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/*!
\page sourcebreaks.html
\title C++ API changes
\brief Lists the source incompatible API changes in Qt 5.

Qt 5 introduces some source incompatible changes. Here we list some important
ones, but you can find more complete lists in
\c {<Qt 5 Install Dir>/qtbase/dist/changes-5.x.x}.

The following sections list the API changes in each module and provide
recommendations for handling those changes.

\section1 Changes to Qt Core
    \list
     \li \l{QLibrary::resolve()} now returns a function pointer instead of \c{void} pointer.
     \li \c{QLibraryInfo::buildKey()} and the corresponding \c{QT_BUILD_KEY} macro are removed.
         You must remove all references to this function and macro, as build key is not necessary now.
     \li The \l{QTranslator::translate()} function signature is changed to set the default value of \c{n} to -1.
          We recommend you to update the implementation of this virtual function in your sources.
     \li \c{QBool} is removed. In Qt 4, \l{QString::contains()}, \l{QByteArray::contains()}, and \l{QList::contains()}
         returned an internal \c{QBool} type so that the Qt3 code
        \c{if (a.contains() == 2)} would not compile anymore.
         If your code uses \c{QBool}, replace it with \c{bool}.
     \li The \c{QUuid::operator QString()} implicit conversion operator is
         removed. Use the \l{QUuid::toString()} function instead.
    \li \l{QProcess::ForwardedChannels} no longer forwards the output to the
        GUI applications on the Windows platform, unless those applications
        create a console.
    \li \c{QSystemLocale} is not public anymore. Use \l{QLocale} instead.
    \li Default value of the \l{QSortFilterProxyModel::dynamicSortFilter}
        property is changed to \c{true}.
    \li \c{QTextCodecPlugin} is removed as all the text codecs are part of
        Qt Core now.
    \li \c{QFSFileEngine}, \c{QAbstractFileEngine}, \c{QAbstractFileEngineIterator},
        and \c{QAbstractFileEngineHandler} are no longer public.
        We recommend you to avoid using these classes as there is no
        compatibility promise.
    \li \l{qDebug()}, \l{qWarning()}, \l{qCritical()}, and \l{qFatal()} are
        changed to macros now to track the origin of the message in source code.
        The information to be printed can be configured (for the default message
        handler) by setting the new \c{QT_MESSAGE_PATTERN} environment variable.
        \l{qInstallMsgHandler()} is deprecated, so we recommend using
        \l{qInstallMessageHandler()} instead.
    \li \l{QPointer} is changed to use \l{QWeakPointer}. The old guard mechanism
        has been removed, which causes a slight change in behavior when using
        \l{QPointer}. In earlier Qt versions, if a \l{QPointer} is used on a
        \l{QWidget} (or a subclass of QWidget), the \l{QPointer} was cleared by
        the \l{QWidget} destructor. In Qt 5, the \l{QPointer} is cleared by the
        \l{QObject} destructor along with the \l{QWeakPointer}s. Any
        \l{QPointer} tracking a widget is not cleared before the \l{QWidget}
        destructor destroys the children for the widget being tracked.
    \li \l{Qt::WFlags} is deprecated, use \l{Qt::WindowFlags} instead.
        This typedef dates from the Qt 1 days, and such abbreviations are not
        current Qt style.
    \li \l{Qt::HANDLE} typedef is now defined as \c{void *} on all platforms.
    \li The non-atomic convenience methods of \l QAtomicInt and
        \l QAtomicPointer (that is, \c operator=, \c {operator int},
        \c {operator T*}, \c operator!, \c operator==, \c operator!=, and
        \c operator->) have been removed as they performed implicit loads and
        stores of unspecified memory ordering. Code dealing with loading and
        storing is expected to use \c load(), \c loadAquire(), \c store(), and
        \c storeRelease(), instead.
    \li The return type of \c {QFlags<Enum>::operator int()} matches the enum's
        underlying type (signed or unsigned) instead of always being \c int.
        This allows QFlags over enums of the unsigned type (for example,
        Qt::MouseButton).
    \li Because of major changes in the behavior of
        \l QTextBoundaryFinder::boundaryReasons(), the \c StartWord and
        \c EndWord enum values were replaced with the \c StartOfItem and
        \c EndOfItem values to enforce revision of the affected code.
    \li A number of functions in <QtAlgorithms> are deprecated. Use the
        implementations available in the STL, as described in
        \l{Porting Guidelines}.
    \li \c {setSharable()} and \c {isSharable()} in Qt containers are
        deprecated and will be removed in Qt 6. You should not use them in new
        applications. If you used them in existing applications, even though
        they are not documented, you should port away from them.
    \endlist

    \section2 Changes to QAction

    The Softkeys API is removed, so the following functions and enums are
    removed:

    \list
        \li \c QAction::setSoftKeyRole()
        \li \c QAction::softKeyRole()
        \li \c QAction::SoftKeyRole
        \li \c Qt::WA_MergeSoftkeys
        \li \c Qt::WA_MergeSoftkeysRecursively
        \li \c Qt::WindowSoftkeysVisibleHint
        \li \c Qt::WindowSoftkeysRespondHint
    \endlist

