[KDE/Mac] Review Request 126198: [OS X] adaptations for the KdePlatformTheme (and autotests)

René J.V. Bertin rjvbertin at gmail.com
Mon Nov 30 15:51:37 UTC 2015

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(Updated Nov. 30, 2015, 4:51 p.m.)

Review request for KDE Software on Mac OS X, KDE Frameworks and Valorie Zimmerman.


Hopefully all 4 snaps will upload, and in the correct order...

I didn't want to include example screenshots at first because atm. the only Qt5-based application I have have with a more complex UI is Qt Creator, and that one isn't the most representive (it uses an internal theme).

Also, please disregard my actual font of choice, focus on font size and style instead.

The 1st snap should show give an indication of what the native theming looks like on OS X (and Qt Creator actually looks a bit better than many other Qt5 applications). You get a single large font (with a much smaller size where apparently a bold typeface should be used); not just in the dialog but also in the bottom toolbar where it's a more constant waste of space. You also get a tabbing style that really shows its age. It's still used by some OS X applications, but I notice it less and less.

The 2nd snap shows the effect of using `-style kde` with the native plugin: widget drawing routines are taken from the KDE theme (here QtCurve), but the fonts are mostly unchanged.

The 3rd snap is the result that can be obtained with the patches proposed here, using again QtCurve configured to fit in as well as possible with the native look. Except for the typeface of course (though that's not entirely true on my own desktop :)).

Lastly, a 4th snap is intended for comparison with the 1st: it shows how the same dialog (from the same Qt version) looks on Linux when not using any KDE theming.

Repository: frameworkintegration


The KdePlatformTheme plugin can be enabled on OS X with a minimal patch to Qt5; all that is required is to include the `qgenericunixservices` and `qgenericunixthemes` components in the build, and to append `"kde"` to the list returned by `QCocoaIntegration::themeNames()` for instance under the condition that `KDE_SESSION_VERSION` is set to a suitable value in the environment.

This will allow KF5 and Qt5 applications to use the theme selected through KDE if FrameworkIntegration is installed and KDE_SESSION_VERSION is set, which seems like a sufficiently specific set of conditions that is easy to avoid by users who prefer to use the Mac native theme.

While requestion the KDE theme is also possible through `-style kde` or `env QT_STYLE_OVERRIDE=kde` the use of the KdePlatformTheme plugin appears to be the only way to get the full theme, including the font and colour selection. In my opinion it is above all the font customisation which is a very welcome feature for Qt/Mac; by default Qt applications use the default system font (Lucida Grande 13pt or even 14pt) throughout. This is a good UI font, but not at that size (and most "native" OS X applications indeed use a range of smaller sizes, depending on role.

It does have introduce a number of regressions, which the current patch aims to address. The most visible and problematic of these regressions is the loss of the Mac-style menu bar and thus of all menu items (actions).

The fix is straightforward : on OS X (and similarly affected platforms?), an instance of the native Cocoa platform theme is created through the private API, and used as a fallback rather than immediately falling back to the default implementations from `QPlatformTheme`. In addition, methods missing from (not overridden by) `KdePlatformTheme` are provided on OS X and call the corresponding methods from the native theme. It is this change which restores the menubar and even the Dock menu functionality.
One minor regression remains but should be easy to fix (elsewhere?): the Preferences menu loses its keyboard shortcut (Command-,).

Given the fallback nature of the native platform instance I have preferred to print a warning rather than using something like `qFatal`, above all because the message printed by qFatal tends to get lost on OS X. I can replace my use of `qWarning` with a dialog giving the choice between continuing or exiting the application - code that would be called in the menu methods because only there is it certain that the application actually needs a menubar.

In line with experience and feedback from the KDE(4)-Mac community I have decided to force the use of native dialogs rather than the ones from the KdePlatformPlugin.

In addition I set the fallback value for `ShowIconsOnPushButtons` to false in line with platform guidelines, and ensure that the autotests are not built as app bundles.


  autotests/CMakeLists.txt 7c2129c 
  src/kstyle/kstyle.cpp 6ba5d51 
  src/platformtheme/kdeplatformtheme.h 97d09df 
  src/platformtheme/kdeplatformtheme.cpp 80dbcb7 
  src/platformtheme/khintssettings.cpp 8adf6c5 

Diff: https://git.reviewboard.kde.org/r/126198/diff/


On Mac OS X with Qt 5.5.1, KF5 frameworks 5.16.0 and QtCurve git/head.

I have not verified to what extent my use of a private `QGuiApplication` API links builds to a specific Qt version (I consider that nothing shocking and a minor price to pay).
>>> Do I need to add some glue to the CMake file so that it will warn if the private headerfiles are not available? Apparently no changes were required to find them.

File Attachments (updated)

purely native OS X theme
native theme but with `-style kde`
using the KDEPlatformTheme
on Linux, using a purely "native" theme


René J.V. Bertin

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