Expander Styles and Templates

This topic describes the styles and templates for the Expander control. You can modify the default ControlTemplate to give the control a unique appearance. For more information, see Customizing the Appearance of an Existing Control by Creating a ControlTemplate.

Expander Parts

The Expander control does not have any named parts.

Expander States

The following table lists the visual states for the Expander control.

VisualState Name VisualStateGroup Name Description
Normal CommonStates The default state.
MouseOver CommonStates The mouse pointer is positioned over the control.
Disabled CommonStates The control is disabled.
Focused FocusStates The control has focus.
Unfocused FocusStates The control does not have focus.
Expanded ExpansionStates The control is expanded.
Collapsed ExpansionStates The control is not expanded.
ExpandDown ExpandDirectionStates The control expands down.
ExpandUp ExpandDirectionStates The control expands up.
ExpandLeft ExpandDirectionStates The control expands left.
ExpandRight ExpandDirectionStates The control expands right.
Valid ValidationStates The control uses the Validation class and the Validation.HasError attached property is false.
InvalidFocused ValidationStates The Validation.HasError attached property is true has the control has focus.
InvalidUnfocused ValidationStates The Validation.HasError attached property is true has the control does not have focus.

Expander ControlTemplate Example

The following example shows how to define a ControlTemplate for the Expander control.

<ControlTemplate x:Key="ExpanderToggleButton"
                 TargetType="{x:Type ToggleButton}">
  <Border x:Name="Border"
          CornerRadius="2,0,0,0"
          BorderThickness="0,0,1,0">
    <Border.Background>
      <LinearGradientBrush EndPoint="0.5,1"
                           StartPoint="0.5,0">
        <GradientStop Color="{DynamicResource ControlLightColor}" />
        <GradientStop Color="{DynamicResource ControlMediumColor}"
                      Offset="1" />
      </LinearGradientBrush>
    </Border.Background>
    <Border.BorderBrush>
      <LinearGradientBrush StartPoint="0,0"
                           EndPoint="0,1">
        <LinearGradientBrush.GradientStops>
          <GradientStopCollection>
            <GradientStop Color="{DynamicResource BorderLightColor}"
                          Offset="0.0" />
            <GradientStop Color="{DynamicResource BorderDarkColor}"
                          Offset="1.0" />
          </GradientStopCollection>
        </LinearGradientBrush.GradientStops>
      </LinearGradientBrush>

    </Border.BorderBrush>
    <VisualStateManager.VisualStateGroups>
      <VisualStateGroup x:Name="CommonStates">
        <VisualState x:Name="Normal" />
        <VisualState x:Name="MouseOver">
          <Storyboard>
            <ColorAnimationUsingKeyFrames Storyboard.TargetName="Border"
                                          Storyboard.TargetProperty="(Panel.Background).
                (GradientBrush.GradientStops)[1].(GradientStop.Color)">
              <EasingColorKeyFrame KeyTime="0"
                                   Value="{StaticResource ControlMouseOverColor}" />
            </ColorAnimationUsingKeyFrames>
          </Storyboard>
        </VisualState>
        <VisualState x:Name="Pressed">
          <Storyboard>
            <ColorAnimationUsingKeyFrames Storyboard.TargetName="Border"
                                          Storyboard.TargetProperty="(Panel.Background).
                (GradientBrush.GradientStops)[1].(GradientStop.Color)">
              <EasingColorKeyFrame KeyTime="0"
                                   Value="{StaticResource ControlPressedColor}" />
            </ColorAnimationUsingKeyFrames>
          </Storyboard>
        </VisualState>
        <VisualState x:Name="Disabled">
          <Storyboard>
            <ColorAnimationUsingKeyFrames Storyboard.TargetName="Border"
                                          Storyboard.TargetProperty="(Panel.Background).
                (GradientBrush.GradientStops)[1].(GradientStop.Color)">
              <EasingColorKeyFrame KeyTime="0"
                                   Value="{StaticResource DisabledControlDarkColor}" />
            </ColorAnimationUsingKeyFrames>
            <ColorAnimationUsingKeyFrames Storyboard.TargetName="Border"
                                          Storyboard.TargetProperty="(Border.BorderBrush).
                (GradientBrush.GradientStops)[1].(GradientStop.Color)">
              <EasingColorKeyFrame KeyTime="0"
                                   Value="{StaticResource DisabledBorderLightColor}" />
            </ColorAnimationUsingKeyFrames>
          </Storyboard>
        </VisualState>
      </VisualStateGroup>
      <VisualStateGroup x:Name="CheckStates">
        <VisualState x:Name="Checked">
          <Storyboard>
            <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="(UIElement.Visibility)"
                                           Storyboard.TargetName="CollapsedArrow">
              <DiscreteObjectKeyFrame KeyTime="0"
                                      Value="{x:Static Visibility.Hidden}" />
            </ObjectAnimationUsingKeyFrames>
            <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="(UIElement.Visibility)"
                                           Storyboard.TargetName="ExpandededArrow">
              <DiscreteObjectKeyFrame KeyTime="0"
                                      Value="{x:Static Visibility.Visible}" />
            </ObjectAnimationUsingKeyFrames>
          </Storyboard>
        </VisualState>
        <VisualState x:Name="Unchecked" />
        <VisualState x:Name="Indeterminate" />
      </VisualStateGroup>
    </VisualStateManager.VisualStateGroups>
    <Grid>
      <Path x:Name="CollapsedArrow"
            HorizontalAlignment="Center"
            VerticalAlignment="Center"
            Data="M 0 0 L 4 4 L 8 0 Z">
        <Path.Fill>
          <SolidColorBrush Color="{DynamicResource GlyphColor}" />
        </Path.Fill>
      </Path>
      <Path x:Name="ExpandededArrow"
            HorizontalAlignment="Center"
            VerticalAlignment="Center"
            Visibility="Collapsed"
            Data="M 0 4 L 4 0 L 8 4 Z">
        <Path.Fill>
          <SolidColorBrush Color="{DynamicResource GlyphColor}" />
        </Path.Fill>
      </Path>
    </Grid>
  </Border>
</ControlTemplate>

