QAbstractFontEngine Class Reference

The QAbstractFontEngine class is the base class for font engine plugins in Qt for Embedded Linux. More...

#include <qabstractfontengine_qws.h>

Inheritance diagram for QAbstractFontEngine:

Classes
class	FixedPoint
	QAbstractFontEngine::FixedPoint defines a point in the place using 26.6 fixed point precision. More...
class	GlyphMetrics
	QAbstractFontEngine::GlyphMetrics defines the metrics of a single glyph. More...

Public Types
enum	Capability { CanOutlineGlyphs = 1, CanRenderGlyphs_Mono = 2, CanRenderGlyphs_Gray = 4, CanRenderGlyphs = CanRenderGlyphs_Mono | CanRenderGlyphs_Gray }
	This enum describes the capabilities of a font engine. More...
typedef int	Fixed
	This type is int, interpreted as a 26. More...
enum	FontProperty {   Ascent, Descent, Leading, XHeight,   AverageCharWidth, LineThickness, UnderlinePosition, MaxCharWidth,   MinLeftBearing, MinRightBearing, GlyphCount, CacheGlyphsHint,   OutlineGlyphsHint }
	This enum describes the properties of a font provided by a font engine. More...
enum	TextShapingFlag { RightToLeft = 0x0001, ReturnDesignMetrics = 0x0002 }
	This enum describes flags controlling conversion of characters to glyphs and their metrics. More...

Public Functions
virtual void	addGlyphOutlinesToPath (uint *glyphs, int numGlyphs, FixedPoint *positions, QPainterPath *path)
	Implemented in subclasses to add the outline of the glyphs specified by glyphs and numGlyphs at the specified positions to the painter path path. More...
virtual Capabilities	capabilities () const =0
	Implemented in subclasses to specify the font engine's capabilities. More...
virtual bool	convertStringToGlyphIndices (const QChar *string, int length, uint *glyphs, int *numGlyphs, TextShapingFlags flags) const =0
	Implemented in subclasses to convert the characters specified by string and length to glyph indicies, using flags. More...
virtual QVariant	fontProperty (FontProperty property) const =0
	Implemented in subclasses to return the value of the font attribute property. More...
virtual void	getGlyphAdvances (const uint *glyphs, int numGlyphs, Fixed *advances, TextShapingFlags flags) const =0
	Implemented in subclasses to retrieve the advances of the array specified by glyphs and numGlyphs, using flags. More...
virtual GlyphMetrics	glyphMetrics (uint glyph) const =0
	Implemented in subclass to return the metrics for glyph. More...
	QAbstractFontEngine (QObject *parent=0)
	Constructs a new QAbstractFontEngine with the given parent. More...
virtual bool	renderGlyph (uint glyph, int depth, int bytesPerLine, int height, uchar *buffer)
	Implemented in subclasses to render the specified glyph into a buffer with the given depth , bytesPerLine and height. More...
	~QAbstractFontEngine ()
	Destroys this QAbstractFontEngine object. More...
Public Functions inherited from QObject
bool	blockSignals (bool b)
	If block is true, signals emitted by this object are blocked (i.e., emitting a signal will not invoke anything connected to it). More...
const QObjectList &	children () const
	Returns a list of child objects. More...
bool	connect (const QObject *sender, const char *signal, const char *member, Qt::ConnectionType type=Qt::AutoConnection) const
bool	disconnect (const char *signal=0, const QObject *receiver=0, const char *member=0)
bool	disconnect (const QObject *receiver, const char *member=0)
void	dumpObjectInfo ()
	Dumps information about signal connections, etc. More...
void	dumpObjectTree ()
	Dumps a tree of children to the debug output. More...
QList< QByteArray >	dynamicPropertyNames () const
	Returns the names of all properties that were dynamically added to the object using setProperty(). More...
virtual bool	event (QEvent *)
	This virtual function receives events to an object and should return true if the event e was recognized and processed. More...
virtual bool	eventFilter (QObject *, QEvent *)
	Filters events if this object has been installed as an event filter for the watched object. More...
template<typename T >
T	findChild (const QString &aName=QString()) const
	Returns the child of this object that can be cast into type T and that is called name, or 0 if there is no such object. More...
template<typename T >
QList< T >	findChildren (const QString &aName=QString()) const
	Returns all children of this object with the given name that can be cast to type T, or an empty list if there are no such objects. More...
template<typename T >
QList< T >	findChildren (const QRegExp &re) const
bool	inherits (const char *classname) const
	Returns true if this object is an instance of a class that inherits className or a QObject subclass that inherits className; otherwise returns false. More...
void	installEventFilter (QObject *)
	Installs an event filter filterObj on this object. More...
bool	isWidgetType () const
	Returns true if the object is a widget; otherwise returns false. More...
void	killTimer (int id)
	Kills the timer with timer identifier, id. More...
virtual const QMetaObject *	metaObject () const
	Returns a pointer to the meta-object of this object. More...
void	moveToThread (QThread *thread)
	Changes the thread affinity for this object and its children. More...
QString	objectName () const
QObject *	parent () const
	Returns a pointer to the parent object. More...
QVariant	property (const char *name) const
	Returns the value of the object's name property. More...
Q_INVOKABLE	QObject (QObject *parent=0)
	Constructs an object with parent object parent. More...
void	removeEventFilter (QObject *)
	Removes an event filter object obj from this object. More...
void	setObjectName (const QString &name)
void	setParent (QObject *)
	Makes the object a child of parent. More...
bool	setProperty (const char *name, const QVariant &value)
	Sets the value of the object's name property to value. More...
void	setUserData (uint id, QObjectUserData *data)
bool	signalsBlocked () const
	Returns true if signals are blocked; otherwise returns false. More...
int	startTimer (int interval)
	Starts a timer and returns a timer identifier, or returns zero if it could not start a timer. More...
QThread *	thread () const
	Returns the thread in which the object lives. More...
QObjectUserData *	userData (uint id) const
virtual	~QObject ()
	Destroys the object, deleting all its child objects. More...

