Change DependencyProperty on the ControlTemplate - xaml

Question

I have a Button with two different images - one for normal state and one - for PointerOver state:
public sealed class MyButtonTwo : Button
{
public static readonly DependencyProperty ImageSourceProperty = DependencyProperty.Register(
"ImageSource", typeof (ImageSource), typeof (MyButtonTwo), new PropertyMetadata(default(ImageSource)));
public ImageSource ImageSource
{
get { return (ImageSource) GetValue(ImageSourceProperty); }
set { SetValue(ImageSourceProperty, value); }
}
public static readonly DependencyProperty ImageSource2Property = DependencyProperty.Register(
"ImageSource2", typeof (ImageSource), typeof (MyButtonTwo), new PropertyMetadata(default(ImageSource)));
public ImageSource ImageSource2
{
get { return (ImageSource) GetValue(ImageSource2Property); }
set { SetValue(ImageSource2Property, value); }
}
I am using this property in the Control Template in the Style:
<Image x:Name="Image"
Source="{TemplateBinding ImageSource}" />
In the style I can change the properties of the MyButton:
<VisualStateManager.VisualStateGroups>
<VisualStateGroup x:Name="CommonStates">
<VisualState x:Name="Normal"/>
<VisualState x:Name="PointerOver">
<Storyboard>
<ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="Background" Storyboard.TargetName="FullGrid">
<DiscreteObjectKeyFrame KeyTime="0" Value="White"/>
But I can not change my dependency property such way:
<ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="Source" Storyboard.TargetName="Image">
<DiscreteObjectKeyFrame KeyTime="0" Value="{TemplateBinding ImageSource2}"/>
Only one way I have found is to add two different Images on the Template and change Visibility of them.
May be there is any better way?

Answer 1

It works with a regular Binding instead of a TemplateBinding:
<ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="Source"
Storyboard.TargetName="Image">
<DiscreteObjectKeyFrame KeyTime="0"
Value="{Binding ImageSource2,
RelativeSource={RelativeSource Mode=TemplatedParent}}"/>
</ObjectAnimationUsingKeyFrames>