lottie/src/main/java/com/airbnb/lottie/PointKeyframeAnimation.java

package com.airbnb.lottie;

import android.graphics.PointF;
import android.view.animation.Interpolator;

import java.util.List;

class PointKeyframeAnimation extends KeyframeAnimation<PointF> {
  private final PointF point = new PointF();
  private final List<PointF> points;

  PointKeyframeAnimation(long duration, LottieComposition composition, List<Float> keyTimes,
      List<PointF> points, List<Interpolator> interpolators) {
    super(duration, composition, keyTimes, interpolators);
    this.points = points;
  }

  @Override public PointF getValue() {
    if (progress <= 0f) {
      return points.get(0);
    } else if (progress > 1f) {
      return points.get(points.size() - 1);
    }

    int keyframeIndex = getKeyframeIndex();

    float startKeytime = keyTimes.get(keyframeIndex);
    float endKeytime = keyTimes.get(keyframeIndex + 1);

    float percentageIntoFrame = 0;
    if (!isDiscrete) {
      percentageIntoFrame = (progress - startKeytime) / (endKeytime - startKeytime);
      if (interpolators != null) {
        percentageIntoFrame =
            interpolators.get(keyframeIndex).getInterpolation(percentageIntoFrame);
      }
    }

    PointF startPoint = points.get(keyframeIndex);
    PointF endPoint = points.get(keyframeIndex + 1);

    point.set(startPoint.x + percentageIntoFrame * (endPoint.x - startPoint.x),
        startPoint.y + percentageIntoFrame * (endPoint.y - startPoint.y));
    return point;
  }
}