ListView的用音乐专辑图片滞后 [英] ListView lags with Music Album pictures
本文介绍了ListView的用音乐专辑图片滞后的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
我建立了应有的albumcover的标题ARTISTNAME和图像一个ListView音乐播放器。这似乎变得非常laggy。如何提高性能？
我的函数来获得这些图片是这样的：
公共静态位图getAlbumart（上下文的背景下，龙album_id）{
位图BM = NULL;
BitmapFactory.Options选项=新BitmapFactory.Options（）;
尝试{
最后乌里sArtworkUri = Uri.parse（内容：//媒体/外部/音频/ albumart）;
URI URI = ContentUris.withAppendedId（sArtworkUri，album_id）;
ParcelFileDescriptor PFD = context.getContentResolver（）openFileDescriptor（URI，R）。
如果（PFD！= NULL）{
FD的FileDescriptor = pfd.getFileDescriptor（）;
BM = BitmapFactory.de codeFileDescriptor（FD，空，期权）;
PFD = NULL;
FD = NULL;
}
}赶上（错误EE）{BM = BitmapFactory.de codeResource（context.getResources（），R.drawable.cd_128x128）; }
赶上（例外五）{BM = BitmapFactory.de codeResource（context.getResources（），R.drawable.cd_128x128）;}
返回BM;}
如果我在getView功能做到这一点，每次在App杀死自己。于是，我就先救他们位图的ArrayList的但是这个时间太长。我已经尝试过了Viewholder但这真的不影响性能。
我getview看起来像这样
`@覆盖
公共查看getView（INT位置，查看视图的ViewGroup父）{ 查看rview =视图。
支架=无效;
如果（rview == NULL）
{
LayoutInflater吹气= context.getLayoutInflater（）;
rview = inflater.inflate（R.layout.row_song，空，真）;
持有人=新ViewHolder（rview）;
rview.setTag（保持器）;
}
其他
{
支架=（ViewHolder）rview.getTag（）;
}
holder.imgAlbumart.setImageBitmap（Music.getAlbumart（上下文，Long.valueOf（AL_songlist.get（位置）.getAlbumID（））））; holder.txtTitle.setText（AL_songlist.get（位置）.getTitle（））;
holder.txtArtist.setText（AL_songlist.get（位置）.getArtist（））;
返回rview;
}`
编辑： ![](\"http://i.stack.imgur.com/y9ukA.png\")
这是相同的，当我尝试过。
android.provider.MediaStore.Audio.AlbumColumns.ALBUM_ART
解决方案使用我的
AlbumArtLoader.java。我是从Android开发者网站，但无法找到该网页。我修改它，使之比所提供的code顺畅。/ *加载图像在平稳的ListView * /
公共类AlbumArtLoader {
私人上下文CTX;
私人诠释artSize;
私人最终位图mPlaceHolderBitmap;
私人绘制对象[] =可绘制新绘制对象[2];
公共AlbumArtLoader（上下文C）{
CTX = C;
artSize = c.getResources（）getDimensionPixelSize（R.dimen.albumart_size）。
mPlaceHolderBitmap = BitmapFactory.de codeResource（ctx.getResources（），R.drawable.transparent）;
mPlaceHolderBitmap = Bitmap.createScaledBitmap（mPlaceHolderBitmap，artSize，artSize，FALSE）;
可绘制[0] =新BitmapDrawable（ctx.getResources（），mPlaceHolderBitmap）;
}
类BitmapWorkerTask扩展的AsyncTask＆LT;弦乐，太虚，TransitionDrawable＆GT; {
私人最终的WeakReference＆LT; ImageView的＆GT; imageViewReference;
私人字符串路径;
公共BitmapWorkerTask（ImageView的ImageView的）{
//使用的WeakReference，确保ImageView的可以被垃圾收集
imageViewReference =新的WeakReference＆LT; ImageView的＆GT;（ImageView的）;
}
//在后台德code图像。
@覆盖
保护TransitionDrawable doInBackground（字符串... PARAMS）{
路径=参数[0];
// TransitionDrawable让你做2绘项目之间的交叉淡入淡出动画
//它增加光滑的感觉
TransitionDrawable TD = NULL; //该albumart_unknown位图重新对每个相册没有专辑封面，以保持甚至滚动
如果（路径== NULL）{
位图B = Bitmap.createScaledBitmap（BitmapFactory.de codeResource（ctx.getResources（），R.drawable.albumart_unknown），artSize，artSize，真正的）;
