[KDE/Mac] Review Request 126198: [OS X] adaptations for the KdePlatformTheme (and autotests)
Boudhayan Gupta
bgupta at kde.org
Wed Dec 2 16:45:17 UTC 2015
> On Dec. 2, 2015, 3:15 p.m., Boudhayan Gupta wrote:
> > src/platformtheme/kdemactheme.mm, line 39
> > <https://git.reviewboard.kde.org/r/126198/diff/3/?file=420466#file420466line39>
> >
> > This makes me very nervous.
> >
> > Using private APIs is almost always a guarantee the application won't preserve binary compatibility even across point releases (eg Qt 5.5.0 - 5.5.1), let alone across major releases.
> >
> > What makes it even more dangerous is that this file won't be built only on MacPorts/Fink but also by people making normal AppBundle releases - where you have no control over what versions of dependencies are being used.
> >
> > Please try to find a public API alternative, even if it ends up being a giant hack. I once found a very elegant private API solution to making a QQuickWidget emit a release event on the mouse cursor, but just because of the whole binary compat problem (some Linux distros don't even ship apps depending on private headers) I had to create a dummy item inside the QtQuick code and interact with it to get the cursor released. Giant hack, but at least no private API usage.
> >
> > Private API is **private** for a reason.
>
> Luigi Toscano wrote:
> Afaik frameworkintegration is supposed to be an extension of the internal Qt world and it has already been the case (I asked the same question few Akademys ago). If you want to use QPA, you need to go down in the stack.
>
> Martin Gräßlin wrote:
> yeah frameworkintegration is bound to use private API. So not really a problem in this special case.
>
> AFAIK some distros have adjusted the packaging to force a recompile for new Qt releases.
>
> Boudhayan Gupta wrote:
> Ah, that makes sense. Okay, I'm dropping this issue.
>
> René J.V. Bertin wrote:
> Whew - Hacking is so much more fun if you can do it there where you're not supposed to go, rather than to avoid exactly that ;)
> However, it might be possible to replace the direct call of the private function by a call through a function pointer to `createPlatformTheme` obtained through a dynamic resolver. Any idea if that is bound to fail through a Qt function because it'd detect a request for a private API?
>
> In any case, you (Boudhayan) are right that this modified framework might end up being used also in *standalone* AppBundle builds rather than only in builds using shared resources (in which applications are also built as app bundles!). At least I hope it will, for the very reason I've been pushing the patch. But I think you're wrong to assume that using private APIs is a problem there. If anything it should be (much) less the case, because standalone app bundles form a much more protected environment. They're not meant to be upgraded internally, except maybe by some special mechanism controlled by the developer(s) in charge. Updates to Qt without an accompanying forced rebuild ("revbump" in MacPorts speak) to frameworkintegration are much more likely to occur in a shared environment.
>
> Boudhayan Gupta wrote:
> There's no reason to go through a dynamic function resolver if the rest of FWI uses private APIs happily. Luigi says, "frameworkintegration is supposed to be an extension of the internal Qt world" - in that case it makes perfect sense to make use of private APIs to get your job done.
>
> As for the AppBundles point - I'm thinking if it's possible Qt is installed from e.g. the SDKs provided by qt.io and standalone AppBundles end up depending on that. If not, using private APIs in standalone AppBundles makes no difference - you won't upgrade Qt without upgrading the entire AppBundle.
>
> René J.V. Bertin wrote:
> Dynamic resolution appears out of the question anyway, because the createPlatformTheme function is not a static member function. There's a `static QCocoaIntegration *instance()` (`_ZN17QCocoaIntegration8instanceEv`), though, which should return `QGuiApplicationPrivate::platform_integration`. Regardless of whether it's acceptable to use a private API here, there is still the question of handling a conflict/mismatch situation in a sensible way, one in which it's apparent immediately what went wrong.
> But maybe there's an easier way to do that, simply by comparing a hard-coded Qt version with the runtime version.
>
> Standalone app bundles are by definition not dependent on anything but system libraries, that's the whole idea behind them. When signed (e.g. because shipped through the App Store) you can also not modify them because if you do they won't launch. Of course you can build partially standalone app bundles, but I think that most devs will either aim for truly standalone products, or else product that share as much as possible (in which case Qt + KF5 frameworks could be built as a composite framework bundle).
Don't complicate code too much unless you really, really need it :-) Simpler code has less bugs and is easier to maintain. In this case, it'll just be easier to make FWI depend on an exact version of Qt than to do a dynamic resolver.
- Boudhayan
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On Dec. 2, 2015, 1:59 a.m., René J.V. Bertin wrote:
>
> -----------------------------------------------------------
> This is an automatically generated e-mail. To reply, visit:
> https://git.reviewboard.kde.org/r/126198/
> -----------------------------------------------------------
>
> (Updated Dec. 2, 2015, 1:59 a.m.)
>
>
> Review request for KDE Software on Mac OS X, KDE Frameworks and Valorie Zimmerman.
>
>
> Repository: frameworkintegration
>
>
> Description
> -------
>
> 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.
>
>
> Diffs
> -----
>
> autotests/CMakeLists.txt 7c2129c
> src/kstyle/CMakeLists.txt bc26667
> src/kstyle/kstyle.mm PRE-CREATION
> src/platformtheme/CMakeLists.txt 23f590e
> src/platformtheme/kdemactheme.h PRE-CREATION
> src/platformtheme/kdemactheme.mm PRE-CREATION
> src/platformtheme/khintssettingsmac.h PRE-CREATION
> src/platformtheme/khintssettingsmac.mm PRE-CREATION
> src/platformtheme/main_mac.cpp PRE-CREATION
>
> Diff: https://git.reviewboard.kde.org/r/126198/diff/
>
>
> Testing
> -------
>
> 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
> ----------------
>
> purely native OS X theme
> https://git.reviewboard.kde.org/media/uploaded/files/2015/11/30/650d0da7-52b3-40d1-a1f9-cb610494cf77__Screen_Shot_2015-11-30_at_15.42.31.png
> native theme but with `-style kde`
> https://git.reviewboard.kde.org/media/uploaded/files/2015/11/30/72e2a6aa-2a7c-465b-b404-fc1e52b6fc69__Screen_Shot_2015-11-30_at_15.43.02.png
> using the KDEPlatformTheme
> https://git.reviewboard.kde.org/media/uploaded/files/2015/11/30/309e5995-74fa-42fb-a6f3-936cedbf5246__Screen_Shot_2015-11-30_at_15.43.31.png
> on Linux, using a purely "native" theme
> https://git.reviewboard.kde.org/media/uploaded/files/2015/11/30/eaa1d907-bf05-4ca2-821b-83dc062aea04__QtCreatorNativeLNX.png
> KDEPlatformTheme with the "macintosh" native theme selected
> https://git.reviewboard.kde.org/media/uploaded/files/2015/12/01/de55a91f-3500-4db8-8a3b-d252fd7ea169__Screen_Shot_2015-12-01_at_13.52.35.png
>
>
> Thanks,
>
> René J.V. Bertin
>
>
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