Lottie framework implementation principle analysis: vector animation tool in the Java class library

Lottie is a powerful vector animation tool that is developed and open source by Airbnb. It can convert the Adobe After Effects animation file created by the designer into a format that can be played on the mobile and web.The implementation principle of the Lottie framework is relatively complicated, and it will be parsed below. The Lottie framework mainly includes three components: parser, rendering and animation engine. 1. Analyst: Lottie uses a parser to analyze Adobe After Effects Animation Files (.json format) and convert it to the data structure that can be recognized by the Lottie framework.The parser will traverse the hierarchical structure in the JSON file to obtain the timeline information, layer attributes and key frame data of the animation. 2. Rendezer: The Lottie framework provides multiple renderers to display vector animation on different platforms.For example, Lottie on the Android platform supports Canvas renderers and hardware acceleration renderers, and the Core Animation renderer is used on the iOS platform.These renderers convert the analysis of the animation data structures into the image drawing instructions on the specific platform to show the animation effect. 3. Animation engine: A high -performance animation engine is realized inside the Lottie framework. It drives the playback of animation based on timeline information and key frame data.The animation engine is responsible for calculating the value of each attribute based on the progress of the animation timeline, and applies it to the layer on the renderer to achieve the playback effect of the animation.In addition, the animation engine supports the interactive control of animation, allowing developers to control the playback, suspension, and cycle according to the user's gestures or other trigger events. Below is a simple Java code example to demonstrate how to load and play vector animation on the Android platform. import com.airbnb.lottie.LottieAnimationView; public class MainActivity extends AppCompatActivity { private LottieAnimationView animationView; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); animationView = findViewById(R.id.animation_view); animationView.Setanimation ("Animation.json"); // Set animation files animationView.loop (true); // Set loop playback animationView.playanimation (); // Play animation } @Override protected void onPause() { super.onPause(); animationView.cancelanimation (); // Cancel animation playback when the page is suspended } } In the above code, we first added a LotTieanimationView to the XML layout file to show vector animation.Then, in the Java code, we set up an animated file called "Animation.json" by calling the Setanimation method.Then, we set up the attributes of the circular playback and called the Playanimation method to start the animation. In summary, the Lottie framework converts Adobe After Effects animation files to the data structure available to the Lottie framework, and then uses the renderer to display vector animation on each platform and drive the animation playback through the animation engine.Such a design allows developers to easily achieve exquisite vector animation effects on the mobile and web.