    \section2 Changes to QChar

    \list
        \li \c{QChar::NoCategory} is removed. The \l{QChar::Other_NotAssigned}
            enum value is returned for unassigned codepoints now.
        \li \l{QChar::Joining} and \l{QChar::joining()} are deprecated. Use the
            \l{QChar::JoiningType} enum and \l{QChar::joiningType()} function
            instead.
    \endlist

    \section2 Changes to QCoreApplication

    \list
        \li \l{QCoreApplication::translate()} no longer returns the source text
            if the translation is empty. Use the Qt Linguist Release tool
            (\c{lrelease -removeidentical}) instead for optimization.
        \li \c{QCoreApplication::setEventFilter()} and
            \c{QApplication::x11EventFilter/macEventFilter/qwsEventFilter/winEventFilter}
            are replaced with \l{QCoreApplication::installNativeEventFilter()}
            and \l{QCoreApplication::removeNativeEventFilter()} for an API much
            closer to QEvent filtering.
            \note The native events that can be filtered this way depend on the
            \l{Qt Platform Abstraction}{QPA} backend chosen at runtime. On X11,
            XEvents are replaced with
            \c{xcb_generic_event_t} due to the switch to XCB, which requires
            porting the application code to XCB as well.
        \li \c QCoreApplication::Type and \c QApplication::type() are removed.
            These Qt 3 legacy application types did not match the application
            types available in Qt 5. Use \c qobject_cast instead to dynamically
            find out the exact application type.
        \li \l{QCoreApplication::hasPendingEvents} and
            \l{QAbstractEventDispatcher::hasPendingEvents} are deprecated.
    \endlist

    \section2 Changes to QEvent

    \list
        \li \c{QEvent::AccessibilityPrepare}, \c{QEvent::AccessibilityHelp}, and
            \c{QEvent::AccessibilityDescription} are removed.
        \li \l{QEvent::TouchCancel} is introduced to use it on systems where it
            makes sense to differentiate between a regular \l{QEvent::TouchEnd}
            and abrupt touch sequence cancellations caused by the compositor.
            For example, when a swype gesture is recognized.
    \endlist

    \section2 Changes to QFile

    \list
        \li \l{QFile::setEncodingFunction()} and \l{QFile::setDecodingFunction()}
            are deprecated.
        \li \l{QFile::encodeName()} and \l{QFile::decodeName()} are now
            hard-coded to operate\ on \l{QString::fromLocal8Bit()} and
            \l{QString::toLocal8Bit()} only. The old behavior is still possible
            using \l{QTextCodec::setCodecForLocale()}, but the new code should
            not make assumptions about the file system encoding and older code
            should remove such assumptions.
    \endlist

    \section2 Changes to QFont

    \list
        \li \c QFont::handle() is removed.
        \li \l{QFont::rawName()} and \l{QFont::setRawName()} are deprecated.
    \endlist

    \section2 Changes to QMetaType

      \list
       \li \c{QMetaType::construct()} is renamed as \l{QMetaType::create()}.
       \li \c{QMetaType::unregisterType()} is removed.
       \li \l{QMetaType} now records whether the type argument inherits QObject.
            Such information can be useful for scripting APIs, so that custom QObject subclasses
            are treated as QObject pointers. For example, in \l{Qt Script} this
            means \l{QScriptValue::isQObject()} can be \c true, where it was
            \c false before.
       \li \c{QMetaType::QWidgetStar} is removed. Use \l{qMetaTypeId()}{qMetaTypeId<QWidget*>()}
           or \l{QVariant::canConvert()}{QVariant::canConvert<QWidget*>()} instead.
       \li \c{Q_DECLARE_METATYPE(type)} now requires \c{type} to be fully defined.
           This means, \c{Q_DECLARE_METATYPE(QSharedPointer<t>)} and \c{Q_DECLARE_METATYPE(QWeakPointer<t>)}
           also need \c{type} to be fully defined.
           In cases where a forward declared type is needed as a meta-type, use \c{Q_DECLARE_OPAQUE_POINTER(type)}.
      \endlist

    \section2 Changes to QMetaMethod

      \list
       \li \c{QMetaMethod::signature()} is renamed as \l{QMetaMethod::methodSignature()},
            and the return type is changed to \l{QByteArray}. This change is to enable
            generating the signature string on demand, rather than storing it in
            the meta-data.
        \li \l{QMetaMethod::typeName()} no longer returns an empty string if the return
            type is \c{void}, instead it returns \c{"void"}. The recommended way of checking whether a
            method returns \c{void} is to compare the return value of \l{QMetaMethod::returnType()}
            with \l{QMetaType::Void}.
       \endlist

    \section2 Changes to QObject

    \list
        \li \l{QObject::connectNotify()} and \l {QObject::disconnectNotify()}
            now need a \l{QMetaMethod} argument that identifies the signal,
            rather than a \c{const char} pointer.
        \li \l{QObject::trUtf8()} and \c{QCoreApplication::Encoding} are
            deprecated. Qt assumes that the source code is encoded in UTF-8.
    \endlist

