Qwt User's Guide: QwtSymbol Class Reference

Qwt User's Guide 6.3.0

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Public Types | Public Member Functions | Protected Member Functions | List of all members
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.
| 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.

Definition at line 31 of file qwt_symbol.h.

## 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 )

Definition at line 150 of file qwt_symbol.h.

## ◆ 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.

Definition at line 38 of file qwt_symbol.h.

## Constructor & Destructor Documentation

## ◆ QwtSymbol() [1/3]

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() [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()

Definition at line 858 of file qwt_symbol.cpp.

## ◆ 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()

Definition at line 878 of file qwt_symbol.cpp.

## ◆ ~QwtSymbol()

QwtSymbol::~QwtSymbol | ( |  | ) |
| virtual

Destructor.

Definition at line 886 of file qwt_symbol.cpp.

## Member Function Documentation

## ◆ boundingRect()

QRect QwtSymbol::boundingRect | ( |  | ) | const
| virtual

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

Returns
  Bounding rectangle

Definition at line 1637 of file qwt_symbol.cpp.

## ◆ brush()

const QBrush & QwtSymbol::brush | ( |  | ) | const

Returns
  Brush

See also
  setBrush()

Definition at line 1123 of file qwt_symbol.cpp.

## ◆ cachePolicy()

QwtSymbol::CachePolicy QwtSymbol::cachePolicy | ( |  | ) | const

Returns
  Cache policy

See also
  CachePolicy, setCachePolicy()

Definition at line 913 of file qwt_symbol.cpp.

## ◆ 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

Definition at line 238 of file qwt_symbol.h.

## ◆ 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

Definition at line 1434 of file qwt_symbol.cpp.

## ◆ 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

Definition at line 1307 of file qwt_symbol.cpp.

## ◆ 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

Definition at line 251 of file qwt_symbol.h.

## ◆ graphic()

const QwtGraphic & QwtSymbol::graphic | ( |  | ) | const

Returns
  Assigned graphic

See also
  setGraphic()

Definition at line 1027 of file qwt_symbol.cpp.

## ◆ 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()

Definition at line 1770 of file qwt_symbol.cpp.

## ◆ isPinPointEnabled()

bool QwtSymbol::isPinPointEnabled | ( |  | ) | const

Returns
  True, when the pin point translation is enabled

See also
  setPinPoint(), setPinPointEnabled()

Definition at line 1291 of file qwt_symbol.cpp.

## ◆ path()

const QPainterPath & QwtSymbol::path | ( |  | ) | const

Returns
  Painter path for displaying the symbol

See also
  setPath()

Definition at line 977 of file qwt_symbol.cpp.

## ◆ pen()

const QPen & QwtSymbol::pen | ( |  | ) | const

Returns
  Pen

See also
  setPen(), brush()

Definition at line 1171 of file qwt_symbol.cpp.

## ◆ pinPoint()

QPointF QwtSymbol::pinPoint | ( |  | ) | const

Returns
  Pin point

See also
  setPinPoint(), setPinPointEnabled()

Definition at line 1267 of file qwt_symbol.cpp.

## ◆ pixmap()

const QPixmap & QwtSymbol::pixmap | ( |  | ) | const

Returns
  Assigned pixmap

See also
  setPixmap()

Definition at line 1002 of file qwt_symbol.cpp.

## ◆ 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

Definition at line 1513 of file qwt_symbol.cpp.

## ◆ 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()

Definition at line 1107 of file qwt_symbol.cpp.

## ◆ setCachePolicy()

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

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.

## ◆ 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()

Definition at line 1186 of file qwt_symbol.cpp.

## ◆ 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

Definition at line 1017 of file qwt_symbol.cpp.

## ◆ 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 );
QwtSymbol
A class for drawing symbols.
Definition qwt_symbol.h:32
QwtSymbol::path
const QPainterPath & path() const
Definition qwt_symbol.cpp:977
QwtSymbol::setPen
void setPen(const QColor &, qreal width=0.0, Qt::PenStyle=Qt::SolidLine)
Definition qwt_symbol.cpp:1141
QwtSymbol::setPath
void setPath(const QPainterPath &)
Set a painter path as symbol.
Definition qwt_symbol.cpp:966
QwtSymbol::QwtSymbol
QwtSymbol(Style=NoSymbol)
Definition qwt_symbol.cpp:843
QwtSymbol::setPinPoint
void setPinPoint(const QPointF &pos, bool enable=true)
Set and enable a pin point.
Definition qwt_symbol.cpp:1249
QwtSymbol::setSize
void setSize(const QSize &)
Definition qwt_symbol.cpp:1081
QwtSymbol::pen
const QPen & pen() const
Definition qwt_symbol.cpp:1171
QwtSymbol::setBrush
void setBrush(const QBrush &)
Assign a brush.
Definition qwt_symbol.cpp:1107

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.

## ◆ 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()

Definition at line 1141 of file qwt_symbol.cpp.

## ◆ 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()

Definition at line 1155 of file qwt_symbol.cpp.

## ◆ 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()

Definition at line 1249 of file qwt_symbol.cpp.

## ◆ setPinPointEnabled()

void QwtSymbol::setPinPointEnabled | ( | bool | on | ) |

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.

## ◆ 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

Definition at line 992 of file qwt_symbol.cpp.

## ◆ setSize() [1/2]

void QwtSymbol::setSize | ( | const QSize & | size | ) |

Set the symbol's size

Parameters

  size | Size

See also
  size()

Definition at line 1081 of file qwt_symbol.cpp.

## ◆ 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()

Definition at line 1067 of file qwt_symbol.cpp.

## ◆ setStyle()

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

Specify the symbol style

Parameters

  style | Style

See also
  style()

Definition at line 1782 of file qwt_symbol.cpp.

## ◆ 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

Definition at line 1044 of file qwt_symbol.cpp.

## ◆ size()

const QSize & QwtSymbol::size | ( |  | ) | const

Returns
  Size

See also
  setSize()

Definition at line 1094 of file qwt_symbol.cpp.

## ◆ style()

QwtSymbol::Style QwtSymbol::style | ( |  | ) | const

Returns
  Current symbol style

See also
  setStyle()

Definition at line 1795 of file qwt_symbol.cpp.