bitmap.copy() throws out of memory error

问题

I am using universal-image-loader library to load images, but when I call copy() on a loaded bitmap file in some cases I get OutOfMemoryError. Here is my code:

    ImageLoader.getInstance().loadImage(path, new ImageLoadingListener() {

        @Override
        public void onLoadingStarted(String arg0, View arg1) {
            // TODO Auto-generated method stub

        }

        @Override
        public void onLoadingFailed(String arg0, View arg1, FailReason arg2) {
            // TODO Auto-generated method stub

        }

        @Override
        public void onLoadingComplete(String arg0, View arg1, Bitmap arg2) {
            bm = arg2;
        }

        @Override
        public void onLoadingCancelled(String arg0, View arg1) {
            // TODO Auto-generated method stub

        }
    });
 Bitmap bm2= bm.copy(Bitmap.Config.ARGB_8888, true); //where the crash happens

I need the second Bitmap not to be mutable so I can draw on it.

回答1:

First of all try to find a little time to read good official documentation about bitmaps: Displaying Bitmaps Efficiently

It will give you understanding why and when java.lang.OutofMemoryError happens. And how to avoid it.

What about your question: see this article: Android: convert Immutable Bitmap into Mutable

But from API Level 11 only options.inMutable available to load the file into a mutable bitmap.

So, if we are building application with API level less than 11, then we have to find some other alternatives.

One alternative is creating another bitmap by copying the source

bitmap. mBitmap = mBitmap.copy(ARGB_8888 ,true);

But the will throw OutOfMemoryException if the source file is big. Actually incase if we want to edit an original file, then we will face this issue. We should be able to load at-least image into memory, but most we can not allocate another copy into memory.

So, we have to save the decoded bytes into some where and clear existing bitmap, then create a new mutable bitmap and load back the saved bytes into bitmap again. Even to copy bytes we cannot create another ByteBuffer inside the memory. In that case need to use MappedByteBuffer that will allocate bytes inside a disk file.

Following code would explain clearly:

//this is the file going to use temporally to save the bytes. 

File file = new File("/mnt/sdcard/sample/temp.txt");
file.getParentFile().mkdirs();

//Open an RandomAccessFile
/*Make sure you have added uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"
into AndroidManifest.xml file*/
RandomAccessFile randomAccessFile = new RandomAccessFile(file, "rw"); 

// get the width and height of the source bitmap.
int width = bitmap.getWidth();
int height = bitmap.getHeight();

//Copy the byte to the file
//Assume source bitmap loaded using options.inPreferredConfig = Config.ARGB_8888;
FileChannel channel = randomAccessFile.getChannel();
MappedByteBuffer map = channel.map(MapMode.READ_WRITE, 0, width*height*4);
bitmap.copyPixelsToBuffer(map);
//recycle the source bitmap, this will be no longer used.
bitmap.recycle();
//Create a new bitmap to load the bitmap again.
bitmap = Bitmap.createBitmap(width, height, Config.ARGB_8888);
map.position(0);
//load it back from temporary 
bitmap.copyPixelsFromBuffer(map);
//close the temporary file and channel , then delete that also
channel.close();
randomAccessFile.close();

And here is sample code.

回答2:

You cant do much about the bitmap outofmemory error except ensuring that the bitmap you are copying or displaying is not much large. Fortunately universal imageloader has a feature to compress bitmap by changing the config. So give Bitmap.Config.RGG_565 a try. Its supposed to half the memory footprint of the bitmap. You can also request for large heap size. Another thing you can do is copy the scaled version of the bitmap.

回答3:

As Illegel Argument said, you need to make sure that the Bitmap is not TOO large. Also, make sure that you are only loading one Bitmap at a time into memory.

You can dynamically scale the bitmap using BitmapFactory

Bitmap b = BitmapFactory.decodeByteArray(imageAsBytes, 0, imageAsBytes.length)
image.setImageBitmap(Bitmap.createScaledBitmap(b, 300, 300, false));

回答4:

Be thankful that it happens on your device, and not only on your user's devices.

1) That's something you have to cope with, and react to appropriately. Display error message, or load lower resolution of the bitmap. Your app will run on many kinds of devices, each has different amount of memory.

2) Use important function Bitmap.recycle after each operation which makes your old bitmap redundant. This will immediately free memory for next work without waiting for GC to run, and possible out of memory errors.

回答5:

Download this code from the site

http://www.androidhive.info/2012/02/android-custom-listview-with-image-and-text/

extract its ImageLoader , file cache , memory cache classes use them in your bitmap to do things wont create out of memory exception at all and will cache images and increase performance

回答6:

Use this Code to fullfill your purpose

Make the following classes in your code and in last use imageloader to load url pass it url , imageview and drawable to show incase url is not returning any image

FileCache.java

public class FileCache {

private File cacheDir;

public FileCache(Context context){
    //Find the dir to save cached images
    if (android.os.Environment.getExternalStorageState().equals(android.os.Environment.MEDIA_MOUNTED))
        cacheDir=new File(android.os.Environment.getExternalStorageDirectory(),"LazyList");
    else
        cacheDir=context.getCacheDir();
    if(!cacheDir.exists())
        cacheDir.mkdirs();
}

public File getFile(String url){
    //I identify images by hashcode. Not a perfect solution, good for the demo.
    String filename=String.valueOf(url.hashCode());
    //Another possible solution (thanks to grantland)
    //String filename = URLEncoder.encode(url);
    File f = new File(cacheDir, filename);
    return f;

}

public void clear(){
    File[] files=cacheDir.listFiles();
    if(files==null)
        return;
    for(File f:files)
        f.delete();
}

