QwtSymbol(3) Qwt User's Guide QwtSymbol(3)

QwtSymbol - A class for drawing symbols.

#include <qwt_symbol.h>


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 }


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 ()


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

A class for drawing symbols.

Definition at line 31 of file qwt_symbol.h.

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

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

Definition at line 150 of file qwt_symbol.h.

enum QwtSymbol::Style

Symbol Style

See also

setStyle(), style()

Enumerator

No Style. The symbol cannot be drawn.
Ellipse or circle.
Rectangle.
Diamond.
Triangle pointing upwards.
Triangle pointing downwards.
Triangle pointing upwards.
Triangle pointing left.
Triangle pointing right.
Cross (+)
Diagonal cross (X)
Horizontal line.
Vertical line.
X combined with +.
Six-pointed star.
Hexagon.
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()
The symbol is represented by a pixmap. The pixmap is centered or aligned to its pin point.

See also

setPinPoint()
The symbol is represented by a graphic. The graphic is centered or aligned to its pin point.

See also

setPinPoint()
The symbol is represented by a SVG graphic. The graphic is centered or aligned to its pin point.

See also

setPinPoint()
Styles >= QwtSymbol::UserSymbol are reserved for derived classes of QwtSymbol that overload drawSymbols() with additional application specific symbol types.

Definition at line 38 of file qwt_symbol.h.

QwtSymbol::QwtSymbol (Style style = NoSymbol) [explicit]

Default Constructor

Parameters

style Symbol Style

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

Definition at line 843 of file qwt_symbol.cpp.

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()

Definition at line 858 of file qwt_symbol.cpp.

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()

Definition at line 878 of file qwt_symbol.cpp.

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

Returns

Bounding rectangle

Definition at line 1637 of file qwt_symbol.cpp.

Returns

Brush

See also

setBrush()

Definition at line 1123 of file qwt_symbol.cpp.

QwtSymbol::CachePolicy QwtSymbol::cachePolicy () const

Returns

Cache policy

See also

CachePolicy, setCachePolicy()

Definition at line 913 of file qwt_symbol.cpp.

Draw the symbol at a specified position.

Parameters

painter Painter
pos Position of the symbol in screen coordinates

Definition at line 238 of file qwt_symbol.h.

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

Definition at line 1434 of file qwt_symbol.cpp.

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

Definition at line 1307 of file qwt_symbol.cpp.

Draw symbols at the specified points.

Parameters

painter Painter
points Positions of the symbols in screen coordinates

Definition at line 251 of file qwt_symbol.h.

Returns

Assigned graphic

See also

setGraphic()

Definition at line 1027 of file qwt_symbol.cpp.

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()

Definition at line 1770 of file qwt_symbol.cpp.

Returns

True, when the pin point translation is enabled

See also

setPinPoint(), setPinPointEnabled()

Definition at line 1291 of file qwt_symbol.cpp.

Returns

Painter path for displaying the symbol

See also

setPath()

Definition at line 977 of file qwt_symbol.cpp.

Returns

Pen

See also

setPen(), brush()

Definition at line 1171 of file qwt_symbol.cpp.

Returns

Pin point

See also

setPinPoint(), setPinPointEnabled()

Definition at line 1267 of file qwt_symbol.cpp.

Returns

Assigned pixmap

See also

setPixmap()

Definition at line 1002 of file qwt_symbol.cpp.

Render the symbol to series of points

Parameters

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

Definition at line 1513 of file qwt_symbol.cpp.

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

Parameters

brush Brush

See also

brush()

Definition at line 1107 of file qwt_symbol.cpp.

Change the cache policy

The default policy is AutoCache

Parameters

policy Cache policy

See also

CachePolicy, cachePolicy()

Definition at line 899 of file qwt_symbol.cpp.

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()

Definition at line 1186 of file qwt_symbol.cpp.

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

Definition at line 1017 of file qwt_symbol.cpp.

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 );

Parameters

path Painter path

Note

The style is implicitly set to QwtSymbol::Path.

See also

path(), setSize()

Definition at line 966 of file qwt_symbol.cpp.

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()

Definition at line 1141 of file qwt_symbol.cpp.

Assign a pen

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

Parameters

pen Pen

See also

pen(), setBrush()

Definition at line 1155 of file qwt_symbol.cpp.

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()

Definition at line 1249 of file qwt_symbol.cpp.

En/Disable the pin point alignment

Parameters

on Enabled, when on is true

See also

setPinPoint(), isPinPointEnabled()

Definition at line 1278 of file qwt_symbol.cpp.

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

Definition at line 992 of file qwt_symbol.cpp.

Set the symbol's size

Parameters

size Size

See also

size()

Definition at line 1081 of file qwt_symbol.cpp.

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()

Definition at line 1067 of file qwt_symbol.cpp.

Specify the symbol style

Parameters

style Style

See also

style()

Definition at line 1782 of file qwt_symbol.cpp.

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

Definition at line 1044 of file qwt_symbol.cpp.

Returns

Size

See also

setSize()

Definition at line 1094 of file qwt_symbol.cpp.

QwtSymbol::Style QwtSymbol::style () const

Returns

Current symbol style

See also

setStyle()

Definition at line 1795 of file qwt_symbol.cpp.

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Sun Jul 18 2021 Version 6.2.0