With your current implementation a progress bar will not be working well, as the whole 'load image data and build a drawable' is done in a single line Drawable drawable = Drawable.createFromStream(is, "src");
. So there is no way for you to determine how many percents of the loading are done.
What you can do, is to use an indeterminate progress indicator (aka the spinning wheel).
You could e.g. overlay an instance of such a ProgressBar view over the image while it is loading and remove (or hide) it as soon as the image loading is done.