Android Glide in RecyclerView，only load visible item when page return，Kotlin

base on this article：

Android Glide preload RecyclerView切入后台不可见再切换可见只加载当前视野可见区域item图片，Kotlin_zhangphil的博客-CSDN博客【代码】Android Paging 3,kotlin（1）在实际的开发中，虽然Glide解决了快速加载图片的问题，但还有一个问题悬而未决：比如用户的头像，往往用户的头像是从服务器端读出的一个普通矩形图片，但是现在的设计一般要求在APP端的用户头像显示成圆形头像，那么此时虽然Glide可以加载，但加载出来的是一个矩形，如果要Glide_android 毛玻璃圆角。《Android图片加载与缓存开源框架：Android Glide》Android Glide是一个开源的图片加载和缓存处理的第三方框架。https://blog.csdn.net/zhangphil/article/details/132592405

    <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
    <uses-permission android:name="android.permission.READ_MEDIA_IMAGES" />

plugins {
    id("org.jetbrains.kotlin.kapt")
}

    implementation("com.github.bumptech.glide:glide:4.16.0")
    kapt("com.github.bumptech.glide:compiler:4.16.0")

import android.content.Context
import android.graphics.Bitmap
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.TextView
import androidx.appcompat.app.AppCompatActivity
import androidx.appcompat.widget.AppCompatImageView
import androidx.recyclerview.widget.GridLayoutManager
import androidx.recyclerview.widget.RecyclerView
import com.bumptech.glide.load.DataSource
import com.bumptech.glide.load.engine.GlideException
import com.bumptech.glide.request.RequestListener
import com.bumptech.glide.request.target.Target

const val PHOTO_SIZE = 150

class MainActivity : AppCompatActivity() {
    private val TAG = "Glide Load"

    private var mItems = ArrayList<MyData>()
    private var mLayoutManager: GridLayoutManager? = null
    private var mAdapter: MyAdapter? = null
    private var mGlideLoad: GlideLoad? = null

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.recycler_view)
        init()
    }

    //当按了home键后，再次调出app，会进入onRestart
    override fun onRestart() {
        super.onRestart()
        Log.d(TAG, "onRestart")
        mGlideLoad?.clear()
    }

    override fun onStop() {
        super.onStop()
        Log.d(TAG,"onStop")
    }

    private fun init() {
        val spanCount = 8

        val rv = findViewById<RecyclerView>(R.id.recycler_view)

        mLayoutManager = GridLayoutManager(this, spanCount)
        rv.layoutManager = mLayoutManager

        mAdapter = MyAdapter(this)
        rv.adapter = mAdapter

        mItems = readAllImage(applicationContext)
        mAdapter?.onChange(mItems)

        mGlideLoad = GlideLoad(this, rv)
    }

    fun loadItem(holder: MyVH, position: Int) {
        val target: Target<*> = GlideApp.with(holder.itemView.context)
            .asBitmap()
            .load(mItems[position].path)
            .centerCrop()
            .addListener(object : RequestListener<Bitmap> {
                override fun onLoadFailed(
                    e: GlideException?,
                    model: Any?,
                    target: Target<Bitmap>,
                    isFirstResource: Boolean
                ): Boolean {
                    mGlideLoad?.setLoadStatus(position, GlideLoad.NONE, null)
                    return false
                }

                override fun onResourceReady(
                    resource: Bitmap,
                    model: Any,
                    target: Target<Bitmap>?,
                    dataSource: DataSource,
                    isFirstResource: Boolean
                ): Boolean {
                    holder.image.setImageBitmap(resource)
                    mGlideLoad?.setLoadStatus(position, GlideLoad.NONE, null)

                    // 特别注意此处返回是true，而不能是false。
                    // 因为如果返回false，当按home键把app切入后台后，再按app图标调出app切换到前台可见，反复切换，
                    // 会造成Bitmap未回收的崩溃。
                    return true
                }
            }).preload(
                PHOTO_SIZE,
                PHOTO_SIZE
            )

        mGlideLoad?.setLoadStatus(position, GlideLoad.LOAD, target)
    }

    inner class MyAdapter(private val context: Context) : RecyclerView.Adapter<MyVH>() {
        private var items = ArrayList<MyData>()

        fun onChange(items: ArrayList<MyData>) {
            this.items = items

            notifyDataSetChanged()
        }

        override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): MyVH {
            val v = LayoutInflater.from(context).inflate(R.layout.item, parent, false)
            val params = v.layoutParams
            params.width = PHOTO_SIZE
            params.height = PHOTO_SIZE
            return MyVH(v)
        }