可绘[1] =新BitmapDrawable（ctx.getResources（），B）;
}其他{
位图B：
尝试{
B = Bitmap.createScaledBitmap（BitmapFactory.de codeFILE（路径），artSize，artSize，真正的）;
}赶上（例外五）{
B = Bitmap.createScaledBitmap（BitmapFactory.de codeResource（ctx.getResources（），R.drawable.albumart_unknown），artSize，artSize，真正的）;
}
可绘[1] =新BitmapDrawable（ctx.getResources（），B）;
}
TD =新TransitionDrawable（可绘制）;
td.setCrossFadeEnabled（真）;
返回运输署;
}
//完成后，看是否ImageView的仍然是围绕并设置位图。
@覆盖
保护无效onPostExecute（TransitionDrawable TD）{
如果（isCancelled（））{
TD = NULL;
}
如果（imageViewReference = NULL＆放大器;！＆安培;！TD = NULL）{
最后ImageView的ImageView的= imageViewReference.get（）;
最后BitmapWorkerTask bitmapWorkerTask = getBitmapWorkerTask（ImageView的）;
如果（这== bitmapWorkerTask和放大器;＆安培;！ImageView的= NULL）{
imageView.setImageDrawable（TD）;
td.startTransition（200）;
}
}
}
} 公共无效loadBitmap（字符串路径，ImageView的ImageView的）{
如果（cancelPotentialWork（路径，ImageView的））{
最后BitmapWorkerTask任务=新BitmapWorkerTask（ImageView的）;
最后AsyncDrawable asyncDrawable =新AsyncDrawable（ctx.getResources（），mPlaceHolderBitmap，任务）;
imageView.setImageDrawable（asyncDrawable）;
task.execute（路径）;
}
} 静态类AsyncDrawable扩展BitmapDrawable {
私人最终的WeakReference＆LT; BitmapWorkerTask＆GT; bitmapWorkerTaskReference;
公共AsyncDrawable（资源资源，位图的位图，BitmapWorkerTask bitmapWorkerTask）{
超（RES，位图）;
bitmapWorkerTaskReference =新的WeakReference＆LT; BitmapWorkerTask＆GT;（bitmapWorkerTask）;
}
公共BitmapWorkerTask getBitmapWorkerTask（）{
返回bitmapWorkerTaskReference.get（）;
}
} 公共静态布尔cancelPotentialWork（字符串路径，ImageView的ImageView的）{
最后BitmapWorkerTask bitmapWorkerTask = getBitmapWorkerTask（ImageView的）;
如果（bitmapWorkerTask！= NULL）{
最后弦乐的位图数据= bitmapWorkerTask.path;
//如果位图数据尚未设置，或者它从新的数据不同
如果（位图数据== NULL ||位图数据！=路径）{
//取消previous任务
bitmapWorkerTask.cancel（真）;
}其他{
//同样的工作已在进行中
返回false;
}
}
//没有任务与ImageView的关联，或者现有任务被取消
返回true;
} // Helper方法
私有静态BitmapWorkerTask getBitmapWorkerTask（ImageView的ImageView的）{
如果（ImageView的！= NULL）{
最终可绘制可绘制= imageView.getDrawable（）;
如果（绘制的instanceof AsyncDrawable）{
最后AsyncDrawable asyncDrawable =（AsyncDrawable）绘制;
返回asyncDrawable.getBitmapWorkerTask（）;
}
}
返回null;
}
}要使用它，创建在
适配器一个AlbumArtLoader实例AlbumArtLoader mArtLoader;使用实例化它
mArtLoader =新AlbumArtLoader（背景）;您
适配器的构造函数，它接收在上下文从活动。然后在
getView（）mArtLoader.loadBitmap（pathToAlbumArt，vh.imgAlbumart）;EXTRA：从你的光标获取专辑封面路径
INT artColumnIndex = albumCursor.getColumnIndex（MediaStore.Audio.AlbumColumns.ALBUM_ART）;如果（albumCursor =空＆放大器;！＆放大器; albumCursor.moveToFirst（））{
做{
字符串artPath = albumCursor.getString（artColumnIndex）;
}而（albumCursor.moveToNext（））;
}I'm building a music player which should have a listView with title-artistname and Image of the albumcover. This seems to get very laggy. How can I improve performance?
