RecyclerView横向和竖向滑动冲突

Posted 2022-03-12 小图包

public class BetterRecyclerView extends RecyclerView 

    private int touchSlop;
    private Context mContext;
    private int INVALID_POINTER = -1;
    private int scrollPointerId = INVALID_POINTER;

    private int initialTouchX;
    private int initialTouchY;


    private final static String TAG = "BetterRecyclerView";

    public BetterRecyclerView(Context context) 
//        super(context);
        this(context, null);
    

    public BetterRecyclerView(Context context, @Nullable AttributeSet attrs) 
//        super(context, attrs);
        this(context, attrs, 0);
    

    public BetterRecyclerView(Context context, @Nullable AttributeSet attrs, int defStyle) 
        super(context, attrs, defStyle);
        ViewConfiguration vc = ViewConfiguration.get(context);
        touchSlop =vc.getScaledEdgeSlop() ;
        mContext =context ;

    

    @Override
    public void setScrollingTouchSlop(int slopConstant) 
        super.setScrollingTouchSlop(slopConstant);
        ViewConfiguration vc = ViewConfiguration.get(mContext);
        switch (slopConstant) 
            case TOUCH_SLOP_DEFAULT:
                touchSlop = vc.getScaledTouchSlop();
                break;
            case TOUCH_SLOP_PAGING:
                touchSlop = ViewConfigurationCompat.getScaledPagingTouchSlop(vc);
                break;

        

    

    @Override
    public boolean onInterceptTouchEvent(MotionEvent e) 

        if (e==null)
            return  false ;
        
        int action = MotionEventCompat.getActionMasked(e);
        int actionIndex = MotionEventCompat.getActionIndex(e);

        switch (action)
            case MotionEvent.ACTION_DOWN :
                scrollPointerId = MotionEventCompat.getPointerId(e, 0);
                initialTouchX = Math.round(e.getX() + 0.5f);
                initialTouchY = Math.round(e.getY() + 0.5f);

                return super.onInterceptTouchEvent(e);

            case MotionEvent.ACTION_POINTER_DOWN:

                scrollPointerId = MotionEventCompat.getPointerId(e, actionIndex);
                initialTouchX = Math.round(MotionEventCompat.getX(e, actionIndex) + 0.5f);
                initialTouchY = Math.round(MotionEventCompat.getY(e, actionIndex) + 0.5f);

                return super.onInterceptTouchEvent(e);
            case MotionEvent.ACTION_MOVE:
                final int index =e.findPointerIndex(scrollPointerId);


                if ( index<0)
                    return  false ;
                

                int x = Math.round(MotionEventCompat.getX(e, index) + 0.5f);
                int y = Math.round(MotionEventCompat.getY(e,index)+0.5f);

                if (getScrollState()!=SCROLL_STATE_DRAGGING)

                    int dx =x-initialTouchX ;

                    int  dy = y-initialTouchY ;
                    boolean startScroll = false;
                    if ((getLayoutManager().canScrollHorizontally()&&Math.abs(dx)>touchSlop)&&(getLayoutManager().canScrollVertically()||Math.abs(dx)>Math.abs((dy))))
                           startScroll = true ;
                    

                    if ((getLayoutManager().canScrollHorizontally()&&Math.abs(dy)>touchSlop)&&(getLayoutManager().canScrollHorizontally()||Math.abs(dy)>Math.abs((dx))))

                        startScroll = true ;

                    
                    return  startScroll && super.onInterceptTouchEvent(e);
                
                return super.onInterceptTouchEvent(e);
        
        return super.onInterceptTouchEvent(e);
    

多点触摸手势 当多个pointer同时触摸屏幕，系统会生成如下事件：

        ACTION_DOWN—For the first pointer that touches the screen. This starts the gesture. The pointer data for this pointer is always at index 0 in the MotionEvent.
        ACTION_POINTER_DOWN—For extra pointers that enter the screen beyond the first. The pointer data for this pointer is at the index returned by getActionIndex().
        ACTION_MOVE—A change has happened during a press gesture.
        ACTION_POINTER_UP—Sent when a non-primary pointer goes up.
        ACTION_UP—Sent when the last pointer leaves the screen.
        　　你可以依靠每一个pointer的index和ID来追踪每一个pointer：

        　　Index：MotionEvent会把每一个pointer的信息放在一个数组里，index即是这个数组索引。大多数你用的MotionEvent方法是以这个index作为参数的。

        　　ID：每一个pointer还有一个ID映射，在touch事件中保持恒定一致（persistent），这样就可以在整个手势中跟踪一个单独的pointer。



        　　pointer在一个motion event中出现的顺序是未定的，所以pointer的index在不同的事件中是可变的，但是只要pointer保持active，它的ID是保持不变的。

        　　通过getPointerId()获得ID，这样就可以在多个motion event中追踪pointer。然后对于连续的motion event，可以使用findPointerIndex()方法来获得指定ID的pointer在当前事件中的index。

        　　比如：

        复制代码
private int mActivePointerId;

public boolean onTouchEvent(MotionEvent event) 
        ....
        // Get the pointer ID
        mActivePointerId = event.getPointerId(0);

        // ... Many touch events later...

        // Use the pointer ID to find the index of the active pointer 
        // and fetch its position
        int pointerIndex = event.findPointerIndex(mActivePointerId);
        // Get the pointer's current position
        float x = event.getX(pointerIndex);
        float y = event.getY(pointerIndex);