Add Qt6 Support #7339

tresf · 2024-06-22T19:58:57Z

Resolves #6614.

messmerd · 2024-10-23T19:34:33Z

I successfully built LMMS with Qt 6.8.0 on Linux without the Core5Compat module.

When compiling, there were a number of deprecation warnings unrelated to that change that we should probably address in this PR.

tresf · 2025-02-09T04:51:41Z

When compiling, there were a number of deprecation warnings unrelated to that change that we should probably address in this PR.

I'm wondering if we should put our efforts into fixing merge conflicts with the qt6 branch and getting it merged before the codebase diverts further? I also believe that we should have at least one automated build to ensure new features added don't cause compilation errors for future qt6 efforts.

messmerd · 2025-02-09T05:06:49Z

@tresf I'd be fine with that.

Maybe Windows MSVC could be our Qt 6 build in the CI since it wouldn't be hard to update the dependency to Qt 6, and the MinGW build is still available in case any issues arise with it. We could do it in this PR after fixing the merge conflicts.

src/core/AutomationClip.cpp

src/gui/clips/AutomationClipView.cpp

tresf · 2025-02-18T22:43:40Z

@tresf I'd be fine with that.

Maybe Windows MSVC could be our Qt 6 build in the CI since it wouldn't be hard to update the dependency to Qt 6, and the MinGW build is still available in case any issues arise with it. We could do it in this PR after fixing the merge conflicts.

Merge conflicts fixed. Some touched lines don't appear to be related to this PR I've started a conversation thread on these files, please mark as resolved if they're warranted.

The history is a bit weird (as most rebases are) and I made plenty of mistakes merging, but the branch should be in pretty good shape right now. I think it's ready for a CI job to run against Qt6 as well as a few set of eyes particularly from those that have helped with the code leading up to this point.

Please push patches directly to this branch.

plugins/ZynAddSubFx/CMakeLists.txt

Co-authored-by: michaelgregorius <[email protected]> Co-authored-by: Rossmaxx <[email protected]>

- Fix linking issues with Qt Framework files - Fix qmake detection

Fix implicit conversion from int when using QString.arg(...)

* Adds win32EventFilter a wrapper for nativeEventFilter on Windows * win32EventFilter is currently used to intercept top-level Window events (currently, to avoid VSTs setting transparency of the parent application)

QComboBox activated() replaced with textActivated() since Qt 5.14

* enabled VST support for Qt 6 builds * Note : Embedding on QT6 will be buggy on linux as a result of using qt embedding, which unfortunately is a qt bug which hasn't been resolved.

* Added lines in between bars * Changed bar lines to follow snap size * Changed default zoom and quantization value * Added constants for line widths * Added QSS configuration for new grid line colors * Tied line widths to QSS properties * Changed default quantization to 1/4 * Removed clear() from destructor model * Removed destructor in ComboBoxModel.h * Changed member set/get functions to pass by value * Updated signal connection with newer syntax

* ensured mouse event != nullptr before deref * separation of concerns: AFP WaveView updateCursor extract check to pointerCloseToStartEndOrLoop() * marked some function parameters as const

The Qt bug that used to be present appears to have been fixed, so the workaround can be removed

messmerd

Just making note of two places where I'm not sure why a change was made.

The rest of the changes made in this PR I have reviewed and understand.

include/ControlLayout.h

src/gui/tracks/TrackView.cpp

messmerd · 2025-07-11T00:58:47Z

This PR is functionally complete and ready for review and testing.

Testing instructions

Test the GUI on the Windows MSVC build to see if there are any regressions in how things appear or in interactions with GUI elements. If you find a bug that is also present in Windows MSVC on nightly, that's okay since it wasn't caused by this PR.

For now, only Windows MSVC is using Qt6 and rest of the builds remain on Qt5. The Qt5 builds should behave the same as before this PR unless an egregious mistake was made in the deprecation helpers or elsewhere, so a quick check of the Qt5 builds might be a good idea.

SameExpert · 2025-08-16T12:53:49Z

I managed to build lmms from the latest commit of qt6 branch, 48422da, with a small modification to OpulenZ to fix compilation error, in Guix system. Projects are not opening. The project browser window opens, but after I select the project and click on open, nothing happens, just the project browser window closes as if I did not open any project.

(Edit):
With the commit 9de3f3b, of the same qt6 branch, I did not have this problem.

(Edit 2):
I also tested building with qt5, with the same commit 48422da. With qt5, I don't have this problem. Projects are loading without any problem.

tresf · 2025-08-17T15:39:05Z

I managed to build lmms from the latest commit of qt6 branch, 48422da, with a small modification to OpulenZ to fix compilation error, in Guix system. Projects are not opening. The project browser window opens, but after I select the project and click on open, nothing happens, just the project browser window closes as if I did not open any project.

Mind sharing the patch? PR is welcome as well!

SameExpert · 2025-08-17T16:51:03Z

I managed to build lmms from the latest commit of qt6 branch, 48422da, with a small modification to OpulenZ to fix compilation error, in Guix system. Projects are not opening. The project browser window opens, but after I select the project and click on open, nothing happens, just the project browser window closes as if I did not open any project.

Mind sharing the patch? PR is welcome as well!

#8040

Conflicts: - src/gui/clips/ClipView.cpp - src/gui/editors/Editor.cpp - src/gui/editors/PianoRoll.cpp

messmerd · 2025-10-21T06:52:36Z

@SameExpert

Projects are not opening. The project browser window opens, but after I select the project and click on open, nothing happens, just the project browser window closes as if I did not open any project.

Thanks for catching this. I've fixed it in the latest commit (fbee2e7)

Another issue I noticed is a couple failed Qt assertions about sending events to objects owned by a different thread. This occurs in debug builds when I release my mouse when playing a note on the Piano Roll's piano. I'll have to look into this some more.

