QwtPlotShapeItem - A plot item, which displays any graphical shape, that can be defined by a QPainterPath.

NAME

QwtPlotShapeItem − A plot item, which displays any graphical shape, that can be defined by a QPainterPath.

SYNOPSIS

#include <qwt_plot_shapeitem.h>

Inherits QwtPlotItem.

Public Types

enum PaintAttribute { ClipPolygons = 0x01 }
enum LegendMode { LegendShape, LegendColor }
Mode how to display the item on the legend.
typedef QFlags< PaintAttribute > PaintAttributes

Public Types inherited from QwtPlotItem

enum RttiValues { Rtti_PlotItem = 0, Rtti_PlotGrid, Rtti_PlotScale, Rtti_PlotLegend, Rtti_PlotMarker, Rtti_PlotCurve, Rtti_PlotSpectroCurve, Rtti_PlotIntervalCurve, Rtti_PlotHistogram, Rtti_PlotSpectrogram, Rtti_PlotGraphic, Rtti_PlotTradingCurve, Rtti_PlotBarChart, Rtti_PlotMultiBarChart, Rtti_PlotShape, Rtti_PlotTextLabel, Rtti_PlotZone, Rtti_PlotVectorField, Rtti_PlotUserItem = 1000 }
Runtime type information.
enum ItemAttribute { Legend = 0x01, AutoScale = 0x02, Margins = 0x04 }
Plot Item Attributes.
enum ItemInterest { ScaleInterest = 0x01, LegendInterest = 0x02 }
Plot Item Interests.
enum RenderHint { RenderAntialiased = 0x1 }
Render hints.
typedef QFlags< ItemAttribute > ItemAttributes
typedef QFlags< ItemInterest > ItemInterests
typedef QFlags< RenderHint > RenderHints

Public Member Functions

QwtPlotShapeItem (const QString &title=QString())
Constructor.
QwtPlotShapeItem (const QwtText &title)
Constructor.
virtual ˜QwtPlotShapeItem ()
Destructor.
void setPaintAttribute (PaintAttribute, bool on=true)
bool testPaintAttribute (PaintAttribute) const
void setLegendMode (LegendMode)
LegendMode legendMode () const
void setRect (const QRectF &)
Set a path built from a rectangle.
void setPolygon (const QPolygonF &)
Set a path built from a polygon.
void setShape (const QPainterPath &)
Set the shape to be displayed.
QPainterPath shape () const
void setPen (const QColor &, qreal width=0.0, Qt::PenStyle=Qt::SolidLine)
void setPen (const QPen &)
Assign a pen.
QPen pen () const
void setBrush (const QBrush &)
QBrush brush () const
void setRenderTolerance (double)
Set the tolerance for the weeding optimization.
double renderTolerance () const
virtual QRectF boundingRect () const override
Bounding rectangle of the shape.
virtual void draw (QPainter *, const QwtScaleMap &xMap, const QwtScaleMap &yMap, const QRectF &canvasRect) const override
virtual QwtGraphic legendIcon (int index, const QSizeF &) const override
virtual int rtti () const override

Public Member Functions inherited from QwtPlotItem

QwtPlotItem ()
QwtPlotItem (const QString &title)
QwtPlotItem (const QwtText &title)
virtual ˜QwtPlotItem ()
Destroy the QwtPlotItem.
void attach (QwtPlot *plot)
Attach the item to a plot.
void detach ()
This method detaches a QwtPlotItem from any QwtPlot it has been associated with.
QwtPlot * plot () const
Return attached plot.
void setTitle (const QString &title)
void setTitle (const QwtText &title)
const QwtText & title () const
void setItemAttribute (ItemAttribute, bool on=true)
bool testItemAttribute (ItemAttribute) const
void setItemInterest (ItemInterest, bool on=true)
bool testItemInterest (ItemInterest) const
void setRenderHint (RenderHint, bool on=true)
bool testRenderHint (RenderHint) const
void setRenderThreadCount (uint numThreads)
uint renderThreadCount () const
void setLegendIconSize (const QSize &)
QSize legendIconSize () const
double z () const
void setZ (double z)
Set the z value.
void show ()
Show the item.
void hide ()
Hide the item.
virtual void setVisible (bool)
bool isVisible () const
void setAxes (QwtAxisId xAxis, QwtAxisId yAxis)
void setXAxis (QwtAxisId)
QwtAxisId xAxis () const
Return xAxis.
void setYAxis (QwtAxisId)
QwtAxisId yAxis () const
Return yAxis.
virtual void itemChanged ()
virtual void legendChanged ()
virtual void getCanvasMarginHint (const QwtScaleMap &xMap, const QwtScaleMap &yMap, const QRectF &canvasRect, double &left, double &top, double &right, double &bottom) const
Calculate a hint for the canvas margin.
virtual void updateScaleDiv (const QwtScaleDiv &, const QwtScaleDiv &)
Update the item to changes of the axes scale division.
virtual void updateLegend (const QwtPlotItem *, const QList< QwtLegendData > &)
Update the item to changes of the legend info.
QRectF scaleRect (const QwtScaleMap &, const QwtScaleMap &) const
Calculate the bounding scale rectangle of 2 maps.
QRectF paintRect (const QwtScaleMap &, const QwtScaleMap &) const
Calculate the bounding paint rectangle of 2 maps.
virtual QList< QwtLegendData > legendData () const
Return all information, that is needed to represent the item on the legend.

