QwtSymbol Class Reference

A class for drawing symbols. More...

#include <qwt_symbol.h>

Public Types
enum	Style {   NoSymbol = -1, Ellipse, Rect, Diamond,   Triangle, DTriangle, UTriangle, LTriangle,   RTriangle, Cross, XCross, HLine,   VLine, Star1, Star2, Hexagon,   Path, Pixmap, Graphic, SvgDocument,   UserStyle = 1000 }
enum	CachePolicy { NoCache, Cache, AutoCache }

Public Member Functions
	QwtSymbol (Style=NoSymbol)
	QwtSymbol (Style, const QBrush &, const QPen &, const QSize &)
	Constructor. More...
	QwtSymbol (const QPainterPath &, const QBrush &, const QPen &)
	Constructor. More...
virtual	~QwtSymbol ()
	Destructor.
void	setCachePolicy (CachePolicy)
CachePolicy	cachePolicy () const
void	setSize (const QSize &)
void	setSize (int width, int height=-1)
	Specify the symbol's size. More...
const QSize &	size () const
void	setPinPoint (const QPointF &pos, bool enable=true)
	Set and enable a pin point. More...
QPointF	pinPoint () const
void	setPinPointEnabled (bool)
bool	isPinPointEnabled () const
virtual void	setColor (const QColor &)
	Set the color of the symbol. More...
void	setBrush (const QBrush &)
	Assign a brush. More...
const QBrush &	brush () const
void	setPen (const QColor &, qreal width=0.0, Qt::PenStyle=Qt::SolidLine)
void	setPen (const QPen &)
const QPen &	pen () const
void	setStyle (Style)
Style	style () const
void	setPath (const QPainterPath &)
	Set a painter path as symbol. More...
const QPainterPath &	path () const
void	setPixmap (const QPixmap &)
const QPixmap &	pixmap () const
void	setGraphic (const QwtGraphic &)
const QwtGraphic &	graphic () const
void	setSvgDocument (const QByteArray &)
void	drawSymbol (QPainter *, const QRectF &) const
	Draw the symbol into a rectangle. More...
void	drawSymbol (QPainter *, const QPointF &) const
	Draw the symbol at a specified position. More...
void	drawSymbols (QPainter *, const QPolygonF &) const
	Draw symbols at the specified points. More...
void	drawSymbols (QPainter *, const QPointF *, int numPoints) const
virtual QRect	boundingRect () const
void	invalidateCache ()

Protected Member Functions
virtual void	renderSymbols (QPainter *, const QPointF *, int numPoints) const

Detailed Description

A class for drawing symbols.

Member Enumeration Documentation

CachePolicy

enum QwtSymbol::CachePolicy

Depending on the render engine and the complexity of the symbol shape it might be faster to render the symbol to a pixmap and to paint this pixmap.

F.e. the raster paint engine is a pure software renderer where in cache mode a draw operation usually ends in raster operation with the the backing store, that are usually faster, than the algorithms for rendering polygons. But the opposite can be expected for graphic pipelines that can make use of hardware acceleration.

The default setting is AutoCache

See also

setCachePolicy(), cachePolicy()

Note

The policy has no effect, when the symbol is painted to a vector graphics format ( PDF, SVG ).

Warning

Since Qt 4.8 raster is the default backend on X11

Enumerator
NoCache	Don't use a pixmap cache.
Cache	Always use a pixmap cache.
AutoCache	Use a cache when one of the following conditions is true: The symbol is rendered with the software renderer ( QPaintEngine::Raster )

Style

enum QwtSymbol::Style

Symbol Style

See also

setStyle(), style()

Enumerator
NoSymbol	No Style. The symbol cannot be drawn.
Ellipse	Ellipse or circle.
Rect	Rectangle.
Diamond	Diamond.
Triangle	Triangle pointing upwards.
DTriangle	Triangle pointing downwards.
UTriangle	Triangle pointing upwards.
LTriangle	Triangle pointing left.
RTriangle	Triangle pointing right.
Cross	Cross (+)
XCross	Diagonal cross (X)
HLine	Horizontal line.
VLine	Vertical line.
Star1	X combined with +.
Star2	Six-pointed star.
Hexagon	Hexagon.
Path	The symbol is represented by a painter path, where the origin ( 0, 0 ) of the path coordinate system is mapped to the position of the symbol. See also setPath(), path()
Pixmap	The symbol is represented by a pixmap. The pixmap is centered or aligned to its pin point. See also setPinPoint()
Graphic	The symbol is represented by a graphic. The graphic is centered or aligned to its pin point. See also setPinPoint()
SvgDocument	The symbol is represented by a SVG graphic. The graphic is centered or aligned to its pin point. See also setPinPoint()
UserStyle	Styles >= QwtSymbol::UserSymbol are reserved for derived classes of QwtSymbol that overload drawSymbols() with additional application specific symbol types.

