Changing the "Hover Area" Shape of a Button - wpf

Question

<Button x:Name="ListItem_Button_Play" VerticalAlignment="Center"
Style="{StaticResource PlayButtonStyle}" Foreground="{x:Null}">
<Image Source="Resources/ListItem_Button_Play.png"/>
</Button>
I have a Button in my DataTemplate. I applied a Style to it to remove the default hover effect. Also, to make it grow bigger when mouse pointer enter the hover area.
<Style x:Key="PlayButtonStyle" TargetType="Button">
<Setter Property="OverridesDefaultStyle" Value="True"/>
<Setter Property="Margin" Value="5"/>
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="Button">
<Border x:Name="border"
Width="{Binding Path=ActualHeight, ElementName=border}"
BorderThickness="0"
CornerRadius="{Binding Path=ActualHeight, ElementName=border}"
Background="{TemplateBinding Background}">
<ContentPresenter HorizontalAlignment="Center" VerticalAlignment="Center" />
</Border>
<ControlTemplate.Triggers>
<Trigger Property="IsMouseOver" Value="True">
<Setter TargetName="border" Property="BorderBrush" Value="Black" />
</Trigger>
</ControlTemplate.Triggers>
</ControlTemplate>
</Setter.Value>
</Setter>
<Setter Property="Height" Value="93"/>
<Setter Property="Width" Value="93"/>
<Style.Triggers>
<Trigger Property="IsMouseOver" Value="True">
<Trigger.EnterActions>
<BeginStoryboard>
<Storyboard>
<DoubleAnimation From="93" To="103" Storyboard.TargetProperty="Height" Duration="0:0:0.2"/>
<DoubleAnimation From="93" To="103" Storyboard.TargetProperty="Width" Duration="0:0:0.2"/>
</Storyboard>
</BeginStoryboard>
</Trigger.EnterActions>
<Trigger.ExitActions>
<BeginStoryboard>
<Storyboard>
<DoubleAnimation From="103" To="93" Storyboard.TargetProperty="Height" Duration="0:0:0.2"/>
<DoubleAnimation From="103" To="93" Storyboard.TargetProperty="Width" Duration="0:0:0.2"/>
</Storyboard>
</BeginStoryboard>
</Trigger.ExitActions>
</Trigger>
</Style.Triggers>
</Style>
I successfully changed the Border shape of the Button to follow the Image (ellipse). But not the hover area.
After some experiments, i can conclude that although the shape of the Border has changed, the shape of hover area are still the same. The red area above is the hover area.
Is there a way to change the Hover Area shape just like the "Play" Image ??

Answer 1

Avoid things like the Height/Width bindings you have whose path is itself. RelativeSource if you need, but in this case none of that should be necessary. Besides, you already have two Setter's halfway down with your Height and Width hard set already...
I made a few minor tweaks but this should sort you out and tests fine on my end.
<Style x:Key="PlayButtonStyle" TargetType="Button">
<Setter Property="OverridesDefaultStyle" Value="True"/>
<Setter Property="Background" Value="Purple"/>
<Setter Property="Margin" Value="5"/>
<Setter Property="Height" Value="93"/>
<Setter Property="Width" Value="93"/>
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="Button">
<Border x:Name="border"
CornerRadius="50"
Background="{TemplateBinding Background}"
BorderBrush="{TemplateBinding BorderBrush}"
BorderThickness="{TemplateBinding BorderThickness}">
<ContentPresenter HorizontalAlignment="Center" VerticalAlignment="Center" />
</Border>
<ControlTemplate.Triggers>
<Trigger Property="IsMouseOver" Value="True">
<Setter TargetName="border" Property="BorderBrush" Value="Black" />
</Trigger>
</ControlTemplate.Triggers>
</ControlTemplate>
</Setter.Value>
</Setter>
<Style.Triggers>
<Trigger Property="IsMouseOver" Value="True">
<Trigger.EnterActions>
<BeginStoryboard>
<Storyboard>
<DoubleAnimation From="93" To="103" Storyboard.TargetProperty="Height" Duration="0:0:0.2"/>
<DoubleAnimation From="93" To="103" Storyboard.TargetProperty="Width" Duration="0:0:0.2"/>
</Storyboard>
</BeginStoryboard>
</Trigger.EnterActions>
<Trigger.ExitActions>
<BeginStoryboard>
<Storyboard>
<DoubleAnimation From="103" To="93" Storyboard.TargetProperty="Height" Duration="0:0:0.2"/>
<DoubleAnimation From="103" To="93" Storyboard.TargetProperty="Width" Duration="0:0:0.2"/>
</Storyboard>
</BeginStoryboard>
</Trigger.ExitActions>
</Trigger>
</Style.Triggers>
</Style>