[External] : Re: Headless glass platform

[Andy Goryachev]

Thank you for clarifications, Johan!

- Would there be any other way of simulating user input apart from Robot?

Not sure I understand the question. In theory, input with mouse etc would be possible but then that would be sort of a duplication/rewrite of the Robot. I'm missing the usecase for this I guess?

I was thinking of accepting keystrokes from the actual keyboard, i.e. launch a headless application and type something in the console/terminal.  Would that work?

Thanks!
-andy


From: Johan Vos <johan.vos at gluonhq.com>
Date: Wednesday, January 31, 2024 at 01:24
To: Andy Goryachev <andy.goryachev at oracle.com>
Cc: openjfx-dev <openjfx-dev at openjdk.org>
Subject: [External] : Re: Headless glass platform


On Tue, Jan 30, 2024 at 5:14 PM Andy Goryachev <andy.goryachev at oracle.com<mailto:andy.goryachev at oracle.com>> wrote:
Excellent development, Johan, thank you!

I’ve asked a few questions in the ticket https://bugs.openjdk.org/browse/JDK-8324941

I suppose I should also do it here:

- How do you get information on a (virtual) screen?
- How would one control how many virtual screens are there?

Good questions. This is currently hardcoded in HeadlessApplication.staticScreen_getScreens() but that can be extended to take input via environment variables or System properties.

- Would there be any other way of simulating user input apart from Robot?

Not sure I understand the question. In theory, input with mouse etc would be possible but then that would be sort of a duplication/rewrite of the Robot. I'm missing the usecase for this I guess?

- Is the graphics still accelerated?

Yes, the headless platform does not influence the prism settings. If will still use the hw acceleration by default, and fall back to sw-rendering if hw fails, or if prism.order is set to explicitly use sw rendering.

- Are there any functional gaps between Headless and headful modes (fonts, rendering, etc.)?

Not as far as I know, as that functionality is not in Glass.

Most importantly,
- Is there a JEP/tutorial for the new mode?

Thank you
-andy


From: openjfx-dev <openjfx-dev-retn at openjdk.org<mailto:openjfx-dev-retn at openjdk.org>> on behalf of Johan Vos <johan.vos at gluonhq.com<mailto:johan.vos at gluonhq.com>>
Date: Tuesday, January 30, 2024 at 03:47
To: openjfx-dev <openjfx-dev at openjdk.org<mailto:openjfx-dev at openjdk.org>>
Subject: Headless glass platform
Hi,

I created a branch in the jfx-sandbox repository for experimenting with a headless glass platform: https://github.com/openjdk/jfx-sandbox/tree/johanvos-headless<https://urldefense.com/v3/__https:/github.com/openjdk/jfx-sandbox/tree/johanvos-headless__;!!ACWV5N9M2RV99hQ!M4BVAW3kLG4OKKwMqweRpyPjEd7HC2WkN5Qjv4wYRDjFX3Yl5cElOBMWFO-y_IARZgRq7XIHx8l62e_WqcpZqhebzw$>

This addresses https://bugs.openjdk.org/browse/JDK-8324941 where I suggest a POC for a Headless platform.

There are a number of usecases for this, including:
1. applications that require JavaFX rendering without presenting this to a window (and instead send it to a printer for example)
2. running tests without requiring a window manager.

Regarding the second usecase, we already did some basic experiments using a modified version of TestFX where instead of the Monocle Headless subplatform, the POC Headless platform is used.

By using a first-class Headless glass platform instead of a Monocle subplatform, it should be easier to use by developers.
The monocle code contains very platform/os specific parts, which often don't make sense outside the target platform. This is very valuable, but it is also a very different usecase than a headless platform and it requires a much more complex build procedure.

I added an initial, limited HeadlessRobot to do some basic tests. That code is mainly taken from the existing Monocle implementation, but I want to be careful to avoid anything that is not applicable to the headless scenarios.

- Johan

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