How to load tiles from a large bitmap in Android?

Question

If I have a large bitmap file that would normally generate an "Out of memory" exception, how can I load it as tiles? e.g. I have a 10,000x10,000 image, I want to split it up into a 10x10 grid of 1,000x1,000 pixel tiles.

I've seen the function Bitmap.createBitmap(sourceBitmap, x, y, width, height) but it requires my large image as the source input.

How can I get a tile from my input image, without fully loading the input image?

Answer 1

Answer from Romain Guy in Is it possible to chop a bitmap to small pieces without loading the entire thing into memory?:

Android 2.3.3 has a new API called android.graphics.BitmapRegionDecoder that lets you do exactly what you want.

You would for instance do the following:

BitmapRegionDecoder decoder = BitmapRegionDecoder.newInstance(myStream, false);  
Bitmap region = decoder.decodeRegion(new Rect(10, 10, 50, 50), null);

Easy :)