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项目中首页列表页需要统计每个item的曝光情况#xff0c;给产品运营提供数据报表分析用户行为#xff0c;于是封装了一个通用的列表Item曝光工具#xff0c;方便曝光埋点上报
源码分析
核心就是监听RecyclerView的滚动#xff0c;在滚动状态为SCROLL_STATE_IDLE的时…背景
项目中首页列表页需要统计每个item的曝光情况给产品运营提供数据报表分析用户行为于是封装了一个通用的列表Item曝光工具方便曝光埋点上报
源码分析
核心就是监听RecyclerView的滚动在滚动状态为SCROLL_STATE_IDLE的时候开始计算哪些item是可见的
private fun calculateVisibleItemInternal() {if (!isRecording) {return}val lastRange currVisibleRangeval currRange findItemVisibleRange()val newVisibleItemPosList createCurVisiblePosList(lastRange, currRange)visibleItemCheckTasks.forEach {it.updateVisibleRange(currRange)}if (newVisibleItemPosList.isNotEmpty()) {VisibleCheckTimerTask(newVisibleItemPosList, this, threshold).also {visibleItemCheckTasks.add(it)}.execute()}currVisibleRange currRange}根据LayoutManager找出当前可见item的范围剔除掉显示不到80%的item
private fun findItemVisibleRange(): IntRange {return when (val lm currRecyclerView?.layoutManager) {is GridLayoutManager - {val first lm.findFirstVisibleItemPosition()val last lm.findLastVisibleItemPosition()return fixCurRealVisibleRange(first, last)}is LinearLayoutManager - {val first lm.findFirstVisibleItemPosition()val last lm.findLastVisibleItemPosition()return fixCurRealVisibleRange(first, last)}is StaggeredGridLayoutManager - {val firstItems IntArray(lm.spanCount)lm.findFirstVisibleItemPositions(firstItems)val lastItems IntArray(lm.spanCount)lm.findLastVisibleItemPositions(lastItems)val first when (RecyclerView.NO_POSITION) {firstItems[0] - {firstItems[lm.spanCount - 1]}firstItems[lm.spanCount - 1] - {firstItems[0]}else - {min(firstItems[0], firstItems[lm.spanCount - 1])}}val last when (RecyclerView.NO_POSITION) {lastItems[0] - {lastItems[lm.spanCount - 1]}lastItems[lm.spanCount - 1] - {lastItems[0]}else - {max(lastItems[0], lastItems[lm.spanCount - 1])}}return fixCurRealVisibleRange(first, last)}else - {IntRange.EMPTY}}}对可见的item进行分组形成一个位置列表上一次和这一次的分开组队
private fun createCurVisiblePosList(lastRange: IntRange, currRange: IntRange): ListInt {val result mutableListOfInt()currRange.forEach { pos -if (pos !in lastRange) {result.add(pos)}}return result}将分组好的列表装进一个定时的task在延迟一个阈值的时间后执行onVisibleCheck
class VisibleCheckTimerTask(input: ListInt,private val callback: VisibleCheckCallback,private val delay: Long
) : Runnable {private val visibleList mutableListOfInt()private var isExecuted falseinit {visibleList.addAll(input)}fun updateVisibleRange(keyRange: IntRange) {val iterator visibleList.iterator()while (iterator.hasNext()) {val entry iterator.next()if (entry !in keyRange) {iterator.remove()}}}override fun run() {callback.onVisibleCheck( this, visibleList)}fun execute() {if (isExecuted) {return}mHandler.postDelayed(this, delay)isExecuted true}fun cancel() {mHandler.removeCallbacks(this)}interface VisibleCheckCallback {fun onVisibleCheck(task: VisibleCheckTimerTask, visibleList: ListInt)}
}达到阈值后再获取一遍可见item的范围对于仍然可见的item回调onItemShow
override fun onVisibleCheck(task: VisibleCheckTimerTask, visibleList: ListInt) {val visibleRange findItemVisibleRange()visibleList.forEach {if (it in visibleRange) {notifyItemShow(it)}}visibleItemCheckTasks.remove(task)}完整源码
val mHandler Handler(Looper.getMainLooper())class ListItemExposeUtil(private val threshold: Long 100): RecyclerView.OnScrollListener(), VisibleCheckTimerTask.VisibleCheckCallback {private var currRecyclerView: RecyclerView? nullprivate var isRecording falseprivate var currVisibleRange: IntRange IntRange.EMPTYprivate val visibleItemCheckTasks mutableListOfVisibleCheckTimerTask()private val itemShowListeners mutableListOfOnItemShowListener()fun attachTo(recyclerView: RecyclerView) {recyclerView.addOnScrollListener(this)currRecyclerView recyclerView}fun start() {isRecording truecurrRecyclerView?.post {calculateVisibleItemInternal()}}fun stop() {visibleItemCheckTasks.forEach {it.cancel()}visibleItemCheckTasks.clear()currVisibleRange IntRange.EMPTYisRecording false}fun detach() {if (isRecording) {stop()}itemShowListeners.clear()currRecyclerView?.removeOnScrollListener(this)currRecyclerView