    \section2 Changes to QVariant

     \list
     \li The \l{QVariant} constructor which takes \l{Qt::GlobalColor} argument is removed.
          Code constructing such variants must explicitly call \l{QColor} constructor now.
          For example, instead of \c{QVariant(Qt::red)}, use
          \c{QVariant(QColor(Qt::red))} to create a \l{QVariant} instance.
     \li Implicit creation of QVariant objects from the enum values Qt::BrushStyle,
         Qt::PenStyle, and Qt::CursorShape has been removed. Create objects
         explicitly or use \c static_cast<int>(Qt::SolidLine) to create a
         QVariant of type \c int with the same value as the enum.
     \endlist

    \section2 Changes to QAbstractEventDispatcher

      \list
       \li The signature for the pure-virtual \c{registerTimer()} function is changed.
           All subclasses of \l{QAbstractEventDispatcher} must re-implement the function
           with this new signature:

           \code
              virtual void registerTimer(int timerId, int interval,Qt::TimerType timerType, QObject *object) = 0;
           \endcode
       \li QAbstractEventDispatcher::TimerInfo is no longer a \c{typedef} of \c{QPair<int, int>}.
           It is now a \c{struct} with 3 members: \c{int timerId}, \c{int interval}, and \c{Qt::TimerType timerType}.
           Update the \l{QAbstractEventDispatcher::registeredTimers()} function
           with this change.
      \endlist

    \section2 Changes to QDir

      \list
       \li The \c{convertSeparators()} function is removed. Use \l{QDir::toNativeSeparators()} instead.
       \li The \c{QDir::NoDotAndDotDot} enum value is removed. Use \l{QDir::NoDot} or \l{QDir::NoDotDot} instead.
      \endlist

    \section2 Changes to QLocale

     \list
     \li The QLocale data has been updated to CLDR 22.1. The historical language
         and country names were updated to their modern values and some
         deprecated names were dropped or mapped to their modern alternatives.
     \li The \l{QLocale::toShort()}, \l{QLocale::toUShort()}, \l{QLocale::toInt()},
         \l{QLocale::toUInt()}, \l{QLocale::toLongLong()}, and \l{QLocale::toULongLong()} functions
         no longer take the argument for base. They localize base 10 conversions. To convert other bases, use the \l{QString} functions instead.
     \endlist

    \section2 Changes to QAbstractItemModel

      \list
       \li \l{QAbstractItemModel::beginMoveRows()} no longer emits the
            \c{layoutAboutToBeChanged} signal, and \l{QAbstractItemModel::endMoveRows()}
            no longer emits the \c{layoutChanged} signal.
            All proxy models must connect to (and disconnect from) the
            \l{QAbstractItemModel::rowsAboutToBeMoved} and
            \l{QAbstractItemModel::rowsMoved} signals.
       \li \l{QAbstractItemModel::sibling()} is virtual now to allow implementations to optimize based on internal data.
       \li \l{QAbstractItemModel::createIndex()} method now only provides the
            \c void* and \c quintptr overloads, making calls with a literal \c 0
            (\c{createIndex(row, col, 0)}) ambiguous. Either cast
            \c{quintptr(0)} or omit the third argument to get the \c void*
            overload.
       \li \l{QAbstractItemModel::setRoleNames()} is deprecated. Use \l{QAbstractItemModel::roleNames()} instead.
           \l{QAbstractItemModel::roleNames()} is virtual now to allow a consistent API with the rest of QAbstractItemModel. Reimplementing the virtual methods to provide the elements is preferred to setting those directly.
      \endlist

    \section2 Changes to QString

    \list
     \li \l{QString} and \l{QByteArray} constructors now use a negative size to
         indicate that the string passed is null-terminated (a null-terminated
         array of \l{QChar}, in the case of QString). In Qt 4, negative sizes
         were ignored, which resulted in empty \l{QString} and \l{QByteArray}.
         The size argument now has a default value of \c -1, replacing the
         separate constructors that did the same.
     \li \l{QString::mid()}, \l{QString::midRef()}, and \l{QByteArray::mid()} now return an empty \c{QString}, \c{QStringRef}, and \c{QByteArray} respectively,
         if the position passed is equal to the length (that is, right after the
         last character or byte).
         In Qt 4, they returned a null \c{QString} or a null \c{QStringRef}.
     \li The following \l{QString} functions use the C locale instead of the default or system locale:
      \list
       \li \l{QString::toLongLong()}{toLongLong()}
       \li \l{QString::toULongLong()}{toULongLong()}
       \li \l{QString::toLong()}{toLong()}
       \li \l{QString::toULong()}{toULong()}
       \li \l{QString::toInt()}{toInt()}
       \li \l{QString::toUInt()}{toUInt()}
       \li \l{QString::toShort()}{toShort()}
       \li \l{QString::toUShort()}{toUShort()}
       \li \l{QString::toDouble()}{toDouble()}
       \li \l{QString::toFloat()}{toFloat()}
      \endlist
      This is to guarantee consistent default conversion of strings. For locale-aware conversions
      use the equivalent \l{QLocale} functions.
    \endlist

