Android 手势识别中的两个默认实现SimpleOnScaleGestureListener、SimpleOnGestureListener

//SimpleOnGestureListener implements OnGestureListener, OnDoubleTapListener
class ZoomGesture extends GestureDetector.SimpleOnGestureListener {//单手指操作

@Override //双击
public boolean onDoubleTap(MotionEvent e) {
System.out.println("--onDoubleTap---");
return true;
}

@Override
public boolean onDoubleTapEvent(MotionEvent e) {
System.out.println("--onDoubleTapEvent---");
return super.onDoubleTapEvent(e);
}
}

//SimpleOnScaleGestureListener implements OnScaleGestureListener
class ScaleGesture extends ScaleGestureDetector.SimpleOnScaleGestureListener {//双手指操作

@Override
public boolean onScale(ScaleGestureDetector detector) {
detector.getCurrentSpan();//两点间的距离跨度
detector.getCurrentSpanX();//两点间的x距离
detector.getCurrentSpanY();//两点间的y距离
detector.getFocusX();		//
detector.getFocusY();		//
detector.getPreviousSpan();	//上次
detector.getPreviousSpanX();//上次
detector.getPreviousSpanY();//上次
detector.getEventTime();	//当前事件的事件
detector.getTimeDelta();    //两次事件间的时间差
detector.getScaleFactor();  //与上次事件相比，得到的比例因子

return true;
}

}

private GestureDetector gestureDetector; //手势探测器
private ScaleGestureDetector scaleGestureDetector;//比率手势探测器
...
gestureDetector = new GestureDetector(context, new ZoomGesture());
scaleGestureDetector = new ScaleGestureDetector(context, new ScaleGesture());

public boolean onTouchEvent(MotionEvent event) {
//单点
gestureDetector.onTouchEvent(event);
//双点
scaleGestureDetector.onTouchEvent(event);
return true;
}