        override fun onBindViewHolder(holder: MyVH, position: Int) {
            loadItem(holder, position)
            holder.text.text = "$position"
        }

        override fun getItemCount(): Int {
            return items.size
        }
    }

    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
        )

        while (cursor!!.moveToNext()) {
            //图片路径 uri
            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))
        }

        cursor.close()

        return photos
    }
}

class MyVH(itemView: View) : RecyclerView.ViewHolder(itemView) {
    var image: AppCompatImageView
    var text: TextView

    init {
        image = itemView.findViewById(R.id.image)
        text = itemView.findViewById(R.id.text)
    }
}

class MyData(var path: String)

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <androidx.recyclerview.widget.RecyclerView
        android:id="@+id/recycler_view"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />

</RelativeLayout>

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:padding="1px">

    <androidx.appcompat.widget.AppCompatImageView
        android:id="@+id/image"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:scaleType="centerCrop"
        android:src="@drawable/ic_launcher_background" />

    <TextView
        android:id="@+id/text"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerInParent="true"
        android:background="@android:color/holo_green_light"
        android:paddingLeft="1dp"
        android:paddingRight="1dp"
        android:text="-.-"
        android:textColor="@android:color/holo_red_dark"
        android:textSize="5dp" />
</RelativeLayout>

import android.content.Context
import android.util.Log
import androidx.recyclerview.widget.GridLayoutManager
import androidx.recyclerview.widget.RecyclerView
import com.bumptech.glide.request.target.Target
import java.lang.ref.WeakReference

class GlideLoad {
    private val TAG = "Glide Load"

    companion object {
        const val NONE: Int = 0
        const val LOAD: Int = 1
    }

    private var mLayoutManager: GridLayoutManager? = null
    private var mRecyclerView: RecyclerView? = null
    private var mVisibleItemPosition: IntArray? = null
    private var mContext: Context? = null

    private var mStatusItems: ArrayList<Status>? = ArrayList()

    constructor(ctx: Context?, rv: RecyclerView?) {
        mContext = ctx
        mRecyclerView = rv

        repeat(mRecyclerView?.adapter?.itemCount!!) {
            mStatusItems?.add(Status())
        }

        mLayoutManager = mRecyclerView?.layoutManager as? GridLayoutManager
        mRecyclerView?.addOnScrollListener(object : RecyclerView.OnScrollListener() {
            override fun onScrolled(recyclerView: RecyclerView, dx: Int, dy: Int) {
                super.onScrolled(recyclerView, dx, dy)
                mVisibleItemPosition = getVisibleItemPosition()
            }
        })
    }

    fun setLoadStatus(pos: Int, status: Int, target: Target<*>?) {
        mStatusItems!![pos].position = pos
        mStatusItems!![pos].status = status
        if (target != null) {
            mStatusItems!![pos].targetRef = WeakReference(target)
        } else {
            mStatusItems!![pos].targetRef = null
        }
    }

    fun clear() {
        Log.d(TAG, "可见区域 ${mVisibleItemPosition!![0]}->${mVisibleItemPosition!![1]}")

        for (i in 0 until mStatusItems!!.size) {
            if (i !in mVisibleItemPosition!![0]..mVisibleItemPosition!![1]) {
                if (mStatusItems!![i].status == LOAD) {
                    mStatusItems!![i].targetRef?.get()?.let {
                        GlideApp.with(mContext!!).clear(it)
                    }

                    mStatusItems!![i].status = NONE
                    mStatusItems!![i].targetRef = null
                }
            }
        }
    }

    private fun getVisibleItemPosition(): IntArray {
        val first = mLayoutManager?.findFirstVisibleItemPosition()
        val last = mLayoutManager?.findLastVisibleItemPosition()
        return intArrayOf(first!!, last!!)
    }

    class Status {
        var targetRef: WeakReference<Target<*>>? = null
        var status = NONE
        var position = 0
    }
}

import android.content.Context
import android.util.Log
import com.bumptech.glide.GlideBuilder
import com.bumptech.glide.annotation.GlideModule
import com.bumptech.glide.module.AppGlideModule

@GlideModule
class MyModule : AppGlideModule() {
    override fun applyOptions(context: Context, builder: GlideBuilder) {
        builder.setLogLevel(Log.DEBUG)
    }

    override fun isManifestParsingEnabled(): Boolean {
        return false
    }
}