    \section2 Changes to QDate, QTime, and QDateTime

      \list
       \li QDate only implements the Gregorian calendar, and the switch to the Julian
           calendar before 1582 has been removed. This means all QDate functions return
           different results for dates prior to 15 October 1582, and there is
           no longer a gap between 4 October 1582 and 15 October 1582.
       \li \l{QDate::setYMD()} is deprecated, use \l{QDate::setDate()} instead.
       \li Adding days to a null QDate or seconds to a null QTime will no longer return a valid QDate/QTime.
       \li The \l{QDate::addDays()} and QDateTime::addDays() functions now take
           a \c{qint64} argument, and the \l{QDate::daysTo()} and
           \l{QDateTime::daysTo()} functions now return a \c{qint64} value.
       \li \l QDate and \l QTime are the \c userProperty for the \l QTimeEdit
           and \l QDateEdit classes, insted of QDateTime as it was for the 4.7
           and 4.8 releases. The USER property for these classes was removed
           before Qt 4.7.0 and added again in Qt 5.0.
       \li The serialization behavior for \l QDateTime is reverted to pre-Qt 5,
           because \l Qt::LocalTime is the local time (that is, \c {ymd hms})
           regardless of the underlying system time, time zone, or changes in
           the system zone. Therefore, the consistent behavior when serialising
           is to save and restore as the local time and not its UTC equivalent.
           This means that the \l QDataStream version is 14 since Qt 5.1.
       \li The supported date range in \l QDateTime has been reduced to about
           +/- 292 million years, the range supported by the number of msecs
            since the Unix epoch of 1 Jan 1970 as stored in a \c qint64, and as
            able to be used in \l{QDateTime::setMSecsSinceEpoch()} and
            \l{QDateTime::toMSecsSinceEpoch()}.
        \li \l{QDate::fromString()} and \l{QDateTime::fromString()} require
            non-numeric date component separators when parsing \l{Qt::ISODate}.
            A string like \e 2000901901 will no longer be recognized as a valid
            ISO date, whereas \e 2000/01/01 will, even though it differs from
            the ISO format \e 2000-01-01.
      \endlist

    \section2 Changes to QTextCodec

        \list
         \li \c{QTextCodec::codecForCStrings()} and \c{QTextCodec::setCodecForCStrings()} are removed as they were
             creating uncertainty/bugs in using QString easily and (to a lesser extent) performance issues.
         \li \c{QTextCodec::codecForTr()} and \c{QTextCodec::setCodecForTr()} are removed.
        \endlist

    \section2 Changes to QUrl

    \l{QUrl} changed considerably in Qt 5 to comply better with the URL
    specifications and with brokenness out there. The following list summarizes
    the most important functional changes:

    \list
     \li \l{QUrl::setPath()} no longer handles relative paths. They are by
         definition invalid. Use the \l{QUrl::NormalizePathSegments} flag to
         remove /./ or /../ sequences as much as possible. It will not
         remove /../ from the beginning of the path.
     \li \l{QUrl} has been changed to operate only on percent-encoded forms. Fully-decoded forms where the percent character stands for itself,
         can no longer be encoded, as the getters and setters with \e encoded
         in the name are deprecated (except \l{QUrl::toEncoded()} and
         \l{QUrl::fromEncoded()}).

         The most notable difference with this change is when dealing with
         \l{QUrl::toString()}. In earlier Qt versions, this function would
         return percent characters in the URL, but now it returns \e %25 like
         \l{QUrl::toEncoded()} does.
    \li \l{QUrl} no longer decodes %7B and %7D to "{" and "}" in the
        output of \l{QUrl::toString()}.
    \li \l{QUrl} now defaults to decoded mode in the getters and setters for
        \c userName, \c password, \c host, \c topLevelDomain, \c path and
        \c fileName. This means a % in one of those fields is now returned (or
        set) as \c % rather than \c %25. If the former behavior was expected,
        pass \c PrettyDecoded to the getter and \c TolerantMode to the
        setter.
    \li \l{QUrl} no longer has functions that handle individual query items and query delimiters, such as \c addQueryItem() and \c queryPairDelimiter().
        These have been moved to the new \l{QUrlQuery} class.
    \li \l{QUrl} no longer considers all delimiter characters equivalent to
        their percent-encoded forms. \l{QUrl} and \l{QUrlQuery} always keep
        all delimiters exactly as they were in the original URL text.
    \li \l{QUrl} no longer supports \l{QUrl::FullyDecoded} mode in
        \l{QUrl::authority()} and \l{QUrl::userInfo()}, nor \l{QUrl::DecodedMode}
        in \l{QUrl::setAuthority()} and \l{QUrl::setUserInfo()}.
    \li \l{QUrl} no longer decodes %23 found in the fragment to "#"
        in the output of \l{QUrl::toString} (\c FullyEncoded) or
        \l{QUrl::toEncoded()}.
    \endlist

    \section1 Changes to Qt Concurrent

    \l{Qt Concurrent} has been moved from \l {Qt Core} to its own module. To
    link against the Qt Core module, add this line to the project file:

    \code
    QT += concurrent
    \endcode

    \note The \c {QtConcurrent::Exception} class is renamed \l{QException} and
    \c {QtConcurrent::UnhandledException} class is renamed
    \l{QUnhandledException}. They remain in Qt Core.

