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.File


class 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 = adapter

        CoroutineScope(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>? = null

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

        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 = 0
        while (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.RecyclerView
        android: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" />

 

 

 

 

Android Glide自定义AppGlideModule，让Glide在app启动后基于定制化GlideModule加载，kotlin_zhangphil的博客-CSDN博客在实际的开发中，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/131592226Android load all photos into RecyclerView,pinch to zoom by ScaleGestureDetector,kotlin(4)_zhangphil的博客-CSDN博客Android RecyclerView的StaggeredGridLayoutManager实现交错排列的子元素分组先看实现的结果如图：设计背景：现在的产品对设计的需求越来越多样化，如附录文章2是典型的联系人分组RecyclerView，子元素排列到一个相同的组，但是有些时候，UI要求把这些元素不是垂直方向的，而是像本文开头的图中所示样式排列，这就需要用StaggeredGridLayoutMa。在处理大图的浏览查看动作过程中，往往还有其他额外的事情需要处理，典型的以微信。https://blog.csdn.net/zhangphil/article/details/131296499

Android RecyclerView AsyncListUtil手动刷新fillData，kotlin_zhangphil的博客-CSDN博客基于Android官方Paging Library的RecyclerView分页加载框架我之前写了一篇RecyclerView分页加载机制的文章，是基于Android官方的AsyncListUtil实现的，详情见附录文章1。基于Android官方Paging Library的RecyclerView分页加载框架我之前写了一篇RecyclerView分页加载机制的文章，是基于Android官方的AsyncListUtil实现的，详情见附录文章1。【代码】Android Paging 3,kotlin（1）https://blog.csdn.net/zhangphil/article/details/131519811