[Bug 2109623] [NEW] Java UI is extremely small with fractional scaling

[Sitsofe Wheeler]

Public bug reported:

Description of the problem
Using any fractional scaling makes the UI of Java programs very small compared to everything else on the desktop.

Steps to reproduce:
1. apt install -y default-jre
2. Go to https://docs.oracle.com/javase/tutorial/uiswing/examples/components/index.html#table
3. Download "Border Demo Project" (https://docs.oracle.com/javase/tutorial/uiswing/examples/zipfiles/components-BorderDemoProject.zip )
4. Unpack the zip.
5. cd components-BorderDemoProject/src/components/
6. Run java BorderDemo.java
7. Note the size of the UI that appears and close it
8. Run /usr/bin/gnome-control-center display
9. Click on a display
10. Select Fractional Scaling so the radio moves to the right.
11. Tick on Scale and change it from 100% to 125%.
12. Click Apply
13. Run java BorderDemo.java

Expected results
The size of the UI at step 11 to be slightly bigger than the UI at step 13?

Actual result
The size of the UI at step 11 is significantly smaller than the UI at step 13

How reproducible is the problem?
The problem happens every time

Version information
Ubuntu 25.04
openjdk-21-jre:amd64 21.0.7~8ea-1

Additional information
I don't remember this happening on Ubuntu 24.10 despite using fractional scaling there so this feels like a regression. I actually have two monitors (one internal HiDPI laptop screen and one standard res external monitor) and the problem occurs even if it's only the laptop display set to be fractional (even when the Java app is on the non-fractional monitor). This may also be related to https://bugs.openjdk.org/browse/JDK-8326428 (although that ticket mentions KDE). Using JAVA_TOOL_OPTIONS=-Dsun.java2d.uiScale=2 java BorderDemo.java stops the UI feeling too small compared to everything else.

ProblemType: Bug
DistroRelease: Ubuntu 25.04
Package: openjdk-21-jre 21.0.7~8ea-1
ProcVersionSignature: Ubuntu 6.14.0-15.15-generic 6.14.0
Uname: Linux 6.14.0-15-generic x86_64
ApportVersion: 2.32.0-0ubuntu5
Architecture: amd64
CasperMD5CheckResult: pass
CurrentDesktop: ubuntu:GNOME
Date: Tue Apr 29 15:56:01 2025
InstallationDate: Installed on 2025-03-24 (36 days ago)
InstallationMedia: Ubuntu 24.10 "Oracular Oriole" - Release amd64 (20241009.4)
SourcePackage: openjdk-21
UpgradeStatus: Upgraded to plucky on 2025-04-18 (11 days ago)

** Affects: openjdk-21 (Ubuntu)
     Importance: Undecided
         Status: New


** Tags: amd64 apport-bug plucky wayland-session

-- 
You received this bug notification because you are a member of Ubuntu
Foundations Bugs, which is subscribed to openjdk-21 in Ubuntu.
https://bugs.launchpad.net/bugs/2109623

Title:
  Java UI is extremely small with fractional scaling

Status in openjdk-21 package in Ubuntu:
  New

Bug description:
  Description of the problem
  Using any fractional scaling makes the UI of Java programs very small compared to everything else on the desktop.

  Steps to reproduce:
  1. apt install -y default-jre
  2. Go to https://docs.oracle.com/javase/tutorial/uiswing/examples/components/index.html#table
  3. Download "Border Demo Project" (https://docs.oracle.com/javase/tutorial/uiswing/examples/zipfiles/components-BorderDemoProject.zip )
  4. Unpack the zip.
  5. cd components-BorderDemoProject/src/components/
  6. Run java BorderDemo.java
  7. Note the size of the UI that appears and close it
  8. Run /usr/bin/gnome-control-center display
  9. Click on a display
  10. Select Fractional Scaling so the radio moves to the right.
  11. Tick on Scale and change it from 100% to 125%.
  12. Click Apply
  13. Run java BorderDemo.java

  Expected results
  The size of the UI at step 11 to be slightly bigger than the UI at step 13?

  Actual result
  The size of the UI at step 11 is significantly smaller than the UI at step 13

  How reproducible is the problem?
  The problem happens every time

  Version information
  Ubuntu 25.04
  openjdk-21-jre:amd64 21.0.7~8ea-1

  Additional information
  I don't remember this happening on Ubuntu 24.10 despite using fractional scaling there so this feels like a regression. I actually have two monitors (one internal HiDPI laptop screen and one standard res external monitor) and the problem occurs even if it's only the laptop display set to be fractional (even when the Java app is on the non-fractional monitor). This may also be related to https://bugs.openjdk.org/browse/JDK-8326428 (although that ticket mentions KDE). Using JAVA_TOOL_OPTIONS=-Dsun.java2d.uiScale=2 java BorderDemo.java stops the UI feeling too small compared to everything else.

  ProblemType: Bug
  DistroRelease: Ubuntu 25.04
  Package: openjdk-21-jre 21.0.7~8ea-1
  ProcVersionSignature: Ubuntu 6.14.0-15.15-generic 6.14.0
  Uname: Linux 6.14.0-15-generic x86_64
  ApportVersion: 2.32.0-0ubuntu5
  Architecture: amd64
  CasperMD5CheckResult: pass
  CurrentDesktop: ubuntu:GNOME
  Date: Tue Apr 29 15:56:01 2025
  InstallationDate: Installed on 2025-03-24 (36 days ago)
  InstallationMedia: Ubuntu 24.10 "Oracular Oriole" - Release amd64 (20241009.4)
  SourcePackage: openjdk-21
  UpgradeStatus: Upgraded to plucky on 2025-04-18 (11 days ago)

To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/openjdk-21/+bug/2109623/+subscriptions