使用ValueAnimator作曲线运动，抛物线、正弦、心形线

作抛物线运动：

运动曲线：y=x^2/1000

ValueAnimator animation = ValueAnimator.ofFloat(0f, 800f);
    animation.setDuration(2000);
    animation.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
        @Override
        public void onAnimationUpdate(ValueAnimator animation) {
            
            float translateX=(float)animation.getAnimatedValue();
            
            //y=x^2/1000
            mText.setTranslationX(translateX);
            mText.setTranslationY((2*translateX*translateX/1000));
        }
    });
    animation.start();

作正弦线运动：

运动曲线：y=400*sin(x/100)

ObjectAnimator objectAnimator=ObjectAnimator.ofObject(new TextHolder(mText1),
    "xY",
    new SineTypeEvaluator(),
    new XYHolder(0f,400f),
    new XYHolder(628f,400f));
    
objectAnimator.setDuration(2000);
objectAnimator.start();

TextHolder：

private class TextHolder{

    private TextView view;

    public TextHolder(TextView textView){
        view=textView;
    }

    public XYHolder getXY() {
        return new XYHolder(view.getX(),view.getY());
    }

    public void setXY(XYHolder xyHolder) {
        view.setX(xyHolder.getX());
        view.setY(xyHolder.getY());
    }
}

SineTypeEvaluator：

public class SineTypeEvaluator implements TypeEvaluator<XYHolder> {

    @Override
    public XYHolder evaluate(float fraction, XYHolder startValue, XYHolder endValue) {
        float xHolder=startValue.getX()+fraction*(endValue.getX()-startValue.getX());
        float yHolder=(float) (300*Math.sin(xHolder/100)+endValue.getY());
        return new XYHolder(xHolder,yHolder );
    }
}

作心形曲线运动：

运动曲线：

x=a*(2cos(t)-cos(2t));

y=a*(2sin(t)-sin(2t));

变换为：

y=a*(-2cos(t)+cos(2t));

x=a*(-2sin(t)+sin(2t));

ValueAnimator animation = ValueAnimator.ofInt(0, 360);
    animation.setDuration(6000);
    animation.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
        @Override
        public void onAnimationUpdate(ValueAnimator animation) {
            int angle=(int)animation.getAnimatedValue();
            //x=a*(2*cos(t)-cos(2*t));
            //y=a*(2*sin(t)-sin(2*t))
            //变换
            //y=a*(-2*cos(t)+cos(2*t));
            //x=a*(-2*sin(t)+sin(2*t))
            double t=2*3.14/360*angle;//弧度制
            mText2.setTranslationY((float) (100*(-2*Math.cos(t)+Math.cos(2*t))));
            mText2.setTranslationX((float) (100*(-2*Math.sin(t)+Math.sin(2*t))));
        }
    });
    animation.start();

fengfancky/PropertyValueAnim

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