KDE Core/Platform 11/Eliminating Duplication With Qt

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Team Members

Olivier, Volker,John, Helios, Ishmail.

Post-it Notes

  • Merge, Augment, Kill
  • Small changes in Qt to improve KDE contributions
  • How can we get mindset change in KDE towards Qt
  • Bigger things like Printing, QDateTime, maintainerships
  • Fixing QUrl so that KUrl is not necessary
  • Replacing QSettings with KConfig DConf? Kiosk?
  • KAction - Add default shortcut to QAction, global shortcuts
  • KLocale - Move to Qt
  • tr / i18n - gettext, script, KLocalizedString - move to Qt

Notes

Kconfig / QSettings / DConf - No-one felt qualified to discuss this, needs a separate break-out group

  • A Good Thing (TM), let's do it
  • Freeze kdelibs4, but not too hard may need changes or can backport some KDE5 stuff
  • Must start now to get what we need into Qt5 or will miss the chance
  • Not everything needs to be in Qt 5.0, but do need to be structured so we can cleanly add new features in 5.1, 5.2
  • Much depends on success of OpenGov
  • All contributions from KDE must be seen as for better of Qt not just KDE, we need to be pragmatic
  • If get in early with quality contributions can establish position of trust and authority
  • Start small with some test cases to prove process, gain trust:
    • KUrl/QUrl - Very simple case with minimal change required
    • KLineEdit/QLineEdit(?) - More involved case
    • QDateTime - Test for working with Qt Brisbane to develop common requirements
    • Printing - Big test case for major changes + maintainership
  • Review progress at Desktop Summit, if good progress then commit to full process
  • Need class-by-class review:
    • Work with dependencies team, need common notes somewhere
    • Will need expert advice on each class, we can't know every reason for duplication
    • Find if a Qt equivalent (not always obvious!)
    • Determine why KDE version exists
    • Determine if Qt version is already good enough (may have improved since K class created)
    • Determine if we really still need any extra features
    • Need to consider features, quality, performance
    • Reach a conclusion:
      • Keep K class entirely
      • Keep K class but move some features to Qt
      • Remove K class, use Q class completely
      • Remove K class, use Q class with new K helper class
  • Licence:
    • Need review by eV lawyers to reassure contributors they don't lose rights, are fully informed of consequences, start asap as may take time
    • Create list of known contributors who have/will agree to Qt license so we can reuse their code if appropriate (will still need explicit agreement per contribution?)
    • Need to be very careful don't copy code of those who oppose code donations
  • Automated tools for convert?

Specific classes/modules

Some obvious stuff from off top of our collective head:

  • QtLocation: Move QGeoCoordinate and poss QGeoAddress from QtLocation to QtCore as fundamental data type
  • KUrl / QUrl
  • KIcon / QIcon
  • KDateTime / QDateTime
  • KLocale / QLocale
  • KAction / QAction
  • KSSL*
  • KCodec
  • KlineEdit / QlineEdit
  • KComboBox / QComboBox
  • KCompleter
  • ...


Some random other notes:

  • QDate/QTime don't have a qHash?


Locale

What's wrong with KLocale:

  • Gtk/Qt apps running under kde-workspace don't use KDE locale
  • KDE apps running under other platforms/workspaces do not use host locale
  • Class merges settings, formatters, parsers and translations in one giant blob
  • Unnecessary dependency for Qt-Addon libraries

What's great about KLocale:

  • Users can change settings
  • Apps can change settings
  • Superior settings, date/time, etc support

What's wrong with QLocale:

  • Not all settings are supported
  • Apps and users unable to change settings

What's good with QLocale:

  • Uses host settings on all platforms
  • Low-level common class so good for Qt Addons

The Plan:

  • Add all KDE settings that already exist in CLDR to QLocale
  • Use QLocale to replace KLocale's role as settings container
    • Gives correct Windows, Mac, Gnome, Meego settings
  • KDE Workspace to set locale envvar on login if KDE locale different to system locale
    • Gives correct locale Gtk/Qt apps
  • KCM to load settings from QLocale, write out as both POSIX and CLDR format files only if user chooses different settings
    • locale envvar then set to absolute path to users POSIX file so all Gtk apps get right settings
    • QLocale loads CLDR file so KDE/Qt apps get right settings
  • Apps use parser/formatter classes/api's to alter settings for one-off calls rather than changing the locale itself, or create a whole new locale object.

Big Questions:

  • Date/Time formats: Keep POSIX formats (need own formatter/parser that translates Unicode format) or switch to Unicode format (not SC, QDateTime may not support all our features)
  • How will QLocale load custom CLDR? Fallback to custom POSIX but lacks some features.

Date/Time

Printing

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