}

MemoryCache.java

public class MemoryCache {
private Map<String, SoftReference<Bitmap>> cache=Collections.synchronizedMap(new HashMap<String, SoftReference<Bitmap>>());

public Bitmap get(String id){
    if(!cache.containsKey(id))
        return null;
    SoftReference<Bitmap> ref=cache.get(id);
    return ref.get();
}

public void put(String id, Bitmap bitmap){
    cache.put(id, new SoftReference<Bitmap>(bitmap));
}

public void clear() {
    cache.clear();
}
}

Utils.java

public class Utils {
public static void CopyStream(InputStream is, OutputStream os)
{
    final int buffer_size=1024;
    try
    {
        byte[] bytes=new byte[buffer_size];
        for(;;)
        {
          int count=is.read(bytes, 0, buffer_size);
          if(count==-1)
              break;
          os.write(bytes, 0, count);
        }
    }
    catch(Exception ex){}
}
}

ImageLoader.java

public class ImageLoader {

MemoryCache memoryCache=new MemoryCache();
FileCache fileCache;
private Map<ImageView, String> imageViews=Collections.synchronizedMap(new WeakHashMap<ImageView, String>());
ExecutorService executorService; 

public ImageLoader(Context context){
    fileCache=new FileCache(context);
    executorService=Executors.newFixedThreadPool(5);
}

final int stub_id = R.drawable.no_image;
public void DisplayImage(String url, ImageView imageView)
{
    imageViews.put(imageView, url);
    Bitmap bitmap=memoryCache.get(url);
    if(bitmap!=null)
        imageView.setImageBitmap(bitmap);
    else
    {
        queuePhoto(url, imageView);
        imageView.setImageResource(stub_id);
    }
}

private void queuePhoto(String url, ImageView imageView)
{
    PhotoToLoad p=new PhotoToLoad(url, imageView);
    executorService.submit(new PhotosLoader(p));
}

private Bitmap getBitmap(String url) 
{
    File f=fileCache.getFile(url);

    //from SD cache
    Bitmap b = decodeFile(f);
    if(b!=null)
        return b;

    //from web
    try {
        Bitmap bitmap=null;
        URL imageUrl = new URL(url);
        HttpURLConnection conn = (HttpURLConnection)imageUrl.openConnection();
        conn.setConnectTimeout(30000);
        conn.setReadTimeout(30000);
        conn.setInstanceFollowRedirects(true);
        InputStream is=conn.getInputStream();
        OutputStream os = new FileOutputStream(f);
        Utils.CopyStream(is, os);
        os.close();
        bitmap = decodeFile(f);
        return bitmap;
    } catch (Exception ex){
       ex.printStackTrace();
       return null;
    }
}

//decodes image and scales it to reduce memory consumption
private Bitmap decodeFile(File f){
    try {
        //decode image size
        BitmapFactory.Options o = new BitmapFactory.Options();
        o.inJustDecodeBounds = true;
        BitmapFactory.decodeStream(new FileInputStream(f),null,o);

        //Find the correct scale value. It should be the power of 2.
        final int REQUIRED_SIZE=70;
        int width_tmp=o.outWidth, height_tmp=o.outHeight;
        int scale=1;
        while(true){
            if(width_tmp/2<REQUIRED_SIZE || height_tmp/2<REQUIRED_SIZE)
                break;
            width_tmp/=2;
            height_tmp/=2;
            scale*=2;
        }

        //decode with inSampleSize
        BitmapFactory.Options o2 = new BitmapFactory.Options();
        o2.inSampleSize=scale;
        return BitmapFactory.decodeStream(new FileInputStream(f), null, o2);
    } catch (FileNotFoundException e) {}
    return null;
}

//Task for the queue
private class PhotoToLoad
{
    public String url;
    public ImageView imageView;
    public PhotoToLoad(String u, ImageView i){
        url=u; 
        imageView=i;
    }
}

class PhotosLoader implements Runnable {
    PhotoToLoad photoToLoad;
    PhotosLoader(PhotoToLoad photoToLoad){
        this.photoToLoad=photoToLoad;
    }

    @Override
    public void run() {
        if(imageViewReused(photoToLoad))
            return;
        Bitmap bmp=getBitmap(photoToLoad.url);
        memoryCache.put(photoToLoad.url, bmp);
        if(imageViewReused(photoToLoad))
            return;
        BitmapDisplayer bd=new BitmapDisplayer(bmp, photoToLoad);
        Activity a=(Activity)photoToLoad.imageView.getContext();
        a.runOnUiThread(bd);
    }
}

boolean imageViewReused(PhotoToLoad photoToLoad){
    String tag=imageViews.get(photoToLoad.imageView);
    if(tag==null || !tag.equals(photoToLoad.url))
        return true;
    return false;
}

//Used to display bitmap in the UI thread
class BitmapDisplayer implements Runnable
{
    Bitmap bitmap;
    PhotoToLoad photoToLoad;
    public BitmapDisplayer(Bitmap b, PhotoToLoad p){bitmap=b;photoToLoad=p;}
    public void run()
    {
        if(imageViewReused(photoToLoad))
            return;
        if(bitmap!=null)
            photoToLoad.imageView.setImageBitmap(bitmap);
        else
            photoToLoad.imageView.setImageResource(stub_id);
    }
}

public void clearCache() {
    memoryCache.clear();
    fileCache.clear();
}

}

call this code where you want to cache or download or manage images

  imageLoader.DisplayImage(song.get(CustomizedListView.KEY_THUMB_URL), thumb_image);

来源：https://stackoverflow.com/questions/23763405/bitmap-copy-throws-out-of-memory-error