ViewPager检测当用户试图刷出界 [英] ViewPager detect when user is trying to swipe out of bounds

问题描述

我使用的包括6页的ViewPager显示一些数据。我希望能够当用户在位置0，并试图向右滑动（向后），或5位，并试图刷卡向左（向前）来调用一个方法，即使这些没有更多的网页存在方向。有什么办法，我可以听这些情况？

I am using the ViewPager consisting of 6 pages to display some data. I want to be able to call a method when the user is at position 0 and tries to swipe to the right (backwards), or at position 5 and tries to swipe to the left (forward), even though no more pages exist for these directions. Is there any way I can listen for these scenarios?

推荐答案

扩展ViewPager并覆盖 onInterceptTouchEvent（）是这样的：

Extend ViewPager and override onInterceptTouchEvent() like this:

public class CustomViewPager extends ViewPager {

    float mStartDragX;
    OnSwipeOutListener mListener;


    public void setOnSwipeOutListener(OnSwipeOutListener listener) {
        mListener = listener;
    }


    @Override
    public boolean onInterceptTouchEvent(MotionEvent ev) {
        float x = ev.getX();
        switch (ev.getAction()) {
        case MotionEvent.ACTION_DOWN:
            mStartDragX = x;
            break;
        case MotionEvent.ACTION_MOVE:
            if (mStartDragX < x && getCurrentItem() == 0) {
                mListener.onSwipeOutAtStart();
            } else if (mStartDragX > x && getCurrentItem() == getAdapter().getCount() - 1) {
                mListener.onSwipeOutAtEnd();
            }
            break;
        }
        return super.onInterceptTouchEvent(ev);
    }

    public interface OnSwipeOutListener {
        public void onSwipeOutAtStart();
        public void onSwipeOutAtEnd();
    }

}

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