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我一直在关注这个问题来制作彩色动画。

我可以创建动画并且它运行良好，直到动画再次开始。有一刻感觉动画已经开始/停止了一会儿。我希望动画顺利运行，这样它就不会在颜色中显示任何重新启动效果。有可能这样做吗？

我正在使用以下代码：

        <Storyboard x:Key="GradientAnimation"
                RepeatBehavior="Forever"
                Storyboard.TargetName="BackgroundBrush"
                SpeedRatio="0.3">
        <ColorAnimationUsingKeyFrames
            Storyboard.TargetProperty="(UIElement.Background).(LinearGradientBrush.GradientStops)[0].(GradientStop.Color)"
            EnableDependentAnimation="True"
            BeginTime="-0:0:0.5">

            <LinearColorKeyFrame KeyTime="0:0:0" Value="Black"/>
            <LinearColorKeyFrame KeyTime="0:0:1" Value="Red"/>
            <LinearColorKeyFrame KeyTime="0:0:2" Value="Black"/>
            <LinearColorKeyFrame KeyTime="0:0:3" Value="Red"/>
            <LinearColorKeyFrame KeyTime="0:0:4" Value="Black"/>
            <LinearColorKeyFrame KeyTime="0:0:5" Value="Red"/>
            <LinearColorKeyFrame KeyTime="0:0:6" Value="Black"/>
            <LinearColorKeyFrame KeyTime="0:0:7" Value="Red"/>

        </ColorAnimationUsingKeyFrames>
        <ColorAnimationUsingKeyFrames
            Storyboard.TargetProperty="(UIElement.Background).(LinearGradientBrush.GradientStops)[1].(GradientStop.Color)"
            EnableDependentAnimation="True">

            <LinearColorKeyFrame KeyTime="0:0:0" Value="Red"/>
            <LinearColorKeyFrame KeyTime="0:0:1" Value="Black"/>
            <LinearColorKeyFrame KeyTime="0:0:2" Value="Red"/>
            <LinearColorKeyFrame KeyTime="0:0:3" Value="Black"/>
            <LinearColorKeyFrame KeyTime="0:0:4" Value="Red"/>
            <LinearColorKeyFrame KeyTime="0:0:5" Value="Black"/>
            <LinearColorKeyFrame KeyTime="0:0:6" Value="Red"/>
            <LinearColorKeyFrame KeyTime="0:0:7" Value="Black"/>

        </ColorAnimationUsingKeyFrames>
    </Storyboard>

我在代码隐藏中开始这个动画：

((Storyboard)Resources["GradientAnimation"]).Begin();

也许有某种“缓动”方法可以混合动画的开始和停止，使其看起来像长时间运行的动画一样流畅。有什么建议么？

4

1 回答 1

14

您可以尝试EasingColorKeyFrame，但动画永远不会流畅，因为它在 UI 线程（即EnableDependentAnimation="True"）上运行。

这里有一些好消息和坏消息。好处是我们现在在合成层级别有了新的渐变画笔 API，这意味着它完全可以动画化并且可以在 UI 线程之外运行。因此，在性能方面，它将比当前的解决方案好得多Storyboard。但它仅在 Windows 10 Insider Preview 16225 及更高版本中可用，这意味着它不适用于除内部人员之外的大多数当前用户。

但是，我仍将在此处发布此新解决方案以供将来参考，因为尚无有关此主题的示例。

请注意，我在动画中添加了一些额外的调味料以使其更有趣。如果您只希望颜色被动画化，请随意移动EndPoint和RotationAngleInDegrees动画（我使用EndPoint动画在应用程序启动时将动画从纯色背景颜色变为渐变，并RotationAngleInDegrees永远旋转渐变画笔）。

var compositor = Window.Current.Compositor;

// Initially, we set the end point to be (0,0) 'cause we want to animate it at start.
// If you don't want this behavior, simply set it to a different value within (1,1).
_gradientBrush = compositor.CreateLinearGradientBrush();
_gradientBrush.EndPoint = Vector2.Zero;

