path: root/doc/src/qt4-intro.qdoc

/****************************************************************************
**
** Copyright (C) 2013 Digia Plc and/or its subsidiary(-ies).
** Contact: http://www.qt-project.org/legal
**
** This file is part of the documentation of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:FDL$
** Commercial License Usage
** Licensees holding valid commercial Qt licenses may use this file in
** accordance with the commercial license agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and Digia.  For licensing terms and
** conditions see http://qt.digia.com/licensing.  For further information
** use the contact form at http://qt.digia.com/contact-us.
**
** GNU Free Documentation License Usage
** Alternatively, this file may be used under the terms of the GNU Free
** Documentation License version 1.3 as published by the Free Software
** Foundation and appearing in the file included in the packaging of
** this file.  Please review the following information to ensure
** the GNU Free Documentation License version 1.3 requirements
** will be met: http://www.gnu.org/copyleft/fdl.html.
** $QT_END_LICENSE$
**
****************************************************************************/

/*!
    \page qt4-intro.html
    \title What's New in Qt 4

    \startpage index.html Qt Reference Documentation
    \nextpage The Tulip Container Classes

    This document covers the most important differences between Qt 3
    and Qt 4. Although it is not intended to be a comprehensive
    porting guide, it tells you about the most important portability
    issues that you may encounter. It also explains how to turn on Qt
    3 compatibility support.

    \section1 New Technologies in Qt 4

    Qt 4 introduces the following core technologies:

    \list
    \o \l{The Tulip Container Classes}{Tulip}, a new set of template container classes.

    \o \l{The Interview Framework}{Interview}, a model/view architecture for item views.

    \o \l{The Arthur Paint System}{Arthur}, the Qt 4 painting framework.

    \o \l{The Scribe Classes}{Scribe}, the Unicode text renderer with a public API
    for performing low-level text layout.

    \o \l{The Qt 4 Main Window Classes}{Mainwindow}, a modern action-based
    mainwindow, toolbar, menu, and docking architecture.

    \o The new \l{The New Qt Designer}{\QD} user interface design tool.
    \endlist

    \section1 Recent Additions to Qt 4

    The following features have been added to Qt since the first release of Qt 4.

    In Qt 4.8:
    \list
    \o \l{Qt Quick} 1.1 offers changes to the \l{QML Elements} and performance
    upgrades
    \
    \endlist
    In Qt 4.7:
    \list
    \o Declarative UI Development with \l{Qt Quick}, technologies for creating
       fluid, dynamic user interfaces.
    \o Support for \l{Bearer Management}{network bearer management}, enabling
       features such as control over network interfaces and support for roaming
       between networks.
    \o Feature and performance improvements in QtWebKit, including a new tiled
       backing store, control over scroll bars used in frames and framesets,
       accelerated compositing and \l{The QtWebKit Bridge}{support for hybrid
       development}.
    \o General performance improvements, including the use of "alien widgets"
       on Mac OS X, the QStaticText class for optimized text rendering, a new
       \l{QPainter::drawPixmapFragments()}{API for rendering pixmap fragments}
       and an updated version of the JavaScriptCore engine for the QtScript
       module with improved performance.
    \endlist

    In Qt 4.6:
    \list
    \o Support for \l{The Symbian platform - Introduction to Qt}{the Symbian Platform}
       as a mainstream Qt platform, with integration into the S60 framework.
    \o The \l{The Animation Framework}{animation framework} allows animations to be
       created using both widgets and graphics items.
    \o The \l{The State Machine Framework}{state machine framework} provides a robust
       state chart implementation based on Harel statecharts and SCXML.
    \o Support for \l{QTouchEvent}{touch input} and \l{Gestures Programming}{gestures}
       enable developers to create intuitive user interfaces for touch-based devices.
    \o A \l{QWebElement}{DOM access API} for QtWebKit provides a cleaner and safer way
       to access elements and structures of Web pages without the use of JavaScript.
    \o A collection of performance improvements, covering QGraphicsView, QPixmapCache,
       QNetworkAccessManager, QContiguousCache class, hardware-accelerated rendering
       support through \l{OpenVG Rendering in Qt}{OpenVG}, and the removal of Win9x
       support.
    \o A collection of \l{QGraphicsEffect}{graphics effects} make it easy to apply
       and simple effects to graphics items and combine them to produce more complex
       effects.
    \o Support for XML schema validation in the QtXmlPatterns module covering
       large parts of version 1.0 of the specification.
    \o Qt3D enablers, including math primitives for \l{QMatrix4x4}{matrix multiplication},
       \l{QVector3D}{vectors}, \l{QQuaternion}{quaternions} (client-side), and an API
       for \l{QGLShader}{vertex and fragment shaders}, GLSL/ES.
    \o \l{QtMultimedia Module}{Multimedia services} providing low-level access to the
       system's audio system.
    \endlist

    In Qt 4.5:
    \list
    \o The WebKit browser engine included with Qt has been
       upgraded to the latest upstream (trunk) version of WebKit,
       bringing the latest features and improvements to Qt applications.
    \o Qt for Mac OS X has been substantially rewritten to use
       Apple's Cocoa API, enabling Qt applications to be deployed on
       64-bit Macintosh hardware.
    \o The QtXmlPatterns module has been extended to cover XSLT, a
       transformation language for XML documents.
    \o Qt Script introduced its debugger,
       providing error reporting for scripts, and to let users track down
       bugs in their own scripts.
    \o Qt 4.5 includes support for writing rich text documents as
       OpenDocument files via the newly-introduced QTextDocumentWriter
       class.
    \o Qt Linguist can load and edit multiple translation
       files simultaneously.
    \o Support for ARGB top-level widgets (i.e., translucent
       windows).
    \endlist

