Gallery 内的 ScrollView,两者都独立滚动 [英] ScrollView inside Gallery, both scrolling independently

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问题描述

我有一个带有适配器的 Gallery,它提供 ScrollViews 作为它的子视图.我需要确保按预期正确处理触摸事件:

I have a Gallery with an adapter which supplies it ScrollViews as its child views. I need to make sure that the touch events are handled correctly and as expected:

  1. 当用户水平滚动时,图库也会水平滚动.
  2. 当用户垂直滚动时,滚动视图也会垂直滚动.
  3. 绝不能在同一个手势上进行两次滚动(用户必须抬起手指才能滚动另一个视图).
  4. 一切都必须平滑滚动.

在不覆盖任何方法的情况下,滚动视图是唯一滚动的东西 - 图库从不滚动.

Without overriding any methods, the scroll view is the only thing that scrolls - the gallery never scrolls.

所以我知道我需要在图库中使用 onInterceptTouchEvent(...) 来决定接管某个系列的 MotionEvents,但我不确定如何检查触摸是水平的还是垂直的.

So I understand I need to use onInterceptTouchEvent(...) in the gallery to decide to take over a certain series of MotionEvents but I am unsure how to check if the touch is horizontal or vertical in nature.

推荐答案

好的,经过一些主要的摆弄和 logcat hacking,这里是解决方案:

OK, after some major fiddling and logcat hacking, here's the solution:

public class SwipeInterceptingGallery extends Gallery {

    private float mInitialX;
    private float mInitialY;
    private boolean mNeedToRebase;
    private boolean mIgnore;

    public SwipeInterceptingGallery(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
    }

    public SwipeInterceptingGallery(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    public SwipeInterceptingGallery(Context context) {
        super(context);
    }

    @Override
    public boolean onScroll(MotionEvent e1, MotionEvent e2, float distanceX,
            float distanceY) {
        if (mNeedToRebase) {
            mNeedToRebase = false;
            distanceX = 0;
        }
        return super.onScroll(e1, e2, distanceX, distanceY);
    }

    @Override
    public boolean onInterceptTouchEvent(MotionEvent e) {
        switch (e.getAction()) {
            case MotionEvent.ACTION_DOWN: {
                mIgnore = false;
                mNeedToRebase = true;
                mInitialX = e.getX();
                mInitialY = e.getY();
                return false;
            }

            case MotionEvent.ACTION_MOVE: {
                if (!mIgnore) {
                    float deltaX = Math.abs(e.getX() - mInitialX);
                    float deltaY = Math.abs(e.getY() - mInitialY);
                    mIgnore = deltaX < deltaY;
                    return !mIgnore;
                }
                return false;
            }
            default: {
                return super.onInterceptTouchEvent(e);
            }
        }
    }
}

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