滑动冲突

有时候 viewpager 嵌套 webview 后，左右滑动冲突，直接消费或者处理拦截导致上下不能滑动，所以需要根据滑动情况判断处理，只在上下滑动时判断事件交给子view

class ScrollWebView(context: Context, attrs: AttributeSet) : WebView(context, attrs) {

    private var mSlop = 0
    private var mDownY = 0f

    init {
        mSlop = ViewConfiguration.get(context).scaledTouchSlop
    }

    override fun onTouchEvent(event: MotionEvent?): Boolean {
        when (event?.action) {
            MotionEvent.ACTION_DOWN -> mDownY = event.y
            MotionEvent.ACTION_MOVE -> {
                val off = mDownY - event.y
                if (abs(off) >= mSlop) {
                    parent.requestDisallowInterceptTouchEvent(true)
                }
            }
            MotionEvent.ACTION_UP, MotionEvent.ACTION_CANCEL -> {
                parent.requestDisallowInterceptTouchEvent(false)
            }
        }
        return super.onTouchEvent(event)
    }
}

举一反三，很多滑动冲突都可以类似解决，至于是对父容器处理，还是子节点处理，根据情况来定

又比如在 viewpager 下嵌套 Recyclerview，Recyclerview 中又嵌套 viewpager 或者 Recyclerview，此时子 view 左右滑动起了冲突，这个确实不怪业务逻辑复杂了，只能自定义解决了

class NestedViewPager(context: Context, attrs: AttributeSet) : ViewPager(context, attrs) {

    private var x1 = 0f
    private var y1 = 0f
    private var isScroll = false

    override fun dispatchTouchEvent(evt: MotionEvent?): Boolean {
        evt?.let {
            when (evt.action) {
                MotionEvent.ACTION_DOWN -> {
                    x1 = evt.x
                    y1 = evt.y
                    isScroll = false
                }
                MotionEvent.ACTION_MOVE -> {
                    // 通知其父控件不拦截
                    val x2 = evt.x
                    val y2 = evt.y
                    if (x1 - x2 > 1) {
                        //str = "向右滑"
                        parent.requestDisallowInterceptTouchEvent(true)
                        isScroll = false
                    } else if (x2 - x1 > 1) {
                        //str = "向左滑"
                        parent.requestDisallowInterceptTouchEvent(true)
                        isScroll = false
                    } else if (y1 - y2 > 100) {
                        parent.requestDisallowInterceptTouchEvent(false)
                        //str = "向上滑"
                        isScroll = true
                    } else if (y2 - y1 > 100) {
                        parent.requestDisallowInterceptTouchEvent(false)
                        //str = "向下滑"
                        isScroll = true
                    }
                }
                MotionEvent.ACTION_UP, MotionEvent.ACTION_CANCEL -> {
                    if (isScroll) {
                        parent.requestDisallowInterceptTouchEvent(false)
                    } else {
                        parent.requestDisallowInterceptTouchEvent(true)
                    }
                }
            }
        }
        return super.dispatchTouchEvent(evt)
    }

}

依然一顿梭哈解决，但是能不自定义就别自定义，特别是复杂的定义

这种滑动可以适配很多滑动冲突，比如 viewpager 下，嵌套了一个横向 Recyclerview，此时横向滑动很容易会触发 viewpager 的滑动，导致不丝滑，还是一样的处理

class ScrollRecyclerView(context: Context, attrs: AttributeSet) : RecyclerView(context, attrs) {

    private var x1 = 0f
    private var y1 = 0f
    private var isScroll = false

    override fun dispatchTouchEvent(evt: MotionEvent?): Boolean {
        evt?.let {
            when (evt.action) {
                MotionEvent.ACTION_DOWN -> {
                    x1 = evt.x
                    y1 = evt.y
                    isScroll = false
                }
                MotionEvent.ACTION_MOVE -> {
                    // 通知其父控件不拦截
                    val x2 = evt.x
                    val y2 = evt.y
                    if (x1 - x2 > 1) {
                        //str = "向右滑"
                        parent.requestDisallowInterceptTouchEvent(true)
                        isScroll = false
                    } else if (x2 - x1 > 1) {
                        //str = "向左滑"
                        parent.requestDisallowInterceptTouchEvent(true)
                        isScroll = false
                    } else if (y1 - y2 > 100) {
                        parent.requestDisallowInterceptTouchEvent(false)
                        //str = "向上滑"
                        isScroll = true
                    } else if (y2 - y1 > 100) {
                        parent.requestDisallowInterceptTouchEvent(false)
                        //str = "向下滑"
                        isScroll = true
                    }
                }
                MotionEvent.ACTION_UP, MotionEvent.ACTION_CANCEL -> {
                    if (isScroll) {
                        parent.requestDisallowInterceptTouchEvent(false)
                    } else {
                        parent.requestDisallowInterceptTouchEvent(true)
                    }
                }
            }
        }
        return super.dispatchTouchEvent(evt)
    }

}

只需要换个集成的对象就行，一样的逻辑，如果对于阈值需要调整，可以使用上面的 scale