null}override fun onScrollStateChanged(recyclerView: RecyclerView, newState: Int) {if (newState RecyclerView.SCROLL_STATE_IDLE) {calculateVisibleItemInternal()}}private fun calculateVisibleItemInternal() {if (!isRecording) {return}val lastRange currVisibleRangeval currRange findItemVisibleRange()val newVisibleItemPosList createCurVisiblePosList(lastRange, currRange)visibleItemCheckTasks.forEach {it.updateVisibleRange(currRange)}if (newVisibleItemPosList.isNotEmpty()) {VisibleCheckTimerTask(newVisibleItemPosList, this, threshold).also {visibleItemCheckTasks.add(it)}.execute()}currVisibleRange currRange}private fun findItemVisibleRange(): IntRange {return when (val lm currRecyclerView?.layoutManager) {is GridLayoutManager - {val first lm.findFirstVisibleItemPosition()val last lm.findLastVisibleItemPosition()return fixCurRealVisibleRange(first, last)}is LinearLayoutManager - {val first lm.findFirstVisibleItemPosition()val last lm.findLastVisibleItemPosition()return fixCurRealVisibleRange(first, last)}is StaggeredGridLayoutManager - {val firstItems IntArray(lm.spanCount)lm.findFirstVisibleItemPositions(firstItems)val lastItems IntArray(lm.spanCount)lm.findLastVisibleItemPositions(lastItems)val first when (RecyclerView.NO_POSITION) {firstItems[0] - {firstItems[lm.spanCount - 1]}firstItems[lm.spanCount - 1] - {firstItems[0]}else - {min(firstItems[0], firstItems[lm.spanCount - 1])}}val last when (RecyclerView.NO_POSITION) {lastItems[0] - {lastItems[lm.spanCount - 1]}lastItems[lm.spanCount - 1] - {lastItems[0]}else - {max(lastItems[0], lastItems[lm.spanCount - 1])}}return fixCurRealVisibleRange(first, last)}else - {IntRange.EMPTY}}}/*** 检查该item是否真实可见* view区域80%显示出来就算*/private fun checkItemCurrRealVisible(pos: Int): Boolean {val holder currRecyclerView?.findViewHolderForAdapterPosition(pos)return if (holder null) {false} else {val rect Rect()holder.itemView.getGlobalVisibleRect(rect)if (holder.itemView.width 0 holder.itemView.height 0) {return (rect.width() * rect.height() / (holder.itemView.width * holder.itemView.height).toFloat()) 0.8f} else {return false}}}/*** 双指针寻找真实可见的item的范围有一些item没显示完整剔除*/private fun fixCurRealVisibleRange(first: Int, last: Int): IntRange {return if (first 0 last 0) {var realFirst firstwhile (!checkItemCurrRealVisible(realFirst) realFirst last) {realFirst}var realLast lastwhile (!checkItemCurrRealVisible(realLast) realLast realFirst) {realLast--}if (realFirst realLast) {realFirst..realLast} else {IntRange.EMPTY}} else {IntRange.EMPTY}}/*** 创建当前可见的item位置列表*/private fun createCurVisiblePosList(lastRange: IntRange, currRange: IntRange): ListInt {val result mutableListOfInt()currRange.forEach { pos -if (pos !in lastRange) {result.add(pos)}}return result}/*** 达到阈值后再获取一遍可见item的范围对于仍然可见的item回调onItemShow*/override fun onVisibleCheck(task: VisibleCheckTimerTask, visibleList: ListInt) {val visibleRange findItemVisibleRange()visibleList.forEach {if (it in visibleRange) {notifyItemShow(it)}}visibleItemCheckTasks.remove(task)}private fun notifyItemShow(pos: Int) {itemShowListeners.forEach {it.onItemShow(pos)}}fun addItemShowListener(listener: OnItemShowListener) {itemShowListeners.add(listener)}
}interface OnItemShowListener {fun onItemShow(pos: Int)
}class VisibleCheckTimerTask(input: ListInt,private val callback: VisibleCheckCallback,private val delay: Long) : Runnable {private val visibleList mutableListOfInt()private var isExecuted falseinit {visibleList.addAll(input)}fun updateVisibleRange(keyRange: IntRange) {val iterator visibleList.iterator()while (iterator.hasNext()) {val entry iterator.next()if (entry !in keyRange) {iterator.remove()}}}override fun run() {callback.onVisibleCheck(this, visibleList)}fun execute() {if (isExecuted) {return}mHandler.postDelayed(this, delay)isExecuted true}fun cancel() {mHandler.removeCallbacks(this)}interface VisibleCheckCallback {fun onVisibleCheck(task: VisibleCheckTimerTask, visibleList: ListInt)}
}测试代码 运行结果
