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 What's New in Qt 4 page.

Declarative UI Development with Qt Quick

Qt 4.7 introduces 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:

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.
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++.
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

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.

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 this blog.

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

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).

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 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 pixmap fragments.

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

New Classes, Functions, Macros, etc.

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

New Classes
New Member Functions
New Global Functions
New QML Elements

New Classes

New Member Functions

Class QFileSystemModel:

void	directoryLoaded ( const QString & path )

Class QDBusMessage:

bool	autoStartService () const
void	setAutoStartService ( bool enable )

Class QScriptEngine:

QScriptValue	evaluate ( const QScriptProgram & program )
void	reportAdditionalMemoryCost ( int size )

Class VideoWidget:

QImage snapshot () const

Class QGraphicsItem:

void	updateMicroFocus ()

Class QState:

QList<QAbstractTransition *> transitions () const

Class QGraphicsObject:

void	updateMicroFocus ()

Class QIconEngineV2:

QString iconName ()

Class QNetworkAccessManager:

QNetworkConfiguration	activeConfiguration () const
QNetworkConfiguration	configuration () const
NetworkAccessibility	networkAccessible () const
QNetworkReply *	sendCustomRequest ( const QNetworkRequest & request, const QByteArray & verb, QIODevice * data = 0 )
void	setConfiguration ( const QNetworkConfiguration & config )
void	setNetworkAccessible ( NetworkAccessibility accessible )

Class QPlainTextEdit:

QString anchorAt ( const QPoint & pos ) const

Class QGLShader:

bool	hasOpenGLShaders ( ShaderType type, const QGLContext * context = 0 )

Class QGLShaderProgram:

GLenum	geometryInputType () const
GLenum	geometryOutputType () const
int	geometryOutputVertexCount () const
int	maxGeometryOutputVertices () const
void	setAttributeArray ( int location, GLenum type, const void * values, int tupleSize, int stride = 0 )
void	setAttributeArray ( const char * name, GLenum type, const void * values, int tupleSize, int stride = 0 )
void	setAttributeBuffer ( int location, GLenum type, int offset, int tupleSize, int stride = 0 )
void	setAttributeBuffer ( const char * name, GLenum type, int offset, int tupleSize, int stride = 0 )
void	setGeometryOutputType ( GLenum outputType )
void	setGeometryOutputVertexCount ( int count )
void	setUniformValue ( int location, const GLfloat[2][2] value )
void	setUniformValue ( int location, const GLfloat[3][3] value )
void	setUniformValue ( const char * name, const GLfloat[2][2] value )
void	setUniformValue ( const char * name, const GLfloat[3][3] value )

Class QGraphicsScale:

void	xScaleChanged ()
void	yScaleChanged ()
void	zScaleChanged ()

Class QAudioDeviceInfo:

QList<int>	supportedChannelCounts () const
QList<int>	supportedSampleRates () const

Class QNetworkRequest:

Priority	priority () const
void	setPriority ( Priority priority )

Class QWebFrame:

void	pageChanged ()
void	scrollToAnchor ( const QString & anchor )

Class QAuthenticator:

QVariant	option ( const QString & opt ) const
QVariantHash	options () const
void	setOption ( const QString & opt, const QVariant & value )