LottieXamarin

Lottie is a mobile library for Android and iOS that parses Adobe After Effects animations exported as json with Bodymovin and renders them natively on mobile!

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Android: iOS: Xamarin.Forms:

For the first time, designers can create and ship beautiful animations without an engineer painstakingly recreating it by hand. They say a picture is worth 1,000 words so here are 13,000:

All of these animations were created in After Effects, exported with Bodymovin, and rendered natively with no additional engineering effort.

Bodymovin is an After Effects plugin created by Hernan Torrisi that exports After effects files as json and includes a javascript web player. We've built on top of his great work to extend its usage to Android, iOS, and React Native.

Read more about it on our blog post Or get in touch on Twitter (gpeal8) or via lottie@airbnb.com

Sample App

You can build the sample app yourself or download it from the Play Store. The sample app includes some built in animations but also allows you to load an animation from internal storage or from a url.

Using Lottie for Xamarin.Forms

A normal sample is:

<forms:AnimationView
    x:Name="animationView"
    Animation="LottieLogo1.json"
    AnimationSource="AssetOrBundle"
    Command="{Binding ClickCommand}"
    VerticalOptions="FillAndExpand"
    HorizontalOptions="FillAndExpand" />

All possible options are:

<forms:AnimationView 
    x:Name="animationView"
    Animation="LottieLogo1.json"
    AnimationSource="AssetOrBundle"
    AutoPlay="True"
    CacheComposition="True"
    Clicked="animationView_Clicked"
    Command="{Binding ClickCommand}"
    FallbackResource="{Binding Image}"
    ImageAssetsFolder="Assets/lottie"
    IsAnimating="{Binding IsAnimating}"
    MaxFrame="100"
    MaxProgress="100"
    MinFrame="0"
    MinProgress="0"
    OnAnimationLoaded="animationView_OnAnimationLoaded"
    OnAnimationUpdate="animationView_OnAnimationUpdate"
    OnFailure="animationView_OnFailure"
    OnFinishedAnimation="animationView_OnFinishedAnimation"
    OnPauseAnimation="animationView_OnPauseAnimation"
    OnPlayAnimation="animationView_OnPlayAnimation"
    OnRepeatAnimation="animationView_OnRepeatAnimation"
    OnResumeAnimation="animationView_OnResumeAnimation"
    OnStopAnimation="animationView_OnStopAnimation"
    Progress="{Binding Progress}"
    RepeatCount="3"
    RepeatMode="Restart"
    Scale="1"
    Speed="1"
    VerticalOptions="FillAndExpand"
    HorizontalOptions="FillAndExpand" />

Using Lottie for Xamarin Android

Lottie supports Ice Cream Sandwich (API 14) and above. The simplest way to use it is with LottieAnimationView:

<com.airbnb.lottie.LottieAnimationView
        android:id="@+id/animation_view"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        app:lottie_fileName="hello-world.json"
        app:lottie_loop="true"
        app:lottie_autoPlay="true" />

Or you can load it programatically in multiple ways. From a json asset in app/src/main/assets:

LottieAnimationView animationView = FindViewById<LottieAnimationView>(Resource.Id.animation_view);
animationView.SetAnimation("hello-world.json");
animationView.Loop = true;

This method will load the file and parse the animation in the background and asynchronously start rendering once completed.

If you want to reuse an animation such as in each item of a list or load it from a network request JSONObject:

 LottieAnimationView animationView = FindViewById<LottieAnimationView>(Resource.Id.animation_view);
 ...
 LottieComposition composition = LottieComposition.Factory.FromJson(Resources, jsonObject, (composition) => 
 {
     animationView.SetComposition(composition);
     animationView.PlayAnimation();
 });

You can then control the animation or add listeners:

animationView.AddAnimatorUpdateListener(animationListener);
animationView.PlayAnimation();
...
if (animationView.IsAnimating) 
{
    // Do something.
}
...
animationView.Progress = 0.5f;
...
// Custom animation speed or duration.
ValueAnimator animator = ValueAnimator.OfFloat(0f, 1f).SetDuration(500);
animator.Update += (sender, e) => animationView.Progress = (float)e.Animation.AnimatedValue;
animator.Start();
...
animationView.CancelAnimation();