    In Qt 4.4:
    \list
    \o \l{WebKit in Qt}{Qt WebKit integration}, making it possible for developers
    to use a fully-featured Web browser to display documents and access online
    services.
    \o A multimedia API provided by the \l{Phonon Overview}{Phonon Multimedia Framework}.
    \o \l{QtXmlPatterns Module}{XQuery and XPath} support, providing facilities for
    XML processing beyond that supported by the QtXml module.
    \o Support for embedded widgets in \l{Graphics View} scenes.
    \o The \l{Thread Support in Qt}{QtConcurrent framework} for
    concurrent programming using Qt paradigms and threading features.
    \o An \l{QtHelp Module}{improved help system} that can be used in conjunction
    with Qt Assistant or as an independent help resource manager.
    \o Printing system improvements, including the QPrinterInfo, QPrintPreviewWidget
    and QPrintPreviewDialog classes.
    \o Support for \l{Windows CE - Introduction to using Qt}{Qt for Windows CE} as
    a mainstream Qt platform.
    \o Improvements in performance of Qt for Embedded Linux and extended support for
    display hardware.
    \endlist

    In Qt 4.3:
    \list
    \o Support for different \l{The Qt 4 Main Window Classes}{main window paradigms and styles},
       such as those found in Visual Studio or KDevelop.
    \o The \l{QtScript} module, providing support for application scripting with ECMAScript.
    \o Improved graphics features, including an experimental Direct3D paint engine
       and improved provision for hardware accelerated rendering with OpenGL, and
       support for OpenGL ES in Qt for Embedded Linux.
    \o \l{QSvgGenerator}{Scalable Vector Graphics (SVG) export}, allowing SVG drawings to
       be created using the standard QPainter API.
    \o Support for arbitrary matrix transformations and set operations on painter paths.
    \o Native look and feel on Windows Vista; improved look and feel on Mac OS X.
    \o An improved \l{QMdiArea}{Multiple Document Interface (MDI)} implementation.
    \o Continuous improvements to \QD, including support for
       \l{Qt Designer's Widget Editing Mode#The Property Editor}{dynamic properties}.
    \o Support for Secure Socket Layer (SSL) communications via the QSslSocket class.
    \o Support for XML Localization Interchange File Format (XLIFF) files in \QL.
    \o A new font subsystem for Qt for Embedded Linux.
    \endlist

    In Qt 4.2:
    \list
    \o The \l{Graphics View} framework for producing interactive graphics.
    \o \l{Desktop Integration}{Desktop integration} facilities for applications.
    \o \l{Qt Style Sheets} enable easy, yet powerful customization of
       user interfaces.
    \o Support for the \l{intro-to-dbus.html}{D-Bus} Inter-Process Communication (IPC) and Remote Procedure Calling (RPC) mechanism.
    \o An \l{Undo Framework}{Undo framework} based on the
       \l{Books about GUI Design#Design Patterns}{Command pattern}.
    \o Support for model-based \l{QCompleter}{text completion} in standard and
       custom widgets.
    \o New widgets and GUI features, such as QCalendarWidget and
       QGLFramebufferObject.
    \o Classes to provide higher level application infrastructure, such as
       QFileSystemWatcher and QDataWidgetMapper.
    \endlist

    In Qt 4.1:
    \list
    \o Integrated support for rendering
    \l{The Arthur Paint System#SVG Rendering Support}{Scalable Vector Graphics}
    (SVG) drawings and animations.
    \o Support for
       \l{QWidget#Transparency and Double Buffering}{child widget transparency}
       on all platforms.
    \o A Portable Document Format (PDF) backend for Qt's printing system.
    \o A \l{QTestLib Manual}{unit testing framework} for Qt applications and
       libraries.
    \o Modules for \l{QtDesigner}{extending \QD} and
       \l{QtUiTools}{dynamic user interface building}.
    \o New \l{Proxy Models}{proxy models} to enable view-specific sorting and
       filtering of data displayed using item views.
    \o Support for \l{Installing Qt for Mac OS X}{universal binaries} on Mac OS X.
    \o Additional features for developers using \l{QtOpenGL}{OpenGL}, such as
    support for pixel and sample buffers.
    \o A flexible \l{QSyntaxHighlighter}{syntax highlighting class} based on the
       \l{Scribe} rich text framework.
    \o Support for \l{QNetworkProxy}{network proxy} servers using the SOCKS5
       protocol.
    \o Support for OLE verbs and MIME data handling in \l{ActiveQt}.
    \endlist

    For more information about improvements in each Qt release, see
    the \l{http://qt.nokia.com/developer/changes/}
    {detailed lists of changes}.

    \section1 Significant Improvements

    The following modules have been significantly improved for Qt 4:

    \list
    \o A fully cross-platform \l{accessibility}
    module, with support for the emerging SP-API Unix standard in
    addition to Microsoft and Mac Accessibility.
    \o The \l{qt4-sql.html}{SQL module}, which is now based on the
    Interview model/view framework.
    \o The \l{qt4-network.html}{network module}, with better support
    for UDP and synchronous sockets.
    \o The \l{qt4-styles.html}{style API}, which is now decoupled from
    the widgets, meaning that you can draw any user interface element on
    any device (widget, pixmap, etc.).
    \o Enhanced \l{qt4-threads.html}{thread support}, with signal-slot
    connections across threads and per-thread event loops.
    \o A new \l{resource system} for embedding images
    and other resource files into the application executable.
    \endlist

    \section1 Build System

    Unlike previous Qt releases, Qt 4 is a collection of smaller
    libraries. A complete list of libraries in the current release
    of Qt can be found on the \l{All Modules} page. The following
    table describes the initial set of libraries released with Qt 4.