Constructor & Destructor Documentation

QwtSymbol() [1/3]

QwtSymbol::QwtSymbol

(

Style

style = NoSymbol

)

Default Constructor

Parameters

style

Symbol Style

The symbol is constructed with gray interior, black outline with zero width, no size and style 'NoSymbol'.

QwtSymbol() [2/3]

QwtSymbol::QwtSymbol	(	QwtSymbol::Style	style,
		const QBrush &	brush,
		const QPen &	pen,
		const QSize &	size
	)

Constructor.

Parameters

style	Symbol Style
brush	brush to fill the interior
pen	outline pen
size	size

See also

setStyle(), setBrush(), setPen(), setSize()

QwtSymbol() [3/3]

QwtSymbol::QwtSymbol	(	const QPainterPath &	path,
		const QBrush &	brush,
		const QPen &	pen
	)

Constructor.

The symbol gets initialized by a painter path. The style is set to QwtSymbol::Path, the size is set to empty ( the path is displayed unscaled ).

Parameters

path	painter path
brush	brush to fill the interior
pen	outline pen

See also

setPath(), setBrush(), setPen(), setSize()

Member Function Documentation

boundingRect()

QRect QwtSymbol::boundingRect ( ) const

virtual

Calculate the bounding rectangle for a symbol at position (0,0).

Returns

Bounding rectangle

brush()

const QBrush & QwtSymbol::brush

(

)

const

Returns

Brush

See also

setBrush()

cachePolicy()

QwtSymbol::CachePolicy QwtSymbol::cachePolicy

(

)

const

Returns

Cache policy

See also

CachePolicy, setCachePolicy()

drawSymbol() [1/2]

void QwtSymbol::drawSymbol ( QPainter *  painter, const QPointF &  pos  ) const

inline

Draw the symbol at a specified position.

Parameters

painter	Painter
pos	Position of the symbol in screen coordinates

drawSymbol() [2/2]

void QwtSymbol::drawSymbol	(	QPainter *	painter,
		const QRectF &	rect
	)		const

Draw the symbol into a rectangle.

The symbol is painted centered and scaled into the target rectangle. It is always painted uncached and the pin point is ignored.

This method is primarily intended for drawing a symbol to the legend.

Parameters

painter	Painter
rect	Target rectangle for the symbol

drawSymbols() [1/2]

void QwtSymbol::drawSymbols	(	QPainter *	painter,
		const QPointF *	points,
		int	numPoints
	)		const

Render an array of symbols

Painting several symbols is more effective than drawing symbols one by one, as a couple of layout calculations and setting of pen/brush can be done once for the complete array.

Parameters

painter	Painter
points	Array of points
numPoints	Number of points

drawSymbols() [2/2]

void QwtSymbol::drawSymbols ( QPainter *  painter, const QPolygonF &  points  ) const

inline

Draw symbols at the specified points.

Parameters

painter	Painter
points	Positions of the symbols in screen coordinates

graphic()

const QwtGraphic & QwtSymbol::graphic

(

)

const

Returns

Assigned graphic

See also

setGraphic()

invalidateCache()

void QwtSymbol::invalidateCache

(

)

Invalidate the cached symbol pixmap

The symbol invalidates its cache, whenever an attribute is changed that has an effect ob how to display a symbol. In case of derived classes with individual styles ( >= QwtSymbol::UserStyle ) it might be necessary to call invalidateCache() for attributes that are relevant for this style.

See also

CachePolicy, setCachePolicy(), drawSymbols()

isPinPointEnabled()

bool QwtSymbol::isPinPointEnabled

(

)

const

Returns

True, when the pin point translation is enabled

See also

setPinPoint(), setPinPointEnabled()

path()

const QPainterPath & QwtSymbol::path

(

)

const

Returns

Painter path for displaying the symbol

See also

setPath()

pen()

const QPen & QwtSymbol::pen

(

)

const

Returns

Pen

See also

setPen(), brush()

pinPoint()

QPointF QwtSymbol::pinPoint

(

)

const

Returns

Pin point

See also

setPinPoint(), setPinPointEnabled()

pixmap()

const QPixmap & QwtSymbol::pixmap

(

)

const

Returns

Assigned pixmap

See also

setPixmap()

renderSymbols()

void QwtSymbol::renderSymbols ( QPainter *  painter, const QPointF *  points, int  numPoints  ) const

protectedvirtual

Render the symbol to series of points

Parameters

painter	Qt painter
points	Positions of the symbols
numPoints	Number of points

setBrush()

void QwtSymbol::setBrush

(

const QBrush &

brush

)

Assign a brush.

The brush is used to draw the interior of the symbol.

Parameters

brush

Brush

See also

brush()

setCachePolicy()

void QwtSymbol::setCachePolicy

(

QwtSymbol::CachePolicy

policy

)

Change the cache policy

The default policy is AutoCache

Parameters

policy

Cache policy

See also

CachePolicy, cachePolicy()

setColor()

void QwtSymbol::setColor ( const QColor &  color )

virtual

Set the color of the symbol.