<Style TargetType="{x:Type Expander}">
  <Setter Property="Template">
    <Setter.Value>
      <ControlTemplate TargetType="{x:Type Expander}">
        <Grid>
          <Grid.RowDefinitions>
            <RowDefinition Height="Auto" />
            <RowDefinition x:Name="ContentRow"
                           Height="0" />
          </Grid.RowDefinitions>
          <VisualStateManager.VisualStateGroups>
            <VisualStateGroup x:Name="CommonStates">
              <VisualState x:Name="Normal" />
              <VisualState x:Name="MouseOver" />
              <VisualState x:Name="Disabled">
                <Storyboard>
                  <ColorAnimationUsingKeyFrames Storyboard.TargetName="Border"
                                                Storyboard.TargetProperty="(Panel.Background).
                      (GradientBrush.GradientStops)[1].(GradientStop.Color)">
                    <EasingColorKeyFrame KeyTime="0"
                                         Value="{StaticResource DisabledControlDarkColor}" />
                  </ColorAnimationUsingKeyFrames>
                  <ColorAnimationUsingKeyFrames Storyboard.TargetName="Border"
                                                Storyboard.TargetProperty="(Border.BorderBrush).
                      (GradientBrush.GradientStops)[1].(GradientStop.Color)">
                    <EasingColorKeyFrame KeyTime="0"
                                         Value="{StaticResource DisabledBorderLightColor}" />
                  </ColorAnimationUsingKeyFrames>
                </Storyboard>
              </VisualState>
            </VisualStateGroup>
          </VisualStateManager.VisualStateGroups>
          <Border x:Name="Border"
                  Grid.Row="0"
                  BorderThickness="1"
                  CornerRadius="2,2,0,0">
            <Border.BorderBrush>
              <LinearGradientBrush EndPoint="0,1"
                                   StartPoint="0,0">
                <GradientStop Color="{DynamicResource BorderLightColor}"
                              Offset="0" />
                <GradientStop Color="{DynamicResource BorderDarkColor}"
                              Offset="1" />
              </LinearGradientBrush>

            </Border.BorderBrush>
            <Border.Background>

              <LinearGradientBrush StartPoint="0,0"
                                   EndPoint="0,1">
                <LinearGradientBrush.GradientStops>
                  <GradientStopCollection>
                    <GradientStop Color="{DynamicResource ControlLightColor}"
                                  Offset="0.0" />
                    <GradientStop Color="{DynamicResource ControlMediumColor}"
                                  Offset="1.0" />
                  </GradientStopCollection>
                </LinearGradientBrush.GradientStops>
              </LinearGradientBrush>

