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

ゝ一世哀愁。 2023-10-15 16:49 44阅读 0赞

### 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。![favicon32.ico][]https://blog.csdn.net/zhangphil/article/details/132592405][Android Glide preload RecyclerView_item_Kotlin_zhangphil_-CSDN_Android Paging 3_kotlin_1_Glide_APP_Glide_Glide_android _Android_Android Glide_Android Glide_favicon32.ico_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
        }
    }

[favicon32.ico]: https://g.csdnimg.cn/static/logo/favicon32.ico
[Android Glide preload RecyclerView_item_Kotlin_zhangphil_-CSDN_Android Paging 3_kotlin_1_Glide_APP_Glide_Glide_android _Android_Android Glide_Android Glide_favicon32.ico_https_blog.csdn.net_zhangphil_article_details_132592405]: https://blog.csdn.net/zhangphil/article/details/132592405