BallScaleMultipleIndicator.java

package com.github.jdsjlzx.progressindicator.indicators;

import android.animation.ValueAnimator;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.view.animation.LinearInterpolator;

import com.github.jdsjlzx.progressindicator.Indicator;

import java.util.ArrayList;

/**
 * Created by Jack on 2015/10/19.
 */
public class BallScaleMultipleIndicator extends Indicator {

    float[] scaleFloats=new float[]{1,1,1};
    int[] alphaInts=new int[]{255,255,255};

    @Override
    public void draw(Canvas canvas, Paint paint) {
        float circleSpacing=4;
        for (int i = 0; i < 3; i++) {
            paint.setAlpha(alphaInts[i]);
            canvas.scale(scaleFloats[i],scaleFloats[i],getWidth()/2,getHeight()/2);
            canvas.drawCircle(getWidth()/2,getHeight()/2,getWidth()/2-circleSpacing,paint);
        }
    }

    @Override
    public ArrayList<ValueAnimator> onCreateAnimators() {
        ArrayList<ValueAnimator> animators=new ArrayList<>();
        long[] delays=new long[]{0, 200, 400};
        for (int i = 0; i < 3; i++) {
            final int index=i;
            ValueAnimator scaleAnim= ValueAnimator.ofFloat(0,1);
            scaleAnim.setInterpolator(new LinearInterpolator());
            scaleAnim.setDuration(1000);
            scaleAnim.setRepeatCount(-1);
            addUpdateListener(scaleAnim,new ValueAnimator.AnimatorUpdateListener() {
                @Override
                public void onAnimationUpdate(ValueAnimator animation) {
                    scaleFloats[index] = (float) animation.getAnimatedValue();
                    postInvalidate();
                }
            });
            scaleAnim.setStartDelay(delays[i]);

            ValueAnimator alphaAnim= ValueAnimator.ofInt(255,0);
            alphaAnim.setInterpolator(new LinearInterpolator());
            alphaAnim.setDuration(1000);
            alphaAnim.setRepeatCount(-1);
            addUpdateListener(alphaAnim,new ValueAnimator.AnimatorUpdateListener() {
                @Override
                public void onAnimationUpdate(ValueAnimator animation) {
                    alphaInts[index] = (int) animation.getAnimatedValue();
                    postInvalidate();
                }
            });
            scaleAnim.setStartDelay(delays[i]);

            animators.add(scaleAnim);
            animators.add(alphaAnim);
        }
        return animators;
    }

}