    \table
    \header \o Library          \o Description
    \row    \o \l{QtCore}       \o Core non-GUI functionality
    \row    \o \l{QtGui}        \o Core GUI functionality
    \row    \o \l{QtNetwork}    \o Network module
    \row    \o \l{QtOpenGL}     \o OpenGL module
    \row    \o \l{QtSql}        \o SQL module
    \row    \o \l{QtSvg}        \o SVG rendering classes
    \row    \o \l{QtXml}        \o XML module
    \row    \o \l{Qt3Support}   \o Qt 3 support classes
    \row    \o \l{QAxContainer} \o ActiveQt client extension
    \row    \o \l{QAxServer}    \o ActiveQt server extension
    \row    \o \l{QtHelp}       \o Classes for integrating online documentation
    \row    \o \l{QtDesigner}   \o Classes for extending and embedding Qt Designer
    \row    \o \l{QtUiTools}    \o Classes for dynamic GUI generation
    \row    \o \l{QtTest}       \o Tool classes for unit testing
    \endtable

    QtCore contains tool classes like QString, QList, and QFile, as
    well as kernel classes like QObject and QTimer. The QApplication
    class has been refactored so that it can be used in non-GUI
    applications. It is split into QCoreApplication (in \l QtCore)
    and QApplication (in \l QtGui).

    This split makes it possible to develop server applications using Qt
    without linking in any unnecessary GUI-related code and without
    requiring GUI-related system libraries to be present on the target
    machine (e.g. Xlib on X11, Carbon on Mac OS X).

    If you use qmake to generate your makefiles, qmake will by default
    link your application against QtCore and QtGui. To remove the
    dependency upon QtGui, add the line

    \snippet doc/src/snippets/code/doc_src_qt4-intro.pro 0

    to your .pro file. To enable the other libraries, add the line

    \snippet doc/src/snippets/code/doc_src_qt4-intro.pro 1

    Another change to the build system is that moc now understands
    preprocessor directives. qmake automatically passes the defines set
    for your project (using "DEFINES +=") on to moc, which has its own
    built-in C++ preprocessor.

    To compile code that uses UI files, you will also need this line in
    the .pro file:

    \snippet doc/src/snippets/code/doc_src_qt4-intro.pro 2

    \section1 Include Syntax

    The syntax for including Qt class definitions has become

    \snippet doc/src/snippets/code/doc_src_qt4-intro.cpp 3

    For example:

    \snippet doc/src/snippets/code/doc_src_qt4-intro.cpp 4

    This is guaranteed to work for any public Qt class. The old syntax,

    \snippet doc/src/snippets/code/doc_src_qt4-intro.cpp 5

    still works, but we encourage you to switch to the new syntax.

    If you attempt to include a header file from a library that isn't
    linked against the application, this will result in a
    compile-time warning (e.g., "QSqlQuery: No such file or
    directory"). You can remedy to this problem either by removing
    the offending include or by specifying the missing library in the
    QT entry of your \c .pro file (see \l{Build System} above).

    To include the definitions for all the classes in a library, simply
    specify the name of that library. For example:

    \snippet doc/src/snippets/code/doc_src_qt4-intro.cpp 6

    \section1 Namespaces

    Qt 2 introduced a class called Qt for global-like constants
    (e.g., \c{Qt::yellow}). The C++ namespace construct was not used
    because not all compilers understood it when it was released.

    With Qt 4, the Qt class has become the Qt namespace. If you want
    to access a constant that is part of the Qt namespace, prefix it
    with \c{Qt::} (e.g., \c{Qt::yellow}), or add the directive

    \snippet doc/src/snippets/code/doc_src_qt4-intro.cpp 7

    at the top of your source files, after your \c #include
    directives. If you use the \c{using namespace} syntax you don't
    need the prefix (e.g., \c yellow is sufficient).

    When porting Qt 3 applications, you may run into some source
    compatibility problems with some of these symbols. For example,
    in Qt 3, it was legal to write \c QWidget::yellow instead of \c
    Qt::yellow, because QWidget inherited from Qt. This won't work in
    Qt 4; you must write \c Qt::yellow or add the "using namespace"
    directive and drop the \c{Qt::} prefix.

    The \l{qt3to4 - The Qt 3 to 4 Porting Tool}{qt3to4} porting tool
    automates this conversion.

    \section1 QObject/QWidget Constructors

    In Qt 4 we have tried to simplify the constructors of QObject/QWidget
    subclasses. This makes subclassing easier, at the same time as it
    helps make the Qt library more efficient.

    Constructors no longer take a "const char *name" parameter. If
    you want to specify a name for a QObject, you must call
    QObject::setObjectName() after construction. The object name is
    now a QString. The reasons for this change are:

    \list
    \o  Code that used it looked confusing, for example:

        \snippet doc/src/snippets/code/doc_src_qt4-intro.cpp 8

        \c label1 is a QLabel that displays the text "Hello"; \c
        label2 is a QLabel with no text, with the object name
        "Hello".