// Create gradient initial colors.
var gradientStop1 = compositor.CreateColorGradientStop();
gradientStop1.Offset = 0.0f;
gradientStop1.Color = GradientStop1StartColor;
var gradientStop2 = compositor.CreateColorGradientStop();
gradientStop2.Offset = 1.0f;
gradientStop2.Color = GradientStop2StartColor;
_gradientBrush.ColorStops.Add(gradientStop1);
_gradientBrush.ColorStops.Add(gradientStop2);

// Assign the gradient brush to the Root element's Visual.
_backgroundVisual = compositor.CreateSpriteVisual();
_backgroundVisual.Brush = _gradientBrush;
ElementCompositionPreview.SetElementChildVisual(Root, _backgroundVisual);

// There are 3 animations going on here.
// First, we kick off an EndPoint offset animation to create an special entrance scene.
// Once it's finished, we then kick off TWO other animations simultaneously. 
// These TWO animations include a set of gradient stop color animations and
// a rotation animation that rotates the gradient brush.

var linearEase = compositor.CreateLinearEasingFunction();
var batch = compositor.CreateScopedBatch(CompositionBatchTypes.Animation);
batch.Completed += (s, e) =>
{
    StartGradientColorAnimations();
    StartGradientRotationAnimation();
};
var endPointOffsetAnimation = compositor.CreateVector2KeyFrameAnimation();
endPointOffsetAnimation.Duration = TimeSpan.FromSeconds(3);
endPointOffsetAnimation.InsertKeyFrame(1.0f, Vector2.One);
_gradientBrush.StartAnimation(nameof(_gradientBrush.EndPoint), endPointOffsetAnimation);
batch.End();

void StartGradientColorAnimations()
{
    var color1Animation = compositor.CreateColorKeyFrameAnimation();
    color1Animation.Duration = TimeSpan.FromSeconds(10);
    color1Animation.IterationBehavior = AnimationIterationBehavior.Forever;
    color1Animation.Direction = AnimationDirection.Alternate;
    color1Animation.InsertKeyFrame(0.0f, GradientStop1StartColor, linearEase);
    color1Animation.InsertKeyFrame(0.5f, Color.FromArgb(255, 65, 88, 208), linearEase);
    color1Animation.InsertKeyFrame(1.0f, Color.FromArgb(255, 43, 210, 255), linearEase);
    gradientStop1.StartAnimation(nameof(gradientStop1.Color), color1Animation);

    var color2Animation = compositor.CreateColorKeyFrameAnimation();
    color2Animation.Duration = TimeSpan.FromSeconds(10);
    color2Animation.IterationBehavior = AnimationIterationBehavior.Forever;
    color2Animation.Direction = AnimationDirection.Alternate;
    color2Animation.InsertKeyFrame(0.0f, GradientStop2StartColor, linearEase);
    color1Animation.InsertKeyFrame(0.5f, Color.FromArgb(255, 200, 80, 192), linearEase);
    color2Animation.InsertKeyFrame(1.0f, Color.FromArgb(255, 43, 255, 136), linearEase);
    gradientStop2.StartAnimation(nameof(gradientStop2.Color), color2Animation);
}

void StartGradientRotationAnimation()
{
    var rotationAnimation = compositor.CreateScalarKeyFrameAnimation();
    rotationAnimation.Duration = TimeSpan.FromSeconds(15);
    rotationAnimation.IterationBehavior = AnimationIterationBehavior.Forever;
    rotationAnimation.InsertKeyFrame(1.0f, 360.0f, linearEase);
    _gradientBrush.StartAnimation(nameof(_gradientBrush.RotationAngleInDegrees), rotationAnimation);
}

这是一个工作示例，以下是它的外观。:)

在此处输入图像描述

于 2017-08-19T08:51:57.017 回答