\section1 Changes to Qt GUI
    \list
     \li \l{QPen} now has a default width of 1 instead of 0. Thus, it is no longer \l{QPen::isCosmetic()}{cosmetic} by default.
     \li \l{QAccessibleActionInterface} is now based on providing a list of
         action names. All functions have been changed to take arguments of type
         \c string insted of \c{int}.
     \li The constructor of \l{QAccessibleEvent} does not need the \c{child} parameter anymore,
         and the corresponding \c{QAccessibleEvent::child()} function is removed.
     \li The constructor of \l{QTabletEvent} does not need the \c{hiResGlobalPos} argument anymore,
          as all coordinates are floating point-based now.
     \li \c{QIconEngineV2} is now merged into \l{QIconEngine}. Update your sources to use \c{QIconEngine} instead of \c{QIconEngineV2}.
     \li \l{QSound} is moved to Qt Multimedia from Qt GUI.
    \li \c QDesktopServices::storageLocation() and \c QDesktopServices::displayName() are replaced by \l{QStandardPaths::writableLocation()}
        and \l{QStandardPaths::displayName()} respectively. They are now in the \l{Qt Core} module.
        Make sure to read the \l{QDesktopServices::storageLocation()} documentation when porting from \l{QDesktopServices::DataLocation}.
    \li \c QPixmap::grabWindow() and \c QPixmap::grabWidget() are removed. Use \l{QScreen::grabWindow()} instead.
    \li The session management API has been simplified. The \c commitData()
        function is removed and replaced by the signal
        \l{QGuiApplication::commitDataRequest()}. \l QApplication and
        \l QGuiApplication will emit this signal from 5.2 onward on supported
        platforms (Linux and Windows).
    \li \c{QWidget *widget()} is replaced with \c {QObject *target()} to avoid
        \l{QWidget} dependencies.
    \endlist

    \section2 Changes to QAccessibleInterface

    \list
        \li The \e child integer parameters are removed to bring
            \l{QAccessibleInterface} closer to IAccessible2. This means that
            the following functions lose the integer parameter:
            \list
                \li \c{text(Text t, int child)} is now
                    \l{QAccessibleInterface::text()}{text(Text t)}
                \li \c{rect(int child)} is now
                    \l{QAccessibleInterface::rect()}{rect()}
                \li \c{setText(Text t, int child, const QString &text)} is now
                    \l{QAccessibleInterface::setText()}{setText(Text t, const QString &text)}
                \li \c{role(int child)} is now \l{QAccessibleInterface::role()}
                    {role()}
                \li \c{state(int child)} is now
                    \l{QAccessibleInterface::state()}{state()}
            \endlist
        \li \c{navigate()} is replaced with \l{QAccessibleInterface::parent()}
            {parent()} and \l{QAccessibleInterface::child()}{child()} to
            navigate the hierarchy.
        \li \c{relationTo()} is replaced with
            \l{QAccessibleInterface::relations()}{relations()}.
        \li \c{QAccessibleInterface::userActionCount()},
            \c{QAccessibleInterface::actionText()}, and
            \c{QAccessibleInterface::doAction()} are removed.
            We recommend using the \l{QAccessibleInterface} subclasses to
            implement the \l{QAccessibleActionInterface} instead.
      \endlist

    \section2 Changes to QImage

    \list
        \li \l{QImage::fill()} on an image with format \c{Format_RGB888} now
            expects image data in RGB layout as opposed to BGR layout.
            This is to ensure consistency with RGB32 and other 32-bit formats.
        \li The behavior of \l{QImage::load()}, \l{QImage::loadFromData()},
            \l{QPixmap::load()}, and \l{QPixmap::loadFromData()} on a non-null
            image changed so that if the functions fail to load the image
            (return \c false), the the existent image data is invalidated, so
            that \c isNull() is guaranteed to return \c true in this case.
    \endlist

    \section2 Changes to QPainter

    \list
        \li \l{QPainter} does not support uniting clipped regions anymore. Use
            \l{QRegion::united()} instead to unite clips and pass the result to
            \l{QPainter}.
        \li \l{QPainter} fill rules when not using antialiased painting
            have changed so that the aliased and antialiased coordinate systems
            match. There used to be an offset of slightly less than half a pixel
            when doing sub-pixel rendering, in order to be consistent with the
            old X11 paint engine. The new behavior should be more predictable
            and give the same consistent rounding for images and pixmaps as for
            paths and rectangle filling. To get the old behavior, set the
            \l{QPainter::Qt4CompatiblePainting} render hint.
    \endlist

    \section2 Changes to QTouchEvent

      \list
       \li \c{QTouchEvent::DeviceType} and \c{QTouchEvent::deviceType()} are deprecated
           as \l{QTouchDevice} provides a better way to identify and access the
           device from which the events originate.
       \li The constructor now takes a \l{QTouchDevice} pointer instead of \c{DeviceType} value.
       \li \c TouchPointStateMask and \c TouchPointPrimary are removed from the
           \l{Qt::TouchPointStates} enum.
       \li \c{QTouchEvent::TouchPoint::isPrimary()} is removed.

