How to overlay information on Android's launcher app?

Question

I want to create an accessibility feature for Android where a hint appears whenever a person presses or long-presses on an app icon. To do, this I have a few questions:

1. How to identify when a user clicks on the icon of an app on the homescreen or app launcher?
2. How to make use of this event to then pull appropriate information and present it to the user?

Do I need to develop a custom launcher app to be able to identify user presses etc.? Or can I somehow retrieve this information from whatever launcher a user uses and give the hint?

Answer 1

There are a couple of different ways to get after the information you are looking for.

The first option is to create a custom launcher, as you suggested. This has obvious drawbacks. Most obviously, having to re-create an entire launcher applications is obviously difficult, and likely to create more issues than fixes. You could search out an open source launcher application, and attempt to add your feature to this, however you'd then be reliant on the purveyors of this codebase to accept your feature.

The second, and the way I'd recommend, to access this information is through accessibility services. This information is available to services like TalkBack. It is essential to how they function. The difficulties you'll face here are interacting properly with the numerous launchers available out there. However, most of these launchers are based off of a similar starting point, which is the Android base open source launcher. As such, the portions of the launcher that you care to interact with should be coded very similarly in most launcher examples.

The downside to this approach is that only one accessibility service can be active on a device at a time. So, users who are partially blind, who may want to use your feature and TalkBack at the same time, won't be able to. It is of course to you to determine which set of difficulties/benefits you'd prefer to deal with, but these are your options.