说说GestureDetector.OnGestureListener onScroll函数-白红宇

public abstract boolean onScroll ( e1, e2, float distanceX, float distanceY)

Since:

Notified when a scroll occurs with the initial on down and the current move . The distance in x and y is also supplied for convenience.

Parameters

e1	The first down motion event that started the scrolling.
e2	The move motion event that triggered the current onScroll.
distanceX	The distance along the X axis that has been scrolled since the last call to onScroll. This is NOT the distance between `e1` and `e2`.
distanceY	The distance along the Y axis that has been scrolled since the last call to onScroll. This is NOT the distance between `e1` and `e2`.

Returns

true if the event is consumed, else false

e1 初次触控地图的event1 down事件

e2 每次触发onScroll函数得到的的event2 最后一次move事件

distance是上一次的event2 减去当前event2得到的结果 //注意到顺序

lastEvent2 - event2 = distance

验证：

[java]
if (lastE2 != null){  
    Log.i(TAG, "distanceX:" + distanceX + " = " + (lastE2.getX()-e2.getX()));   
    Log.i(TAG, "distanceY:" + distanceY + " = " + (lastE2.getY()-e2.getY()));   
}  
lastE2 = MotionEvent.obtain(e2);  

本文转自一点点征服博客园博客，原文链接：

http://www.cnblogs.com/ldq2016/p/7000315.html

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