Android Glide预加载RecyclerViewPreloader,ViewPreloadSizeProvider,kotlin
implementation 'com.github.bumptech.glide:glide:4.15.1'implementation ("com.github.bumptech.glide:recyclerview-integration:4.14.2") {// Excludes the support library because it's already included by Glide.transitive = false}
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" /><uses-permission android:name="android.permission.READ_MEDIA_IMAGES" />
import android.content.Context
import android.os.Bundle
import android.provider.MediaStore
import android.util.Log
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import android.widget.ImageView
import androidx.appcompat.app.AppCompatActivity
import androidx.recyclerview.widget.GridLayoutManager
import androidx.recyclerview.widget.RecyclerView
import com.bumptech.glide.Glide
import com.bumptech.glide.ListPreloader
import com.bumptech.glide.RequestBuilder
import com.bumptech.glide.integration.recyclerview.RecyclerViewPreloader
import com.bumptech.glide.util.ViewPreloadSizeProvider
import kotlinx.coroutines.CoroutineScope
import kotlinx.coroutines.Dispatchers
import kotlinx.coroutines.launch
import kotlinx.coroutines.withContext
import java.io.Fileclass MainActivity : AppCompatActivity() {companion object {const val TAG = "fly"}override fun onCreate(savedInstanceState: Bundle?) {super.onCreate(savedInstanceState)setContentView(R.layout.activity_main)var recyclerView: RecyclerView = findViewById(R.id.recycler_view)recyclerView?.layoutManager = GridLayoutManager(this, 3).apply {orientation = GridLayoutManager.VERTICAL}val adapter = MyAdapter()recyclerView?.adapter = adapterCoroutineScope(Dispatchers.IO).launch {val items = readAllImage(applicationContext)withContext(Dispatchers.Main) {adapter.onChange(items)}}var preloadSizeProvider = ViewPreloadSizeProvider<MyData>()val preloadModelProvider = MyPreloadModelProvider(adapter, this)val preloader = RecyclerViewPreloader(this,preloadModelProvider,preloadSizeProvider,100 //maxPreload预加载数量)recyclerView?.addOnScrollListener(preloader)}class MyPreloadModelProvider(private val adapter: MyAdapter,private val context: Context) : ListPreloader.PreloadModelProvider<MyData> {// 从当前屏幕结束的位置开始,再加载maxPreload条item,// 不可见的item即为屏幕外的position位置// 如果对于一个给定的位置不需要加载任何东西,getPreloadItems 可以返回一个空表。override fun getPreloadItems(position: Int): MutableList<MyData> {val data: MyData = adapter.getItems()[position]Log.d(TAG, "getPreloadItems pos:$position index:${data.index}")return mutableListOf(data)}override fun getPreloadRequestBuilder(item: MyData): RequestBuilder<*>? {Log.d(TAG, "getPreloadRequestBuilder ${item.index}")return Glide.with(context).load(File(item.path))}}class MyAdapter : RecyclerView.Adapter<MyViewHolder>() {private var items: ArrayList<MyData>? = nullfun onChange(items: ArrayList<MyData>?) {this.items = itemsnotifyDataSetChanged()}fun getItems(): ArrayList<MyData> {return items!!}override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): MyViewHolder {val view = LayoutInflater.from(parent.context).inflate(R.layout.item, parent, false)return MyViewHolder(view)}override fun onBindViewHolder(holder: MyViewHolder, position: Int) {Glide.with(holder.itemView.context).load(File(items?.get(position)?.path)).into(holder.image)}override fun getItemCount(): Int {return items?.size ?: 0}}class MyViewHolder(itemView: View) : RecyclerView.ViewHolder(itemView) {val image: ImageView = itemView.findViewById(R.id.image)}private fun readAllImage(context: Context): ArrayList<MyData> {val photos = ArrayList<MyData>()//读取手机图片val cursor = context.contentResolver.query(MediaStore.Images.Media.EXTERNAL_CONTENT_URI,null,null,null,null)var index = 0while (cursor!!.moveToNext()) {//图片路径val path = cursor.getString(cursor.getColumnIndexOrThrow(MediaStore.Images.Media.DATA))//图片名称//val name = cursor.getString(cursor.getColumnIndexOrThrow(MediaStore.Images.Media.DISPLAY_NAME))//图片大小//val size = cursor.getLong(cursor.getColumnIndexOrThrow(MediaStore.Images.Media.SIZE))photos.add(MyData(path, index++))}cursor.close()return photos}class MyData(var path: String, val index: Int)
}
<?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"><androidx.recyclerview.widget.RecyclerViewandroid:id="@+id/recycler_view"android:layout_width="match_parent"android:layout_height="match_parent"tools:context=".MainActivity" /></androidx.constraintlayout.widget.ConstraintLayout>
<?xml version="1.0" encoding="utf-8"?>
<ImageView xmlns:android="http://schemas.android.com/apk/res/android"android:id="@+id/image"android:layout_width="100dp"android:layout_height="100dp" />
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