Create a Blink animation in WPF in code behind

问题:

I want to apply a Blink animation to a Canvas so that all the objects I have drawn on it would blink with it.

I have been somewhat successful using the code below which changes the Opacity property of the Canvas rather fast to achieve this effect but I'm kinda not satisfied with it.

I would prefer a pure blink without any FadeOut/FadeIn as in my current code. How can I do it the right way?

var blinkAnimation = new DoubleAnimation
{
    From = 1,
    To = 0
};

var blinkStoryboard = new Storyboard
{
    Duration = TimeSpan.FromMilliseconds(500),
    RepeatBehavior = RepeatBehavior.Forever,
    AutoReverse = true
};

Storyboard.SetTarget(blinkAnimation, MyCanvas);
Storyboard.SetTargetProperty(blinkAnimation, new PropertyPath(OpacityProperty));

blinkStoryboard.Children.Add(blinkAnimation);
MyCanvas.BeginStoryboard(blinkStoryboard);

Maybe I can do that using the VisibilityProperty but I couldn't get it right.

回答1:

You might use a second animation with an appropriate BeginTime:

var switchOffAnimation = new DoubleAnimation
{
    To = 0,
    Duration = TimeSpan.Zero
};

var switchOnAnimation = new DoubleAnimation
{
    To = 1,
    Duration = TimeSpan.Zero,
    BeginTime = TimeSpan.FromSeconds(0.5)
};

var blinkStoryboard = new Storyboard
{
    Duration = TimeSpan.FromSeconds(1),
    RepeatBehavior = RepeatBehavior.Forever
};

Storyboard.SetTarget(switchOffAnimation, MyCanvas);
Storyboard.SetTargetProperty(switchOffAnimation, new PropertyPath(Canvas.OpacityProperty));
blinkStoryboard.Children.Add(switchOffAnimation);

Storyboard.SetTarget(switchOnAnimation, MyCanvas);
Storyboard.SetTargetProperty(switchOnAnimation, new PropertyPath(Canvas.OpacityProperty));
blinkStoryboard.Children.Add(switchOnAnimation);

MyCanvas.BeginStoryboard(blinkStoryboard);

回答2:

If you want on/off state for your animation you can change your animation to DoubleAnimationUsingKeyFrames

var blinkAnimation = new DoubleAnimationUsingKeyFrames();
blinkAnimation.KeyFrames.Add(new DiscreteDoubleKeyFrame(1, KeyTime.FromTimeSpan(TimeSpan.FromMilliseconds(0))));
blinkAnimation.KeyFrames.Add(new DiscreteDoubleKeyFrame(0, KeyTime.FromTimeSpan(TimeSpan.FromMilliseconds(250))));

var blinkStoryboard = new Storyboard
{
    Duration = TimeSpan.FromMilliseconds(500),
    RepeatBehavior = RepeatBehavior.Forever,
};

Storyboard.SetTarget(blinkAnimation, MyCanvas);
Storyboard.SetTargetProperty(blinkAnimation, new PropertyPath(OpacityProperty));

blinkStoryboard.Children.Add(blinkAnimation);
blinkStoryboard.Begin();