Additional Inherited Members

Protected Member Functions inherited from QwtPlotItem

QwtGraphic defaultIcon (const QBrush &, const QSizeF &) const
Return a default icon from a brush.

Detailed Description

A plot item, which displays any graphical shape, that can be defined by a QPainterPath.

A QPainterPath is a shape composed from intersecting and uniting regions, rectangles, ellipses or irregular areas defined by lines, and curves. QwtPlotShapeItem displays a shape with a pen and brush.

QwtPlotShapeItem offers a couple of optimizations like clipping or weeding. These algorithms need to convert the painter path into polygons that might be less performant for paths built from curves and ellipses.

More complex shapes, that can’t be expressed by a QPainterPath can be displayed using QwtPlotGraphicItem.

See also

QwtPlotZone, QwtPlotGraphicItem

Definition at line 38 of file qwt_plot_shapeitem.h.

Member Typedef Documentation

typedef QFlags<PaintAttribute > QwtPlotShapeItem::PaintAttributes

An ORed combination of PaintAttribute values.

Definition at line 61 of file qwt_plot_shapeitem.h.

Member Enumeration Documentation

enum QwtPlotShapeItem::LegendMode

Mode how to display the item on the legend.

Enumerator
LegendShape

Display a scaled down version of the shape.

LegendColor

Display a filled rectangle.

Definition at line 64 of file qwt_plot_shapeitem.h.

enum QwtPlotShapeItem::PaintAttribute

Attributes to modify the drawing algorithm. The default disables all attributes

See also

setPaintAttribute(), testPaintAttribute()

Enumerator
ClipPolygons

Clip polygons before painting them. In situations, where points are far outside the visible area (f.e when zooming deep) this might be a substantial improvement for the painting performance

But polygon clipping will convert the painter path into polygons what might introduce a negative impact on the performance of paths composed from curves or ellipses.

Definition at line 47 of file qwt_plot_shapeitem.h.

Constructor & Destructor Documentation

QwtPlotShapeItem::QwtPlotShapeItem (const QString & title = QString())[explicit]

Constructor. Sets the following item attributes:

	•		QwtPlotItem::AutoScale: true
	•		QwtPlotItem::Legend: false

Parameters

title Title

Definition at line 112 of file qwt_plot_shapeitem.cpp.

QwtPlotShapeItem::QwtPlotShapeItem (const QwtText & title) [explicit]

Constructor. Sets the following item attributes:

	•		QwtPlotItem::AutoScale: true
	•		QwtPlotItem::Legend: false

Parameters

title Title

Definition at line 127 of file qwt_plot_shapeitem.cpp.

QwtPlotShapeItem::˜QwtPlotShapeItem () [virtual]

Destructor.

Definition at line 134 of file qwt_plot_shapeitem.cpp.

Member Function Documentation

QRectF QwtPlotShapeItem::boundingRect () const [override], [virtual]

Bounding rectangle of the shape.

Reimplemented from QwtPlotItem.

Definition at line 205 of file qwt_plot_shapeitem.cpp.

QBrush QwtPlotShapeItem::brush () const

Returns

Brush used to fill the shape

See also

setBrush(), pen()

Definition at line 336 of file qwt_plot_shapeitem.cpp.

void QwtPlotShapeItem::draw (QPainter * painter, const QwtScaleMap & xMap,const QwtScaleMap & yMap, const QRectF & canvasRect) const [override],[virtual]

Draw the shape item

Parameters

painter Painter
xMap X-Scale Map
yMap Y-Scale Map
canvasRect Contents rect of the plot canvas

Implements QwtPlotItem.