Change the color of the brush for symbol types with a filled area. For all other symbol types the color will be assigned to the pen.

Parameters

color

Color

See also

setBrush(), setPen(), brush(), pen()

setGraphic()

void QwtSymbol::setGraphic

(

const QwtGraphic &

graphic

)

Set a graphic as symbol

Parameters

graphic

Graphic

See also

graphic(), setPixmap()

Note

the style() is set to QwtSymbol::Graphic

brush() and pen() have no effect

setPath()

void QwtSymbol::setPath

(

const QPainterPath &

path

)

Set a painter path as symbol.

The symbol is represented by a painter path, where the origin ( 0, 0 ) of the path coordinate system is mapped to the position of the symbol.

When the symbol has valid size the painter path gets scaled to fit into the size. Otherwise the symbol size depends on the bounding rectangle of the path.

Example

The following code defines a symbol drawing an arrow:

#include <qwt_symbol.h>
 
QwtSymbol *symbol = new QwtSymbol();
 
QPen pen( Qt::black, 2 );
pen.setJoinStyle( Qt::MiterJoin );
 
symbol->setPen( pen );
symbol->setBrush( Qt::red );
 
QPainterPath path;
path.moveTo( 0, 8 );
path.lineTo( 0, 5 );
path.lineTo( -3, 5 );
path.lineTo( 0, 0 );
path.lineTo( 3, 5 );
path.lineTo( 0, 5 );
 
QTransform transform;
transform.rotate( -30.0 );
path = transform.map( path );
 
symbol->setPath( path );
symbol->setPinPoint( QPointF( 0.0, 0.0 ) );
 
setSize( 10, 14 );

\endpar

Parameters

path	Painter path

Note

The style is implicitely set to QwtSymbol::Path.

See also

path(), setSize()

setPen() [1/2]

void QwtSymbol::setPen	(	const QColor &	color,
		qreal	width = 0.0,
		Qt::PenStyle	style = Qt::SolidLine
	)

Build and assign a pen

In Qt5 the default pen width is 1.0 ( 0.0 in Qt4 ) what makes it non cosmetic ( see QPen::isCosmetic() ). This method has been introduced to hide this incompatibility.

Parameters

color	Pen color
width	Pen width
style	Pen style

See also

pen(), brush()

setPen() [2/2]

void QwtSymbol::setPen

(

const QPen &

pen

)

Assign a pen

The pen is used to draw the symbol's outline.

Parameters

pen

Pen

See also

pen(), setBrush()

setPinPoint()

void QwtSymbol::setPinPoint	(	const QPointF &	pos,
		bool	enable = true
	)

Set and enable a pin point.

The position of a complex symbol is not always aligned to its center ( f.e an arrow, where the peak points to a position ). The pin point defines the position inside of a Pixmap, Graphic, SvgDocument or PainterPath symbol where the represented point has to be aligned to.

Parameters

pos	Position
enable	En/Disable the pin point alignment

See also

pinPoint(), setPinPointEnabled()

setPinPointEnabled()

void QwtSymbol::setPinPointEnabled

(

bool

on

)

En/Disable the pin point alignment

Parameters

on	Enabled, when on is true

See also

setPinPoint(), isPinPointEnabled()

setPixmap()

void QwtSymbol::setPixmap

(

const QPixmap &

pixmap

)

Set a pixmap as symbol

Parameters

pixmap

Pixmap

See also

pixmap(), setGraphic()

Note

the style() is set to QwtSymbol::Pixmap

brush() and pen() have no effect

setSize() [1/2]

void QwtSymbol::setSize

(

const QSize &

size

)

Set the symbol's size

Parameters

size

Size

See also

size()

setSize() [2/2]

void QwtSymbol::setSize	(	int	width,
		int	height = -1
	)

Specify the symbol's size.

If the 'h' parameter is left out or less than 0, and the 'w' parameter is greater than or equal to 0, the symbol size will be set to (w,w).

Parameters

width	Width
height	Height (defaults to -1)

See also

size()

setStyle()

void QwtSymbol::setStyle

(

QwtSymbol::Style

style

)

Specify the symbol style

Parameters

style

Style

See also

style()

setSvgDocument()

void QwtSymbol::setSvgDocument

(

const QByteArray &

svgDocument

)

Set a SVG icon as symbol

Parameters

svgDocument

SVG icon

See also

setGraphic(), setPixmap()

Note

the style() is set to QwtSymbol::SvgDocument

brush() and pen() have no effect

size()

const QSize & QwtSymbol::size

(

)

const

Returns

Size

See also

setSize()

style()

QwtSymbol::Style QwtSymbol::style

(

)

const

Returns

Current symbol style

See also

setStyle()