      \endlist

\section1 Changes to Qt Widgets
    \list
     \li \l{QItemEditorFactory::createEditor()} and
         \l{QItemEditorFactory::valuePropertyName()} signatures
         are changed to take arguments of type \c{int} instead of \l{QVariant::Type}.
     \li \c{QInputContext} is removed as related getter and setter functions in \l{QWidget} and \l{QApplication} are removed.
         Input contexts are now platform-specific.
     \li \l{QInputDialog::getInteger()} is deprecated. Use \l{QInputDialog::getInt()} instead.
    \li The \c{QStyleOption*V{2,3,4}} classes are removed, and their members
        are merged with the respective base classes. The removed classes are
        left as typedefs for binary compatibility.
    \li \l{QGraphicsItem} and its derived classes can no longer pass a
        \l{QGraphicsScene} to the item's constructor.
        Construct the item without a scene and call \l{QGraphicsScene::addItem()}
        to add the item to the scene.
    \li \c{QProxyModel} is removed. Use \l{QAbstractProxyModel} and the related
        classes instead. A copy of \c{QProxyModel} is available in the
        \l{http://wiki.qt.io/Qt_5_UI_Helpers}{Ui Helpers} repository.
     \endlist

    \section2 Changes to QApplication

    \list
        \li \c QApplication::setGraphicsSystem() is removed, because the
            introduction  of \l{Qt Platform Abstraction}{QPA} made it redundant.
        \li \c{QApplication::commitData} and \c{QApplication::saveState} virtual
            methods that were used for session management are removed. Connect
            to the \l{QApplication::commitDataRequest} and
            \l{QApplication::saveStateRequest} signals instead. Use
            \l{QApplication::isSavingSession()} if the \l{QWidget::closeEvent}
            if your window needs to know whether it is being called during
            shutdown.
    \endlist

    \section2 Changes to QStyle

    \list
     \li \c{QStyle::standardIconImplementation()} and \c{QStyle::layoutSpacingImplementation()} are removed,
         and the \l{QStyle::standardIcon()} and \l{QStyle::layoutSpacing()} functions are made pure virtual now.
         The removed functions were introduced in Qt 4 for binary compatibility reasons.
    \li \c QMotifStyle, \c QPlastiqueStyle, \c QCleanlooksStyle, and \c QCDEStyle are
        replaced with a new \e fusion style. If your application depends
        on any of these removed styles, you can either use the
        \l{http://code.qt.io/cgit/qt/qtstyleplugins.git/}{qtstyleplugins} project
        to get these styles or update your application to use the new fusion style.
        For more details about this change, see
        \l{https://blog.qt.io/blog/2012/10/30/cleaning-up-styles-in-qt5-and-adding-fusion/}.
    \li The following QStyle implementations have been made internal:
        \list
            \li QFusionStyle
            \li QGtkStyle
            \li QMacStyle
            \li QWindowsCEStyle
            \li QWindowsMobileStyle
            \li QWindowsStyle
            \li QWindowsVistaStyle
            \li QWindowsXPStyle
        \endlist

    Instead of creating instances or inheriting these classes directly, use:
        \list
            \li QStyleFactory for creating instances of specific styles.
            \li QProxyStyle for customizing existing style implementations.
            \li QCommonStyle as a base for implementing full custom styles.
        \endlist
    \endlist

    \section2 Changes to QHeaderView

    The following functions are deprecated:
      \list
       \li \c{void setMovable(bool movable)} - Use \l{QHeaderView::setSectionsMovable()} instead.
       \li \c{bool isMovable() const} - Use \l{QHeaderView::sectionsMovable()} instead.
       \li \c{void setClickable(bool clickable)} - Use \l{QHeaderView::setSectionsClickable()} instead.
       \li \c{bool isClickable() const} - Use \l{QHeaderView::sectionsClickable()} instead.
       \li \c{void setResizeMode(int logicalindex, ResizeMode mode)} - Use \l{QHeaderView::setSectionResizeMode()} instead.
       \li \c{ResizeMode resizeMode(int logicalindex) const} - Use \l{QHeaderView::sectionResizeMode()} instead.
      \endlist

    \section2 Changes to QAbstractItemView

     \list
      \li The derived classes now emit the \c{clicked()} signal on the left mouse click only, instead of all mouse clicks.
      \li The virtual \l{QAbstractItemView::dataChanged()} function signature
          now includes the roles that have changed.
          The signature is consistent with the \c{dataChanged()} signal in the model.
      \endlist

    \section2 Changes to QColorDialog

    \list
     \li \l{QColorDialog::customColor()} now returns a \l{QColor} value instead of \c{QRgb}.
     \li \l{QColorDialog::setCustomColor()} and \l{QColorDialog::setStandardColor()}
         now need a \l{QColor} value as
         their second parameter instead of \c{QRgb}.
    \endlist