Additional Inherited Members
Public Slots inherited from QObject
void	deleteLater ()
	Schedules this object for deletion. More...
Signals inherited from QObject
void	destroyed (QObject *=0)
	This signal is emitted immediately before the object obj is destroyed, and can not be blocked. More...
Static Public Functions inherited from QObject
static bool	connect (const QObject *sender, const char *signal, const QObject *receiver, const char *member, Qt::ConnectionType=Qt::AutoConnection)
	Creates a connection of the given type from the signal in the sender object to the method in the receiver object. More...
static bool	connect (const QObject *sender, const QMetaMethod &signal, const QObject *receiver, const QMetaMethod &method, Qt::ConnectionType type=Qt::AutoConnection)
static bool	disconnect (const QObject *sender, const char *signal, const QObject *receiver, const char *member)
	Disconnects signal in object sender from method in object receiver. More...
static bool	disconnect (const QObject *sender, const QMetaMethod &signal, const QObject *receiver, const QMetaMethod &member)
static uint	registerUserData ()
static QString	tr (const char *sourceText, const char *comment=0, int n=-1)
static QString	trUtf8 (const char *sourceText, const char *comment=0, int n=-1)
Static Public Variables inherited from QObject
static const QMetaObject	staticMetaObject
	This variable stores the meta-object for the class. More...
Protected Functions inherited from QObject
virtual void	childEvent (QChildEvent *)
	This event handler can be reimplemented in a subclass to receive child events. More...
virtual void	connectNotify (const char *signal)
	This virtual function is called when something has been connected to signal in this object. More...
virtual void	customEvent (QEvent *)
	This event handler can be reimplemented in a subclass to receive custom events. More...
virtual void	disconnectNotify (const char *signal)
	This virtual function is called when something has been disconnected from signal in this object. More...
	QObject (QObjectPrivate &dd, QObject *parent=0)
int	receivers (const char *signal) const
	Returns the number of receivers connected to the signal. More...
QObject *	sender () const
	Returns a pointer to the object that sent the signal, if called in a slot activated by a signal; otherwise it returns 0. More...
int	senderSignalIndex () const
virtual void	timerEvent (QTimerEvent *)
	This event handler can be reimplemented in a subclass to receive timer events for the object. More...
Protected Variables inherited from QObject
QScopedPointer< QObjectData >	d_ptr
Static Protected Variables inherited from QObject
static const QMetaObject	staticQtMetaObject
Related Functions inherited from QObject
T	qFindChildqFindChildren (const QObject *obj, const QString &name)()
QList< T >	qFindChildrenqFindChildren (const QObject *obj, const QString &name)()
QList< T >	qFindChildrenqFindChildren (const QObject *obj, const QRegExp &regExp)()
T *	qobject_cast (QObject *object)
	QObjectList
void *	qt_find_obj_child (QObject *parent, const char *type, const QString &name)
	Returns a pointer to the object named name that inherits type and with a given parent. More...