    \o  From surveys we did, most users didn't use the name, although
        they blindly followed Qt's convention and provided a "const
        char *name" in their subclasses's constructors. For example:

        \snippet doc/src/snippets/code/doc_src_qt4-intro.cpp 9

    \o  The name parameter was in Qt since version 1, and it always
        was documented as: "It is not very useful in the current
        version of Qt, but it will become increasingly important in
        the future." Ten years later, it still hasn't fulfilled its
        promise.
    \endlist

    QWidget's \c WFlags data type has been split in two:
    Qt::WindowFlags specifies low-level window flags (the type of
    window and the frame style), whereas Qt::WidgetAttribute
    specifies various higher-level attributes about the widget (e.g.,
    WA_StaticContents). Widget attributes can be set at any time
    using QWidget::setAttribute(); low-level window flags can be
    passed to the QWidget constructor or set later using
    QWidget::setParent(). As a consequence, the constructors of most
    QWidget subclasses don't need to provide a \c WFlags parameter.

    The \e parent parameter of all QObject classes in Qt defaults to
    a 0 pointer, as it used to do in Qt 1. This enables a style of
    programming where widgets are created without parents and then
    inserted in a layout, at which point the layout automatically
    reparents them.

    \section1 Dynamic Casts

    Qt 4 provides a qobject_cast<>() function that performs a dynamic cast
    based on the meta-information generated by moc for QObject
    subclasses. Unlike the standard C++ dynamic_cast<>() construct,
    qobject_cast<>() works even when RTTI is disabled, and it works correctly
    across DLL boundaries.

    Here's the Qt 3 idiom to cast a type to a subtype:

    \snippet doc/src/snippets/code/doc_src_qt4-intro.cpp 10

    The Qt 4 idiom is both cleaner and safer, because typos will always
    result in compiler errors:

    \snippet doc/src/snippets/code/doc_src_qt4-intro.cpp 11

    \section1 QPointer<T>

    The QPointer<T> class provides a pointer to type T (where T inherits
    from QObject) that is automatically set to 0 when the referenced
    object is destroyed. Guarded pointers are useful whenever you want to
    store a pointer to an object you do not own.

    Example:

    \snippet doc/src/snippets/code/doc_src_qt4-intro.cpp 12

    QPointer<T> is more or less the same as the old QGuardedPtr<T> class,
    except that it is now implemented in a much more lightweight manner
    than before. The cost of one QPointer<T> object is now approximately
    the same as that of a signal--slot connection.

    \section1 Paint Events

    Qt 4 supports double buffering transparently on all platforms. This
    feature can be turned off on a per-widget basis by calling
    QWidget::setAttribute(Qt::WA_PaintOnScreen).

    A consequence of this is that all painting must now be done from the
    paintEvent() function. This is also required by the HIView API on Mac
    OS X. In practice, this is seldom a problem, since you can call
    update() from anywhere in your code to create a paint event, with the
    region to update as the argument.

    To help porting, QWidget supports a Qt::WA_PaintOutsidePaintEvent
    attribute that can be set to make it possible to paint outside
    \l{QWidget::paintEvent()}{paintEvent()} on Windows and X11.

    \section1 Qt 3 Support Layer

    Qt 4 provides an extension library that applications based on Qt 3,
    called Qt3Support, that Qt applications can link against. This allows
    for more compatibility than ever before, without bloating Qt.

    \list
    \o  Classes that have been replaced by a different class with the
        same name, such as QListView, and classes that no longer exist in Qt 4
        are available with a \c 3 in their name (e.g., Q3ListView, Q3Accel).

    \o  Other classes provide compatibility functions. Most of these are
        implemented inline, so that they don't bloat the Qt libraries.
    \endlist

    To enable the Qt 3 support classes and functions, add the line

    \snippet doc/src/snippets/code/doc_src_qt4-intro.pro 13

    to your \c .pro file.

    On Visual C++ 7 and GCC 3.2+, using compatibility functions often results
    in a compiler warning (e.g., "'find' is deprecated"). If you want to turn
    off that warning, add the line

    \snippet doc/src/snippets/code/doc_src_qt4-intro.pro 14

    to your \c .pro file.

    If you want to use compatibility functions but don't want to link
    against the Qt3Support library, add the line

    \snippet doc/src/snippets/code/doc_src_qt4-intro.pro 15

    or

    \snippet doc/src/snippets/code/doc_src_qt4-intro.pro 16

    to your \c .pro file, depending on whether you want compatibility
    function calls to generate compiler warnings or not.
*/

/*!
    \page qt4-8-intro.html
    \title What's New in Qt 4.8

    Qt 4.8 provides many improvements and enhancements over the previous
    releases in the Qt 4 series. This document covers the most important
    features in this release, separated by category.

    A list of other Qt 4 features can be found on the \bold{\l{What's
    New in Qt 4}} page.

    \section1 Qt Quick 1.1
    Qt Quick 1.1 introduces \l{What's New in Qt Quick}{new changes} such as
    new properties and better performance.

    \list
    \o \l {QML Right-to-left User Interfaces}{Right-To-Left} text support
    \o Improved image caching
    \o Text input improvements - Support for split-screen virtual keyboard
    \o \l PinchArea Element - enables simple pinch gesture handling
    \o New properties for \l{QML Elements}.
    \endlist


    \section1 Qt Platform Abstraction -- \e Lighthouse

    \e QPA allows porting Qt to different windowing systems and devices
    easier. It provides a clean abstraction layer for porting QtGui to new
    window systems.

