WPF Tab Control + Animations

Question

I'm trying to style/animate a TabControl such that when a tab is selected, the old one fades out, and the new one fades/slides in. I have the tab control styled, to a point, but now I'm trying to work out how to animate the panel. Blend doesn't seem to be much help: there are references to styling "target-element", and references to "Panel" in the xaml, but neither of these seem to work when attempting to animate properties of this element.

I'm attempting to animate the Opacity property, and the transform property. Can anyone please help? Thanks in advance.

XAML attached:

<Style x:Key="HeaderTabControlItem" TargetType="{x:Type TabItem}">
    <Setter Property="FocusVisualStyle" Value="{StaticResource TabItemFocusVisual}"/>
    <Setter Property="Foreground" Value="Black"/>
    <Setter Property="Padding" Value="6,1,6,1"/>
    <Setter Property="BorderBrush" Value="{StaticResource TabControlNormalBorderBrush}"/>
    <Setter Property="Background" Value="{StaticResource ButtonNormalBackground}"/>
    <Setter Property="HorizontalContentAlignment" Value="Stretch"/>
    <Setter Property="VerticalContentAlignment" Value="Stretch"/>
    <Setter Property="Template">
        <Setter.Value>
            <ControlTemplate TargetType="{x:Type TabItem}">
                <ControlTemplate.Resources>
                    <Storyboard x:Key="FadeTabIn">
                        <!-- This is where I am trying to put the animation code, the following (commented) line is an example. -->
                        <!--<DoubleAnimation By="0.6" From="0.5" To="1" Storyboard.TargetName="target-element" Storyboard.TargetProperty="(UIElement.Opacity)" /> -->
                    </Storyboard>
                </ControlTemplate.Resources>
                <Grid x:Name="layoutRoot" SnapsToDevicePixels="true" Opacity="0.6" RenderTransformOrigin="0.5,0.5">
                    <Grid.RenderTransform>
                        <TransformGroup>
                            <ScaleTransform ScaleX="0.9" ScaleY="0.9"/>
                            <SkewTransform/>
                            <RotateTransform/>
                            <TranslateTransform/>
                        </TransformGroup>
                    </Grid.RenderTransform>
                    <ContentPresenter x:Name="Content" ContentSource="Header" HorizontalAlignment="{Binding HorizontalContentAlignment, RelativeSource={RelativeSource AncestorType={x:Type ItemsControl}}}" RecognizesAccessKey="True" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" VerticalAlignment="{Binding VerticalContentAlignment, RelativeSource={RelativeSource AncestorType={x:Type ItemsControl}}}" Margin="0,0,8,0"/>
                </Grid>
                <ControlTemplate.Triggers>
                    <Trigger Property="IsMouseOver" Value="true"/>
                    <Trigger Property="IsSelected" Value="true">
                        <Setter Property="Panel.ZIndex" Value="1"/>
                        <Setter Property="Opacity" TargetName="layoutRoot" Value="1"/>
                    </Trigger>
                    <MultiTrigger>
                        <MultiTrigger.Conditions>
                            <Condition Property="IsSelected" Value="false"/>
                            <Condition Property="IsMouseOver" Value="true"/>
                        </MultiTrigger.Conditions>
                        <Setter Property="Opacity" TargetName="layoutRoot" Value="0.4"/>
                    </MultiTrigger>
                    <Trigger Property="TabStripPlacement" Value="Bottom"/>
                    <Trigger Property="TabStripPlacement" Value="Left"/>
                    <Trigger Property="TabStripPlacement" Value="Right"/>
                    <MultiTrigger>
                        <MultiTrigger.Conditions>
                            <Condition Property="IsSelected" Value="true"/>
                            <Condition Property="TabStripPlacement" Value="Top"/>
                        </MultiTrigger.Conditions>
                    </MultiTrigger>
                    <MultiTrigger>
                        <MultiTrigger.Conditions>
                            <Condition Property="IsSelected" Value="true"/>
                            <Condition Property="TabStripPlacement" Value="Bottom"/>
                        </MultiTrigger.Conditions>
                    </MultiTrigger>
                    <MultiTrigger>
                        <MultiTrigger.Conditions>
                            <Condition Property="IsSelected" Value="true"/>
                            <Condition Property="TabStripPlacement" Value="Left"/>
                        </MultiTrigger.Conditions>
                    </MultiTrigger>
                    <MultiTrigger>
                        <MultiTrigger.Conditions>
                            <Condition Property="IsSelected" Value="true"/>
                            <Condition Property="TabStripPlacement" Value="Right"/>
                        </MultiTrigger.Conditions>
                    </MultiTrigger>
                    <Trigger Property="IsEnabled" Value="false">
                        <Setter Property="Opacity" TargetName="layoutRoot" Value="0.25"/>
                        <Setter Property="RenderTransform" TargetName="layoutRoot">
                            <Setter.Value>
                                <TransformGroup>
                                    <ScaleTransform ScaleX="0.8" ScaleY="0.8"/>
                                    <SkewTransform/>
                                    <RotateTransform/>
                                    <TranslateTransform/>
                                </TransformGroup>
                            </Setter.Value>
                        </Setter>
                    </Trigger>
                    <Trigger Property="Selector.IsSelected" Value="True">
                        <Trigger.EnterActions>
                            <BeginStoryboard x:Name="FadeTabIn_BeginStoryboard" Storyboard="{StaticResource FadeTabIn}"/>
                        </Trigger.EnterActions>
                    </Trigger>
                </ControlTemplate.Triggers>
            </ControlTemplate>
        </Setter.Value>
    </Setter>
</Style>

Answer 1

The problem here is that the tab control is not as versatile as it could be. Your best bet in this situation is to use custom controls for each tab item, and to create handoff storyboards for fading in/out.

My trick for this is to use visual states and behaviours, and custom templated radio buttons as switchers.

Create storyboards to animate the visibility from collapsed > visible, then fade up the opacity from 0 > 100.

You can see an example of this exact technique on my blog, under the Websites section of the homepage Silverlight xap on http://www.blackspike.com