Definition at line 385 of file qwt_plot_shapeitem.cpp.

QwtGraphic QwtPlotShapeItem::legendIcon (int index, const QSizeF & size)const [override], [virtual]

Returns

A rectangle filled with the color of the brush ( or the pen )

Parameters

index Index of the legend entry ( usually there is only one )
size Icon size

See also

setLegendIconSize(), legendData()

Reimplemented from QwtPlotItem.

Definition at line 463 of file qwt_plot_shapeitem.cpp.

QwtPlotShapeItem::LegendMode QwtPlotShapeItem::legendMode () const

Returns

Mode how to represent the item on the legend

See also

legendMode()

Definition at line 199 of file qwt_plot_shapeitem.cpp.

QPen QwtPlotShapeItem::pen () const

Returns

Pen used to draw the outline of the shape

See also

setPen(), brush()

Definition at line 310 of file qwt_plot_shapeitem.cpp.

double QwtPlotShapeItem::renderTolerance () const

Returns

Tolerance for the weeding optimization

See also

setRenderTolerance()

Definition at line 372 of file qwt_plot_shapeitem.cpp.

int QwtPlotShapeItem::rtti () const [override], [virtual]

Returns

QwtPlotItem::Rtti_PlotShape

Reimplemented from QwtPlotItem.

Definition at line 151 of file qwt_plot_shapeitem.cpp.

void QwtPlotShapeItem::setBrush (const QBrush & brush)

Assign a brush.

The brush is used to fill the path

Parameters

brush Brush

See also

brush(), pen()

Definition at line 323 of file qwt_plot_shapeitem.cpp.

void QwtPlotShapeItem::setLegendMode (LegendMode mode)

Set the mode how to represent the item on the legend

Parameters

mode Mode

See also

legendMode()

Definition at line 186 of file qwt_plot_shapeitem.cpp.

void QwtPlotShapeItem::setPaintAttribute (PaintAttribute attribute, bool on= true)

Specify an attribute how to draw the shape

Parameters

attribute Paint attribute
on On/Off

See also

testPaintAttribute()

Definition at line 163 of file qwt_plot_shapeitem.cpp.

void QwtPlotShapeItem::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 284 of file qwt_plot_shapeitem.cpp.

void QwtPlotShapeItem::setPen (const QPen & pen)

Assign a pen. The pen is used to draw the outline of the shape

Parameters

pen Pen

See also

pen(), brush()

Definition at line 297 of file qwt_plot_shapeitem.cpp.

void QwtPlotShapeItem::setPolygon (const QPolygonF & polygon)

Set a path built from a polygon.

Parameters

polygon Polygon

See also

setShape(), setRect(), shape()

Definition at line 230 of file qwt_plot_shapeitem.cpp.

void QwtPlotShapeItem::setRect (const QRectF & rect)

Set a path built from a rectangle.

Parameters

rect Rectangle

See also

setShape(), setPolygon(), shape()

Definition at line 216 of file qwt_plot_shapeitem.cpp.

void QwtPlotShapeItem::setRenderTolerance (double tolerance)

Set the tolerance for the weeding optimization. After translating the shape into target device coordinate ( usually widget geometries ) the painter path can be simplified by a point weeding algorithm ( Douglas-Peucker ).

For shapes built from curves and ellipses weeding might have the opposite effect because they have to be expanded to polygons.

Parameters

tolerance Accepted error when reducing the number of points A value <= 0.0 disables weeding.

See also

renderTolerance(), QwtWeedingCurveFitter

Definition at line 357 of file qwt_plot_shapeitem.cpp.

void QwtPlotShapeItem::setShape (const QPainterPath & shape)

Set the shape to be displayed.

Parameters

shape Shape

See also

setShape(), shape()

Definition at line 244 of file qwt_plot_shapeitem.cpp.

QPainterPath QwtPlotShapeItem::shape () const

Returns

Shape to be displayed

See also

setShape()

Definition at line 266 of file qwt_plot_shapeitem.cpp.

bool QwtPlotShapeItem::testPaintAttribute (PaintAttribute attribute) const

Returns

True, when attribute is enabled

See also

setPaintAttribute()

Definition at line 175 of file qwt_plot_shapeitem.cpp.

Author

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Updated 2026-06-01 - jenkler.se | uex.se