EDIT: It still works fine outside of debug builds. I'm guessing it's unrelated to this PR and also present in Qt 5 builds built with the debug version of the Qt libraries, though I'd have to confirm.

tresf · 2025-10-21T15:01:58Z

Tangentially related, @messmerd the last remaining task (besides adding this to our CI) was MSVC stuff... is that still the case or are we ok to merge into mainline now? If so, we can track any newly discovered bugs separately.

messmerd · 2025-10-21T17:30:00Z

the last remaining task (besides adding this to our CI) was MSVC stuff... is that still the case or are we ok to merge into mainline now?

I still need to look into the changes mentioned here, and spend a little more time using it to make sure there are no other serious issues like the one SameExpert reported.

But other than that, this PR is ready to merge.

… Qt6

tresf · 2025-11-03T15:20:17Z

the last remaining task (besides adding this to our CI) was MSVC stuff... is that still the case or are we ok to merge into mainline now?

I still need to look into the changes mentioned here, and spend a little more time using it to make sure there are no other serious issues like the one SameExpert reported.

But other than that, this PR is ready to merge.

If you're comfortable, let's resolve the above convo and merge. This will provide Qt6 support to the masses right now and we can sort any minor issues as we encounter them.

One thing that we may want to consider is adding at least one Qt6 CI task to catch compilation errors, but that can be a follow-up.

messmerd · 2025-11-03T15:39:56Z

One thing that we may want to consider is adding at least one Qt6 CI task to catch compilation errors, but that can be a follow-up.

This PR does that already - Windows MSVC is building with Qt6.

tresf · 2025-11-03T16:52:20Z

One thing that we may want to consider is adding at least one Qt6 CI task to catch compilation errors, but that can be a follow-up.

This PR does that already - Windows MSVC is building with Qt6.

Ooooh, it ditches Qt5. Cool. Ok, well, who pulls the trigger? 🪙 / 🪙

JohannesLorenz added this to the 1.3 milestone Aug 4, 2024

tresf mentioned this pull request Dec 5, 2024

Defining an MSYS2 build command list #7526

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tresf mentioned this pull request Feb 10, 2025

Improve Qt5 detection on macOS #7699

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tresf force-pushed the qt6 branch from 9de3f3b to 8db07be Compare February 18, 2025 22:11

tresf commented Feb 18, 2025

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tresf mentioned this pull request Feb 18, 2025

Add Qt 6 support #6614

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messmerd reviewed Feb 21, 2025

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tresf and others added 12 commits February 22, 2025 19:28

Rebase against master

124113e

Co-authored-by: michaelgregorius <[email protected]> Co-authored-by: Rossmaxx <[email protected]>

Fix Qt6 DMG on Apple (#7240)

9e07736

- Fix linking issues with Qt Framework files - Fix qmake detection

Fixes after rebase

1afd5d5

Fix embed.cpp compilation

1d6338a

Fix implicit conversion from int when using QString.arg(...)

Fix Qt6 signature change for nativeEventFilter (#7254)

b1f0ace

* Adds win32EventFilter a wrapper for nativeEventFilter on Windows * win32EventFilter is currently used to intercept top-level Window events (currently, to avoid VSTs setting transparency of the parent application)

fix broken signal slot connections (#7274)

8dd521a

QComboBox activated() replaced with textActivated() since Qt 5.14

Enabled VSTs on Qt 6 (#7273)

5471ab1

* enabled VST support for Qt 6 builds * Note : Embedding on QT6 will be buggy on linux as a result of using qt embedding, which unfortunately is a qt bug which hasn't been resolved.

Fix compilation

c55f76c

Fix MSVC builds

1497298

fix nullptr deref in AudioFileProcessor (qt6 branch) (#7532)

045a059

* ensured mouse event != nullptr before deref * separation of concerns: AFP WaveView updateCursor extract check to pointerCloseToStartEndOrLoop() * marked some function parameters as const

Remove Core5Compat usage

5a1b745

messmerd added 3 commits July 10, 2025 20:18

Fix style

87d6b91

Simplify Spectrum Analyzer mouse events

10969b1

The Qt bug that used to be present appears to have been fixed, so the workaround can be removed

Minor changes

48422da

messmerd reviewed Jul 11, 2025

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src/gui/tracks/TrackView.cpp Outdated Show resolved Hide resolved

messmerd added the needs testing This pull request needs more testing label Jul 17, 2025

tresf mentioned this pull request Sep 3, 2025

Set minimum deployment target for macOS builds #8004

Merged

messmerd added 3 commits October 20, 2025 00:13

Merge branch 'master' into qt6

b9244a8

Conflicts: - src/gui/clips/ClipView.cpp - src/gui/editors/Editor.cpp - src/gui/editors/PianoRoll.cpp

Fix deprecated QCheckBox signal

42d8b67

Fix setContent helper functions

fbee2e7

messmerd added 5 commits October 24, 2025 02:21

Remove QMultiMap usage from ControlLayout

36736e5

Remove SIGNAL and SLOT macros

ccdf3f8

Revert TrackView.cpp changes

2039c96

Merge branch 'master' into qt6

1839955

Remove Q_DISABLE_MOVE usage since it does not seem to be available in…

65f6b1e

… Qt6

messmerd approved these changes Nov 3, 2025

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Veratil merged commit 51529ce into master Nov 3, 2025
21 checks passed

messmerd deleted the qt6 branch November 3, 2025 18:04

This was referenced Nov 6, 2025

Add missing keyboard shortcuts #6768

Open

Tool to sync translations with Transifex #8111

Closed

JohannesLorenz mentioned this pull request Nov 7, 2025

Upgrade to Qt6 #8118

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Add Qt6 Support #7339

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