    \section1 Qt WebKit 2.2

    The new Qt WebKit release introduces bug fixes, performance improvements,
    and greater compiler compatibility.

    \section1 Threaded OpenGL

    Many Qt OpenGL functions are now thread-safe. Threads that cater to
    different situations are now available.

    \list
    \o Buffer swapping thread
    \o Texture uploading thread
    \o \l QPainter thread
    \endlist

    \section1 Deprecated Items in Qt 4.8

    As part of Open Governance, modules in Qt 4.8 will receive maintainers and
    receive different support levels.

    Currently, a module has an activity classification, the \e{Module Maturity Level}.
    As well, a list of modules and their maturity level is in the \l{Qt Developer Network}.

    \list
        \o \l{Qt Modules' Maturity Level - Description} - description of the
        different \e{maturity levels}
        \o \l{Qt Modules' Maturity Levels - Modules List} - list of the Qt
        modules and their maturity level
    \endlist
    \section1 Additions to the Qt API

    Qt 4.8 introduces changes to the Qt API.
    \list
    \o C++11 support:
    Qt supports some of the features of the C++11 standard. QList, QVector and
    QStringList can be initialized with initializer lists. Most of the tool
    classes have a move operator. It is possible to use lambda functions in some
    of the QtConcurrent functions.
    
    \o Localization API

    Changes to the Localization APIs include improvements to \l QLocale and more
    support for different language code formats.

        \list
        \o \l {QLocale::quoteString()} - for localized quotes
        \o \l {QLocale::createSeparatedList()} - for localized list separation (e.g. "1, 2 and 3")
        \o \l {QLocale::bcp47Name()} - for locale names in the canonical form
        according to \l {RFC 5646 - BCP47}
        \o \l {QLocale::matchingLocales()} - to get a list of locales that match a
        criteria - e.g. a list of locales that use French language.
        \o \l {QLocale::firstDayOfWeek()}
        \o \l {QLocale::weekdays()}
        \o \l{QLocale::currencySymbol()}
        \o \l{QLocale::toCurrencyString()} - number formatting for currencies
        \o \l{QLocale::uiLanguages()}
        \o \l{QLocale::nativeLanguageName()}
        \o \l{QLocale::nativeCountryName()}
        \endlist
    \o IP Multicast API
    \o Multithreaded HTTP
    \o QThreadLocalStorage can now store simple objects in addition to pointers
    \endlist

    \section1 New Classes, Functions, Macros, etc.
    \sincelist 4.8
*/

/*!
    \page qt4-7-intro.html
    \title What's New in Qt 4.7

    Qt 4.7 provides many improvements and enhancements over the
    previous releases in the Qt 4 series. This document covers the
    most important features in this release, separated by category.

    A list of other Qt 4 features can be found on the \bold{\l{What's
    New in Qt 4}} page.

    \section1 Declarative UI Development with Qt Quick

    \image quick_screens.png

    Qt 4.7 introduces \l{Qt Quick}, the Qt UI Creation Kit. that enables
    the creation of dynamic user interfaces, easier and more effective
    than possible with existing UI technologies. This UI Creation Kit
    consists of three technologies:

    \list
    \i QML is a declarative language oriented on JavaScript that utilizes
    Qt's Meta-Object capabilities to enable designers and developers to
    collaborate tightly and create animated and fluid user experiences,
    using existing knowledge in script language and design.

    \i Qt Declarative is a C++ library that provides the underlying engine,
    which translates the declarative description of the UI in QML into
    items on a QGraphicsScene. The library also provides APIs to bind
    custom C++ types and elements to QML, and to connect the QML UI with
    the underlying application logic written in C++.

    \i Qt Creator has been improved to support interactive editing of
    QML UIs through drag-and-drop. The text editor supports the QML
    syntax and provides authoring assistance such as auto-completion,
    error lookup, help lookup and easy preview of QML UI's. The Qt
    Quick features in Qt Creator will be released with Qt Creator 2.1
    \endlist

    \section1 Network Bearer Management

    Bearer Management controls the connectivity state of the system.
    The new Bearer Management API in the QtNetwork module allows the
    application to identify whether the system is online and how many
    interfaces there are, as well as start and stop interfaces, or
    roam transparently between access points.

    QNetworkAccessManager uses this API for HTTP level roaming.

    \section1 Feature Improvements in QtWebKit

    The QGraphicsWebView class has a new tiled backing store, which
    improves scrolling and zooming performance. You can even create
    animated zoom-in or zoom-out effects (see
    QWebSettings::TiledBackingStoreEnabled).

    On mobile platforms, it is often useful to avoid displaying
    separate scrollbars for iframes and framesets. If you switch on
    frame flattening, QtWebKit will resize frames to fit their content
    to avoid separate scrollbars (see
    QWebSettings::FrameFlatteningEnabled).

    Qt 4.7 adds support for accelerated compositing, which enhances
    the performance of CSS animations and transitions. Read more in
    \l{http://labs.trolltech.com/blogs/2010/05/17/qtwebkit-now-accelerates-css-animations-3d-transforms/}{this blog}.

    For hybrid QtWebKit and C++ projects, Qt 4.7 has added support for
    transporting \l{QPixmap}s between Qt C++ and WebKit. We have also
    improved the documentation for hybrid development. Read more here:
    \l{The QtWebKit Bridge}.

    \section1 QtWebKit Performance Benchmarks

    We have introduced a set of performance benchmarks for QtWebKit,
    and made numerous improvements in rendering performance, page
    loading performance, scrolling performance and CSS performance.
    Here are some examples from the benchmarks run on a 64-bit Linux
    workstation with the raster graphics system.

