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).

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

Class VideoWidget:

QImage snapshot() const

Class QWebFrame:

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

Class QTextCodec:

QTextDecoder * makeDecoder(ConversionFlags flags) const
QTextEncoder * makeEncoder(ConversionFlags flags) const

Class QProcess:

QString nativeArguments() const
void setNativeArguments(const QString & arguments)

Class QVariant:

QEasingCurve toEasingCurve() const

Class QState:

QList<QAbstractTransition *> transitions() const

Class QByteArray:

QByteArray & replace(int pos, int len, const char * after, int alen)
QByteArray & setRawData(const char * data, uint size)

Class QChar:

bool isHighSurrogate(uint ucs4)
bool isLowSurrogate(uint ucs4)
bool requiresSurrogates(uint ucs4)

Class QDateTime:

QDateTime currentDateTimeUtc()
qint64 currentMSecsSinceEpoch()
QDateTime fromMSecsSinceEpoch(qint64 msecs)
qint64 msecsTo(const QDateTime & other) const
void setMSecsSinceEpoch(qint64 msecs)
qint64 toMSecsSinceEpoch() const

Class QList:

void reserve(int alloc)

Class QLocale:

Qt::LayoutDirection textDirection() const

Class QString:

QString & setRawData(const QChar * unicode, int size)

Class QDBusMessage:

bool autoStartService() const
void setAutoStartService(bool enable)

Class QFileSystemModel:

void directoryLoaded(const QString & path)

Class QWizard:

void pageAdded(int id)
void pageRemoved(int id)
void setSideWidget(QWidget * widget)
QWidget * sideWidget() const

Class QGraphicsItem:

Class QGraphicsObject:

Class QGraphicsScale:

Class QIcon:

QString name() const

Class QIconEngineV2:

QString iconName()

Class QImage:

int bitPlaneCount() const
const uchar * constBits() const
const uchar * constScanLine(int i) const

Class QPixmap:

bool convertFromImage(const QImage & image, Qt::ImageConversionFlags flags = Qt::AutoColor)

Class QItemSelectionRange:

bool isEmpty() const

Class QColor:

bool isValidColor(const QString & name)

Class QPainter:

void drawPixmapFragments(const PixmapFragment * fragments, int fragmentCount, const QPixmap & pixmap, PixmapFragmentHints hints = 0)
void drawStaticText(const QPointF & topLeftPosition, const QStaticText & staticText)
void drawStaticText(const QPoint & topLeftPosition, const QStaticText & staticText)
void drawStaticText(int left, int top, const QStaticText & staticText)

Class PixmapFragment:

PixmapFragment create(const QPointF & pos, const QRectF & sourceRect, qreal scaleX = 1, qreal scaleY = 1, qreal rotation = 0, qreal opacity = 1)

Class QPrinter:

int copyCount() const
void setCopyCount(int count)
bool supportsMultipleCopies() const

Class QTextDocument:

void clearUndoRedoStacks(Stacks stacksToClear = UndoAndRedoStacks)

Class QTextCursor:

bool keepPositionOnInsert() const
int positionInBlock() const
void setKeepPositionOnInsert(bool b)
void setVerticalMovementX(int x)
int verticalMovementX() const

Class QTextLine:

qreal horizontalAdvance() const

Class QTextBlock:

Qt::LayoutDirection textDirection() const

Class QLabel:

int selectionStart() const
void setSelection(int start, int length)

Class QPlainTextEdit:

QString anchorAt(const QPoint & pos) const

Class QToolBar:

void visibilityChanged(bool visible)

Class QAudioDeviceInfo:

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

Class QAudioFormat:

int channelCount() const
int sampleRate() const
void setChannelCount(int channels)
void setSampleRate(int samplerate)

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 QNetworkRequest:

Priority priority() const
void setPriority(Priority priority)

Class QAuthenticator:

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

Class QTcpServer:

void addPendingConnection(QTcpSocket * socket)

Class QGLFormat:

int majorVersion() const
int minorVersion() const
OpenGLContextProfile profile() const
void setProfile(OpenGLContextProfile profile)
void setVersion(int major, int minor)

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 QScriptEngine:

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

New Functions in Namespaces

const char * benchmarkMetricName(QBenchmarkMetric metric)
const char * benchmarkMetricUnit(QBenchmarkMetric metric)
void setBenchmarkResult(qreal result, QBenchmarkMetric metric)

New Global Functions

uint qHash(const QUrl & url)

New Enum Types

enum OpenGLContextProfile { NoProfile, CoreProfile, CompatibilityProfile }
enum Operation { HeadOperation, GetOperation, PutOperation, PostOperation, DeleteOperation, CustomOperation }
enum Attribute { HttpStatusCodeAttribute, HttpReasonPhraseAttribute, RedirectionTargetAttribute, ConnectionEncryptedAttribute, ..., UserMax }
enum LoadControl { Automatic, Manual }
enum Priority { HighPriority, NormalPriority, LowPriority }
enum PixmapFragmentHint { OpaqueHint }
enum QBenchmarkMetric { FramesPerSecond, BitsPerSecond, BytesPerSecond, WalltimeMilliseconds, ..., Events }

New Typedefs

typedef VideoWidgetInterfaceLatest
typedef const_iterator
typedef const_pointer
typedef const_reference
typedef difference_type
typedef iterator
typedef pointer
typedef reference
typedef size_type
typedef value_type

New Properties

New QML Types

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