My function to get these pictures is like this:
public static Bitmap getAlbumart(Context context,Long album_id){ Bitmap bm = null; BitmapFactory.Options options = new BitmapFactory.Options(); try{ final Uri sArtworkUri = Uri.parse("content://media/external/audio/albumart"); Uri uri = ContentUris.withAppendedId(sArtworkUri, album_id); ParcelFileDescriptor pfd = context.getContentResolver().openFileDescriptor(uri, "r"); if (pfd != null){ FileDescriptor fd = pfd.getFileDescriptor(); bm = BitmapFactory.decodeFileDescriptor(fd, null, options); pfd = null; fd = null; } } catch(Error ee){bm = BitmapFactory.decodeResource(context.getResources(),R.drawable.cd_128x128); } catch (Exception e) { bm = BitmapFactory.decodeResource(context.getResources(),R.drawable.cd_128x128);} return bm;}If I do this everytime in my getView function the App kills itself. So I tried to save them first in a Arraylist of Bitmaps but this takes too long. I already tried with a Viewholder but this really doesn't affect the performance.
My getview looks like this
`@Override public View getView(int position, View view, ViewGroup parent) { View rview = view; holder = null; if (rview == null) { LayoutInflater inflater = context.getLayoutInflater(); rview= inflater.inflate(R.layout.row_song, null, true); holder = new ViewHolder(rview); rview.setTag(holder); } else { holder = (ViewHolder) rview.getTag(); } holder.imgAlbumart.setImageBitmap(Music.getAlbumart(context, Long.valueOf(AL_songlist.get(position).getAlbumID()))); holder.txtTitle.setText(AL_songlist.get(position).getTitle()); holder.txtArtist.setText(AL_songlist.get(position).getArtist()); return rview; }`EDIT:
It's the same when I try it through.
android.provider.MediaStore.Audio.AlbumColumns.ALBUM_ART
解决方案Use my
AlbumArtLoader.java. I got it from android developers website but can't find the page. I modified it to make it smoother than the provided code./* Loads images smoothly in ListView */ public class AlbumArtLoader { private Context ctx; private int artSize; private final Bitmap mPlaceHolderBitmap; private Drawable[] drawables = new Drawable[2]; public AlbumArtLoader(Context c) { ctx = c; artSize = c.getResources().getDimensionPixelSize(R.dimen.albumart_size); mPlaceHolderBitmap = BitmapFactory.decodeResource(ctx.getResources(), R.drawable.transparent); mPlaceHolderBitmap = Bitmap.createScaledBitmap(mPlaceHolderBitmap, artSize, artSize, false); drawables[0] = new BitmapDrawable(ctx.getResources(), mPlaceHolderBitmap); } class BitmapWorkerTask extends AsyncTask<String, Void, TransitionDrawable> { private final WeakReference<ImageView> imageViewReference; private String path; public BitmapWorkerTask(ImageView imageView) { // Use a WeakReference to ensure the ImageView can be garbage collected imageViewReference = new WeakReference<ImageView>(imageView); } // Decode image in background. @Override protected TransitionDrawable doInBackground(String... params) { path = params[0]; // TransitionDrawable let you to make a crossfade animation between 2 drawables // It increase the sensation of smoothness TransitionDrawable td = null; // The albumart_unknown bitmap is recreated for each album without album art to maintain even scrolling if(path == null) { Bitmap b = Bitmap.createScaledBitmap(BitmapFactory.decodeResource(ctx.getResources(), R.drawable.albumart_unknown), artSize, artSize, true); drawables[1] = new