android - ScrollView 触摸处理中的 Horizo​​ntalScrollView

Question

我有一个 ScrollView 围绕我的整个布局，以便整个屏幕都可以滚动。我在这个 ScrollView 中的第一个元素是一个 Horizo​​ntalScrollView block ，它具有可以水平滚动的功能。我在水平 ScrollView 中添加了一个 ontouchlistener 来处理触摸事件并强制 View “捕捉”到 ACTION_UP 事件上最近的图像。

所以我想要的效果就像普通的 android 主屏幕，您可以在其中从一个滚动到另一个，当您抬起手指时它会捕捉到一个屏幕。

这一切都很好，除了一个问题:我需要从左到右几乎完美地水平滑动才能注册 ACTION_UP。如果我至少垂直滑动(我认为很多人在左右滑动时倾向于在手机上这样做)，我将收到 ACTION_CANCEL 而不是 ACTION_UP。我的理论是这是因为水平 ScrollView 在 ScrollView 中， ScrollView 劫持垂直触摸以允许垂直滚动。

如何在水平 ScrollView 中禁用 ScrollView 的触摸事件，但仍允许在 ScrollView 的其他位置正常垂直滚动？

这是我的代码示例:

   public class HomeFeatureLayout extends HorizontalScrollView {
    private ArrayList<ListItem> items = null;
    private GestureDetector gestureDetector;
    View.OnTouchListener gestureListener;
    private static final int SWIPE_MIN_DISTANCE = 5;
    private static final int SWIPE_THRESHOLD_VELOCITY = 300;
    private int activeFeature = 0;

    public HomeFeatureLayout(Context context, ArrayList<ListItem> items){
        super(context);
        setLayoutParams(new LayoutParams(LayoutParams.FILL_PARENT, LayoutParams.WRAP_CONTENT));
        setFadingEdgeLength(0);
        this.setHorizontalScrollBarEnabled(false);
        this.setVerticalScrollBarEnabled(false);
        LinearLayout internalWrapper = new LinearLayout(context);
        internalWrapper.setLayoutParams(new LayoutParams(LayoutParams.FILL_PARENT, LayoutParams.FILL_PARENT));
        internalWrapper.setOrientation(LinearLayout.HORIZONTAL);
        addView(internalWrapper);
        this.items = items;
        for(int i = 0; i< items.size();i++){
            LinearLayout featureLayout = (LinearLayout) View.inflate(this.getContext(),R.layout.homefeature,null);
            TextView header = (TextView) featureLayout.findViewById(R.id.featureheader);
            ImageView image = (ImageView) featureLayout.findViewById(R.id.featureimage);
            TextView title = (TextView) featureLayout.findViewById(R.id.featuretitle);
            title.setTag(items.get(i).GetLinkURL());
            TextView date = (TextView) featureLayout.findViewById(R.id.featuredate);
            header.setText("FEATURED");
            Image cachedImage = new Image(this.getContext(), items.get(i).GetImageURL());
            image.setImageDrawable(cachedImage.getImage());
            title.setText(items.get(i).GetTitle());
            date.setText(items.get(i).GetDate());
            internalWrapper.addView(featureLayout);
        }
        gestureDetector = new GestureDetector(new MyGestureDetector());
        setOnTouchListener(new View.OnTouchListener() {
            @Override
            public boolean onTouch(View v, MotionEvent event) {
                if (gestureDetector.onTouchEvent(event)) {
                    return true;
                }
                else if(event.getAction() == MotionEvent.ACTION_UP || event.getAction() == MotionEvent.ACTION_CANCEL ){
                    int scrollX = getScrollX();
                    int featureWidth = getMeasuredWidth();
                    activeFeature = ((scrollX + (featureWidth/2))/featureWidth);
                    int scrollTo = activeFeature*featureWidth;
                    smoothScrollTo(scrollTo, 0);
                    return true;
                }
                else{
                    return false;
                }
            }
        });
    }

    class MyGestureDetector extends SimpleOnGestureListener {
        @Override
        public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY) {
            try {
                //right to left 
                if(e1.getX() - e2.getX() > SWIPE_MIN_DISTANCE && Math.abs(velocityX) > SWIPE_THRESHOLD_VELOCITY) {
                    activeFeature = (activeFeature < (items.size() - 1))? activeFeature + 1:items.size() -1;
                    smoothScrollTo(activeFeature*getMeasuredWidth(), 0);
                    return true;
                }  
                //left to right
                else if (e2.getX() - e1.getX() > SWIPE_MIN_DISTANCE && Math.abs(velocityX) > SWIPE_THRESHOLD_VELOCITY) {
                    activeFeature = (activeFeature > 0)? activeFeature - 1:0;
                    smoothScrollTo(activeFeature*getMeasuredWidth(), 0);
                    return true;
                }
            } catch (Exception e) {
                // nothing
            }
            return false;
        }
    }
}

Answer 1

更新:我想通了。在我的 ScrollView 上，我需要重写 onInterceptTouchEvent 方法以仅在 Y 运动大于 X 运动时拦截触摸事件。似乎 ScrollView 的默认行为是在有任何 Y 运动时拦截触摸事件。因此，通过修复，ScrollView 只会在用户故意在 Y 方向滚动时拦截事件，并且在这种情况下将 ACTION_CANCEL 传递给子级。

这是包含 Horizo​​ntalScrollView 的 Scroll View 类的代码:

public class CustomScrollView extends ScrollView {
    private GestureDetector mGestureDetector;

    public CustomScrollView(Context context, AttributeSet attrs) {
        super(context, attrs);
        mGestureDetector = new GestureDetector(context, new YScrollDetector());
        setFadingEdgeLength(0);
    }

    @Override
    public boolean onInterceptTouchEvent(MotionEvent ev) {
        return super.onInterceptTouchEvent(ev) && mGestureDetector.onTouchEvent(ev);
    }

    // Return false if we're scrolling in the x direction  
    class YScrollDetector extends SimpleOnGestureListener {
        @Override
        public boolean onScroll(MotionEvent e1, MotionEvent e2, float distanceX, float distanceY) {             
            return Math.abs(distanceY) > Math.abs(distanceX);
        }
    }
}