R – How to make a Silverlight 2.0 button entirely transparent

silverlight-2.0

I have a button that I am using on a toolbar that has a nice gradient. I want the button to be completely transparent so that just its contents show against the gradient. When I try, the button appears white rather than being transparent.

The XAML for my button is:

<Button Name="NewAppointmentButton" Style="{StaticResource ToolbarButtonStyle}">
  <TextBlock>X</TextBlock>
</Button>

and the style is:

<Style x:Key="ToolbarButtonStyle" TargetType="Button">
  <Setter Property="Background" Value="Transparent"/>
  <Setter Property="BorderThickness" Value="0"/>
  <Setter Property="Height" Value="24"/>
  <Setter Property="Width" Value="24"/>
</Style>

Best Solution

The best way is to define a new button template. Adding this to your UserControl.Resources tag should work:

<ControlTemplate x:Key="ButtonControlTemplate1" TargetType="Button">
        <Grid>
            <vsm:VisualStateManager.VisualStateGroups>
                <vsm:VisualStateGroup x:Name="CommonStates">
                    <vsm:VisualState x:Name="Normal"/>
                    <vsm:VisualState x:Name="MouseOver">
                        <Storyboard/>
                    </vsm:VisualState>
                    <vsm:VisualState x:Name="Pressed">
                        <Storyboard/>
                    </vsm:VisualState>
                    <vsm:VisualState x:Name="Disabled">
                        <Storyboard>
                            <DoubleAnimationUsingKeyFrames Storyboard.TargetName="DisabledVisualElement" Storyboard.TargetProperty="Opacity">
                                <SplineDoubleKeyFrame KeyTime="0" Value=".55"/>
                            </DoubleAnimationUsingKeyFrames>
                        </Storyboard>
                    </vsm:VisualState>
                </vsm:VisualStateGroup>
                <vsm:VisualStateGroup x:Name="FocusStates">
                    <vsm:VisualState x:Name="Focused">
                        <Storyboard>
                            <DoubleAnimationUsingKeyFrames Storyboard.TargetName="FocusVisualElement" Storyboard.TargetProperty="Opacity">
                                <SplineDoubleKeyFrame KeyTime="0" Value="1"/>
                            </DoubleAnimationUsingKeyFrames>
                        </Storyboard>
                    </vsm:VisualState>
                    <vsm:VisualState x:Name="Unfocused" />
                </vsm:VisualStateGroup>
            </vsm:VisualStateManager.VisualStateGroups>
            <ContentPresenter
                x:Name="contentPresenter"
                Content="{TemplateBinding Content}"
                ContentTemplate="{TemplateBinding ContentTemplate}"
                VerticalAlignment="{TemplateBinding VerticalContentAlignment}"
                HorizontalAlignment="{TemplateBinding HorizontalContentAlignment}"
                Margin="{TemplateBinding Padding}"/>
            <Rectangle x:Name="DisabledVisualElement" RadiusX="3" RadiusY="3" Fill="#FFFFFFFF" Opacity="0" IsHitTestVisible="false" />
            <Rectangle x:Name="FocusVisualElement" RadiusX="2" RadiusY="2" Margin="1" Stroke="#FF6DBDD1" StrokeThickness="1" Opacity="0" IsHitTestVisible="false" />
        </Grid>
    </ControlTemplate>

Now your button should be defined as:

<Button x:Name="NewAppointmentButton" Template="{StaticResource ButtonControlTemplate1}">
    <TextBlock>X</TextBlock>
</Button>

If you're using expression blend you can use it to edit your button template to your heart's content :) Select your button in design view - just above the design window will be a grey button called 'NewAppointmentButton'. Click on it, then 'Edit control parts' then 'Edit template' - the button should get a yellow outline. You can now edit the visual elements and states and transitions.

Good luck!