            </Border.Background>
            <Grid>
              <Grid.ColumnDefinitions>
                <ColumnDefinition Width="20" />
                <ColumnDefinition Width="*" />
              </Grid.ColumnDefinitions>
              <ToggleButton OverridesDefaultStyle="True"
                            Template="{StaticResource ExpanderToggleButton}"
                            IsChecked="{Binding IsExpanded, Mode=TwoWay, 
                  RelativeSource={RelativeSource TemplatedParent}}">
                <ToggleButton.Background>
                  <LinearGradientBrush EndPoint="0.5,1"
                                       StartPoint="0.5,0">
                    <GradientStop Color="{DynamicResource ControlLightColor}"
                                  Offset="0" />
                    <GradientStop Color="{DynamicResource ControlMediumColor}"
                                  Offset="1" />
                  </LinearGradientBrush>
                </ToggleButton.Background>
              </ToggleButton>
              <ContentPresenter Grid.Column="1"
                                Margin="4"
                                ContentSource="Header"
                                RecognizesAccessKey="True" />
            </Grid>
          </Border>
          <Border x:Name="Content"
                  Grid.Row="1"
                  BorderThickness="1,0,1,1"
                  CornerRadius="0,0,2,2">
            <Border.BorderBrush>
              <SolidColorBrush Color="{DynamicResource BorderMediumColor}" />
            </Border.BorderBrush>
            <Border.Background>
              <SolidColorBrush Color="{DynamicResource ContentAreaColorDark}" />
            </Border.Background>
            <ContentPresenter Margin="4" />
          </Border>
        </Grid>
        <ControlTemplate.Triggers>
          <Trigger Property="IsExpanded"
                   Value="True">
            <Setter TargetName="ContentRow"
                    Property="Height"
                    Value="{Binding DesiredHeight, ElementName=Content}" />
          </Trigger>
        </ControlTemplate.Triggers>
      </ControlTemplate>
    </Setter.Value>
  </Setter>
</Style>

The preceding example uses one or more of the following resources.

<!--Control colors.-->
<Color x:Key="WindowColor">#FFE8EDF9</Color>
<Color x:Key="ContentAreaColorLight">#FFC5CBF9</Color>
<Color x:Key="ContentAreaColorDark">#FF7381F9</Color>

<Color x:Key="DisabledControlLightColor">#FFE8EDF9</Color>
<Color x:Key="DisabledControlDarkColor">#FFC5CBF9</Color>
<Color x:Key="DisabledForegroundColor">#FF888888</Color>

<Color x:Key="SelectedBackgroundColor">#FFC5CBF9</Color>
<Color x:Key="SelectedUnfocusedColor">#FFDDDDDD</Color>

<Color x:Key="ControlLightColor">White</Color>
<Color x:Key="ControlMediumColor">#FF7381F9</Color>
<Color x:Key="ControlDarkColor">#FF211AA9</Color>

<Color x:Key="ControlMouseOverColor">#FF3843C4</Color>
<Color x:Key="ControlPressedColor">#FF211AA9</Color>


<Color x:Key="GlyphColor">#FF444444</Color>
<Color x:Key="GlyphMouseOver">sc#1, 0.004391443, 0.002428215, 0.242281124</Color>

<!--Border colors-->
<Color x:Key="BorderLightColor">#FFCCCCCC</Color>
<Color x:Key="BorderMediumColor">#FF888888</Color>
<Color x:Key="BorderDarkColor">#FF444444</Color>

<Color x:Key="PressedBorderLightColor">#FF888888</Color>
<Color x:Key="PressedBorderDarkColor">#FF444444</Color>

<Color x:Key="DisabledBorderLightColor">#FFAAAAAA</Color>
<Color x:Key="DisabledBorderDarkColor">#FF888888</Color>

<Color x:Key="DefaultBorderBrushDarkColor">Black</Color>

<!--Control-specific resources.-->
<Color x:Key="HeaderTopColor">#FFC5CBF9</Color>
<Color x:Key="DatagridCurrentCellBorderColor">Black</Color>
<Color x:Key="SliderTrackDarkColor">#FFC5CBF9</Color>

<Color x:Key="NavButtonFrameColor">#FF3843C4</Color>

<LinearGradientBrush x:Key="MenuPopupBrush"
                     EndPoint="0.5,1"
                     StartPoint="0.5,0">
  <GradientStop Color="{DynamicResource ControlLightColor}"
                Offset="0" />
  <GradientStop Color="{DynamicResource ControlMediumColor}"
                Offset="0.5" />
  <GradientStop Color="{DynamicResource ControlLightColor}"
                Offset="1" />
</LinearGradientBrush>

<LinearGradientBrush x:Key="ProgressBarIndicatorAnimatedFill"
                     StartPoint="0,0"
                     EndPoint="1,0">
  <LinearGradientBrush.GradientStops>
    <GradientStopCollection>
      <GradientStop Color="#000000FF"
                    Offset="0" />
      <GradientStop Color="#600000FF"
                    Offset="0.4" />
      <GradientStop Color="#600000FF"
                    Offset="0.6" />
      <GradientStop Color="#000000FF"
                    Offset="1" />
    </GradientStopCollection>
  </LinearGradientBrush.GradientStops>
</LinearGradientBrush>

For the complete sample, see Styling with ControlTemplates Sample.

See Also

Style
ControlTemplate
Control Styles and Templates
Control Customization
Styling and Templating
Customizing the Appearance of an Existing Control by Creating a ControlTemplate