Collapse/Expand Groupboxes

I have the following XAML, in which there are three group boxes stacked. In the header of those groupboxes are checkboxes.

What I'd like to achieve : when I check/uncheck a box, I'd like the corresponding groupbox to slowly expand/collapse, with a smooth animation.

I'm trying this in Blend 4 but am quite a newbie. Any help on how to achieve this ? In particular, can the animation be self-contained in the XAML ?

UPDATE : This seems to come close , but I don't quite get it

XAML Designer

<UserControl
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    mc:Ignorable="d"
    x:Class="WpfControlLibrary1.MainControl"
    x:Name="MultiVol">
        <StackPanel x:Name="LayoutRoot" HorizontalAlignment="Stretch">
            <GroupBox Margin="8,0" BorderBrush="#FF88B1D8">
                <GroupBox.Header>
                    <WrapPanel>
                    <CheckBox IsChecked="True" VerticalAlignment="Center" />
                    <Label Content="Volatility" Background="#00000000" Foreground="#FF0033FF" FontWeight="Bold" FontFamily="/WpfControlLibrary1;component/Fonts/#Tahoma" /> 
                    </WrapPanel>
                </GroupBox.Header>
                <UniformGrid Columns="2">
                    <Label Content="Spots"></Label>
                    <TextBox AcceptsReturn="False" AcceptsTab="True" AllowDrop="True" IsTabStop="True" />
                    <Label Content="Hist. references" />
                    <TextBox AcceptsReturn="False" AcceptsTab="True" AllowDrop="True" IsTabStop="True" />
                    <Label Content="Tenors" />
                    <TextBox AcceptsReturn="False" AcceptsTab="True" AllowDrop="True" IsTabStop="True" />

                </UniformGrid>
            </GroupBox>
            <GroupBox  Margin="8,0" BorderBrush="#FF88B1D8">
                <GroupBox.Header>
                    <WrapPanel>
                    <CheckBox IsChecked="True" VerticalAlignment="Center" />
                    <Label Content="Skew" Background="#00000000" Foreground="#FF0033FF" FontWeight="Bold" FontFamily="/WpfControlLibrary1;component/Fonts/#Tahoma" />   
                    </WrapPanel>
                </GroupBox.Header>
                <UniformGrid Columns="2">
                    <Label Content="Spot Intervals"></Label>
                    <TextBox AcceptsReturn="False" AcceptsTab="True" AllowDrop="True" IsTabStop="True" />
                    <Label Content="Hist. references" />
                    <TextBox AcceptsReturn="False" AcceptsTab="True" AllowDrop="True" IsTabStop="True" />
                    <Label Content="Tenors" />
                    <TextBox AcceptsReturn="False" AcceptsTab="True" AllowDrop="True" IsTabStop="True" />
                    <Label Content="Compute 'Power'" />
                    <CheckBox IsChecked="False" VerticalAlignment="Center"/>
                </UniformGrid>
            </GroupBox>
            <GroupBox Margin="8,0" BorderBrush="#FF88B1D8">
                <GroupBox.Header>
                    <WrapPanel>
                    <CheckBox IsChecked="True" VerticalAlignment="Center" />
                    <Label Content="Term structure" Background="#00000000" Foreground="#FF0033FF" FontWeight="Bold" FontFamily="/WpfControlLibrary1;component/Fonts/#Tahoma" /> 
                    </WrapPanel>
                </GroupBox.Header>
                <UniformGrid Columns="2">
                    <Label Content="Spots" />
                    <TextBox AcceptsReturn="False" AcceptsTab="True" AllowDrop="True" IsTabStop="True" />
                    <Label Content="Tenors" />
                    <TextBox AcceptsReturn="False" AcceptsTab="True" AllowDrop="True" IsTabStop="True" />
                </UniformGrid>
            </GroupBox> 
        </StackPanel>
</UserControl>

Solution

Just edit the first group box in your code:

    <GroupBox Margin="8,0" BorderBrush="#FF88B1D8" Height="150">
        <GroupBox.Resources>
            <Style TargetType="GroupBox">
                <Style.Triggers>
                    <EventTrigger RoutedEvent="CheckBox.Unchecked">
                        <BeginStoryboard>
                            <Storyboard>
                                <DoubleAnimation Storyboard.TargetProperty="Height" Duration="0:0:.2"  To="30" />
                            </Storyboard>
                        </BeginStoryboard>
                    </EventTrigger>
                    <EventTrigger RoutedEvent="CheckBox.Checked">
                        <BeginStoryboard>
                            <Storyboard>
                                <DoubleAnimation Storyboard.TargetProperty="Height" Duration="0:0:.2" />
                            </Storyboard>
                        </BeginStoryboard>
                    </EventTrigger>
                </Style.Triggers>
            </Style>
        </GroupBox.Resources>
        <GroupBox.Header>
            <WrapPanel>
                <CheckBox IsChecked="True" VerticalAlignment="Center" />
                <Label Content="Volatility" Background="#00000000" Foreground="#FF0033FF" FontWeight="Bold" />
            </WrapPanel>
        </GroupBox.Header>
        <UniformGrid Columns="2">
            <Label Content="Spots"></Label>
            <TextBox AcceptsReturn="False" AcceptsTab="True" AllowDrop="True" IsTabStop="True" />
            <Label Content="Hist. references" />
            <TextBox AcceptsReturn="False" AcceptsTab="True" AllowDrop="True" IsTabStop="True" />
            <Label Content="Tenors" />
            <TextBox AcceptsReturn="False" AcceptsTab="True" AllowDrop="True" IsTabStop="True" />

