When does "ActionBarDrawerToggle" show its "openDrawerContentDescRes" and "closeDrawerContentDescRes" strings?

Question

Background

The CTOR of "ActionBarDrawerToggle" is as such:

public ActionBarDrawerToggle (Activity activity, DrawerLayout drawerLayout, int openDrawerContentDescRes, int closeDrawerContentDescRes)

or:

public ActionBarDrawerToggle (Activity activity, DrawerLayout drawerLayout, Toolbar toolbar, int openDrawerContentDescRes, int closeDrawerContentDescRes)

The documentation tells you about the strings parameters, that (here ) :

String resources must be provided to describe the open/close drawer actions for accessibility services.

The problem

I can't find a scenario that those strings are being used.

What I've tried

As opposed to action items, where I can see a toast each time I long click an item, here I couldn't find in which case I can see it.

The question

Why is it required? In which cases is it shown?

Is it like what's happening to ImageView ? If so, I'd still like to know when those strings are used and how (on both ImageView and here).

Answer 1

Those are string resources for content descriptions. They are not displayed on screen, but accessibility services can use them to, for example, say aloud what the content is for users who are visually impaired using text-to-speech. That way you could have the device produce audio saying "drawer open" or "drawer closed" (or any other strings) when the drawer opens or closes, so blind users know what happened in the app.