Apparently "robot window" always shows up in a separate browser window?

[amrytov]

Hello,

Webots documentation tells us that "robot windows" would show up in a special panel in Webots UI. I distinctly remember running the robot windows samples (but probably in an older WeBots version) which behaved this way, and these samples (custom_robot_window, custom_robot_window_simple) are obviously designed to be shown in a narrow panel.

However lately in R2022b robot windows always open in a separate browser window, which may be very inconvenient sometimes. I thought I was doing something wrong in WeBots config or code, but apparently WbRobotWindow::openOnWebBrowser() just always starts an external browser. No sign of using Qt WebEngine or similar embedded component, as one might expect to see there?

I'm a fairly new WeBots user and don't know its history well, so could somebody please explain why a documented feature has disappeared from WeBots? Is the change documented somewhere?

[stefaniapedrazzi]

Hi,

since R2022b robot windows are running on standard web browsers and we removed the dependency on the Qt WebEngine module.
This change is an enhancement introducing the new functionalities allowing to run robot windows on a different machine than the one where Webots is executed.
The change is documented in the ChangeLog: https://github.com/cyberbotics/webots/blob/R2022b/docs/reference/changelog-r2022.md?plain=1#L16

Could you link us to the documentation part that is still referring to the robot windows would show up in a special panel in Webots UI?
We may have missed it when updating the documentation.
Thank you!

[omichel]

We do understand your concern on this question. We actually got rid of the dependency on Qt WebEngine because it is not available on the Windows/MSYS2 platform we are using to build Webots. Instead we had to use Qt WbView which not fully compatible with WebEngine and was causing many problems and discrepancies across platforms. Moreover Qt WebEgine is a huge package which was making the Webots installer way bigger than it is today.

Nevertheless we are taking your concern and use-case very seriously and are thinking about various possible solutions:

1. Embed a browser window inside Webots: it might be possible to launch a Firefox or Chrome window inside a Qt sub-window.
2. Improve the Display device to allow for simple user interactions, e.g., click on a button, press keys, etc.
3. Develop a simpler HTML view allowing users to create a mini HTML page. This would however require that we find or develop a lightweight HTML rendering library.

[omichel]

We just had a team discussion about this issue and we came out with some fairly elegant solution: we could allow a Robot to be a child of a Billboard node. Obviously, this robot should not have any physics and should typically be a supervisor. It could contain in particular a Display device allowing to display any information to the user using the Display API. Additionally, since the Supervisor API has a mouse monitoring capability, it should be possible to detect mouse clicks and even mouse motion on the Display which will allow user to develop simple widgets, like buttons, check boxes, etc.

Moreover allowing Robots inside Billboards should be pretty easy to implement.

@amrytov, would that resolve the problem for your use-case?

[amrytov]

Thank you very much, that would be an extremely useful new feature.

Although still doesn't quite solve the problem of providing simple input UI. Perhaps something like https://doc.qt.io/qt-6/qtuitools-module.html could be used.

[omichel]

I believe that it should be possible to build a simple input UI with a Display device in the Billboard by using the supervisor mouse and keyboard APIs. I don't like QtUITool as it introduces a new format that fulfills the same requirements as the HTML robot windows.

[omichel]

I discovered today that there might be a fairly simple possibility to re-introduce the HTML robot windows inside Webots by using Qt6 for MSVC and MSYS2 UCRT64, see #5683 for details.