        </UniformGrid>
    </GroupBox>

If you want to have this on a single group box you could place the Style Element inside this code

<GroupBox.Resources>
  <!--Style Inside HEre-->
</GroupBox.Resources>

to implement it on a single group box.

Another approach is to create a Style inside the stack panel and add a key to it:

    <StackPanel.Resources>
        <Style TargetType="GroupBox" x:Key="groupBoxStyle">
            <Style.Triggers>
                <EventTrigger RoutedEvent="CheckBox.Unchecked">
                        <BeginStoryboard>
                            <Storyboard>
                                <DoubleAnimation Storyboard.TargetProperty="Height" Duration="0:0:.2"  To="30" />
                            </Storyboard>
                        </BeginStoryboard>
                </EventTrigger>
                <EventTrigger RoutedEvent="CheckBox.Checked">
                    <BeginStoryboard>
                        <Storyboard>
                            <DoubleAnimation Storyboard.TargetProperty="Height" Duration="0:0:.2" />
                        </Storyboard>
                    </BeginStoryboard>
                </EventTrigger>
            </Style.Triggers>
        </Style>
    </StackPanel.Resources>

then attach it to the style of the groupbox:

    <GroupBox Margin="8,0" Height="150" BorderBrush="Transparent" Style="{StaticResource groupBoxStyle}">
        <GroupBox.Header>
            <WrapPanel>
                <CheckBox IsChecked="True" VerticalAlignment="Center" />
                <Label Content="Volatility" Background="#00000000" Foreground="#FF0033FF" FontWeight="Bold" />
            </WrapPanel>
        </GroupBox.Header>
        <Border BorderBrush="Black" BorderThickness="2">
        <UniformGrid Columns="2">
            <Label Content="Spots"></Label>
            <TextBox AcceptsReturn="False" AcceptsTab="True" AllowDrop="True" IsTabStop="True" />
            <Label Content="Hist. references" />
            <TextBox AcceptsReturn="False" AcceptsTab="True" AllowDrop="True" IsTabStop="True" />
            <Label Content="Tenors" />
            <TextBox AcceptsReturn="False" AcceptsTab="True" AllowDrop="True" IsTabStop="True" />
        </UniformGrid>
        </Border>
    </GroupBox>

this approach will be more useful if you want to implement multiple groupboxes.

In Case you want to handle the checkbox and unchecked event you could use this code:

    <GroupBox Margin="8,0" Height="150" BorderBrush="Transparent" Style="{StaticResource groupBoxStyle}" CheckBox.Checked="CheckBox_Checked" CheckBox.Unchecked="CheckBox_Unchecked">
        <GroupBox.Header>
            <WrapPanel>
                <CheckBox x:Name="chkHeader" IsChecked="True" VerticalAlignment="Center" />
                <Label Content="Volatility" Background="#00000000" Foreground="#FF0033FF" FontWeight="Bold" />
            </WrapPanel>
        </GroupBox.Header>
        <Border BorderBrush="Black" BorderThickness="2">
        <UniformGrid Columns="2">
            <Label Content="Spots"></Label>
            <TextBox AcceptsReturn="False" AcceptsTab="True" AllowDrop="True" IsTabStop="True" />
            <Label Content="Hist. references" />
            <TextBox AcceptsReturn="False" AcceptsTab="True" AllowDrop="True" IsTabStop="True" />
            <Label Content="Tenors" />
            <TextBox AcceptsReturn="False" AcceptsTab="True" AllowDrop="True" IsTabStop="True" />
        </UniformGrid>
        </Border>
    </GroupBox>

and add this in the code behind:

    private void CheckBox_Checked(object sender, RoutedEventArgs e)
    {
        if ((e.OriginalSource as CheckBox).Name != "chkHeader")
        {
            e.Handled = true;
        }
    }

    private void CheckBox_Unchecked(object sender, RoutedEventArgs e)
    {
        if ((e.OriginalSource as CheckBox).Name != "chkHeader")
        {
            e.Handled = true;
        }
    }