c# – 轻松制作彩色动画

我一直在关注this问题来制作彩色动画.

我可以创建动画,它运行正常,直到动画再次开始.有一刻,感觉动画已经在那里开始/停止片刻.我希望动画能够平滑地运行,以便它不会在颜色中显示任何重新启动的效果.有可能吗？

我使用以下代码：

        <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“缓和”方法混合了动画的开始和停止,因此它看起来像长时间运行的动画一样流畅.有什么建议？

解决方法:

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

这是一些好消息和坏消息.好处是我们现在在Composition层级别有了新的渐变画笔API,这意味着它可以完全动画化并运行UI线程.因此,性能方面明显优于当前的Storyboard解决方案.但它仅在Windows 10 Insider Preview 16225中可用,这意味着除了内部人员之外,它对大多数当前用户不起作用.

但是,我仍然会在此发布此新解决方案以供将来参考,因为此主题尚无可用的示例.

注意我在动画中添加了一些额外的酱,以使其更有趣.如果您只想要对颜色进行动画处理,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实体背景颜色设置为渐变,并使用RotationAngleInDegrees永久旋转渐变画笔).

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sample,以下是它的样子.

标签：c,uwp,uwp-xaml,windows-composition-api
来源： https://codeday.me/bug/20190715/1465006.html