cavas效果实例六个小球旋转聚合 再水波纹扩散

1，colors.xml

    #008577
    #00574B
    #D81B60

    #F8F6EC
    #FF9600
    #02D1AC
    #FFD200
    #00C6FF
    #00E099
    #FF3892

    
        @color/blue
        @color/green
        @color/pink
        @color/orange
        @color/aqua
        @color/yellow
    

2，activity_main.xml 背景图片自己随意插吧 我就不上了

3，SplashView自定义View

public class SplashView extends View {

    //旋转圆的画笔
    private Paint mPaint;
    //扩散圆的画笔
    private Paint mHolePaint;
    //属性动画
    private ValueAnimator mValueAnimator;

    //背景色
    private int mBackgroundColor = Color.WHITE;
    private int[] mCircleColors;

    //表示旋转圆的中心坐标
    private float mCenterX;
    private float mCenterY;
    //表示斜对角线长度的一半,扩散圆最大半径
    private float mDistance;

    //6个小球的半径
    private float mCircleRadius = 18;
    //旋转大圆的半径
    private float mRotateRadius = 90;

    //当前大圆的旋转角度
    private float mCurrentRotateAngle = 0F;
    //当前大圆的半径
    private float mCurrentRotateRadius = mRotateRadius;
    //扩散圆的半径
    private float mCurrentHoleRadius = 0F;
    //表示旋转动画的时长
    private int mRotateDuration = 1200;

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

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

    private void init(Context context) {

        mPaint = new Paint(Paint.ANTI_ALIAS_FLAG);

        mHolePaint = new Paint(Paint.ANTI_ALIAS_FLAG);
        mHolePaint.setStyle(Paint.Style.STROKE);
        mHolePaint.setColor(mBackgroundColor);

        mCircleColors = context.getResources().getIntArray(R.array.splash_circle_colors);
    }

    @Override
    protected void onSizeChanged(int w, int h, int oldw, int oldh) {
        super.onSizeChanged(w, h, oldw, oldh);
        mCenterX = w * 1f / 2;
        mCenterY = h * 1f / 2;
        mDistance = (float) (Math.hypot(w, h) / 2);
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        if (mState == null) {
            mState = new RotateState();
        }
        mState.drawState(canvas);
    }

    private SplashState mState;

    private abstract class SplashState {
        abstract void drawState(Canvas canvas);
    }

    //1.旋转
    private class RotateState extends SplashState {

        private RotateState() {
            //以下是让小球转起来  启动属性动画
            mValueAnimator = ValueAnimator.ofFloat(0, (float) (Math.PI * 2));
            mValueAnimator.setRepeatCount(2);
            mValueAnimator.setDuration(mRotateDuration);
            mValueAnimator.setInterpolator(new LinearInterpolator());
            mValueAnimator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
                @Override
                public void onAnimationUpdate(ValueAnimator animation) {
                    mCurrentRotateAngle = (float) animation.getAnimatedValue();
                    invalidate();
                }
            });
            mValueAnimator.addListener(new AnimatorListenerAdapter() {
                @Override
                public void onAnimationEnd(Animator animation) {
                    super.onAnimationEnd(animation);
                    mState = new MerginState();
                }
            });
            mValueAnimator.start();
        }

        @Override
        void drawState(Canvas canvas) {
            //绘制背景
            drawBackground(canvas);
            //绘制6个小球
            drawCircles(canvas);
        }
    }

    private void drawCircles(Canvas canvas) {
        //两小球之间的角度
        float rotateAngle = (float) (Math.PI * 2 / mCircleColors.length);
        for (int i = 0; i < mCircleColors.length; i++) {
            // x = r * cos(a) + centX;
            // y = r * sin(a) + centY;
            float angle = i * rotateAngle + mCurrentRotateAngle;
            float cx = (float) (Math.cos(angle) * mCurrentRotateRadius + mCenterX);
            float cy = (float) (Math.sin(angle) * mCurrentRotateRadius + mCenterY);
            mPaint.setColor(mCircleColors[i]);
            canvas.drawCircle(cx, cy, mCircleRadius, mPaint);
        }
    }

    private void drawBackground(Canvas canvas) {
        if (mCurrentHoleRadius > 0) {
            //绘制空心圆
            float strokeWidth = mDistance - mCurrentHoleRadius;
            float radius = strokeWidth / 2 + mCurrentHoleRadius;
            mHolePaint.setStrokeWidth(strokeWidth);
            canvas.drawCircle(mCenterX, mCenterY, radius, mHolePaint);
        } else {
            canvas.drawColor(mBackgroundColor);
        }
    }

    //2.扩散聚合
    private class MerginState extends SplashState {

        private MerginState() {
            mValueAnimator = ValueAnimator.ofFloat(mCircleRadius, mRotateRadius);
//            mValueAnimator.setRepeatCount(2);
            mValueAnimator.setDuration(mRotateDuration);
            mValueAnimator.setInterpolator(new OvershootInterpolator(10f));
            mValueAnimator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
                @Override
                public void onAnimationUpdate(ValueAnimator animation) {
                    mCurrentRotateRadius = (float) animation.getAnimatedValue();
                    invalidate();
                }
            });
            mValueAnimator.addListener(new AnimatorListenerAdapter() {
                @Override
                public void onAnimationEnd(Animator animation) {
                    super.onAnimationEnd(animation);
                    mState = new ExpandState();
                }
            });
            mValueAnimator.reverse();
        }

        @Override
        void drawState(Canvas canvas) {
            drawBackground(canvas);
            drawCircles(canvas);
        }
    }

    //3.水波纹
    private class ExpandState extends SplashState {

        public ExpandState() {
            mValueAnimator = ValueAnimator.ofFloat(mCircleRadius, mDistance);
//            mValueAnimator.setRepeatCount(2);
            mValueAnimator.setDuration(mRotateDuration);
            mValueAnimator.setInterpolator(new LinearInterpolator());
            mValueAnimator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
                @Override
                public void onAnimationUpdate(ValueAnimator animation) {
                    mCurrentHoleRadius = (float) animation.getAnimatedValue();
                    invalidate();
                }
            });

            mValueAnimator.start();
        }

        @Override
        void drawState(Canvas canvas) {
            drawBackground(canvas);
        }
    }
}

4，MainActivity

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
    }
}