\section1 Changes to Qt WebKit
    \list
     \li The WebKit module in Qt is now split in two modules, \c{webkit} and \c{webkitwidgets}, in order to allow the dependency of
         the \c{widgets} module to be optional. The benefits will only be
         available once the QQuickWebView API is made public
         through C++ in a future version. The \c{webkitwidgets} module adds the \c{webkit} module automatically to the project,
         so in your application's project file, \c{QT += webkit} should now be modified to:
         \code
             QT += webkitwidgets
         \endcode
     \li The same applies to the module include, \c{#include <QtWebKit/QtWebKit>} should be modified to:
         \code
             #include <QtWebKitWidgets/QtWebKitWidgets>
         \endcode
     \li A consequence of the module split is that classes of the \l{Qt WebKit} API aren't all in the new module, so for a better
         compatibility of your application with both Qt4 and Qt5, #include <QtWebKit/QWebPage>, for example, should be included
         directly as:
         \code
             #include <QWebPage>
         \endcode
         The include path will take care of selecting the right module.
     \li The qwebkitversion.h header has been renamed to q\b{t}webkitversion.h to match other Qt modules, and part of its
         contents has been moved to qwebkitglobal.h. \c{#include <qwebkitversion.h>} should be replaced with
         two includes:
         \code
             #include <qtwebkitversion.h>
             #include <qwebkitglobal.h>
         \endcode
    \endlist

\section1 Changes to Qt Print Support
    \list
     \li The \c{QPageSetupDialog::PageSetupDialogOption} enum and the corresponding set and get functions, \c{QPageSetupDialog::options()}
         and \c{QPageSetupDialog::setOptions()} are removed.
     \li Support for printing PostScript files has been removed.
     \li The \c QAbstractPageSetupDialog class is removed. Use \l QPrintDialog
         instead.
     \li The \l{QPrintEngine::PrintEnginePropertyKey} enum value
         \c PPK_SuppressSystemPrintStatus is removed.
    \li \l{QPrinter} no longer allows you to set an invalid printer name.
    \endlist

\section1 Changes to Qt Network
    \list
     \li The \c{QSsl::TlsV1} enum value is renamed as \l{QSsl::TlsV1_0}.
     \li The \c QHttp, \c QHttpHeader, \c QHttpResponseHeader, and
         \c QHttpRequestHeader classes are removed. Use \l QNetworkAccessManager
         instead.
     \li The \c QFtp and \c QUrlInfo classes are no longer exported. Use
         \l QNetworkAccessManager instead.
         Programs that require raw FTP or HTTP streams can use the
         \l{Qt FTP} and \l{Qt HTTP} compatibility add-on modules that provide
         the \c{QFtp} and \c{QHttp} classes as they existed in Qt 4.
     \li \l{QAbstractSocket::connectToHost()} and \l{QAbstractSocket::disconnectFromHost()}
         are virtual now,
         and \c{QAbstractSocket::connectToHostImplementation()} and \c{QAbstractSocket::disconnectFromHostImplementation()} are removed.
     \li \l{QTcpServer::incomingConnection()} now takes arguments of type
         \c{qintptr} instead of an \c{int}.
     \li \c{QNetworkConfiguration::bearerName()} is removed. Use the \l{QNetworkConfiguration::bearerTypeName()}{bearerTypeName()} instead.
    \endlist

    \section2 Changes to QSslCertificate

    \list
        \li \l{QSslCertificate::subjectInfo()} and \l{QSslCertificate::issuerInfo()}
            now return QStringList instead of a QString. This change makes
            searching the required information a lot easier than scanning a long
            string.
        \li \l{QSslCertificate::isValid()} is deprecated. Use
            \l{QSslCertificate::isBlacklisted()} instead to avoid binary breaks
            in the future.
        \li \l{QSslCertificate::alternateSubjectNames()} is deprecated. Use
            \l{QSslCertificate::subjectAlternativeNames()} instead.
    \endlist

\section1 Changes to Qt SQL
    \list
     \li \l{QSqlQueryModel::indexInQuery()} is virtual now.
     \li \l{QSqlQueryModel::setQuery()} emits fewer signals. The \c{modelAboutToBeReset()}
         and \c{modelReset()} signals are sufficient to inform views that they must re-interrogate
         the model.
     \li \l{QSqlDriver::subscribeToNotification()}, \l{QSqlDriver::unsubscribeFromNotification()},
         \l{QSqlDriver::subscribedToNotifications()}, \l{QSqlDriver::isIdentifierEscaped()}, and
         \l{QSqlDriver::stripDelimiters()} are virtual now. The corresponding \c xxxImplementation
         functions are also removed as the subclasses of \l{QSqlDriver} can re-implement those directly.
    \li \l{QSqlError} now handles alphanumeric error codes that are used by
        QPSQL. The numeric codes are deprecated.
    \endlist

