8248126: JavaFX ignores HiDPI scaling settings on some linux platforms

[pankaj-bansal]

JavaFX ignores the HiDPI scaling settings on Fedora 32 and Ubuntu 20.04.

The scale detection in JavaFX assumes that the "scaling-factor" setting in "org.gnome.desktop.interface" has the correct Hi-DPI setting. But this not true for some systems and "scaling-factor" has value of 0. JavaFX should detect the windows level scale factor automatically in this case, but this logic is missing right now. So, the JavaFX applications are not scaled properly.
This issue can be reproduced by setting the scale from Settings->Displays->Set Scale. Note, the option for scale may not be present from some resolution settings, so you may need to change it to see the option to scale the full windowing system. The issue can be verified by running some JavaFX applications/samples. The application will not be scaled properly according to the UIScale. https://bugs.openjdk.java.net/browse/JDK-8258464 is similar bug and has been closed as duplicate.

This fix adds the logic to detect the scale from windows system itself.
I have ran all automated unit tests and system tests, this fix is not causing any new failures. I have tested this on fedora 32 VM, Ubuntu 20.04 VM and Ubuntu 20.10 VM.

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Progress

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Issue

• JDK-8248126: JavaFX ignores HiDPI scaling settings on some linux platforms

Reviewers

• Kevin Rushforth (@kevinrushforth - Reviewer)
• Ambarish Rapte (@arapte - Reviewer)

Download

$ git fetch https://git.openjdk.java.net/jfx pull/396/head:pull/396
$ git checkout pull/396

[bridgekeeper]

👋 Welcome back pbansal! A progress list of the required criteria for merging this PR into master will be added to the body of your pull request. There are additional pull request commands available for use with this pull request.

[mlbridge]

Webrevs

• 00: Full (49b5f4c)

[kevinrushforth]

This is a simple enough fix, but it would be helpful to have a second reviewer take a look, and test it.

/reviewers 2

[openjdk]

@kevinrushforth
The number of required reviews for this PR is now set to 2 (with at least 1 of role reviewers).

[kevinrushforth]

Looks good. I tested on Ubuntu 20.04 with both GTK3 and GTK2.

[arapte]

Looks good, verified with Ubuntu 20.04.

[openjdk]

@pankaj-bansal This change now passes all automated pre-integration checks.

ℹ️ This project also has non-automated pre-integration requirements. Please see the file CONTRIBUTING.md for details.

After integration, the commit message for the final commit will be:

8248126: JavaFX ignores HiDPI scaling settings on some linux platforms

Reviewed-by: kcr, arapte

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At the time when this comment was updated there had been 4 new commits pushed to the master branch:

• a23d4ae: 8252099: JavaFX does not render Myanmar script correctly
• 9c8d30a: 8249737: java.lang.RuntimeException: Too many touch points reported
• e85ce5a: 8258986: getColor throws IOOBE when PixelReader reads the same pixel twice
• 676cf3e: 8259046: ViewPainter.ROOT_PATHS holds reference to Scene causing memory leak

Please see this link for an up-to-date comparison between the source branch of this pull request and the master branch.
As there are no conflicts, your changes will automatically be rebased on top of these commits when integrating. If you prefer to avoid this automatic rebasing, please check the documentation for the /integrate command for further details.

➡️ To integrate this PR with the above commit message to the master branch, type /integrate in a new comment.

[pankaj-bansal]

/integrate

[openjdk]

@pankaj-bansal Since your change was applied there have been 4 commits pushed to the master branch:

• a23d4ae: 8252099: JavaFX does not render Myanmar script correctly
• 9c8d30a: 8249737: java.lang.RuntimeException: Too many touch points reported
• e85ce5a: 8258986: getColor throws IOOBE when PixelReader reads the same pixel twice
• 676cf3e: 8259046: ViewPainter.ROOT_PATHS holds reference to Scene causing memory leak

Your commit was automatically rebased without conflicts.

Pushed as commit 782f22a.

💡 You may see a message that your pull request was closed with unmerged commits. This can be safely ignored.

[rnayabed]

This is amazing. I had to set uiScale on startup because it wouldnt work on ubuntu 20.04