Support multiple screens

[bwikbs]

Background?

There are requirements for multiple screens. There's nothing specific, everything can change, but multiple screens don't change. 😄 So I checked how multi-screen support is going on in Flutter. And I found the following:

https://docs.google.com/document/d/11_4wntz_9IJTQOo_Qhp7QF4RfpIMTfVygtOTxQ4OGHY/edit
https://github.com/flutter/flutter/issues/30701
https://github.com/google/flutter-desktop-embedding/issues/98

IMO, Supporting multiple windows didn't seem to happen soon at this moment. So I decided to look for Plan B.
That is EngineGroup feature.(https://flutter.dev/docs/development/add-to-app/multiple-flutters)
Technically, It’s a little different but I thought It would be able to produce similar looking with multi screen app.
So, I aimed the first step of this task to port sample app(https://github.com/flutter/samples/tree/master/add_to_app/multiple_flutters) at tizen.

---

EngineGroup

As you can see in the example, this is part of how to embed Flutter in a native app. The best way is to embed Flutter in tizen as one of the GUI widgets , but this is not easy In the current implementation. (Many of our rendering behavior are
based on window)
Here is my rough plan based on these.

1. Make windows externally and use them. This will allow us to create and place partial windows at single app. (Support partial window engine#98)
2. Create spawn API in embedder.
3. Create FlutterEngineGroup API at native API
4. Port sample app to tizen

(Of course, I am not insisting that this feature should be done this way. Any ideas are welcome. 😄 )

[bwikbs]

Currently, My goal is to get the following screen with a new FlutterEngineGroup API. Because I think this can satisfy the requirements what I understand.

[bwikbs]

@xuelian-bai @swift-kim Any comments?

[xuelian-bai]

I'm not sure about this, but I think, if we want to support multi-screens, we can just create multiple flutter engines, each engine has its own window, this may consume many resources, but it's easy to do this way.
I think multiple-flutters solution is actually from hybrid application on android(some pages are written in kotlin, some pages are written in dart). I will check more details tommorow.

[xuelian-bai]

for multiscreen requirement, is it for multiple monitor? One monitor display one window? Only one window can handle input events? If that's the scenario, we can use eom to present another window(image) on another display. https://code.sec.samsung.net/confluence/display/WSI/EOM

[swift-kim]

@xuelian-bai Yes, I heard the second monitor wouldn't accept touch input and only display visual contents (mostly ads) without user interaction for now. Probably the API you mentioned will be used (I don't know the details). However, the scenario may be changed in the future and I think @bwikbs is preparing for possible future requirements.

[bwikbs]

is it for multiple monitor?

yes

One monitor display one window? Only one window can handle input events?

Nothing has been confirmed yet. I wish I want to know too.. 😄

eom is the solution that other teams have been telling me to use for this. So we will probably use it. But I'm not sure if we can guide this to flutter app developers.

There are many ways that how app developers use this, and I hope you will focus on that and share and discuss our ideas.

[xuelian-bai]

We may refer to this plugin https://github.com/VNAPNIC/presentation-displays.git

[xuelian-bai]

Here is my initial idea, didn't consider much details

[bwikbs]

Thanks for giving me a good idea!
I have a question.
Is this the same process?
Could you explain a bit more running the engine? I have no idea where the dart is and where the native is.

[xuelian-bai]

it's just a rough process, here are more details, almost the same as the referred plugin:
dart app --> define external widget, main widget build() --> init eom plugin --> get outputid from eom --> create new flutter engine --> set window to outputid --> set initialroute as defined external widget for flutter engine in dart.
The referred plugin can use flutterview, but we can't, since we don't need to handle events for window on external display, I think it's ok to create two windows using eom, but we need to confirm this.

[xuelian-bai]

[bwikbs]

The referred plugin can use flutterview, but we can't, since we don't need to handle events for window on external display, I think it's ok to create two windows using eom, but we need to confirm this.

Unfortunately no one can do this. 😄

---

I think your approach is pretty good.(Especially,app developer doesn't need a native app interface) but still need a new engine instance and window instance.(Am I right?)
FlutterEngineGroup API has resource and performance advantages. so.. I think it is still necessary to apply this to Tizen.

IMO, Now is the time to prepare for the unclear requirement, If we can afford it, it would be meaningful to POC both and integrate them later.