Xamarin上的FadeIn/FadeOut背景色动画

<Grid x:Name="myGrid" BackgroundColor="Red">
    <!-- 内容 -->
</Grid>

using Xamarin.Forms;

// 定义Visual State
var fadeInState = new VisualState { Name = "FadeIn" };
var fadeOutState = new VisualState { Name = "FadeOut" };

// 定义背景色动画
var fadeInAnimation = new Animation(v => myGrid.BackgroundColor = Color.FromRgb(v, 0, 0), 0, 1);
var fadeOutAnimation = new Animation(v => myGrid.BackgroundColor = Color.FromRgb(v, 0, 0), 1, 0);

// 将动画添加到Visual State
fadeInState.Targets.Add(new Xamarin.Forms.VisualStateTarget { Element = myGrid, Property = "BackgroundColor", Animation = fadeInAnimation });
fadeOutState.Targets.Add(new Xamarin.Forms.VisualStateTarget { Element = myGrid, Property = "BackgroundColor", Animation = fadeOutAnimation });

// 将Visual State添加到Visual State Manager
VisualStateManager.SetVisualStateGroups(myGrid, new VisualStateGroupList
{
    new VisualStateGroup
    {
        Name = "FadeStates",
        States = { fadeInState, fadeOutState }
    }
});

// 触发FadeIn动画
VisualStateManager.GoToState(myGrid, "FadeIn");

// 触发FadeOut动画
VisualStateManager.GoToState(myGrid, "FadeOut");