How to avoid "out of memory exception" when doing Bitmap processing?

Question

In onPictureTaken, I want to do the following:

Bitmap decodedPicture = BitmapFactory.decodeByteArray(data, 0, data.length);
Matrix matrix = new Matrix();
matrix.preScale(-1.0f, 1.0f);
Bitmap picture = Bitmap.createBitmap(decodedPicture, 0, 0, decodedPicture.getWidth(), decodedPicture.getHeight(), matrix, false);

View v1 = mainLayout.getRootView();
v1.setDrawingCacheEnabled(true);
Bitmap screenshot = Bitmap.createBitmap(v1.getDrawingCache());
v1.setDrawingCacheEnabled(false);

Bitmap scaledPicture = Bitmap.createScaledBitmap(picture, screenshot.getWidth(), screenshot.getHeight(), true);

Bitmap compos = Bitmap.createBitmap(scaledPicture.getWidth(), scaledPicture.getHeight(), Bitmap.Config.ARGB_8888);

Canvas canvas = new Canvas(compos);
canvas.drawBitmap(scaledPicture, new Matrix(), null);
canvas.drawBitmap(screenshot, new Matrix(), null);

MediaStore.Images.Media.insertImage(getContentResolver(), compos, "name" , "description");
sendBroadcast(new Intent(Intent.ACTION_MEDIA_MOUNTED, Uri.parse("file://" + Environment.getExternalStorageDirectory())));

My only requirement is that I'd like to save a high-quality photo... Seems I might have to sacrifice that.

On my Nexus 4 and newer devices, this code runs fine and as expected. But on older devices that have less memory, I'm running out of RAM! :(

How do I do the same image manipulation without running up against the memory limit?? I'm not trying to display these images on screen, so the solutions that have to do with a scaled down image don't really apply here...

Answer 1

you need to read the bitmap in with an increased sample size. the trick is finding the correct sample size that won't result in reduced resolution when you ultimately scale the image. i wrote a blog entry about it here that includes a nice utility class for scaling,

http://zerocredibility.wordpress.com/2011/01/27/android-bitmap-scaling/

you could probably simplify that class quite a bit depending on your specific needs.

the jist is to read just the size of the bitmap. calculate the optimal sample size based on your desired scaled size, read the bitmap in using that sample size, then fine-scale it to exactly the size you want.