Detailed Description

The QAbstractFontEngine class is the base class for font engine plugins in Qt for Embedded Linux.

This function is under development and subject to change.

Since

4.3

QAbstractFontEngine is implemented by font engine plugins through QFontEnginePlugin.

See also

QFontEnginePlugin, QFontEngineInfo

Definition at line 127 of file qabstractfontengine_qws.h.

Typedefs

Fixed

QAbstractFontEngine::Fixed

This type is int, interpreted as a 26.

6 fixed point value.

Definition at line 142 of file qabstractfontengine_qws.h.

Enumerations

Capability

enum QAbstractFontEngine::Capability

This enum describes the capabilities of a font engine.

• CanRenderGlyphs_Gray The font engine can render individual glyphs into 8 bpp images.
• CanRenderGlyphs_Mono The font engine can render individual glyphs into 1 bpp images.
• CanRenderGlyphs The font engine can render individual glyphs into images.
• CanOutlineGlyphs The font engine can convert glyphs to painter paths.

Enumerator
CanOutlineGlyphs
CanRenderGlyphs_Mono
CanRenderGlyphs_Gray
CanRenderGlyphs

Definition at line 131 of file qabstractfontengine_qws.h.

                    {
        CanOutlineGlyphs = 1,
        CanRenderGlyphs_Mono = 2,
        CanRenderGlyphs_Gray = 4,
        CanRenderGlyphs = CanRenderGlyphs_Mono | CanRenderGlyphs_Gray
    };

FontProperty

enum QAbstractFontEngine::FontProperty

This enum describes the properties of a font provided by a font engine.

• Ascent The ascent of the font, specified as a 26.6 fixed point value.
• Descent The descent of the font, specified as a 26.6 fixed point value.
• Leading The leading of the font, specified as a 26.6 fixed point value.
• XHeight The 'x' height of the font, specified as a 26.6 fixed point value.
• AverageCharWidth The average character width of the font, specified as a 26.6 fixed point value.
• LineThickness The thickness of the underline and strikeout lines for the font, specified as a 26.6 fixed point value.
• UnderlinePosition The distance from the base line to the underline position for the font, specified as a 26.6 fixed point value.
• MaxCharWidth The width of the widest character in the font, specified as a 26.6 fixed point value.
• MinLeftBearing The minimum left bearing of the font, specified as a 26.6 fixed point value.
• MinRightBearing The maximum right bearing of the font, specified as a 26.6 fixed point value.
• GlyphCount The number of glyphs in the font, specified as an integer value.
• CacheGlyphsHint A boolean value specifying whether rendered glyphs should be cached by Qt.
• OutlineGlyphsHint A boolean value specifying whether the font engine prefers outline drawing over image rendering for uncached glyphs.

Enumerator
Ascent
Descent
Leading
XHeight
AverageCharWidth
LineThickness
UnderlinePosition
MaxCharWidth
MinLeftBearing
MinRightBearing
GlyphCount
CacheGlyphsHint
OutlineGlyphsHint

Definition at line 162 of file qabstractfontengine_qws.h.

                      {
        Ascent,
        Descent,
        Leading,
        XHeight,
        AverageCharWidth,
        LineThickness,
        UnderlinePosition,
        MaxCharWidth,
        MinLeftBearing,
        MinRightBearing,
        GlyphCount,

        // hints
        CacheGlyphsHint,
        OutlineGlyphsHint
    };

TextShapingFlag

enum QAbstractFontEngine::TextShapingFlag

This enum describes flags controlling conversion of characters to glyphs and their metrics.

• RightToLeft The text is used in a right-to-left context.
• ReturnDesignMetrics Return font design metrics instead of pixel metrics.

Enumerator
RightToLeft
ReturnDesignMetrics

Definition at line 181 of file qabstractfontengine_qws.h.

                         {
        RightToLeft         = 0x0001,
        ReturnDesignMetrics = 0x0002
    };

Constructors and Destructors

QAbstractFontEngine()

QAbstractFontEngine::QAbstractFontEngine ( QObject *  parent = 0 )

explicit

Constructs a new QAbstractFontEngine with the given parent.

Definition at line 471 of file qabstractfontengine_qws.cpp.

    : QObject(*new QAbstractFontEnginePrivate, parent)
{
}

~QAbstractFontEngine()

QAbstractFontEngine::~QAbstractFontEngine

(

)

Destroys this QAbstractFontEngine object.

Definition at line 479 of file qabstractfontengine_qws.cpp.