    In a benchmark that measures the scrolling performance on popular
    websites, we found out that Qt 4.7.0 on this platform is 350%
    faster than Qt 4.6.0, thanks to several rendering related
    improvements.

    Our page loading benchmark shows an improvement of 16% in Qt 4.7.0
    from Qt 4.6.0. This is due to improvements in text layout speed,
    image decoding, resource loading and event handling.

    Several CSS animation benchmarks indicate a speed improvement of
    31% from Qt 4.6.0 to Qt 4.7.0. These benchmarks are effectively
    showing the improvement we get from accelerated compositing (see
    above).

    \section1 Other Performance Related Improvements

    In addition to the QtWebKit module, performance has been a focus
    area in Qt 4.7 throughout the Qt framework. Here are a couple of
    examples about performance related feature improvements.

    On Mac OS X, Qt now uses a different widget implementation (called
    "alien widgets"), which improves the responsiveness of
    applications that have complex user interfaces with several
    widgets.

    Qt 4.7 introduces the QStaticText class, which can be used to
    improve text rendering performance.  More info is available from
    \l{http://labs.trolltech.com/blogs/2010/03/01/insanity-is-shaping-the-same-text-again-and-expecting-a-different-result/}{this blog}.

    The QPainter class has a new API for rendering pixmap fragments
    (QPainter::drawPixmapFragments), which can improve the rendering
    performance of applications that need to render
    \l{QPainter::drawPixmapFragments()}{pixmap fragments}.

    Qt 4.7 has an updated version of the JavaScriptCore engine for the
    QtScript module, which improves JavaScript execution performance.

    \section1 New Classes, Functions, Macros, etc.

    Links to new classes, elements, functions, macros, and other items
    introduced in Qt 4.7.

    \sincelist 4.7
*/

/*!
    \page qt4-6-intro.html
    \title What's New in Qt 4.6

    Qt 4.6 provides many improvements and enhancements over the
    previous releases in the Qt 4 series. This document covers the
    most important features in this release, separated by category.

\omit
    A comprehensive list of changes between Qt 4.5 and Qt 4.6 is
    included in the \c changes-4.6.0 file
    \l{http://qt.nokia.com/developer/changes/changes-4.6.0}{available
    online}. A \l{Known Issues in %VERSION%}{list of known issues}
    for this release is also available.

    Changes between this release and the previous release are provided
    in the \c{changes-%VERSION%} file (also
    \l{http://qt.nokia.com/developer/changes/changes-%VERSION%}{available online}).
\endomit

    A list of other Qt 4 features can be found on the \bold{\l{What's
    New in Qt 4}} page.

    \section1 Support for Symbian

    Qt 4.6 is the first release to include support for the Symbian
    platform, with integration into the S60 framework. The port to
    Symbian and S60 provides all functionality required to develop
    rich end-user applications for devices running S60 3.1 and
    later.

    See the \l{The Symbian platform - Introduction to Qt} for more information.

    \section1 Animation Framework

    The animation framework helps build highly animated,
    high-performance GUIs without the hassle of managing complex
    structures, timers, and easing curves, not to mention the large
    state graphs that all animated GUIs tend to be full of.

    The framework makes it easy to animate \l{QObject}s, including
    QWidgets, by allowing Qt properties to be animated. It also allows
    creating custom animations and interpolation functions. Graphics
    views are not left out; one can animate \l{QGraphicsWidget}s and
    new \l{QGraphicsObject}s which inherit from QGraphicsItem
    (and thereby enable properties).

    Animations are controlled using easing curves and can be grouped
    together. This enables animations of arbitrary complexity.

    The API is easy to grasp with functions such as start(), stop(),
    pause(), and currentTime(). Here is an image from one of the
    examples that come with the framework:

    \image whatsnewanimatedtiles.png

    The animation framework also plugs into the new Qt Statemachine by
    allowing an animation to be played when transitions are triggered.
    The state machine framework is introduced in 4.6 and is described
    below.

    See \l{The Animation Framework} documentation for more information.

    \section1 State Machine Framework

    The state machine framework provides a robust state chart
    implementation based on Harel statecharts and SCXML. Qt's API lets
    you construct such state graphs and execute them. The key benefits
    of a state machine are:

    \list
        \o Simplify complex application semantics.
        \o Use of states to reduce code bloat.
        \o Use states to improve maintainability.
        \o Makes event-driven programming robust and more
           reusable.
    \endlist

    It is especially the last item here that makes using a state
    machine worthwhile. A key characteristic of event-driven systems
    (such as Qt applications) is that behavior often depends not only
    on the last or current event, but also the events that preceded
    it. With statecharts, this information is easy to express.

    The framework fits neatly into Qt by allowing transitions to
    trigger on signals and \l{QEvent}s. By inserting animations into
    the state machine, it is also easier to use the framework for
    animating GUIs, for instance.

    See \l{The State Machine Framework} documentation for more information.

    \section1 Touch and Gestures

    Support for touch input enables users to interact with many
    parts of a user interface at the same time, and provides the basis
    for gestures. Additional infrastructure for gesture recognition
    allows a sequence of touch inputs to be combined to create gestures
    that can be used to activate features and trigger actions in an
    application.

