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();