QwtSymbol - Man Page

A class for drawing symbols.

Synopsis

#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.
QwtSymbol (const QPainterPath &, const QBrush &, const QPen &)
Constructor.
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.
const QSize & size () const
void setPinPoint (const QPointF &pos, bool enable=true)
Set and enable a pin point.
QPointF pinPoint () const
void setPinPointEnabled (bool)
bool isPinPointEnabled () const
virtual void setColor (const QColor &)
Set the color of the symbol.
void setBrush (const QBrush &)
Assign a brush.
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.
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.
void drawSymbol (QPainter *, const QPointF &) const
Draw the symbol at a specified position.
void drawSymbols (QPainter *, const QPolygonF &) const
Draw symbols at the specified points.
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

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 )

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::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::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::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

QRect QwtSymbol::boundingRect () const [virtual]

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

Returns

Bounding rectangle

const QBrush & QwtSymbol::brush () const

Returns

Brush

See also

setBrush()

QwtSymbol::CachePolicy QwtSymbol::cachePolicy () const

Returns

Cache policy

See also

CachePolicy, setCachePolicy()

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

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

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

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

const QwtGraphic & QwtSymbol::graphic () const

Returns

Assigned graphic

See also

setGraphic()

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()

bool QwtSymbol::isPinPointEnabled () const

Returns

True, when the pin point translation is enabled

See also

setPinPoint(), setPinPointEnabled()

const QPainterPath & QwtSymbol::path () const

Returns

Painter path for displaying the symbol

See also

setPath()

const QPen & QwtSymbol::pen () const

Returns

Pen

See also

setPen(), brush()

QPointF QwtSymbol::pinPoint () const

Returns

Pin point

See also

setPinPoint(), setPinPointEnabled()

const QPixmap & QwtSymbol::pixmap () const

Returns

Assigned pixmap

See also

setPixmap()

void QwtSymbol::renderSymbols (QPainter * painter, const QPointF * points, int numPoints) const [protected], [virtual]

Render the symbol to series of points

Parameters

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

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()

void QwtSymbol::setCachePolicy (QwtSymbol::CachePolicy policy)

Change the cache policy

The default policy is AutoCache

Parameters

policy Cache policy

See also

CachePolicy, cachePolicy()

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()

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

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()

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()

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()

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()

void QwtSymbol::setPinPointEnabled (bool on)

En/Disable the pin point alignment

Parameters

on Enabled, when on is true

See also

setPinPoint(), isPinPointEnabled()

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

void QwtSymbol::setSize (const QSize & size)

Set the symbol's size

Parameters

size Size

See also

size()

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()

void QwtSymbol::setStyle (QwtSymbol::Style style)

Specify the symbol style

Parameters

style Style

See also

style()

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

const QSize & QwtSymbol::size () const

Returns

Size

See also

setSize()

QwtSymbol::Style QwtSymbol::style () const

Returns

Current symbol style

See also

setStyle()

Author

Generated automatically by Doxygen for Qwt User's Guide from the source code.

Info

Mon Jun 1 2020 Version 6.1.5 Qwt User's Guide