    \image gestures.png

    This new functionality brings a number of benefits:

    \list
        \o Allows users to interact with applications in more natural ways.
        \o Simplifies finger-based interaction with UI components.
        \o Combines support for common basic gestures and touch gestures
           in a single general framework.
        \o Enables extensibility by design.
    \endlist

    See the QTouchEvent class documentation for more information on touch
    input and QGestureEvent for gestures.

    \section1 DOM Access API

    Web pages and XML both have very complex document object models.
    The W3C selector API provides a very simple way to access and
    manipulate such structures. This API makes it intuitive to access
    DOM, helps reuse CSS selector knowledge, and gives little
    maintenance or footprint overhead.

    \snippet webkitsnippets/webelement/main.cpp FindAll

    See the QWebElement class documentation for more information.

    \section1 Performance Optimizations

    As always, Qt continuously strive to optimize its performance.
    For this release, we have:

    \list
        \o Rewritten the QGraphicsView rendering algorithm.
        \o Made QPixmapCache support efficient Key data structure.
        \o Reduced overhead in QNetworkAccessManager.
        \o Added the QContiguousCache class, which provides efficient caching of
           contiguous data.
        \o Added support for hardware-accelerated rendering through
        \l{OpenVG Rendering in Qt}{OpenVG}
        \o Removed Win9x support.
    \endlist

    \section1 Graphics Effects

    Effects can be used to alter the appearance of UI elements such as
    \l{QGraphicsItem}s and \l{QWidget}s. A couple of standard effects such
    as blurring, colorizing and drop shadow are provided, and it is
    possible to implement custom effects.

    \table
    \row
    \o{2,1} \img graphicseffect-plain.png
    \row
    \o \img graphicseffect-blur.png
    \o \img graphicseffect-colorize.png
    \row
    \o \img graphicseffect-opacity.png
    \o \img graphicseffect-drop-shadow.png
    \endtable

    See the QGraphicsEffect class documentation for more information.

    \section1 XML Schema Validation

    The QtXmlPatterns module can now be used to validate schemas, either
    through C++ APIs in the Qt application, or using the xmlpatternsvalidator
    command line utility. The implementation of XML Schema Validation supports
    the specification version 1.0 in large parts.

    \img xml-schema.png

    See the \l{XML Processing} and QXmlSchema class documentation for more
    information.

    \section1 Qt3D Enablers

    As more of Qt, and more of the applications built on Qt go 3D,
    API's should be provided to simplify this. Mainly, the new API
    aims to make it more easy to create 3D applications with OpenGL.
    It will also unify the Qt OpenGL codebase, and enable
    cross-platform 3D codebase.

    The main features of the Qt3D enablers are currently: Math
    primitives for matrix multiplication, vectors, quaternions
    (client-side), and an API for vertex and fragment shaders, GLSL/ES.
    Future research will, among other things include stencils,
    scissors, vertex buffers and arrays, texture manipulation, and
    geometry shaders.

    \section1 Multimedia Services

    Qt 4.6 comes with new classes for handling audio. These classes
    provide low-level access to the system's audio system. By
    specifying the audio format (QAudioFormat) and supplying audio
    data through a QIODevice, you get direct access to the
    functionality of the sound device. The API also comes with
    functions to query audio devices for which audio formats they
    support.

    See the \l{QtMultimedia Module} documentation for more information.

    \section1 New Classes, Functions, Macros, etc.

    Links to new classes, functions, macros, and other items
    introduced in Qt 4.6.

    \sincelist 4.6

*/

/*
    \page qt4-5-intro.html
    \title What's New in Qt 4.5

    Qt 4.5 provides many improvements and enhancements over the previous releases
    in the Qt 4 series. This document covers the most important features in this
    release, separated by category.

    A comprehensive list of changes between Qt 4.4 and Qt 4.5 is included
    in the \c changes-4.5.0 file
    \l{http://qt.nokia.com/developer/changes/changes-4.5.0}{available online}.
    A \l{Known Issues in %VERSION%}{list of known issues} for this release is also
    available.

    Changes between this release and the previous release are provided
    in the \c{changes-%VERSION%} file (also
    \l{http://qt.nokia.com/developer/changes/changes-%VERSION%}{available online}).

    A list of other Qt 4 features can be found on the
    \bold{\l{What's New in Qt 4}} page.

    \section1 Qt WebKit Integration

    \image webkit-netscape-plugin.png

    The WebKit browser engine included with Qt has been upgraded to the latest
    upstream (trunk) version of WebKit, bringing the latest features and
    improvements to Qt applications. These include:

    \list
    \o Support for full page zooming, with appropriate rescaling of images and fonts.
    \o The CSS-based transformation and animation features provided by a WebKit
    extension.
    \o Performance improvements due to faster JavaScript engine and optimized
    page loading.
    \endlist

    Standards compatibility improvements include provision for the Netscape plugin
    API, allowing most Netscape plugins to be used in-process, support for HTML 5
    audio and video elements using Qt's Phonon integration, and
    \l{Web Application Support}{facilities for client-side storage of Web content}.

    \section1 Performance Improvements

    The introduction of the QtBenchLib performance benchmarking library enables
    performance benchmarking and regression testing. Core parts of Qt itself have
    undergone focused re-engineering for improved graphics performance, including
    paint engine and text rendering improvements, Graphics View and style sheet
    performance improvements.

    The X11 paint engine now uses XSHM (the X shared memory extension), resulting
    in reduced overhead for painting operations.

    A new OpenGL ES 2.0-based paint engine complements the existing OpenGL paint
    engine, but with a focus on embedded devices.

