Glide 3.6.0 proof of concept for loading a Bitmap as Bitmap through Glide

BitmapBitmapResourceDecoder.java

class BitmapBitmapResourceDecoder implements ResourceDecoder<Bitmap, Bitmap> {
	private final BitmapPool pool;
	public BitmapBitmapResourceDecoder(Context context) {
		this(Glide.get(context).getBitmapPool());
	}
	public BitmapBitmapResourceDecoder(BitmapPool pool) {
		this.pool = pool;
	}

	@Override public Resource<Bitmap> decode(Bitmap source, int width, int height) throws IOException {
		return BitmapResource.obtain(source, pool);
	}

	@Override public String getId() { return "BitmapBitmapResourceDecoder"; }
}

initialization_snip.java

GenericRequestBuilder<Bitmap, Bitmap, Bitmap, Bitmap> glide = Glide
	.with(context)
	.using(new PassthroughModelLoader<Bitmap, Bitmap>(), Bitmap.class)
	.from(Bitmap.class)
	.as(Bitmap.class)
	.decoder(new BitmapBitmapResourceDecoder(context))
	.cacheDecoder(new FileToStreamDecoder<Bitmap>(new StreamBitmapDecoder(context)))
	.encoder(new BitmapEncoder())
	// or .diskCacheStrategy(DiskCacheStrategy.NONE) instead of last 2
;

load_snip.java

// simulate a bitmap input coming from somewhere
Bitmap bitmap = getBitmap(android.R.drawable.sym_def_app_icon);

glide
	.clone() // if you use the same glide multiple times (e.g. in Adapter)
	.load(bitmap)
	.signature(new StringSignature("android.R.drawable.sym_def_app_icon")) // required for cache to be correct
	// ... add whatever you want here (transformation, animation ...)
	.into(imageView)
;

Bitmap getBitmap(@DrawableRes int id) {
	Drawable drawable = getResources().getDrawable(id);
	Bitmap bitmap = Bitmap.createBitmap(drawable.getIntrinsicWidth(), drawable.getIntrinsicHeight(), Config.ARGB_8888);
	Canvas canvas = new Canvas(bitmap);
	drawable.setBounds(0, 0, canvas.getWidth(), canvas.getHeight());
	drawable.draw(canvas);
}

PassthroughModelLoader.java

class PassthroughModelLoader<Result, Source extends Result> implements ModelLoader<Source, Result> {
	@Override public DataFetcher<Result> getResourceFetcher(final Source model, int width, int height) {
		return new CastingDataFetcher<Source, Result>(model); // upcasting is ok
	}

	/** Extremely unsafe, use with care. */
	private static class CastingDataFetcher<Source, Result> implements DataFetcher<Result> {
		private final Source model;
		public CastingDataFetcher(Source model) {
			this.model = model;
		}

		@SuppressWarnings("unchecked")
		@Override public Result loadData(Priority priority) throws Exception {
			return (Result) model;
		}

		@Override public void cleanup() { }
		@Override public String getId() { return ""; }
		@Override public void cancel() { }
	}
}