This bug report was migrated from our old Bugzilla tracker.

These attachments are available in the static archive:

• demo app (test_multiwindow.c, text/x-csrc, 2020-06-04 11:43:11 +0000, 14134 bytes)
• prototype patch (patch_MultiWindow-v1.diff, text/plain, 2020-06-04 12:00:06 +0000, 112931 bytes)

Reported in version: don't know
Reported for operating system, platform: Android (All), All

Comments on the original bug report:

On 2020-06-04 11:39:24 +0000, Sylvain wrote:

Currently SDL2 has a limitation of 1 SDL_Window, and it could be possible to create several.

May be interesting when running on chromebook, or phone with several screens.
There is a also a multi-window mode on phone.

On 2020-06-04 11:43:11 +0000, Sylvain wrote:

Created attachment 4368
demo app

This is a small demo app, that creates/deletes SDL_Window and just render a blinking screen and a cursor on each.

Press two fingers at each corner, to create-delete a window.
The first created window is red, created from the top-left.
You can create/delete from the other 3 corners.

On 2020-06-04 12:00:06 +0000, Sylvain wrote:

Created attachment 4369
prototype patch

This is an unfinished patch. most secondary features are not tested, and it has bugs for sure.

It shows we can create several SDL_Window, each one has its own activity and SurfaceView.

Due to the nature of Activity that are "stacked" on a phone, the SDL_Window are also stacked when used on a basic phone. And it's not possible to re-order the stacked composed of several instance of the same activity. (though, it's possible to re-order several different activities).

On a phone that started the multiwindow mode, it's possible to have two window adjacent. But multiwindow isn't meant to be activated by the application. So it's not really useful.

On a chromebook. I don't have one and I simply tested it with the emulator and it indeed creates several windows. This case seems interesting. The emulator isn't really stable, so it's hard to tell more...

A phone with several screen: not tested / don't have one neither.

Some points with the patch:

• SDLWindowActivity class it for creating SDL_window.
• SDLActivity remains to start the SDL thread. this isn't convenient to have this activity ... Android has also "service" class, but it's doesn't create a icon to launch the app ...
  -> what is bad is that there is a glitch transition from SDLActivity to the first SDLWindowActivity, which seems unnecessary.
• after multiple/stress creation/deletion of window, there are issues with backup-restore of egl context, not sure when it comes from ...

Some other point:

• I wonder whether starting a SDL_Window in a new instance of activity is a good choice, maybe it should be run in what android call "fragment" ?

On 2020-06-04 16:05:01 +0000, Sam Lantinga wrote:

Conceptually in SDL all the windows are in a single activity. I don't know how Android represents multiple windows and whether this is a requirement of the system, but it seems worth exploring.