Animation随记

Animation是所有动画（scale,alpha,translate,rotate）的基类，它所具有的标签和对应函数为：
android：duration         setDuration(long) 动画持续时间，以毫秒为单位
android：fillAfter        setFillAfter(boolean) 如果设置为true，控件动画结束时，将保持动画最后时的状态
android:fillBefore        setFillBefore(boolean)    如果设置为true,控件动画结束时，还原到开始动画前的状态
android:fillEnabled       setFillEnabled(boolean)   与android:fillBefore 效果相同，都是在动画结束时，将控件还原到初始化状态
android:repeatCount       setRepeatCount(int)   重复次数
android:repeatMode        setRepeatMode(int)    重复类型，有reverse和restart两个值，取值为RESTART或 REVERSE，必须与repeatCount一起使用才能看到效果。因为这里的意义是重复的类型，即回放时的动作。
android:interpolator      setInterpolator(Interpolator) 设定插值器，其实就是指定的动作效果，比如弹跳效果等

最终实现的小球效果：

QQ图片20190328172931.gif

Evaluator 加速器

public class ArgbEvaluator implements TypeEvaluator {
    @Override
    public Object evaluate(float fraction, Object startValue, Object endValue) {
        int startInt = (Integer) startValue;
        int startA = (startInt >> 24)& 0xff;
        int startR = (startInt >> 16) & 0xff;
        int startG = (startInt >> 8) & 0xff;
        int startB = startInt & 0xff;

        int endInt = (Integer) endValue;
        int endA = (endInt >> 24)& 0xff;
        int endR = (endInt >> 16) & 0xff;
        int endG = (endInt >> 8) & 0xff;
        int endB = endInt & 0xff;

        return (int)((startA + (int)(fraction * (endA - startA))) << 24) |
                (int)((startR + (int)(fraction * (endR - startR))) << 16) |
                (int)((startG + (int)(fraction * (endG - startG))) << 8) |
                (int)((startB + (int)(fraction * (endB - startB))));
    }
}

public class PointEvaluator implements TypeEvaluator<Point> {
    @Override
    public Point evaluate(float fraction, Point startValue, Point endValue) {
        int startRadius = startValue.getRadius();
        int endRadius = endValue.getRadius();
        int resultRadius = (int) (startRadius + fraction * (endRadius - startRadius));
        return new Point(resultRadius);
    }
}

ValueAnimator与ObjectAnimator

  ValueAnimator valueAnimator = ValueAnimator.ofObject(new PointEvaluator(), new Point(20), new Point(200));
        valueAnimator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
            @Override
            public void onAnimationUpdate(ValueAnimator animation) {
                mCurrentPoint = (Point) animation.getAnimatedValue();
                postInvalidate();
            }
        });

        valueAnimator.setDuration(1000);
        valueAnimator.setInterpolator(new BounceInterpolator());
        valueAnimator.start();

  ObjectAnimator animator = ObjectAnimator.ofInt(acv,"PointRadius",0,300,100,200);
        animator.setDuration(3000);
        animator.start();

        ObjectAnimator animator2 = ObjectAnimator.ofInt(acv, "CircleBackgroundColor", 0xffff00ff, 0xffffff00, 0xffff00ff);
        animator2.setDuration(3000);
        animator2.setEvaluator(new ArgbEvaluator());
        animator2.start();

public class AnimationCircleView extends View {

    private Context mContext;
    private Paint mPaint;
    private Point mCurrentPoint = new Point(100);
    private int widthSize;
    private int heightSize;
    private int color = getResources().getColor(R.color.color_4fd8f5);


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

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

    public AnimationCircleView(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        this.mContext = context;
    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
        int widthMode = MeasureSpec.getMode(widthMeasureSpec);
        int heightMode = MeasureSpec.getMode(heightMeasureSpec);
        widthSize = MeasureSpec.getSize(widthMeasureSpec);
        heightSize = getMeasuredHeight();
        if (widthMode == MeasureSpec.AT_MOST || widthMode == MeasureSpec.UNSPECIFIED) {
            heightSize = widthSize;
        } else if (widthMode == MeasureSpec.EXACTLY) {

        }

        setMeasuredDimension(widthSize, heightSize);

    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        if (mCurrentPoint != null) {
            mPaint = new Paint();
            mPaint.setAntiAlias(true);
            mPaint.setColor(color);
            mPaint.setStyle(Paint.Style.FILL);
            mPaint.setDither(true);
            canvas.drawCircle(widthSize/2, heightSize/2, mCurrentPoint.getRadius(), mPaint);
        }
    }

    void setPointRadius(int radius){
        mCurrentPoint.setRadius(radius);
        invalidate();
    }

    void setCircleBackgroundColor(int color){
        this.color = color;
        invalidate();
    }

//    public void doAnimation() {
//        ValueAnimator valueAnimator = ValueAnimator.ofObject(new PointEvaluator(), new Point(20), new Point(200));
//        valueAnimator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
//            @Override
//            public void onAnimationUpdate(ValueAnimator animation) {
//                mCurrentPoint = (Point) animation.getAnimatedValue();
//                postInvalidate();
//            }
//        });
//
//        valueAnimator.setDuration(1000);
//        valueAnimator.setInterpolator(new BounceInterpolator());
//        valueAnimator.start();
//    }
}