{
}

Functions

addGlyphOutlinesToPath()

void QAbstractFontEngine::addGlyphOutlinesToPath ( uint *  glyphs, int  numGlyphs, FixedPoint *  positions, QPainterPath *  path  )

virtual

Implemented in subclasses to add the outline of the glyphs specified by glyphs and numGlyphs at the specified positions to the painter path path.

Definition at line 555 of file qabstractfontengine_qws.cpp.

Referenced by QProxyFontEngine::addGlyphsToPath().

{
    Q_UNUSED(glyphs)
    Q_UNUSED(numGlyphs)
    Q_UNUSED(positions)
    Q_UNUSED(path)
    qWarning("QAbstractFontEngine: addGlyphOutlinesToPath is not implemented in font plugin!");
}

capabilities()

QAbstractFontEngine::Capabilities QAbstractFontEngine::capabilities ( ) const

pure virtual

Implemented in subclasses to specify the font engine's capabilities.

The return value may be cached by the caller and is expected not to change during the lifetime of the font engine.

Referenced by QProxyFontEngine::QProxyFontEngine().

convertStringToGlyphIndices()

bool QAbstractFontEngine::convertStringToGlyphIndices ( const QChar *  string, int  length, uint *  glyphs, int *  numGlyphs, TextShapingFlags  flags  ) const

pure virtual

Implemented in subclasses to convert the characters specified by string and length to glyph indicies, using flags.

The glyph indicies should be returned in the glyphs array provided by the caller. The maximum size of glyphs is specified by the value pointed to by numGlyphs. If successful, the subclass implementation sets the value pointed to by numGlyphs to the actual number of glyph indices generated, and returns true. Otherwise, e.g. if there is not enough space in the provided glyphs array, it should set numGlyphs to the number of glyphs needed for the conversion and return false.

Referenced by QProxyFontEngine::canRender(), and QProxyFontEngine::stringToCMap().

fontProperty()

QVariant QAbstractFontEngine::fontProperty ( FontProperty  property ) const

pure virtual

Implemented in subclasses to return the value of the font attribute property.

The return value may be cached by the caller and is expected not to change during the lifetime of the font engine.

Referenced by QProxyFontEngine::ascent(), QProxyFontEngine::averageCharWidth(), QProxyFontEngine::descent(), QProxyFontEngine::drawAsOutline(), QProxyFontEngine::glyphCount(), QProxyFontEngine::leading(), QProxyFontEngine::lineThickness(), loadSingleEngine(), QProxyFontEngine::maxCharWidth(), QProxyFontEngine::minLeftBearing(), QProxyFontEngine::minRightBearing(), QProxyFontEngine::underlinePosition(), and QProxyFontEngine::xHeight().

getGlyphAdvances()

void QAbstractFontEngine::getGlyphAdvances ( const uint *  glyphs, int  numGlyphs, Fixed *  advances, TextShapingFlags  flags  ) const

pure virtual

Implemented in subclasses to retrieve the advances of the array specified by glyphs and numGlyphs, using flags.

The result is returned in advances, which is allocated by the caller and contains numGlyphs elements.

Referenced by QProxyFontEngine::recalcAdvances().

glyphMetrics()

QAbstractFontEngine::GlyphMetrics QAbstractFontEngine::glyphMetrics ( uint  glyph ) const

pure virtual

Implemented in subclass to return the metrics for glyph.

Referenced by QProxyFontEngine::alphaMapForGlyph(), QProxyFontEngine::boundingBox(), and QProxyFontEngine::canRender().

renderGlyph()

bool QAbstractFontEngine::renderGlyph ( uint  glyph, int  depth, int  bytesPerLine, int  height, uchar *  buffer  )

virtual

Implemented in subclasses to render the specified glyph into a buffer with the given depth , bytesPerLine and height.

Returns true if rendering succeeded, false otherwise.

Definition at line 540 of file qabstractfontengine_qws.cpp.

Referenced by QProxyFontEngine::alphaMapForGlyph().

{
    Q_UNUSED(glyph)
    Q_UNUSED(depth)
    Q_UNUSED(bytesPerLine)
    Q_UNUSED(height)
    Q_UNUSED(buffer)
    qWarning("QAbstractFontEngine: renderGlyph is not implemented in font plugin!");
    return false;
}

---

The documentation for this class was generated from the following files:

• /src/gui/text/qabstractfontengine_qws.h
• /src/gui/text/qabstractfontengine_qws.cpp