ScrollView 触摸处理中的 Horizo​​ntalScrollView

HorizontalScrollView within ScrollView Touch Handling(ScrollView 触摸处理中的 Horizo​​ntalScrollView)

问题描述

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 块，它具有可以水平滚动的功能.我在水平滚动视图中添加了一个 ontouchlistener 来处理触摸事件并强制视图捕捉"到 ACTION_UP 事件上最近的图像.

I have a ScrollView that surrounds my entire layout so that the entire screen is scrollable. The first element I have in this ScrollView is a HorizontalScrollView block that has features that can be scrolled through horizontally. I've added an ontouchlistener to the horizontalscrollview to handle touch events and force the view to "snap" to the closest image on the ACTION_UP event.

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.

So the effect I'm going for is like the stock android homescreen where you can scroll from one to the other and it snaps to one screen when you lift your finger.

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滚动视图在滚动视图中，滚动视图劫持垂直触摸以允许垂直滚动.

This all works great except for one problem: I need to swipe left to right almost perfectly horizontally for an ACTION_UP to ever register. If I swipe vertically in the very least (which I think many people tend to do on their phones when swiping side to side), I will receive an ACTION_CANCEL instead of an ACTION_UP. My theory is that this is because the horizontalscrollview is within a scrollview, and the scrollview is hijacking the vertical touch to allow for vertical scrolling.

如何在水平滚动视图中禁用滚动视图的触摸事件，但仍允许在滚动视图的其他位置正常垂直滚动?

How can I disable the touch events for the scrollview from just within my horizontal scrollview, but still allow for normal vertical scrolling elsewhere in the scrollview?

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;
        }
    }
}

推荐答案

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.

Update: I figured this out. On my ScrollView, I needed to override the onInterceptTouchEvent method to only intercept the touch event if the Y motion is > the X motion. It seems like the default behavior of a ScrollView is to intercept the touch event whenever there is ANY Y motion. So with the fix, the ScrollView will only intercept the event if the user is deliberately scrolling in the Y direction and in that case pass off the ACTION_CANCEL to the children.

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

Here is the code for my Scroll View class that contains the HorizontalScrollView:

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);
        }
    }
}

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