Making a WPF Label (or other element) flash using animation - wpf

Question

I have a label that I only make visible based on one of my ViewModel Properties. Here is the XAML:
<Label HorizontalAlignment="Center" VerticalAlignment="Center"
HorizontalContentAlignment="Center"
VerticalContentAlignment="Center"
FontSize="24" Width="200" Height="200" >
<Label.Content >
Option in the money!
</Label.Content>
<Label.Style>
<Style TargetType="{x:Type Label}">
<Setter Property="Visibility" Value="Hidden" />
<Style.Triggers>
<DataTrigger Binding="{Binding OptionInMoney}" Value="True">
<Setter Property="Visibility"
Value="Visible" />
</DataTrigger>
</Style.Triggers>
</Style>
</Label.Style>
</Label>
I'm not sure this is the best way, but in any case, I'd also like to have the label flashing. Clearly, I only want it flashing when it is visible. Can someone point me to some example code, or write a quick example to do this? I assume I need some sort of trigger, and an animation. Presumably I also need a trigger when the label is no longer visible so that I stop the animation?
Thanks,
Dave
P.S. Is there a good book or site for all these WPF tricks? Something like the "MFC Answer Book" for those that remember that book.

Answer 1

You could add a Storyboard animation to the Style.Resources and start it in the EnterActions section of the DataTrigger.
A simple DoubleAnimation on the Opacity should work fine
Something like this:
<Label.Style>
<Style TargetType="{x:Type Label}">
<Style.Resources>
<Storyboard x:Key="flashAnimation" >
<DoubleAnimation Storyboard.TargetProperty="Opacity" From="1" To="0" AutoReverse="True" Duration="0:0:0.5" RepeatBehavior="Forever" />
</Storyboard>
</Style.Resources>
<Setter Property="Visibility" Value="Hidden" />
<Style.Triggers>
<DataTrigger Binding="{Binding OptionInMoney}" Value="True">
<Setter Property="Visibility" Value="Visible" />
<DataTrigger.EnterActions>
<BeginStoryboard Name="flash" Storyboard="{StaticResource flashAnimation}" />
</DataTrigger.EnterActions>
<DataTrigger.ExitActions>
<StopStoryboard BeginStoryboardName="flash"/>
</DataTrigger.ExitActions>
</DataTrigger>
</Style.Triggers>
</Style>
</Label.Style>

Answer 2

StoryBoard is certainly the WPF way, but it can be achieved by a simple code also. Here it goes, to make a label background blink:
lblTimer is a Lebel on your form with some text, say, "I AM BLINKING"
This can be applied to any property, as VISIBILITY.
// Create a timer.
private void Window_Loaded(object sender, RoutedEventArgs e)
{
DispatcherTimer timer = new DispatcherTimer();
timer.Tick += timer_Tick;
timer.Interval = new TimeSpan(0, 0, 0, 0, 500);
timer.Start();
}
// The timer's Tick event.
private bool BlinkOn = false;
private void timer_Tick(object sender, EventArgs e)
{
if (BlinkOn)
{
lblTimer.Foreground = Brushes.Black;
lblTimer.Background = Brushes.White;
}
else
{
lblTimer.Foreground = Brushes.White;
lblTimer.Background = Brushes.Black;
}
BlinkOn = !BlinkOn;
}

Answer 3

Try this post. It's called 'Blinking TextBlock' but you can easily swap a TextBox for a Label`.