Make the button transparent on mouse over - xaml

Question

I'm building a metro style application using Microsoft Visual Studio Express 2012. I am very new to this applications and I need help. I have defined a button in XAML with button background is set from an image. At mouse over the button changes it background to blank. I want to change it an make the image about 50% transparent on mouse over. Is that possible? Any help? Thank you.
I have declared the button as follows:
<Button Height="100" Width="100" Margin="0,0,0,0">
<Button.Background>
<ImageBrush ImageSource="../Images/home.png"></ImageBrush>
</Button.Background>
</Button>

Answer 1

The Interactivity dll doesn't exist for Windows Store apps. You should use Visual States instead. It's easy to achieve with Blend.
If you open your app in Blend and edit a copy of your button's Template, you'll end up with a complete default button style in your xaml. You just have to edit the PointerOver visual state to achieve what you want.
Your button will look like this :
<Button Height="100" Width="100" Margin="0,0,0,0" Style="{StaticResource ButtonStyle1}">
<Button.Background>
<ImageBrush ImageSource="/Assets/Images/home.png"></ImageBrush>
</Button.Background>
</Button>
and you'll have to define the style in the resources of your app, so that you can use it everywhere.
In the code below, look at the PointerOver visual state. It defines how the button should change when it enters that state. Here, we say that the opacity of the border (which is the content that displays your background image), should be 0.5 :
<DoubleAnimation Duration="0" To="0.5" Storyboard.TargetProperty="(UIElement.Opacity)" Storyboard.TargetName="Border" d:IsOptimized="True"/>
Here is the complete style :
<Style x:Key="ButtonStyle1" TargetType="Button">
<Setter Property="Background" Value="{StaticResource ButtonBackgroundThemeBrush}"/>
<Setter Property="Foreground" Value="{StaticResource ButtonForegroundThemeBrush}"/>
<Setter Property="BorderBrush" Value="{StaticResource ButtonBorderThemeBrush}"/>
<Setter Property="BorderThickness" Value="{StaticResource ButtonBorderThemeThickness}"/>
<Setter Property="Padding" Value="12,4,12,4"/>
<Setter Property="HorizontalAlignment" Value="Left"/>
<Setter Property="VerticalAlignment" Value="Center"/>
<Setter Property="FontFamily" Value="{StaticResource ContentControlThemeFontFamily}"/>
<Setter Property="FontWeight" Value="SemiBold"/>
<Setter Property="FontSize" Value="{StaticResource ControlContentThemeFontSize}"/>
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="Button">
<Grid>
<VisualStateManager.VisualStateGroups>
<VisualStateGroup x:Name="CommonStates">
<VisualState x:Name="Normal"/>
<VisualState x:Name="PointerOver">
<Storyboard>
<DoubleAnimation Duration="0" To="0.5" Storyboard.TargetProperty="(UIElement.Opacity)" Storyboard.TargetName="Border" d:IsOptimized="True"/>
</Storyboard>
</VisualState>
<VisualState x:Name="Pressed">
<Storyboard>
<ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="Background" Storyboard.TargetName="Border">
<DiscreteObjectKeyFrame KeyTime="0" Value="{StaticResource ButtonPressedBackgroundThemeBrush}"/>
</ObjectAnimationUsingKeyFrames>
<ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="Foreground" Storyboard.TargetName="ContentPresenter">
<DiscreteObjectKeyFrame KeyTime="0" Value="{StaticResource ButtonPressedForegroundThemeBrush}"/>
</ObjectAnimationUsingKeyFrames>
</Storyboard>
</VisualState>
<VisualState x:Name="Disabled">
<Storyboard>
<ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="Background" Storyboard.TargetName="Border">
<DiscreteObjectKeyFrame KeyTime="0" Value="{StaticResource ButtonDisabledBackgroundThemeBrush}"/>
</ObjectAnimationUsingKeyFrames>
<ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="BorderBrush" Storyboard.TargetName="Border">
<DiscreteObjectKeyFrame KeyTime="0" Value="{StaticResource ButtonDisabledBorderThemeBrush}"/>
</ObjectAnimationUsingKeyFrames>
<ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="Foreground" Storyboard.TargetName="ContentPresenter">
<DiscreteObjectKeyFrame KeyTime="0" Value="{StaticResource ButtonDisabledForegroundThemeBrush}"/>
</ObjectAnimationUsingKeyFrames>
</Storyboard>
</VisualState>
</VisualStateGroup>
<VisualStateGroup x:Name="FocusStates">
<VisualState x:Name="Focused">
<Storyboard>
<DoubleAnimation Duration="0" To="1" Storyboard.TargetProperty="Opacity" Storyboard.TargetName="FocusVisualWhite"/>
<DoubleAnimation Duration="0" To="1" Storyboard.TargetProperty="Opacity" Storyboard.TargetName="FocusVisualBlack"/>
</Storyboard>
</VisualState>
<VisualState x:Name="Unfocused"/>
<VisualState x:Name="PointerFocused"/>
</VisualStateGroup>
</VisualStateManager.VisualStateGroups>
<Border x:Name="Border" BorderBrush="{TemplateBinding BorderBrush}" BorderThickness="{TemplateBinding BorderThickness}" Background="{TemplateBinding Background}" Margin="3">
<ContentPresenter x:Name="ContentPresenter" ContentTemplate="{TemplateBinding ContentTemplate}" ContentTransitions="{TemplateBinding ContentTransitions}" Content="{TemplateBinding Content}" HorizontalAlignment="{TemplateBinding HorizontalContentAlignment}" Margin="{TemplateBinding Padding}" VerticalAlignment="{TemplateBinding VerticalContentAlignment}"/>
</Border>
<Rectangle x:Name="FocusVisualWhite" IsHitTestVisible="False" Opacity="0" StrokeDashOffset="1.5" StrokeEndLineCap="Square" Stroke="{StaticResource FocusVisualWhiteStrokeThemeBrush}" StrokeDashArray="1,1"/>
<Rectangle x:Name="FocusVisualBlack" IsHitTestVisible="False" Opacity="0" StrokeDashOffset="0.5" StrokeEndLineCap="Square" Stroke="{StaticResource FocusVisualBlackStrokeThemeBrush}" StrokeDashArray="1,1"/>
</Grid>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>