Requesting a wake lock when going fullscreen

[marcoscaceres]

It might be nice to be able to request a screen wake lock when requesting fullscreen. Use case, for example, giving a live presentation via a website (see other possible use case).

I'm imagining something like:

body.requestFullscreen({ keepScreenOn: true });

Unlike the Screen Wake Lock API, this would have several advantages:

• remove the need for developer to have to manage multiple locks.
• explicitly ties into the implicit grant permissions model of the Fullscreen API, while keeping the use in control: When the user exits full screen, the screen wake lock is silently released.
• no information leakage: the website would not know if the request for the wake lock was granted, and the OS or browser could safely drop the request without notifying the website that it no longer has the lock (e.g., the device enters a low-power state).

The behavior would be exactly the same as watching a video full screen, which also acquires a wake lock.

[saschanaz]

Layperson question: do users expect wake lock when the content is not in fullscreen? Skimming the wake lock use cases, I'd expect fullscreen for all of them 👀

[annevk]

I do... When watching an inline movie on Twitter or some such I do not expect the screen to turn off and yet it does at times. (It's not clear how you'd ask the user that though. Probably the system should just be more aware that the user is watching something.)

[saschanaz]

When watching an inline movie on Twitter or some such I do not expect the screen to turn off and yet it does at times.

It seems this covers such case in Gecko: https://bugzilla.mozilla.org/show_bug.cgi?id=1665980

[marcoscaceres]

To @annevk's use case, I think the behavior may be UA specific... like NoSleep.js uses a hidden video to keep the screen awake. Similarly (or more generally), fullscreen video always automatically gets a wake lock.

[saschanaz]

Another question from me: when does a user expect fullscreen-without-wakelock? Can wakelocking be the default behavior?

[marcoscaceres]

yeah, I agree. That's a better question. A few things I can think of... the "distraction free writing" mode like in WordPress... I might get up to make a coffee in the middle of writing, so I'd probably don't want it to hold a wake lock.

Similarly, I think VS Code has a similar "zen" mode. Again, I might be in Zen mode, but might get up to do something (e.g., rest room, answer the door or phone) - so I probably don't want it to hold a wake lock there.