Android Glide自定义AppCompatImageView切分成若干小格子，每个小格子onDraw绘制Bitmap，Kotlin（1）
垂直方向的RecyclerView，每行一个AppCompatImageView，每个AppCompatImageView被均匀切割成n个小格子， 每个小格子通过Glide加载出来Bitmap，然后onDraw绘制整行。
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" /><uses-permission android:name="android.permission.READ_MEDIA_IMAGES" />
implementation("com.github.bumptech.glide:glide:4.16.0")
import android.content.Context
import android.os.Bundle
import android.provider.MediaStore
import android.util.Log
import android.view.ViewGroup
import androidx.appcompat.app.AppCompatActivity
import androidx.lifecycle.lifecycleScope
import androidx.recyclerview.widget.LinearLayoutManager
import androidx.recyclerview.widget.RecyclerView
import kotlinx.coroutines.Dispatchers
import kotlinx.coroutines.launch
import kotlinx.coroutines.withContextclass MainActivity : AppCompatActivity() {companion object {const val VIEW_TYPE = 0const val TAG = "fly/MainActivity"}override fun onCreate(savedInstanceState: Bundle?) {super.onCreate(savedInstanceState)setContentView(R.layout.activity_main)val rv = findViewById<RecyclerView>(R.id.recycler_view)val layoutManager = LinearLayoutManager(this)layoutManager.orientation = LinearLayoutManager.VERTICALrv.layoutManager = layoutManagerval adapter = MyAdapter()rv.adapter = adapterlifecycleScope.launch(Dispatchers.IO) {val items = readAllImage(this@MainActivity)items.reverse()val data = sliceDataList(items)withContext(Dispatchers.Main) {adapter.dataChanged(data)}}}private fun sliceDataList(data: ArrayList<MyData>): ArrayList<ArrayList<MyData>> {var k: Intval lists = ArrayList<ArrayList<MyData>>()for (i in data.indices step BatchBitmapView.ROW_SIZE) {val temp = ArrayList<MyData>()k = 0for (j in 0 until BatchBitmapView.ROW_SIZE) {k = i + jif (k >= data.size) {break}temp.add(data[k])}lists.add(temp)}return lists}class MyAdapter : RecyclerView.Adapter<MyVH>() {private var items = ArrayList<ArrayList<MyData>>()fun dataChanged(items: ArrayList<ArrayList<MyData>>) {this.items = itemsnotifyDataSetChanged()}override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): MyVH {Log.d(TAG, "onCreateViewHolder")val view = BatchBitmapView(parent.context)return MyVH(view)}override fun getItemCount(): Int {return items.size}override fun getItemViewType(position: Int): Int {return VIEW_TYPE}override fun onBindViewHolder(holder: MyVH, position: Int) {Log.d(TAG, "onBindViewHolder $position")val biv = (holder.itemView as? BatchBitmapView)biv?.setRowBitmapData(items[position], position)}}class MyVH(itemView: BatchBitmapView) : RecyclerView.ViewHolder(itemView) {}class MyData(var path: String, var index: Int)private fun readAllImage(context: Context): ArrayList<MyData> {val photos = ArrayList<MyData>()//读取所有图片val cursor = context.contentResolver.query(MediaStore.Images.Media.EXTERNAL_CONTENT_URI, null, null, null, null)var index = 0while (cursor!!.moveToNext()) {//路径 urival 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}
}
import android.content.Context
import android.graphics.Bitmap
import android.graphics.Canvas
import android.graphics.drawable.Drawable
import android.util.AttributeSet
import android.util.Log
import androidx.appcompat.widget.AppCompatImageView
import com.bumptech.glide.Glide
import com.bumptech.glide.request.target.CustomTarget
import com.bumptech.glide.request.transition.Transitionclass BatchBitmapView @JvmOverloads constructor(context: Context,attributeSet: AttributeSet? = null,defStyleAttr: Int = 0
) : AppCompatImageView(context, attributeSet, defStyleAttr) {private val mData = mutableListOf<DataBean>()private val mScreenWidth = resources.displayMetrics.widthPixelsprivate val mTargets = mutableListOf<CustomTarget<Bitmap>>()companion object {const val TAG = "fly/BatchBitmapView"const val ROW_SIZE = 16 //一行多少个bitmapconst val IMAGE_SIZE = 80 //每个小格子图片的尺寸}fun setRowBitmapData(rows: ArrayList<MainActivity.MyData>?, position: Int) {Log.d(TAG, "setRowBitmapData $position")mData.clear()Log.d(TAG, "mTargets.size=${mTargets.size}")mTargets.forEach {Glide.with(context).clear(it) //如果不清楚，会发生有些图错放位置。}mTargets.clear() //mTargets上下滑动列表会越来越大，清空，一直保持ROW_SIZE.rows?.forEachIndexed { index, myData ->val target = object : CustomTarget<Bitmap>() {override fun onResourceReady(resource: Bitmap, transition: Transition<in Bitmap>?) {val bean = DataBean(resource)mData.add(bean)postInvalidate()}override fun onLoadCleared(placeholder: Drawable?) {}}Glide.with(context).asBitmap().centerCrop().override(IMAGE_SIZE).load(myData.path).into(target)mTargets.add(target)}}override fun onMeasure(widthMeasureSpec: Int, heightMeasureSpec: Int) {super.onMeasure(widthMeasureSpec, heightMeasureSpec)setMeasuredDimension(mScreenWidth, IMAGE_SIZE)}override fun onDraw(canvas: Canvas) {super.onDraw(canvas)mData.forEachIndexed { index, dataBean ->canvas.save()var left = (mScreenWidth / ROW_SIZE) * indexcanvas.drawBitmap(dataBean.bitmap, left.toFloat(), 0f, null)canvas.restore()}}data class DataBean(val bitmap: Bitmap)
}上面每一行加载16个bitmap绘图，速度很快，因为是canvas直接绘图。但是，如果使用下文的方式：
Android LinearLayout dynamic add child ImageView，Glide load，kotlin_zhangphil的博客-CSDN博客文章浏览阅读645次。【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/132080406即每一行先初始化一个水平的线性布局，然后逐个添加16个ImageView，对比发现明显卡顿，因为是以ViewGroup的方式布局摆放子view形成View。
Android Glide CustomTarget ,kotlin-CSDN博客文章浏览阅读1.4k次。【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/131661819
