页面过渡

PageTransitions 用于在两个视图之间呈现过渡效果，例如在 Carousel 或 TransitioningContentControl 中。

必须在使用过渡效果之前设置持续时间，并且持续时间必须大于0。否则，会出现错误。

内置 PageTransitions

CrossFade

CrossFade 通过动画设置透明度来淡出当前视图并淡入新视图。

XAML

<CrossFade Duration="0:00:00.500" />

C#

var transition = new CrossFade(TimeSpan.FromMilliseconds(500));

源代码

CrossFade.cs

参考

CrossFade

PageSlide

PageSlide 水平或垂直地滑动内容。您可以通过 Orientation 属性指定滑动轴。默认值为 Horizontal。

XAML

<PageSlide Duration="0:00:00.500" Orientation="Vertical" />

C#

var transition = new PageSlide(TimeSpan.FromMilliseconds(500), PageSlide.SlideAxis.Vertical);

源代码

PageSlide.cs

参考

PageSlide

CompositePageTransition

CompositePageTransition 用于创建几个不同过渡效果的组合过渡效果。下面的示例创建了一个过渡效果，将视图对角线滑动（水平和垂直同时）并淡出和淡入视图。

XAML

<CompositePageTransition>
    <CrossFade Duration="0:00:00.500" />
    <PageSlide Duration="0:00:00.500" Orientation="Horizontal" />
    <PageSlide Duration="0:00:00.500" Orientation="Vertical" />
</CompositePageTransition>

C#

var compositeTransition = new CompositePageTransition();
compositeTransition.PageTransitions.Add(new PageSlide(TimeSpan.FromMilliseconds(500), PageSlide.SlideAxis.Vertical));
compositeTransition.PageTransitions.Add(new PageSlide(TimeSpan.FromMilliseconds(500), PageSlide.SlideAxis.Horizontal));
compositeTransition.PageTransitions.Add(new CrossFade(TimeSpan.FromMilliseconds(500)));

源代码

CompositePageTransition.cs

参考

CompositePageTransition

自定义页面过渡效果

您还可以通过实现 IPageTransition 接口来创建自己的 PageTransition。

该接口有一个成员需要实现：

public Task Start(Visual? from, Visual? to, bool forward, CancellationToken cancellationToken)
{
    // 在此设置过渡效果。
}

示例

以下示例将缩小旧视图并在垂直方向上放大新视图。

public class CustomTransition : IPageTransition
{
    /// <summary>
    /// Initializes a new instance of the <see cref="CustomTransition"/> class.
    /// </summary>
    public CustomTransition()
    {
    }

    /// <summary>
    /// Initializes a new instance of the <see cref="CustomTransition"/> class.
    /// </summary>
    /// <param name="duration">The duration of the animation.</param>
    public CustomTransition(TimeSpan duration)
    {
        Duration = duration;
    }

    /// <summary>
    /// Gets the duration of the animation.
    /// </summary>
    public TimeSpan Duration { get; set; }

    public async Task Start(Visual from, Visual to, bool forward, CancellationToken cancellationToken)
    {
        if (cancellationToken.IsCancellationRequested)
        {
            return;
        }

        var tasks = new List<Task>();
        var parent = GetVisualParent(from, to);
        var scaleYProperty = ScaleTransform.ScaleYProperty;

        if (from != null)
        {
            var animation = new Animation
            {
                FillMode = FillMode.Forward,
                Children =
                {
                    new KeyFrame
                    {
                        Setters = { new Setter { Property = scaleYProperty, Value = 1d } },
                        Cue = new Cue(0d)
                    },
                    new KeyFrame
                    {
                        Setters =
                        {
                            new Setter
                            {
                                Property = scaleYProperty,
                                Value = 0d
                            }
                        },
                        Cue = new Cue(1d)
                    }
                },
                Duration = Duration
            };
            tasks.Add(animation.RunAsync(from, null, cancellationToken));
        }

        if (to != null)
        {
            to.IsVisible = true;
            var animation = new Animation
            {
                FillMode = FillMode.Forward,
                Children =
                {
                    new KeyFrame
                    {
                        Setters =
                        {
                            new Setter
                            {
                                Property = scaleYProperty,
                                Value = 0d
                            }
                        },
                        Cue = new Cue(0d)
                    },
                    new KeyFrame
                    {
                        Setters = { new Setter { Property = scaleYProperty, Value = 1d } },
                        Cue = new Cue(1d)
                    }
                },
                Duration = Duration
            };
            tasks.Add(animation.RunAsync(to, null, cancellationToken));
        }

        await Task.WhenAll(tasks);

        if (from != null && !cancellationToken.IsCancellationRequested)
        {
            from.IsVisible = false;
        }
    }

    /// <summary>
    /// Gets the common visual parent of the two control.
    /// </summary>
    /// <param name="from">The from control.</param>
    /// <param name="to">The to control.</param>
    /// <returns>The common parent.</returns>
    /// <exception cref="ArgumentException">
    /// The two controls do not share a common parent.
    /// </exception>
    /// <remarks>
    /// Any one of the parameters may be null, but not both.
    /// </remarks>
    private static IVisual GetVisualParent(IVisual? from, IVisual? to)
    {
        var p1 = (from ?? to)!.VisualParent;
        var p2 = (to ?? from)!.VisualParent;

        if (p1 != null && p2 != null && p1 != p2)
        {
            throw new ArgumentException("Controls for PageSlide must have same parent.");
        }

        return p1 ?? throw new InvalidOperationException("Cannot determine visual parent.");
    }
}

Custom Transition Example

Source code

IPageTransition.cs

Reference

IPageTransition