TV RecyclerView 焦点处理笔记

确定度 發表於 2025-7-14 15:21:00

面对RecyclerView焦点，特别是复杂视图，多类型情况下，需求有时候不按系统定义的走，比如要求首次落焦在第二个，或者焦点移动到边界就不能移动
如果不遵循焦点流程直接粗暴处理，会导致系统分发事件出异常，焦点乱飞
默认焦点使用 addOnChildAttachStateChangeListener 监听
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<pre>recyclerView.addOnChildAttachStateChangeListener(object :
 RecyclerView.OnChildAttachStateChangeListener {
 override fun onChildViewAttachedToWindow(view: View) {
 val position = recyclerView.getChildAdapterPosition(view)
 log("position $position view $view")
 if (position == 3) view.requestFocus()
 }

 override fun onChildViewDetachedFromWindow(view: View) {

 }
 })</pre>
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对于超出边界时，系统会触发onFocusSearchFailed
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<pre> override fun onFocusSearchFailed(
 focused: View,
 focusDirection: Int,
 recycler: RecyclerView.Recycler,
 state: RecyclerView.State
): View? {
 return when (focusDirection) {
 View.FOCUS_UP -> {
 if (focused.parent.parent is RecyclerView) {
 val position = (focused.parent as? View)?.let { getPosition(it) } ?: -1
 //...
 } else {
 focused.rootView.findViewById<View>(R.id.btn_myself)
 }
 }

 else -> super.onFocusSearchFailed(focused, focusDirection, recycler, state)
 }
}</pre>
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针对焦点移动时自动滚动列表到可见位置，可以使用 onRequestChildFocus
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<pre> override fun onRequestChildFocus(
 parent: RecyclerView,
 state: RecyclerView.State,
 child: View,
 focused: View?
): Boolean {
 val position = parent.getChildAdapterPosition(child)
 scrollToPosition(position)
 return super.onRequestChildFocus(parent, state, child, focused)
}</pre>
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如果针对焦点到边界位置后不能移动，或者边界触底动效，可以使用焦点拦截 onInterceptFocusSearch
完整代码
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<pre>class ScreenMainGridManager(private val mAdapter: BaseAdapter, context: Context) :
GridLayoutManager(context, 4) {

private val marginStart = context.resources.getDimension(R.dimen.common_dp_54)

init {
 spanSizeLookup = object : SpanSizeLookup() {
 override fun getSpanSize(position: Int): Int {
 val viewType = mAdapter.getItemViewType(position)
 return when (viewType) {
 ViewType.TITLE.value, ViewType.BANNER.value -> 4
 else -> 1
 }
 }
 }
}

override fun onInterceptFocusSearch(focused: View, direction: Int): View? {
 return when (direction) {
 View.FOCUS_LEFT -> {
 findLeftFocusView(focused) ?: super.onInterceptFocusSearch(focused, direction)
 }

 View.FOCUS_RIGHT -> {
 var isRightFocus = false
 findRecyclerView(focused)?.let {
 findRootView(focused)?.let { root ->
 val position = it.getChildAdapterPosition(root)
 if (position > 0 && position + 1 < itemCount) {
 val viewType = mAdapter.getItemViewType(position + 1)
 if (viewType == ViewType.TITLE.value) {
 isRightFocus = true
 }
 } else if (position + 1 == itemCount) {
 isRightFocus = true
 }
 }
 }
 if (isRightFocus) focused else super.onInterceptFocusSearch(focused, direction)
 }

 else -> super.onInterceptFocusSearch(focused, direction)
 }
}

private fun findLeftFocusView(focused: View): View? {
 findRecyclerView(focused)?.let {
 val location = IntArray(2)
 focused.getLocationOnScreen(location)
 if (location < marginStart) {
 return focused
 }
 }
 return null
}

private fun findRecyclerView(focused: View): RecyclerView? {
 var parent: ViewParent? = focused.parent
 for (i in 0 until 2) {
 if (parent is RecyclerView) break
 parent = parent?.parent
 }
 return parent as? RecyclerView
}

/** item root view */
private fun findRootView(focused: View): View? {
 var result: View? = focused
 var parent = focused.parent
 for (i in 0 until 2) {
 if (parent is RecyclerView) {
 return result
 }
 result = parent as? View
 parent = parent?.parent
 }
 return result
}

override fun onRequestChildFocus(
 parent: RecyclerView,
 state: RecyclerView.State,
 child: View,
 focused: View?
): Boolean {
 val position = parent.getChildAdapterPosition(child)
 scrollToPosition(position)
 return super.onRequestChildFocus(parent, state, child, focused)
}

override fun onFocusSearchFailed(
 focused: View,
 focusDirection: Int,
 recycler: RecyclerView.Recycler,
 state: RecyclerView.State
): View? {
 return when (focusDirection) {
 View.FOCUS_UP -> {
 if (focused.parent.parent is RecyclerView) {
 val position = (focused.parent as? View)?.let { getPosition(it) } ?: -1
 if (position < 0) {
 super.onFocusSearchFailed(focused, focusDirection, recycler, state)
 } else {
 val item = mAdapter.getItem(position)
 if (item is MainBannerItem || item is MeAddItem) {
 focused.rootView.findViewById<View>(R.id.btn_myself)
 ?: focused.rootView.findViewById<View>(R.id.btn_back)
 } else {
 scrollToPosition(0)
 super.onFocusSearchFailed(focused, focusDirection, recycler, state)
 }
 }
 } else {
 focused.rootView.findViewById<View>(R.id.btn_myself)
 }
 }

 else -> super.onFocusSearchFailed(focused, focusDirection, recycler, state)
 }
}

}</pre>
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避免直接request或者clear焦点
  
来源：https://www.cnblogs.com/LiuZhen/p/18959703

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TV RecyclerView 焦点处理笔记