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GestureDetector.OnGestureListener onScroll()

2015-06-04 17:05 477 查看


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

Added in API level 1

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

Parameters
e1The first down motion event that started the scrolling.
e2The move motion event that triggered the current onScroll.
distanceXThe distance along the X axis that has been scrolled since the last call to onScroll. This is NOT the distance between 
e1
and
e2
.
distanceYThe 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 按下时的Event

e2 每次触发onScroll函数得到的的Event

distance是上一次的e2减去 当前e2得到的结果

定义一个变量，记录e2最后一次的X方向距离

float lastDistanceX;


<span style="color:#ffffff;">
</span>


手指按下时记录lastDistanceX的位置

<span style="white-space:pre">		</span>/**
		 * 在按下动作时被调用
		 */
		@Override
		public boolean onDown(MotionEvent e)
		{
			Log.d("tag", "onDown---" + getActionName(e.getAction()));
			lastDistanceX=e.getX();
			return true;
		}


@Override
		public boolean onScroll(MotionEvent e1, MotionEvent e2, float distanceX, float distanceY)
		{
			Log.d("pingcoo", "onScroll----->"+(lastDistanceX-e2.getX())+"    distanceX="+distanceX);
			lastDistanceX=e2.getX();
			return true;
		}


运行结果

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