lottie/src/main/java/com/airbnb/lottie/model/layer/SolidLayer.java

package com.airbnb.lottie.model.layer;

import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.ColorFilter;
import android.graphics.Matrix;
import android.graphics.Paint;
import android.graphics.RectF;
import android.support.annotation.Nullable;

import com.airbnb.lottie.LottieDrawable;
import com.airbnb.lottie.LottieProperty;
import com.airbnb.lottie.animation.keyframe.BaseKeyframeAnimation;
import com.airbnb.lottie.animation.keyframe.ValueCallbackKeyframeAnimation;
import com.airbnb.lottie.value.LottieValueCallback;

public class SolidLayer extends BaseLayer {

  private final RectF rect = new RectF();
  private final Paint paint = new Paint();
  private final Layer layerModel;
  @Nullable private BaseKeyframeAnimation<ColorFilter, ColorFilter> colorFilterAnimation;

  SolidLayer(LottieDrawable lottieDrawable, Layer layerModel) {
    super(lottieDrawable, layerModel);
    this.layerModel = layerModel;

    paint.setAlpha(0);
    paint.setStyle(Paint.Style.FILL);
    paint.setColor(layerModel.getSolidColor());
  }

  @Override public void drawLayer(Canvas canvas, Matrix parentMatrix, int parentAlpha) {
    int backgroundAlpha = Color.alpha(layerModel.getSolidColor());
    if (backgroundAlpha == 0) {
      return;
    }

    int alpha = (int) (parentAlpha / 255f * (backgroundAlpha / 255f * transform.getOpacity().getValue() / 100f) * 255);
    paint.setAlpha(alpha);
    if (colorFilterAnimation != null) {
      paint.setColorFilter(colorFilterAnimation.getValue());
    }
    if (alpha > 0) {
      updateRect(parentMatrix);
      canvas.drawRect(rect, paint);
    }
  }

  @Override public void getBounds(RectF outBounds, Matrix parentMatrix) {
    super.getBounds(outBounds, parentMatrix);
    updateRect(boundsMatrix);
    outBounds.set(rect);
  }

  private void updateRect(Matrix matrix) {
    rect.set(0, 0, layerModel.getSolidWidth(), layerModel.getSolidHeight());
    matrix.mapRect(rect);
  }

  @SuppressWarnings("unchecked")
  @Override
  public <T> void addValueCallback(T property, @Nullable LottieValueCallback<T> callback) {
    super.addValueCallback(property, callback);
    if (property == LottieProperty.COLOR_FILTER) {
      if (callback == null) {
        colorFilterAnimation = null;
      } else {
        colorFilterAnimation =
            new ValueCallbackKeyframeAnimation<>((LottieValueCallback<ColorFilter>) callback);
      }
    }
  }
}