Under the hood, LottieAnimationView uses LottieDrawable to render its animations. If you need to, you can use the the drawable form directly:

LottieDrawable drawable = new LottieDrawable();
LottieComposition.Factory.FromAssetFileName(Context, "hello-world.json", (composition) => {
    drawable.SetComposition(composition);
});

If your animation will be frequently reused, LottieAnimationView has an optional caching strategy built in. Use LottieAnimationView#SetAnimation(String, CacheStrategy). CacheStrategy can be Strong, Weak, or None to have LottieAnimationView hold a strong or weak reference to the loaded and parsed animation.

You can also use the awaitable version of LottieComposition's asynchronous methods:

var composition = await LottieComposition.Factory.FromAssetFileNameAsync(this.Context, assetName);
..
var composition = await LottieComposition.Factory.FromJsonAsync(Resources, jsonObject);
...
var composition = await LottieComposition.Factory.FromInputStreamAsync(this.Context, stream);

Image Support

You can animate images if your animation is loaded from assets and your image file is in a subdirectory of assets. Just call SetImageAssetsFolder on LottieAnimationView or LottieDrawable with the relative folder inside of assets and make sure that the images that bodymovin export are in that folder with their names unchanged (should be img_#). If you use LottieDrawable directly, you must call RecycleBitmaps when you are done with it.

If you need to provide your own bitmaps if you downloaded them from the network or something, you can provide a delegate to do that:

animationView.SetImageAssetDelegate((LottieImageAsset asset) =>
{
   retun GetBitmap(asset);
});

Using Lottie for Xamarin iOS

Lottie supports iOS 8 and above. Lottie animations can be loaded from bundled JSON or from a URL

The simplest way to use it is with LOTAnimationView:

LOTAnimationView animation = LOTAnimationView.AnimationNamed("LottieLogo1");
this.View.AddSubview(animation);
animation.PlayWithCompletion((animationFinished) => {
  // Do Something
});
//You can also use the awaitable version
//var animationFinished = await animation.PlayAsync();

Or you can load it programmatically from a NSUrl

LOTAnimationView animation = new LOTAnimationView(new NSUrl(url));
this.View.AddSubview(animation);

Lottie supports the iOS UIViewContentModes ScaleAspectFit and ScaleAspectFill

You can also set the animation progress interactively.

CGPoint translation = gesture.GetTranslationInView(this.View);
nfloat progress = translation.Y / this.View.Bounds.Size.Height;
animationView.AnimationProgress = progress;

Want to mask arbitrary views to animation layers in a Lottie View? Easy-peasy as long as you know the name of the layer from After Effects

UIView snapshot = this.View.SnapshotView(afterScreenUpdates: true);
lottieAnimation.AddSubview(snapshot, layer: "AfterEffectsLayerName");

Lottie comes with a UIViewController animation-controller for making custom viewController transitions!

#region View Controller Transitioning
public class LOTAnimationTransitionDelegate : UIViewControllerTransitioningDelegate
{
    public override IUIViewControllerAnimatedTransitioning GetAnimationControllerForPresentedController(UIViewController presented, UIViewController presenting, UIViewController source)
    {
        LOTAnimationTransitionController animationController =
            new LOTAnimationTransitionController(
            animation: "vcTransition1",
            fromLayer: "outLayer",
            toLayer: "inLayer");

        return animationController;
    }

    public override IUIViewControllerAnimatedTransitioning GetAnimationControllerForDismissedController(UIViewController dismissed)
    {
        LOTAnimationTransitionController animationController = 
            new LOTAnimationTransitionController(
                animation: "vcTransition2",
                fromLayer: "outLayer",
                toLayer: "inLayer");

        return animationController;
    } 
}
#endregion

If your animation will be frequently reused, LOTAnimationView has an b