import android.animation.ValueAnimator;

import android.content.Context;

import android.graphics.Canvas;

import android.graphics.Color;

import android.graphics.Paint;

import android.support.annotation.Nullable;

import android.util.AttributeSet;

import android.view.View;

import android.view.animation.LinearInterpolator;

import net.wt.gate.dev.libs.log.L;

import java.util.concurrent.CopyOnWriteArrayList;

public class DoorBellAnimal extends View {

    private int centerX;

    private int centerY;

    private int startRadius = 10;

    private int endRadius = 250;

    private int startAlpha = 250;

    private CopyOnWriteArrayList<RippleCircle> rippleCircles = new CopyOnWriteArrayList<>();

    public DoorBellAnimal(Context context) {

        this(context, null);

    }

    public DoorBellAnimal(Context context, @Nullable AttributeSet attrs) {

        this(context, attrs, 0);

    }

    public DoorBellAnimal(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {

        super(context, attrs, defStyleAttr);

    }

    @Override

    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {

        super.onMeasure(widthMeasureSpec, heightMeasureSpec);

        int width = MeasureSpec.getSize(widthMeasureSpec);

        int height = MeasureSpec.getSize(heightMeasureSpec);

        centerX = width / 2;

        centerY = height / 2;

        setMeasuredDimension(widthMeasureSpec, heightMeasureSpec);

    }

    @Override

    protected void onDraw(Canvas canvas) {

        super.onDraw(canvas);

        for (RippleCircle circle : rippleCircles) {

            circle.draw(canvas);

        }

    }

    @Override

    protected void onAttachedToWindow() {

        super.onAttachedToWindow();

        startRipple();

        startAnimal();

    }

    private void startRipple() {

        postOnAnimationDelayed(() -> {

            RippleCircle rippleCircle = new RippleCircle();

            rippleCircles.add(rippleCircle);

            startRipple();

        }, 500);

    }

    private ValueAnimator valueAnimator;

    @Override

    protected void onDetachedFromWindow() {

        super.onDetachedFromWindow();

        valueAnimator.cancel();

        valueAnimator.end();

    }

    private void startAnimal() {

        valueAnimator = ValueAnimator.ofInt(0, 60);

        valueAnimator.setInterpolator(new LinearInterpolator());

        valueAnimator.setDuration(3000);

        valueAnimator.setRepeatCount(ValueAnimator.INFINITE);

        valueAnimator.setRepeatMode(ValueAnimator.RESTART);

        valueAnimator.addUpdateListener(animation -> postInvalidateOnAnimation());

        valueAnimator.start();

    }

    /**

     * 需要画的 圆圈，需要不断改变半径何透明度

     */

    private class RippleCircle {

        private Paint paint;            //画笔

        private int progress;       //当前进度

        private int perRadius = (endRadius - startRadius) / 60;

        private int perAlpha = startAlpha / 60;

        RippleCircle() {

            paint = new Paint(Paint.ANTI_ALIAS_FLAG);

            paint.setColor(Color.WHITE);

            progress = 0;

        }

        void draw(Canvas canvas) {

            if (paint == null) {

                return;

            }

            if (progress >= 60) {

                rippleCircles.remove(this);

                return;

            }

            progress++;

            float currentAlpha = startAlpha - perAlpha * progress;

            paint.setAlpha((int) (currentAlpha));       //更改透明度

            float current = startRadius + perRadius * progress;

            canvas.drawCircle(centerX, centerY, current, paint);

        }

    }

}