[Feature Request] Support for External Display on Android (USB-C / HDMI)

[TimOelrichs]

It would be highly beneficial if RetroArch for Android supported external displays connected via USB-C (DisplayPort Alt Mode) or HDMI. This would allow cores that support dual screens (e.g., DS emulators, Game Boy multiplayer cores, or debugging overlays) to render different outputs to the internal and external display.

This could be implemented with the Android’s DisplayManager and Presentation APIs.

This is optional and Android-only, with zero impact on other platforms. Could be gated behind compile-time or runtime checks.

[SavannahBlossom]

With the advent of DualScreen handhelds (and as a Retroid Dual Screen owner), this feature would be highly useful.

[gouchi]

Hi,

You want to be able to change monitor display ?

Or being able to display two framebuffers ? If the second, we will need first a new feature per #11838

Thank you.

[warmenhoven]

I don't think this is Android-only as iOS can do something similar.

Also I think it can be done in a fairly straightforward and backwards compatible way in libretro, by providing an environment where cores can specify the number of virtual screens and their rectangles. Continue to render to one frame buffer but specify the rectangles inside it that constitute the multiple screens.

I don't think it reduces the frontend work at all and would still end up needing to be done for each video driver. But providing the hints is something that could be done easily in the cores right now and gives the frontend a lot of flexibility with what to do with it.

[pressRtowin]

With the advent of DualScreen handhelds (and as a Retroid Dual Screen owner), this feature would be highly useful.

Is the solution here general enough that it would warrant renaming this issue to supporting dual screens in general, not just add-on displays via DP/HDMI?

I'm also quite interested in seeing this happen as a recent AYN Thor owner.