I'm studying source code of MaterialDesignToolKit(WPF),and now focosing on Ripple Effect. I found that Ripple Effect is come from Button's custom style(as you can see below). But in Button's ControlTemplate,I don't see any ContenPresenter. Instead,there's a AdornerDecorator.
As I know,Button is ContentControl,if you provide it a new Template,you should put ContentPresenter somewhere.But here,it didn't.
I don't know why, Please help me.Thanks.
<Style x:Key="MaterialDesignRaisedButton" TargetType="{x:Type ButtonBase}">
<Setter Property="FocusVisualStyle" Value="{StaticResource FocusVisual}" />
<Setter Property="Background" Value="{DynamicResource PrimaryHueMidBrush}" />
<Setter Property="BorderBrush" Value="{DynamicResource PrimaryHueMidBrush}" />
<Setter Property="Foreground" Value="{DynamicResource PrimaryHueMidForegroundBrush}" />
<Setter Property="wpf:RippleAssist.Feedback" Value="White" />
<Setter Property="Cursor" Value="Hand" />
<Setter Property="wpf:ShadowAssist.ShadowDepth" Value="Depth1" />
<Setter Property="TextBlock.FontWeight" Value="Medium" />
<Setter Property="TextBlock.FontSize" Value="14" />
<Setter Property="BorderThickness" Value="1" />
<Setter Property="HorizontalContentAlignment" Value="Center" />
<Setter Property="VerticalContentAlignment" Value="Center" />
<Setter Property="Padding" Value="16,4,16,4" />
<Setter Property="Height" Value="32" />
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type ButtonBase}">
<Grid>
<AdornerDecorator CacheMode="{Binding RelativeSource={RelativeSource Self}, Path=(wpf:ShadowAssist.CacheMode)}">
<Grid>
<Border
x:Name="border"
Background="{TemplateBinding Background}"
BorderBrush="{TemplateBinding BorderBrush}"
BorderThickness="{TemplateBinding BorderThickness}"
CornerRadius="2"
Effect="{Binding RelativeSource={RelativeSource TemplatedParent}, Path=(wpf:ShadowAssist.ShadowDepth), Converter={x:Static converters:ShadowConverter.Instance}}" />
<Border
HorizontalAlignment="Left"
Background="{DynamicResource MaterialDesignBackground}"
Opacity=".4">
<Border.Width>
<MultiBinding Converter="{StaticResource RangeLengthConverter}">
<Binding Path="(wpf:ButtonProgressAssist.Minimum)" RelativeSource="{RelativeSource TemplatedParent}" />
<Binding Path="(wpf:ButtonProgressAssist.Maximum)" RelativeSource="{RelativeSource TemplatedParent}" />
<Binding Path="(wpf:ButtonProgressAssist.Value)" RelativeSource="{RelativeSource TemplatedParent}" />
<Binding Path="ActualWidth" RelativeSource="{RelativeSource FindAncestor, AncestorType={x:Type ButtonBase}}" />
</MultiBinding>
</Border.Width>
</Border>
</Grid>
</AdornerDecorator>
<wpf:Ripple
Padding="{TemplateBinding Padding}"
HorizontalContentAlignment="{TemplateBinding HorizontalContentAlignment}"
VerticalContentAlignment="{TemplateBinding VerticalContentAlignment}"
Content="{TemplateBinding Content}"
ContentTemplate="{TemplateBinding ContentTemplate}"
Focusable="False"
SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" />
</Grid>
<ControlTemplate.Triggers>
<Trigger Property="IsMouseOver" Value="true">
<Setter TargetName="border" Property="wpf:ShadowAssist.Darken" Value="True" />
</Trigger>
<Trigger Property="IsKeyboardFocused" Value="true">
<Setter TargetName="border" Property="wpf:ShadowAssist.Darken" Value="True" />
</Trigger>
<Trigger Property="IsEnabled" Value="false">
<Setter Property="Opacity" Value="0.23" />
</Trigger>
</ControlTemplate.Triggers>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
You don't have to include a ContentPresenter in the template ... You just need to provide a means to display the content. A content presenter is just one way to do that.
In this case, the template's content property is bound to the wpf:Ripple control, which in turn presents the content.
Essentially, this control template is passing the responsibility of presenting the content to another control.