Scaling images in Android causes OutOfMemory exception

I'm developing an Android game consisting of many images as sprites.

When I load the images the following way:

public static Bitmap loadBitmap(int resId) {  
    return BitmapFactory.decodeResource(getResources(), resId, options);
}

everything works perfectly fine.

When I try to down-scale or up-scale the bitmap with this code:

public static Bitmap loadBitmap(int resId) {
    Bitmap bitmap = B开发者_运维百科itmapFactory.decodeResource(getResources(), resId, options);
    Matrix matrix = new Matrix();
    matrix.postScale(0.8f, 0.8f);
    Bitmap scaledBitmap = Bitmap.createBitmap(bitmap, 0, 0, bitmap.getWidth(), bitmap.getHeight(), matrix, true);
    bitmap.recycle();
    bitmap = null;
    return scaledBitmap;
}

the application crashes with the following exception:

2211840-byte external allocation too large for this process.  
Out of memory: Heap Size=4935KB, Allocated=2549KB, Bitmap Size=18463KB  
VM won't let us allocate 2211840 bytes

Why is the scaling causing OutOfMemory exception? I even try to recycle the original image in order to save some space. I'm not using Bitmap.createScaledBitmap(...) intentionally, since this method does memory leaking internally (as explained in other online resources).

Thank you in advance,

Zlatko

You are probably just very close to the memory limit. It looks like you are creating a pretty large bitmap (and I'm not sure why you are making it the same size as the original bitmap). From the log, you have used 25MB of Java allocations, and 18MB of bitmap allocations, so you are basically right up against the 48MB heap limit.

Also I think it is very unlikely that createScaledBitmap() leaks. All it does is basically what you are doing here.

You should try to use the variable "inSampleSized" in the BitmapFactory.Options class. This will scale without using excess memory.

http://developer.android.com/reference/android/graphics/BitmapFactory.Options.html#inSampleSize

I guess you´re really close to the heap limit. In your function, you basically are instantiating a second Bitmap, which roughly leads to doubling your memory (Bitmaps are very large). If you´re on an OS earlier than Honeycomb, it´s also misleading to look at memory values, which are printed out somewhere. iirc, Bitmaps are held directly on the system memory heap, whereas everything other is held on the vm heap (and these are the values you see -> 2,5MB). However, the memory for Bitmap allocations also counts in for the memory heap limit. :/

I suggest you have a look at this Google I/O Session: http://www.youtube.com/watch?v=_CruQY55HOk

I think your problem can only be solved by bringing down the resolution of your Bitmap or by using some scale function, that doesn´t instantiate a new Bitmap and modifies the existing one (like the one mentioned by AmandeepGrewal).