    Qt now features a pluggable graphics system, making it possible for users
    and developers to select raster, OpenGL or native graphics systems to take
    into account the specific needs of their applications and get the best
    performance out of them.

    \section1 Mac OS X Cocoa Support

    \image mac-cocoa.png

    Qt for Mac OS X has been substantially rewritten to use Apple's Cocoa API,
    enabling Qt applications to be deployed on 64-bit Macintosh hardware.
    In addition, the new QMacCocoaViewContainer and QMacNativeWidget classes
    provide integration with Cocoa's own features and controls.

    For many applications, a simple recompilation is all that is required
    to produce an executable for 64-bit systems. Applications that use
    specific features may require a few changes first.

    \section1 Windows CE Feature Parity

    Qt for Windows CE has been updated to bring features of Qt 4.4 and Qt 4.5
    to the Windows CE platform, including:

    \list
    \o Phonon Multimedia Framework, using a Direct-Show based backend for audio
    and video playback and a Simple WaveOut backend for devices without DirectShow.
    \o The inclusion of Qt WebKit integration features previously unavailable for
    Qt 4.4 on Windows CE.
    \endlist

    Support on all Windows CE platforms; recommended for WinCE 6 and higher.

    The inclusion of these features enables developers to easily integrate Web and
    multimedia content into Qt applications on Windows CE Standard Edition while
    retaining full cross-platform compatibility with other Qt platforms.

    \section1 XML Transformations with XSLT

    The QtXmlPatterns module has been extended to cover XSLT, a transformation language
    for XML documents. A common application of this is the transformation of XML data
    into human-readable formats for reporting purposes.

    XSLT makes it simple to reformat XML content without changing data structures,
    removes the need for an intermediate DOM layer for presentation, and enables
    rapid solutions to be created; for example, creating reports as HTML or PDF.

    \section1 Qt Script Debugger

    \image qtscript-debugger-small.png

    Developers using Qt Script in their applications can take advantage of
    the new \l{Qt Script Debugger Manual}{Qt Script Debugger} to provide
    error reporting for scripts, and to let users track down bugs in their
    own scripts.

    Many standard features of GUI debugging tools are present, allowing the
    developer to step through running script code, inspect variables,
    automatically catch exceptions, and set conditional breakpoints.

    \section1 OpenDocument File Format Support

    Qt 4.5 includes support for writing rich text documents as OpenDocument files via
    the newly-introduced QTextDocumentWriter class. This provides an generic mechanism
    for file export that can be used to introduce support for additional formats in
    future releases.

    \section1 Improved Network Proxy Support

    Qt's networking classes have been updated with
    \l{QtNetwork Module#Support for Network Proxies}{improved proxy support}.
    This includes improved integration with system proxy settings and the added
    ability to handle non-trivial proxy cases.

    \section1 Qt Designer Improvements

    \image designer-screenshot-small.png

    Qt Designer 4.5 boasts some improvements on usability, for example:

    \list
    \o  \bold{Icon Mode} for the widget box which substantially reduces
        scrolling.
    \o  \bold{Morphing Widgets} which lets you morph similar widget types,
        e.g., a QWidget to a QFrame, types via the context menu's
        \e{Morph into} entry.
    \o  \bold{Filters} for the \gui{Property Editor} that lets you find
        properties or widgets quickly.
    \o  \bold{Find option} for the \gui{Object Inspector} that performs an
        incremental search on the form's widgets. Also, the objects' layout
        state is displayed here with using an icon on the left. Broken
        layouts are represented with the same icon used for the
        \e{Break Layout} action.
    \endlist

    In addition, Qt Designer now features an \gui{Embedded Design} tab that can
    be found in the \gui Preferences dialog. Within this tab, you can define
    embedded device profiles. These profiles contains screen settings, e.g.,
    display resolution, default font and default style. Qt Designer will use
    these settings when you edit forms.

    More information about these improvements can be found in the
    \l{What's New in Qt Designer 4.5} overview.

    \section1 Qt Linguist Improvements

    Qt Linguist can now load and edit multiple translation files simultaneously.

    Support for XML Localization Interchange File Format (XLIFF) files, previously added
    to the \c lupdate tool in Qt 4.3, has been improved and extended to the rest of the
    Qt Linguist toolchain. This enables files stored in Qt's TS translation format to
    be exported for use with other tools.

    The GNU Gettext PO format, which is commonly used in Open Source projects,
    is now supported by Qt Linguist.

    Support for a new way to annotate messages, using comments in the source code,
    has been added to the toolchain. See the QObject::tr() documentation for a detailed
    description and examples.

    The new \c lconvert filter tool facilitates conversion between file formats and
    can be used to perform other transformations on collections of translatable strings.

    \section1 Graphics Enhancements

    In addition to the performance improvements in this release, a number of graphics
    enhancements extend support for existing features to more platforms and expand Qt's
    core set of features with successful add-ons.

    Widget style sheets can now be used on Mac OS X, making this approach to theming
    and styling viable for truly cross-platform applications.

    Support for ARGB top-level widgets, previously available as a separate solution,
    is now provided as an integral part of Qt. This makes it possible to create windows
    with translucent regions on systems with the appropriate support from the user's
    window system. See the \l{QWidget#Creating Translucent Windows}{Creating Translucent
    Windows} section of the QWidget documentation for details of this feature.


    \image gtk-style-screenshot.png

    Improved GTK+ integration provided by the QGtkStyle class improves the look and feel
    of Qt applications in GNOME and other GTK-based environments. The screenshot above
    illustrates this clearly.
*/