\section1 Changes to Qt Test
     \list
      \li The plain-text, XML and lightxml test output formats are updated to
          include test result for every row of test data in data-driven tests. In
          Qt4, only fails and skips were included for individual data rows without
          the passes information. This limitation prevented accurate test run and
            pass rates calculation.
      \li The \c{QTRY_VERIFY} and \c{QTRY_COMPARE} macros are now part of \c{QTestLib}.
          These macros were part of \c{tests/shared/util.h} earlier, but now they are part
          of the <QtTest/QtTest> header.
          In addition, \c{QTRY_VERIFY_WITH_TIMEOUT} and \c{QTRY_COMPARE_WITH_TIMEOUT} are provided
          to specify custom timeout values.
      \li The \c{QTEST_NOOP_MAIN} macro is removed.  If a test
          appears to be inapplicable for a particular build at compile-time, it should
          be omitted either using the .pro file logic or call \c{QSKIP} in the
          \c{initTestCase()} method to skip the entire test. If you're using the later approach,
          report a meaningful explanation in the test log.
      \li The \c{DEPENDS_ON} macro is removed as it misled some users to believe that they could
          make test functions depend on each other or impose an execution order on test functions.
      \li \c{QTest::qt_snprintf()} is removed. This was an
          internal test library function that was exposed in the public API due to its use
          in a public macro. Any calls to this function must be replaced with
          \l{QByteArray::qsnprintf()}.
      \li c{QTest::pixmapsAreEqual()} is removed. Comparison of \l{QPixmap} objects must
          be done using the \c{QCOMPARE} macro, which provides more informative output in the event of a failure.
      \li The \c{"mode"} parameter in \c{QSKIP} macro is removed. This parameter caused problems
          in test metrics calculation because of the \c{SkipAll} mode, which hid information about
          the skipped test data.  Calling \c{QSKIP} in a test function now behaves
          like \c{SkipSingle}, which is skipping a non-data-driven test function or skipping
          only the current data row of a data-driven test function.  Every skipped
          data row is now reported in the test log.
      \li \c{qCompare()} has been replaced by overloading. Code such as
          \c {qCompare<QString>(l, r)} no longer uses the QString-specific
          implementation and may fail to compile. We recommend that you
          replace specialization with overloading. Also, rather than pass
          explicit template arguments to \c qCompare, let the overload
          resolution pick the correct one, and cast arguments in case of
          ambiguous overloads (for example, \c {qCompare(QString(l), r)}).
          The resulting code will continue to work against older QtTestlib
          versions.
      \li \c QTest::qWaitForWindowShown() is replaced with \l{QTest::qWaitForWindowExposed()}.
     \endlist

    \section1 Changes to Qt OpenGL

    Apart from the \l QGLWidget class, the \l{Qt OpenGL} module should not be
    used for new code. Instead, use the corresponding \e OpenGL classes in
    \l{Qt GUI}.

    \list
        \li \l QGLPixelBuffer is deprecated and implemented by using a hidden
            \l QGLWidget and a \l QOpenGLFramebufferObject. For offscreen
            rendering to a texture, switch to using \l QOpenGLFramebufferObject
            directly to improve performance.
        \li The default major version of \l QGLFormat is changed to 2 to align
            it with \l QSurfaceFormat. Applications that want to use a different
            version, should explicitly request it using
            \l{QGLFormat::setVersion()}.
        \li \c{QGLContext::generateFontDisplayLists()} and
            \c{QGLWidget::fontDisplayListBase()} are removed.
        \li The \c listBase parameter is removed from \l{QGLWidget::renderText()}
            functions.
        \li To ensure support on more platforms, stricter requirements have been
            introduced for doing threaded \c OpenGL. First, you must call
            \l{QGLWidget::makeCurrent()} at least once per each
            \l{QGLWidget::swapBuffers()} call, so that the platform has a chance
            to synchronize resizing the \c OpenGL surface. Second, before
            calling \l{QGLWidget::makeCurrent()} or \l{QGLWidget::swapBuffers()}
            in a separate thread, you must call \l{QGLContext::moveToThread()}
            to explicitly let Qt know in which thread a \l QGLContext is
            currently being used. You also need to make sure that the context is
            not current in the current thread before moving it to a different
            thread.
    \endlist

\section1 Changes to Qt Global
    \list
     \li \c{qMacVersion()} is removed. Use \l{QSysInfo::macVersion()} or
        \l{QSysInfo::MacintoshVersion} instead.
     \li \c{Qt::escape()} is deprecated. Use \l{QString::toHtmlEscaped()} instead.
     \li \c{qIsDetached<>} is removed, becauses it is irrelevant for
         multi-threaded applications. There is no replacement for this function.
    \endlist

\section1 Changes to Tools
    \list
     \li The \c {qttest_p4.prf} file is removed. Use \c{CONFIG+=testcase} and
         other flags instead.
     \li The \c{-dwarf2} configure argument is removed. DWARF2 is always used on \macos now.
     \li Configure no longer calls \c{qmake -recursive} by default, because the
         subsequent build invokes qmake as needed. Use \c{-fully-process} to
         restore the old behavior.
     \li The \l {Using lupdate}{lupdate} \c CODECFORTR variable is deprecated, because source
         code written with Qt 5 is expected to use UTF-8 encoding.
    \endlist

\section1 Related Topics
\list
\li \l{New Classes and Functions in Qt 5.5}
\li \l{New Classes and Functions in Qt 5.4}
\li \l{New Classes and Functions in Qt 5.3}
\li \l{New Classes and Functions in Qt 5.2}
\li \l{New Classes and Functions in Qt 5.1}
\endlist
*/