Xamarin forms animation does not repeat - animation

Question

I am trying to animate an Image in Xamarin.Forms (version 2.3.3.168). The animation is working, but it does not repeat.
public class WelcomePage : ContentPage
{
Image img;
public WelcomePage()
{
img = new Image
{
Source = "img.png",
HorizontalOptions = LayoutOptions.Center,
VerticalOptions = LayoutOptions.Center,
};
Content = new StackLayout
{
VerticalOptions = LayoutOptions.Center,
Children = {
img
}
};
}
protected override void OnAppearing()
{
base.OnAppearing();
var a = new Animation();
a.Add(0, 0.5, new Animation((v) =>
{
img.Scale = v;
}, 1.0, 1.2, Easing.CubicInOut, () => { System.Diagnostics.Debug.WriteLine("ANIMATION A"); }));
a.Add(0.5, 1, new Animation((v) =>
{
img.Scale = v;
}, 1.2, 1.0, Easing.CubicInOut, () => { System.Diagnostics.Debug.WriteLine("ANIMATION B"); }));
a.Commit(img, "animation", 16, 2000, Easing.Linear, (d, f) => img.Scale = 1.0, () =>
{
System.Diagnostics.Debug.WriteLine("ANIMATION ALL");
return true;
});
}
}
After running the app for a few seconds, the following debug output is printed:
ANIMATION A
ANIMATION B
ANIMATION ALL
ANIMATION ALL
ANIMATION ALL
I am testing this as a UWP.

Answer 1

According to this thread on the Xamarin forums, others seem to be have the same issue. It seems related to a private property being set in each of the sub-animations.
A workaround is to recreate the animation chain each time the chain completes:
public class WelcomePage : ContentPage
{
Image img;
public WelcomePage()
{
img = new Image
{
Source = "circle_plus.png",
HorizontalOptions = LayoutOptions.Center,
VerticalOptions = LayoutOptions.Center,
};
Content = new StackLayout
{
VerticalOptions = LayoutOptions.Center,
Children = {
img
}
};
}
protected override void OnAppearing()
{
base.OnAppearing();
animate();
}
void animate()
{
var a = new Animation();
a.Add(0, 0.5, new Animation((v) =>
{
img.Scale = v;
}, 1.0, 1.2, Easing.CubicInOut, () => { System.Diagnostics.Debug.WriteLine("ANIMATION A"); }));
a.Add(0.5, 1, new Animation((v) =>
{
img.Scale = v;
}, 1.2, 1.0, Easing.CubicInOut, () => { System.Diagnostics.Debug.WriteLine("ANIMATION B"); }));
a.Commit(img, "animation", 16, 2000, null, (d, f) =>
{
img.Scale = 1.0;
System.Diagnostics.Debug.WriteLine("ANIMATION ALL");
animate();
});
}
}