Android(安卓)RecyclerView轮播图实现 支持放大动画
16lz
2021-12-04
android studio的模拟器录屏会黑屏，也不知道是什么bug
效果演示
主要用到了PagerSnapHelper（使RecyclerView滑动表现和viewpager一致）和滑动监听器
样式
activity_main.xml
<?xml version="1.0" encoding="utf-8"?><androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:app="http://schemas.android.com/apk/res-auto" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent" android:layout_height="match_parent" tools:context=".MainActivity"> <com.example.gallery.GalleryRecyclerView android:id="@+id/recycler_view" android:layout_width="match_parent" android:layout_height="200dp" app:layout_constraintTop_toTopOf="parent" />androidx.constraintlayout.widget.ConstraintLayout>item.xml
<?xml version="1.0" encoding="utf-8"?><androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent" android:layout_height="match_parent"> <ImageView android:id="@+id/image_view" android:layout_width="match_parent" android:layout_height="match_parent" android:scaleType="centerCrop" />androidx.constraintlayout.widget.ConstraintLayout>代码
MainActivity
package com.example.galleryimport android.os.Bundleimport androidx.appcompat.app.AppCompatActivityimport com.example.gallery.databinding.ActivityMainBindingimport java.util.*class MainActivity : AppCompatActivity() { private lateinit var binding: ActivityMainBinding private var timer: Timer = Timer() override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState)// 使用viewBinding binding = ActivityMainBinding.inflate(layoutInflater) setContentView(binding.root) val galleryAdapter = GalleryAdapter(arrayListOf( "https://ss0.bdstatic.com/70cFuHSh_Q1YnxGkpoWK1HF6hhy/it/u=3801171559,43130079&fm=26&gp=0.jpg", "https://img.zcool.cn/community/01936a58be7362a801219c77fe8358.jpg@1280w_1l_2o_100sh.jpg", "https://th.bing.com/th/id/R5d175f44c74fe609a7e7904c1581ba9e?rik=x36FeBN9WfmLcg&riu=http%3a%2f%2fwww.benbenla.cn%2fimages%2f20150626%2fbenbenla-03c.jpg&ehk=HdoV02a0Y%2bAbwlolGa0M%2fdZ073aXMUqidwkvB%2fLo1ZM%3d&risl=&pid=ImgRaw" )) binding.recyclerView.adapter = galleryAdapter binding.recyclerView.scrollToPosition(galleryAdapter.start) val paddingHorizon = 100 val paddingVertical = 50 binding.recyclerView.setPadding(paddingHorizon, paddingVertical, paddingHorizon, paddingVertical) binding.recyclerView.clipToPadding = false } override fun onResume() { super.onResume() timer.schedule(object : TimerTask() { override fun run() { binding.recyclerView.next() } }, 5000, 5000) } override fun onPause() { super.onPause() timer.cancel() }}GalleryRecyclerView
package com.example.galleryimport android.content.Contextimport android.util.AttributeSetimport androidx.recyclerview.widget.LinearLayoutManagerimport androidx.recyclerview.widget.PagerSnapHelperimport androidx.recyclerview.widget.RecyclerViewimport kotlin.math.absimport kotlin.math.minclass GalleryRecyclerView : RecyclerView { constructor(context: Context) : super(context) constructor(context: Context, attrs: AttributeSet?) : super(context, attrs) constructor(context: Context, attrs: AttributeSet?, defStyleAttr: Int) : super( context, attrs, defStyleAttr ) var minScale: Float = 0.9f var maxScale: Float = 1.1f val linearLayoutManager = LinearLayoutManager(context, HORIZONTAL, false) var position: Int = 0 init { layoutManager = linearLayoutManager val pagerSnapHelper = PagerSnapHelper() pagerSnapHelper.attachToRecyclerView(this) // 添加滑动监听 addOnScrollListener(object : RecyclerView.OnScrollListener() { override fun onScrolled(recyclerView: RecyclerView, dx: Int, dy: Int) { val first = linearLayoutManager.findFirstVisibleItemPosition() val last = linearLayoutManager.findLastVisibleItemPosition() val snapView = pagerSnapHelper.findSnapView(linearLayoutManager) ?: return val snap = linearLayoutManager.getPosition(snapView) position = snap if (snap <= 100 || snap >= Int.MAX_VALUE - 100) { scrollToPosition(adapter!!.itemCount / 2) } // 避免当前展示图被遮挡 snapView.z = Float.MAX_VALUE // 放大程度 val scaleSpan: Float = maxScale - minScale// 前一张图片 linearLayoutManager.findViewByPosition(first)?.apply { pagerSnapHelper .calculateDistanceToFinalSnap(linearLayoutManager, this) ?.get(0) ?.let { distance -> // 滑动时，系数ratio值为[0,1] val ratio: Float = min((width - abs(distance)).toFloat() / 800, 1f) scaleX = ratio * scaleSpan + minScale scaleY = scaleX } } // 后一张图片 linearLayoutManager.findViewByPosition(last)?.apply { pagerSnapHelper .calculateDistanceToFinalSnap(linearLayoutManager, this) ?.get(0) ?.let { distance -> val ratio: Float = min((width - abs(distance)).toFloat() / 800, 1f) scaleX = ratio * scaleSpan + minScale scaleY = scaleX } } } }) } fun next() { smoothScrollToPosition(position + 1) }}GalleryAdapter
package com.example.galleryimport android.view.LayoutInflaterimport android.view.Viewimport android.view.ViewGroupimport android.widget.ImageViewimport androidx.recyclerview.widget.RecyclerViewimport com.squareup.picasso.Picassoclass GalleryAdapter(var urls: List<String>) : RecyclerView.Adapter<GalleryAdapter.ViewHolder>() { override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ViewHolder { // Create a new view, which defines the UI of the list item val view = LayoutInflater.from(parent.context) .inflate(R.layout.item, parent, false) return ViewHolder(view) } override fun onBindViewHolder(holder: ViewHolder, position: Int) { val index = position % urls.size Picasso .get() .load(urls[index]) .placeholder(R.drawable.place_holder) .into(holder.imageView) } override fun getItemCount(): Int { return Int.MAX_VALUE } val start: Int get() { val temp = itemCount / 2 return temp - temp % urls.size } class ViewHolder(itemView: View) : RecyclerView.ViewHolder(itemView) { val imageView: ImageView = itemView.findViewById(R.id.image_view) }}更多相关文章
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