩展多，例如不同颜色。

再来就是为了统一基础样式，例如字体大小、样式、颜色，外边框以及水平垂直对称的方式。