Android实现仿微软系统加载动画效果

package com.sjl.keeplive.track;

import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.PointF;

public class Circle {
    private PointF center;
    private float radius;

    public Circle() {
        center = new PointF();
    }

    /**
     * 设置圆球半径
     */
    public void setRadius(float radius) {
        this.radius = radius;
    }

    /**
     * 设置中心点
     *
     * @param x
     * @param y
     */
    public void setCenter(float x, float y) {
        center.set(x, y);
    }

    public void draw(Canvas canvas, Paint paint) {
        canvas.drawCircle(center.x,center.y,radius,paint);
    }
}

package com.sjl.keeplive.track;

import android.animation.ValueAnimator;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.PointF;
import android.support.annotation.Nullable;
import android.util.AttributeSet;
import android.view.View;

public class MinSoftLoadingView extends View {
    private int circleCount = 5;
    private Circle[] circles;
    private Paint paint;
    private int width;
    private int height;
    private PointF center;
    private float circleRadius;
    private float[] rotates;
    private float roateRadius;

    public MinSoftLoadingView(Context context) {
        this(context, null);
    }

    public MinSoftLoadingView(Context context, @Nullable AttributeSet attrs) {
        this(context, attrs, 0);
    }

    public MinSoftLoadingView(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        paint = new Paint();
        paint.setAntiAlias(true);
        paint.setColor(Color.WHITE);
        //每个点旋转的角度
        rotates = new float[circleCount];
    }

    @Override
    protected void onLayout(boolean changed, int left, int top, int right, int bottom) {
        super.onLayout(changed, left, top, right, bottom);
        width = getWidth();
        height = getHeight();
        center = new PointF(width / 2.0f, height / 2.0f);
        //旋转扫描半径
        roateRadius = Math.min(width, height);
        //圆球最大的那个半径
        circleRadius = roateRadius / 10.0f;
        initCircle();
    }

    /**
     * 初始化5个圆球
     */
    private void initCircle() {
        circles = new Circle[circleCount];
        for (int i = 0; i < circleCount; i++) {
            circles[i] = new Circle();
            circles[i].setCenter(center.x, center.y - roateRadius / 2 + circleRadius);
            circles[i].setRadius(circleRadius - circleRadius * i / 5);
        }
        //开始执行动画
        startAnimation();
    }

    private void startAnimation() {
        for (int i = 0; i < circleCount; i++) {
            final int index = i;
            ValueAnimator animator = ValueAnimator.ofFloat(0, 360);
            animator.setRepeatCount(ValueAnimator.INFINITE);//重复
            animator.setDuration(2000);
            animator.setStartDelay(index * 100); //每一个随后的延迟时间
            animator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
                @Override
                public void onAnimationUpdate(ValueAnimator animation) {
                    rotates[index] = (float) animation.getAnimatedValue();
                    invalidate();
                }
            });
            animator.start();
        }
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        for (int i = 0; i < circleCount; i++) {
            canvas.save();
            canvas.rotate(rotates[i], center.x, center.y);
            circles[i].draw(canvas, paint);
            canvas.restore();
        }
    }
}

<com.sjl.keeplive.track.MinSoftLoadingView
        android:layout_width="60dp"
        android:layout_height="60dp"
        android:layout_gravity="center"/>