RecyclerView实现垂直自动无限滚动,类似于中奖信息,跑马灯
实现RecyclerView中的效果有两种:
一种为以item为单体,每隔多少秒进行滚动一次
一种为整体流形式进行缓慢滚动
实现无限滚动
这里实现无限滚动的方式为在adpater中设置itemCount为 Integer.MAX_VALUE
注意:此处基于BaseQuickAdapter的库进行的,也可直接使用原生
class MainAdatper(data: List<String>) : BaseQuickAdapter<String, BaseViewHolder>(R.layout.item_txt, data) {
override fun convert(helper: BaseViewHolder?, item: String?) {
helper?.setText(R.id.mTv, item)
}
override fun getItem(position: Int): String? {
val newPosition = position % data.size
return getData().get(newPosition)
}
override fun getItemViewType(position: Int): Int {
var count = getHeaderLayoutCount() + getData().size
//刚开始进入包含该类的activity时,count为0。就会出现0%0的情况,这会抛出异常,所以我们要在下面做一下判断
if (count <= 0) {
count = 1
}
var newPosition = position % count;
return super.getItemViewType(newPosition);
}
override fun getItemCount(): Int {
return Integer.MAX_VALUE
}
}
item为单位,每隔n秒滚动一个item
这边主要是使用recyclerView中的smoothScrollToPosition() 方法实现,然后再配合自定义layoutManager 控制速度达到目的效果
var layoutManager = object : LinearLayoutManager(this) {
override fun smoothScrollToPosition(recyclerView: RecyclerView?, state: RecyclerView.State?, position: Int) {
var linearSmoothScroller = object : LinearSmoothScroller(recyclerView?.context) {
//返回滑动一个pixel需要多少毫秒
override fun calculateSpeedPerPixel(displayMetrics: DisplayMetrics?): Float {
//这边可以自定义进行控制速度
return 3f / (displayMetrics?.density ?: 1f)
}
}
linearSmoothScroller.setTargetPosition(position)
startSmoothScroll(linearSmoothScroller)
}
}
mRv.layoutManager = layoutManager
mRv.addItemDecoration(DividerItemDecoration(this, DividerItemDecoration.VERTICAL))
mRv.adapter = MainAdatper(data)
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fun startAuto() {
if (mAutoTask != null && (mAutoTask?.isDisposed ?: true))
mAutoTask?.dispose()
//此处的4为当前显示的最后一个item
mAutoTask = Observable.interval(1, 2, TimeUnit.SECONDS).subscribe {
mRv.smoothScrollToPosition((4 + it).toInt())
}
}
fun stopAuto() {
if (mAutoTask != null && (mAutoTask?.isDisposed ?: true)) {
mAutoTask?.dispose()
mAutoTask = null
}
}
override fun onStart() {
super.onStart()
//开始滚动
startAuto()
}
override fun onStop() {
super.onStop()
//停止滚动
stopAuto()
}
流式滚动
流式滚动是使用recyclerView中的 smoothScrollBy(x, y) 方法来实现的
此处是通过自定义recyclerView来进行实现,也可直接在activity中进行实现。
class AutoScrollRecyclerView(mContext: Context, attrs: AttributeSet?) : RecyclerView(mContext, attrs) {
private var mAutoTask: Disposable? = null
//禁止手动滑动
override fun dispatchTouchEvent(ev: MotionEvent?): Boolean {
return true
}
fun start() {
if (mAutoTask != null && !mAutoTask!!.isDisposed) {
mAutoTask!!.dispose()
}
mAutoTask = Observable.interval(1000, 100, TimeUnit.MILLISECONDS).observeOn(AndroidSchedulers.mainThread()).subscribe { smoothScrollBy(0, 20) }
}
fun stop() {
if (mAutoTask != null && !mAutoTask!!.isDisposed) {
mAutoTask!!.dispose()
mAutoTask = null
}
}
}
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//在activity中调用开始滚动与停止滚动
override fun onStart() {
super.onStart()
mRvTwo.start()
}
override fun onStop() {
super.onStop()
mRvTwo.stop()
}