在自定义虚线进度视图中淡出点

Question

我创建了一个自定义虚线进度视图，其中3个点受到@Naveen Shriyan在此问题中的回答How to make custom dotted progress bar in android?

public class DottedProgressView extends View {

//actual dot radius
private int mDotRadius = 25;
private Paint paint = new Paint();

//Bounced Dot Radius
private int mBounceDotRadius = 25;

//to get identified in which position dot has to bounce
private int  mDotPosition;

//specify how many dots you need in a progressbar
private int mDotAmount = 3;

public DottedProgressView(Context context) {
    super(context);
}

public DottedProgressView(Context context, AttributeSet attrs) {
    super(context, attrs);
}

public DottedProgressView(Context context, AttributeSet attrs, int defStyleAttr) {
    super(context, attrs, defStyleAttr);
}

@Override
protected void onDraw(Canvas canvas) {
    super.onDraw(canvas);
    //function to create dot
    createDot(canvas,paint);
}

@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
    super.onMeasure(widthMeasureSpec, heightMeasureSpec);
    int width;
    int height;

    //calculate the view width
    int calculatedWidth = (75*3);

    width = calculatedWidth;
    height = (mDotRadius*2+10);

    //MUST CALL THIS
    setMeasuredDimension(width, height);
}

@Override
protected void onAttachedToWindow() {
    super.onAttachedToWindow();
    startAnimation();
}

private void createDot(Canvas canvas, Paint paint) {
    //here i have setted progress bar with 10 dots , so repeat and wnen i = mDotPosition  then increase the radius of dot i.e mBounceDotRadius
    for(int i = 0; i < mDotAmount; i++ ){
        if(i == mDotPosition){
            paint.setColor(Color.parseColor("#FB8C00"));
            canvas.drawCircle(30+(i*75), mDotRadius, mDotRadius, paint);
        } else if (i == mDotPosition - 1) {
            paint.setColor(Color.parseColor("#FFA726"));
            canvas.drawCircle(30+(i*75), mDotRadius, mDotRadius, paint);
        }
        else {
            paint.setColor(Color.parseColor("#FFE0B2"));
            canvas.drawCircle(30+(i*75), mDotRadius, mDotRadius, paint);
        }
    }
}

private void startAnimation() {
    BounceAnimation bounceAnimation = new BounceAnimation();
    bounceAnimation.setDuration(180);
    bounceAnimation.scaleCurrentDuration(1.5f);
    bounceAnimation.setRepeatCount(Animation.INFINITE);
    bounceAnimation.setInterpolator(new FastOutSlowInInterpolator());
    bounceAnimation.setAnimationListener(new Animation.AnimationListener() {
        @Override
        public void onAnimationStart(Animation animation) {}

        @Override
        public void onAnimationEnd(Animation animation) {}

        @Override
        public void onAnimationRepeat(Animation animation) {
            mDotPosition++;
            //when mDotPosition == mDotAmount , then start again applying animation from 0th positon , i.e  mDotPosition = 0;
            if (mDotPosition == mDotAmount) {
                mDotPosition = 0;
            }

        }
    });
    startAnimation(bounceAnimation);
}


private class BounceAnimation extends Animation {
    @Override
    protected void applyTransformation(float interpolatedTime, Transformation t) {
        super.applyTransformation(interpolatedTime, t);
        //call invalidate to redraw your view againg.
        invalidate();
    }
}

}

我还希望在动画发生时为每个点添加淡出动画，以使3点之间的过渡更加平滑。我怎样才能实现这一目标？