Slide Animation in XAML

Question

I have a tab control that is docked to the right side of a dock panel. The tab control's width is set to 10 and opacity to 0. I would like to have the tab control's width change to 200 and opacity to 100 when I move my mouse over it. Then when I move my mouse away, have the tab control go back to its original values. I cannot figure out how to do that. Can someone help please? Below is my markup, where I was trying to get the tab control to show first.

<UserControl x:Class="Cordata.Mrs.MVVM.Views.Controls.SlideoutView"
         xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
         xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
         xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
         xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
         mc:Ignorable="d">
<UserControl.Resources>
    <Storyboard x:Key="OnMouseEnter1">
        <DoubleAnimationUsingKeyFrames Storyboard.TargetProperty="(FrameworkElement.Width)" Storyboard.TargetName="OptionsSlideout">
            <EasingDoubleKeyFrame KeyTime="0" Value="200"/>
        </DoubleAnimationUsingKeyFrames>
    </Storyboard>
</UserControl.Resources>
<UserControl.Triggers>
    <EventTrigger RoutedEvent="Mouse.MouseEnter">
        <BeginStoryboard Storyboard="{StaticResource OnMouseEnter1}"/>
    </EventTrigger>
</UserControl.Triggers>
<DockPanel HorizontalAlignment="Stretch">
    <TabControl Name="OptionsSlideout" TabStripPlacement="Bottom" Width="10" Margin="0,0,0,5" HorizontalAlignment="Stretch" DockPanel.Dock="Right" Opacity="0">
        <TabItem Header="Configure">
            <StackPanel Orientation="Vertical">
                <Button Name="ConfigurationBuilderButton" Width="80" Cursor="Hand" Click="ConfigurationBuilderButton_Click">
                    <Button.Template>
                        <ControlTemplate TargetType="Button">
                            <StackPanel>
                                <Image Source="/Images/ConfigurationBuilder.png" ToolTip="Run Configuration Builder" />
                                <TextBlock Text="Configuration Builder" TextWrapping="Wrap" FontWeight="Bold" />
                            </StackPanel>
                        </ControlTemplate>
                    </Button.Template>
                </Button>
                <Button Name="LoadConfigurationButton" Width="80" Cursor="Hand" Margin="0,20,0,0" Click="LoadConfigurationButton_Click">
                    <Button.Template>
                        <ControlTemplate TargetType="Button">
                            <StackPanel>
                                <Image Source="/Images/LoadCustomConfiguration.png" ToolTip="Load Custom Configuration" />
                                <TextBlock Text="Load Configuration" TextWrapping="Wrap" FontWeight="Bold" />
                            </StackPanel>
                        </ControlTemplate>
                    </Button.Template>
                </Button>
            </StackPanel>
        </TabItem>
        <TabItem Header="Help">
            <TextBlock Text="Help" />
        </TabItem>
    </TabControl>
</DockPanel>
</UserControl>

Answer 1

I needed to add a Rectangle so that the DockPanel could have some main content and therefore allow us to dock your TabControl to the right. You don't need any of your Resources for this and one other thing... I had to remove your handlers because I didn't have them implemented in my test project. Anyway, this will do what you want just using a Trigger on the IsMouseOver property:

<DockPanel HorizontalAlignment="Stretch">
    <TabControl Name="OptionsSlideout" TabStripPlacement="Bottom" Width="10" Margin="0,0,0,5" DockPanel.Dock="Right" Opacity="0.0">
        <TabControl.Style>
            <Style>
                <Style.Triggers>
                    <Trigger Property="Control.IsMouseOver" Value="True">
                        <Trigger.EnterActions>
                            <StopStoryboard BeginStoryboardName="CloseStoryBoard" />
                            <BeginStoryboard Name="OpenStoryBoard">
                                <Storyboard DecelerationRatio="0.8">
                                    <DoubleAnimation Storyboard.TargetProperty="(FrameworkElement.Width)" To="200.0" />
                                    <DoubleAnimation Storyboard.TargetProperty="Opacity" To="1.0" />
                                </Storyboard>
                            </BeginStoryboard>
                        </Trigger.EnterActions>
                        <Trigger.ExitActions>
                            <StopStoryboard BeginStoryboardName="OpenStoryBoard" />
                            <BeginStoryboard Name="CloseStoryBoard">
                                <Storyboard DecelerationRatio="0.8">
                                    <DoubleAnimation Storyboard.TargetProperty="(FrameworkElement.Width)" To="10.0" />
                                    <DoubleAnimation Storyboard.TargetProperty="Opacity" To="0.0" />
                                </Storyboard>
                            </BeginStoryboard>
                        </Trigger.ExitActions>
                    </Trigger>
                </Style.Triggers>
            </Style>
        </TabControl.Style>
        <TabItem Header="Configure">
            <StackPanel Orientation="Vertical">
                <Button Name="ConfigurationBuilderButton" Width="80" Cursor="Hand">
                    <Button.Template>
                        <ControlTemplate TargetType="Button">
                            <StackPanel>
                                <Image Source="/Images/ConfigurationBuilder.png" ToolTip="Run Configuration Builder" />
                                <TextBlock Text="Configuration Builder" TextWrapping="Wrap" FontWeight="Bold" />
                            </StackPanel>
                        </ControlTemplate>
                    </Button.Template>
                </Button>
                <Button Name="LoadConfigurationButton" Width="80" Cursor="Hand" Margin="0,20,0,0">
                    <Button.Template>
                        <ControlTemplate TargetType="Button">
                            <StackPanel>
                                <Image Source="/Images/LoadCustomConfiguration.png" ToolTip="Load Custom Configuration" />
                                <TextBlock Text="Load Configuration" TextWrapping="Wrap" FontWeight="Bold" />
                            </StackPanel>
                        </ControlTemplate>
                    </Button.Template>
                </Button>
            </StackPanel>
        </TabItem>
        <TabItem Header="Help">
            <TextBlock Text="Help" />
        </TabItem>
    </TabControl>
    <Rectangle Name="DummyContent" Fill="White" />
</DockPanel>

For future reference Mike, this is a bit too much code to put up here. It would have been easier for users to visualize your problem if you had just used coloured Rectangle or Border elements and said I'd like to animate this Border. That way, missing handlers, images, Style and/or Resources elements don't slow down users trying to help you. Simplifying your problem before you post is always good and sometimes, you even end up fixing your own problems. Anyway, it's not a problem and that code does what you want.