BitmapDrawable(ctx.getResources(), b); } else { Bitmap b; try { b = Bitmap.createScaledBitmap(BitmapFactory.decodeFile(path), artSize, artSize, true); } catch(Exception e) { b = Bitmap.createScaledBitmap(BitmapFactory.decodeResource(ctx.getResources(), R.drawable.albumart_unknown), artSize, artSize, true); } drawables[1] = new BitmapDrawable(ctx.getResources(), b); } td = new TransitionDrawable(drawables); td.setCrossFadeEnabled(true); return td; } // Once complete, see if ImageView is still around and set bitmap. @Override protected void onPostExecute(TransitionDrawable td) { if(isCancelled()) { td = null; } if(imageViewReference != null && td != null) { final ImageView imageView = imageViewReference.get(); final BitmapWorkerTask bitmapWorkerTask = getBitmapWorkerTask(imageView); if(this == bitmapWorkerTask && imageView != null) { imageView.setImageDrawable(td); td.startTransition(200); } } } } public void loadBitmap(String path, ImageView imageView) { if(cancelPotentialWork(path, imageView)) { final BitmapWorkerTask task = new BitmapWorkerTask(imageView); final AsyncDrawable asyncDrawable = new AsyncDrawable(ctx.getResources(), mPlaceHolderBitmap, task); imageView.setImageDrawable(asyncDrawable); task.execute(path); } } static class AsyncDrawable extends BitmapDrawable { private final WeakReference<BitmapWorkerTask> bitmapWorkerTaskReference; public AsyncDrawable(Resources res, Bitmap bitmap, BitmapWorkerTask bitmapWorkerTask) { super(res, bitmap); bitmapWorkerTaskReference = new WeakReference<BitmapWorkerTask>(bitmapWorkerTask); } public BitmapWorkerTask getBitmapWorkerTask() { return bitmapWorkerTaskReference.get(); } } public static boolean cancelPotentialWork(String path, ImageView imageView) { final BitmapWorkerTask bitmapWorkerTask = getBitmapWorkerTask(imageView); if(bitmapWorkerTask != null) { final String bitmapData = bitmapWorkerTask.path; // If bitmapData is not yet set or it differs from the new data if(bitmapData == null || bitmapData != path) { // Cancel previous task bitmapWorkerTask.cancel(true); } else { // The same work is already in progress return false; } } // No task associated with the ImageView, or an existing task was cancelled return true; } // Helper method private static BitmapWorkerTask getBitmapWorkerTask(ImageView imageView) { if(imageView != null) { final Drawable drawable = imageView.getDrawable(); if(drawable instanceof AsyncDrawable) { final AsyncDrawable asyncDrawable = (AsyncDrawable) drawable; return asyncDrawable.getBitmapWorkerTask(); } } return null; } }To use it, create an
AlbumArtLoaderinstance in yourAdapterAlbumArtLoader mArtLoader;Instantiate it using
mArtLoader = new AlbumArtLoader(context);inside your
Adapterconstructor, which receivesContextfrom yourActivity.Then in
getView()mArtLoader.loadBitmap(pathToAlbumArt, vh.imgAlbumart);EXTRA: To get album art path from your cursor
int artColumnIndex = albumCursor.getColumnIndex(MediaStore.Audio.AlbumColumns.ALBUM_ART); if(albumCursor!=null && albumCursor.moveToFirst()) { do { String artPath = albumCursor.getString(artColumnIndex); } while (albumCursor.moveToNext()); }
这篇关于ListView的用音乐专辑图片滞后的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
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