KDE Core/Platform 11/Eliminating Duplication With Qt
< KDE Core | Platform 11
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?
Geolocation
Qt5 Proposal: Move QGeoCoordinate and maybe QGeoAddress from QtLocation to QtCore as fundamental data types.
Discussed with Torstan / Marble guys and they are in favour. Torstan may be at QCS so can add input there.
- Basic structure is fine
- Extra to/from string methods would be very good to add, probably acceptable to Qt
- Marble stores matrix/quaternion for performance, not sure how acceptable to Qt
QGeoAddress has no equivalent in Marble, may be useful as is other fundamental type in Geolocation, is a clean stand-alone implementation if not very sophisticated.
GeoCoordinate
Key differences:
- Marble stores in qreal Radians, Qt in double Decimal Degrees
- Marble always in 3d defaults altitude to 0m, Qt allows 2d or 3d
- Marble stores int Detail level
- Marble caches Quaternion/Matrix for performance
- Marble defines M_PI to 41 decimal places, Qt to 20
- Marble defines Earth radius as 6378.000, Qt as 6371.0072
- Marble returns coords in Decimal Degrees or Radians
- Marble is shared (has ref counter), Qt is not
- Marble is able to be subclassed (has virtuals), Qt is not
- Marble is a Qt Meta Type, Qt is not
- Qt provides some Great Circle calculations which use their pi and radius, Marble does these elsewhere
- Marble provides normalize methods, Qt does not
- Marble provides precision parm for toString(), Qt does not
- Marble provides fromString() method, Qt does not
Suggested changes:
- Move to QtCore
- Make Q Meta Type
- Make shared
- Make able to subclass (i.e. allow Marble to derive and store Quaternion if not acceptable)
- Add convenience set/get methods for all 3 components at same time
- Add api to return as degrees or radians
- Add precision to toString()
- Add separate component to toString(), i.e. just lat, lon or alt
- Add fromString()
Nice to have, but can be in wrapper?:
- Quaternion
- Detail level
- Normalize
- isPole()
class GEODATA_EXPORT GeoDataCoordinates
{
public:
enum Unit{
Radian,
Degree
};
enum Notation{
Decimal,
DMS
};
GeoDataCoordinates();
GeoDataCoordinates( qreal lon, qreal lat, qreal alt = 0,
GeoDataCoordinates::Unit unit = GeoDataCoordinates::Radian,
int detail = 0 );
GeoDataCoordinates( const GeoDataCoordinates& other );
virtual ~GeoDataCoordinates();
GeoDataCoordinates& operator=( const GeoDataCoordinates &other );
bool operator==( const GeoDataCoordinates& ) const;
void set( qreal lon, qreal lat, qreal alt = 0,
GeoDataCoordinates::Unit unit = GeoDataCoordinates::Radian );
void geoCoordinates( qreal& lon, qreal& lat,
GeoDataCoordinates::Unit unit = GeoDataCoordinates::Radian ) const;
void setLongitude( qreal lon,
GeoDataCoordinates::Unit unit = GeoDataCoordinates::Radian );
qreal longitude( GeoDataCoordinates::Unit unit = GeoDataCoordinates::Radian )
const;
void setLatitude( qreal lat,
GeoDataCoordinates::Unit unit = GeoDataCoordinates::Radian );
qreal latitude( GeoDataCoordinates::Unit unit = GeoDataCoordinates::Radian ) const;
void setAltitude( const qreal altitude );
qreal altitude() const;
void setDetail( const int det );
int detail() const;
const Quaternion &quaternion() const;
bool isPole( Pole = AnyPole ) const;
static void setDefaultNotation( GeoDataCoordinates::Notation notation );
static GeoDataCoordinates::Notation defaultNotation();
static qreal normalizeLon( qreal lon,
GeoDataCoordinates::Unit = GeoDataCoordinates::Radian );
static qreal normalizeLat( qreal lat,
GeoDataCoordinates::Unit = GeoDataCoordinates::Radian );
static void normalizeLonLat( qreal &lon, qreal &lat,
GeoDataCoordinates::Unit = GeoDataCoordinates::Radian );
static GeoDataCoordinates fromString( const QString &string, bool& successful );
QString toString() const;
QString toString( GeoDataCoordinates::Notation notation, int precision = -1 ) const;
static QString lonToString( qreal lon, GeoDataCoordinates::Notation notation,
GeoDataCoordinates::Unit unit = Radian,
int precision = -1,
char format = 'f' );
QString lonToString() const;
static QString latToString( qreal lat, GeoDataCoordinates::Notation notation,
GeoDataCoordinates::Unit unit = Radian,
int precision = -1,
QString latToString() const;
virtual void pack( QDataStream& stream ) const;
virtual void unpack( QDataStream& stream );
virtual void detach();
};
class Q_LOCATION_EXPORT QGeoCoordinate
{
public:
enum CoordinateType {
InvalidCoordinate,
Coordinate2D,
Coordinate3D
};
enum CoordinateFormat {
Degrees,
DegreesWithHemisphere,
DegreesMinutes,
DegreesMinutesWithHemisphere,
DegreesMinutesSeconds,
DegreesMinutesSecondsWithHemisphere
};
QGeoCoordinate();
QGeoCoordinate(double latitude, double longitude);
QGeoCoordinate(double latitude, double longitude, double altitude);
QGeoCoordinate(const QGeoCoordinate &other);
~QGeoCoordinate();
QGeoCoordinate &operator=(const QGeoCoordinate &other);
bool operator==(const QGeoCoordinate &other) const;
inline bool operator!=(const QGeoCoordinate &other) const {
return !operator==(other);
}
bool isValid() const;
CoordinateType type() const;
void setLatitude(double latitude);
double latitude() const;
void setLongitude(double longitude);
double longitude() const;
void setAltitude(double altitude);
double altitude() const;
qreal distanceTo(const QGeoCoordinate &other) const;
qreal azimuthTo(const QGeoCoordinate &other) const;
QGeoCoordinate atDistanceAndAzimuth(qreal distance, qreal azimuth, qreal distanceUp = 0.0) const;
QString toString(CoordinateFormat format = DegreesMinutesSecondsWithHemisphere) const;
};
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.