RectangleContent.java

package com.airbnb.lottie;

import android.graphics.Path;
import android.graphics.PointF;
import android.graphics.RectF;
import android.support.annotation.Nullable;

import java.util.List;

class RectangleContent implements PathContent, BaseKeyframeAnimation.AnimationListener {
  private final Path path = new Path();
  private final RectF rect = new RectF();

  private final LottieDrawable lottieDrawable;
  private final BaseKeyframeAnimation<?, PointF> positionAnimation;
  private final BaseKeyframeAnimation<?, PointF> sizeAnimation;
  private final BaseKeyframeAnimation<?, Float> cornerRadiusAnimation;

  @Nullable private TrimPathContent trimPath;
  private boolean isPathValid;

  RectangleContent(LottieDrawable lottieDrawable, BaseLayer layer, RectangleShape rectShape) {
    this.lottieDrawable = lottieDrawable;
    positionAnimation = rectShape.getPosition().createAnimation();
    sizeAnimation = rectShape.getSize().createAnimation();
    cornerRadiusAnimation = rectShape.getCornerRadius().createAnimation();

    layer.addAnimation(positionAnimation);
    layer.addAnimation(sizeAnimation);
    layer.addAnimation(cornerRadiusAnimation);

    positionAnimation.addUpdateListener(this);
    sizeAnimation.addUpdateListener(this);
    cornerRadiusAnimation.addUpdateListener(this);
  }

  @Override public void onValueChanged() {
    invalidate();
  }

  private void invalidate() {
    isPathValid = false;
    lottieDrawable.invalidateSelf();
  }

  @Override public void setContents(List<Content> contentsBefore, List<Content> contentsAfter) {
    for (int i = 0; i < contentsBefore.size(); i++) {
      Content content = contentsBefore.get(i);
      if (content instanceof TrimPathContent) {
        trimPath = (TrimPathContent) content;
        trimPath.addListener(this);
      }
    }
  }

  @Override public Path getPath() {
    if (isPathValid) {
      return path;
    }

    path.reset();

    PointF size = sizeAnimation.getValue();
    float halfWidth = size.x / 2f;
    float halfHeight = size.y / 2f;
    float radius = cornerRadiusAnimation == null ? 0f : cornerRadiusAnimation.getValue();
    float maxRadius = Math.min(halfWidth, halfHeight);
    if (radius > maxRadius) {
      radius = maxRadius;
    }

    // Draw the rectangle top right to bottom left.
    PointF position = positionAnimation.getValue();

    path.moveTo(position.x + halfWidth, position.y - halfHeight + radius);

    path.lineTo(position.x + halfWidth, position.y + halfHeight - radius);

    if (radius > 0) {
      rect.set(position.x + halfWidth - 2 * radius,
          position.y + halfHeight - 2 * radius,
          position.x + halfWidth,
          position.y + halfHeight);
      path.arcTo(rect, 0, 90, false);
    }

    path.lineTo(position.x - halfWidth + radius, position.y + halfHeight);

    if (radius > 0) {
      rect.set(position.x - halfWidth,
          position.y + halfHeight - 2 * radius,
          position.x - halfWidth + 2 * radius,
          position.y + halfHeight);
      path.arcTo(rect, 90, 90, false);
    }

    path.lineTo(position.x - halfWidth, position.y - halfHeight + 2 * radius);

    if (radius > 0) {
      rect.set(position.x - halfWidth,
          position.y - halfHeight,
          position.x - halfWidth + 2 * radius,
          position.y - halfHeight + 2 * radius);
      path.arcTo(rect, 180, 90, false);
    }

    path.lineTo(position.x + halfWidth - 2 * radius, position.y - halfHeight);

    if (radius > 0) {
      rect.set(position.x + halfWidth - 2 * radius,
          position.y - halfHeight,
          position.x + halfWidth,
          position.y - halfHeight + 2 * radius);
      path.arcTo(rect, 270, 90, false);
    }
    path.close();

    Utils.applyTrimPathIfNeeded(path, trimPath);

    isPathValid = true;
    return path;
  }
}