QwtPolarItem - Base class for items on a polar plot.

NAME

QwtPolarItem − Base class for items on a polar plot.

SYNOPSIS

#include <qwt_polar_item.h>

Inherited by QwtPolarCurve, QwtPolarGrid, QwtPolarMarker, and QwtPolarSpectrogram.

Public Types

enum RttiValues { Rtti_PolarItem = 0, Rtti_PolarGrid, Rtti_PolarMarker, Rtti_PolarCurve, Rtti_PolarSpectrogram, Rtti_PolarUserItem = 1000 }
Runtime type information.
enum ItemAttribute { Legend = 0x01, AutoScale = 0x02 }
Plot Item Attributes.
enum RenderHint { RenderAntialiased = 0x01 }
Render hints.
typedef QFlags< ItemAttribute > ItemAttributes
typedef QFlags< RenderHint > RenderHints

Public Member Functions

QwtPolarItem (const QwtText &title=QwtText())
virtual ˜QwtPolarItem ()
Destroy the QwtPolarItem.
void attach (QwtPolarPlot *plot)
Attach the item to a plot.
void detach ()
This method detaches a QwtPolarItem from the QwtPolarPlot it has been associated with.
QwtPolarPlot * plot () const
void setTitle (const QString &title)
void setTitle (const QwtText &title)
const QwtText & title () const
virtual int rtti () const
void setItemAttribute (ItemAttribute, bool on=true)
bool testItemAttribute (ItemAttribute) const
void setRenderHint (RenderHint, bool on=true)
bool testRenderHint (RenderHint) const
void setRenderThreadCount (uint numThreads)
uint renderThreadCount () 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
virtual void itemChanged ()
virtual void legendChanged ()
virtual void draw (QPainter *painter, const QwtScaleMap &azimuthMap, const QwtScaleMap &radialMap, const QPointF &pole, double radius, const QRectF &canvasRect) const =0
Draw the item.
virtual QwtInterval boundingInterval (int scaleId) const
virtual void updateScaleDiv (const QwtScaleDiv &, const QwtScaleDiv &, const QwtInterval &)
Update the item to changes of the axes scale division.
virtual int marginHint () const
void setLegendIconSize (const QSize &)
QSize legendIconSize () const
virtual QList< QwtLegendData > legendData () const
Return all information, that is needed to represent the item on the legend.
virtual QwtGraphic legendIcon (int index, const QSizeF &) const

Detailed Description

Base class for items on a polar plot.

A QwtPolarItem is "something that can be painted on the canvas". It is connected to the QwtPolar framework by a couple of virtual methods, that are individually implemented in derived item classes.

QwtPolar offers an implementation of the most common types of items, but deriving from QwtPolarItem makes it easy to implement additional types of items.

Definition at line 37 of file qwt_polar_item.h.

Member Typedef Documentation

typedef QFlags<ItemAttribute > QwtPolarItem::ItemAttributes

An ORed combination of ItemAttribute values.

Definition at line 86 of file qwt_polar_item.h.

typedef QFlags<RenderHint > QwtPolarItem::RenderHints

An ORed combination of RenderHint values.

Definition at line 98 of file qwt_polar_item.h.

Member Enumeration Documentation

enum QwtPolarItem::ItemAttribute

Plot Item Attributes.

See also

setItemAttribute(), testItemAttribute()

Enumerator

Legend

The item is represented on the legend.

AutoScale

The boundingRect() of the item is included in the autoscaling calculation.

Definition at line 74 of file qwt_polar_item.h.

enum QwtPolarItem::RenderHint

Render hints.

See also

setRenderHint(), testRenderHint()

Enumerator
RenderAntialiased

Enable antialiasing.

Definition at line 92 of file qwt_polar_item.h.

enum QwtPolarItem::RttiValues

Runtime type information. RttiValues is used to cast plot items, without having to enable runtime type information of the compiler.

Enumerator
Rtti_PolarItem

Unspecific value, that can be used, when it doesn’t matter.

Rtti_PolarGrid

For QwtPolarGrid.

Rtti_PolarMarker

For QwtPolarMarker.

Rtti_PolarCurve

For QwtPolarCurve.

Rtti_PolarSpectrogram

For QwtPolarSpectrogram.

Rtti_PolarUserItem

Values >= Rtti_PolarUserItem are reserved for plot items not implemented in the QwtPolar library.

Definition at line 46 of file qwt_polar_item.h.

Constructor & Destructor Documentation

QwtPolarItem::QwtPolarItem (const QwtText & title = QwtText()) [explicit]

Constructor

Parameters

title Item title, f.e used on a legend

See also

setTitle()

Definition at line 48 of file qwt_polar_item.cpp.

QwtPolarItem::˜QwtPolarItem () [virtual]

Destroy the QwtPolarItem.

Definition at line 55 of file qwt_polar_item.cpp.

Member Function Documentation

void QwtPolarItem::attach (QwtPolarPlot * plot)

Attach the item to a plot. This method will attach a QwtPolarItem to the QwtPolarPlot argument. It will first detach the QwtPolarItem from any plot from a previous call to attach (if necessary). If a NULL argument is passed, it will detach from any QwtPolarPlot it was attached to.

Parameters

plot Plot widget

See also

QwtPolarItem::detach()

Definition at line 74 of file qwt_polar_item.cpp.

QwtInterval QwtPolarItem::boundingInterval (int scaleId) const [virtual]

Interval, that is necessary to display the item

This interval can be useful for operations like clipping or autoscaling For items ( like the grid ), where a bounding interval makes no sense an invalid interval is returned.

Parameters

scaleId Scale id ( QwtPolar::Scale )

Returns

Bounding interval of the plot item for a specific scale

Reimplemented in QwtPolarCurve, QwtPolarMarker, and QwtPolarSpectrogram.

Definition at line 381 of file qwt_polar_item.cpp.

void QwtPolarItem::detach ()

This method detaches a QwtPolarItem from the QwtPolarPlot it has been associated with. detach() is equivalent to calling attach( NULL )

See also

attach()

Definition at line 95 of file qwt_polar_item.cpp.

virtual void QwtPolarItem::draw (QPainter * painter, const QwtScaleMap &azimuthMap, const QwtScaleMap & radialMap, const QPointF & pole, doubleradius, const QRectF & canvasRect) const [pure virtual]

Draw the item.

Parameters

painter Painter
azimuthMap Maps azimuth values to values related to 0.0, M_2PI
radialMap Maps radius values into painter coordinates.
pole Position of the pole in painter coordinates
radius Radius of the complete plot area in painter coordinates
canvasRect Contents rect of the canvas in painter coordinates

Implemented in QwtPolarCurve, QwtPolarGrid, QwtPolarMarker, and QwtPolarSpectrogram.

void QwtPolarItem::hide ()

Hide the item.

Definition at line 320 of file qwt_polar_item.cpp.

bool QwtPolarItem::isVisible () const

Returns

true if visible

See also

setVisible(), show(), hide()

Definition at line 344 of file qwt_polar_item.cpp.

void QwtPolarItem::itemChanged () [virtual]

Update the legend and call QwtPolarPlot::autoRefresh for the parent plot.

See also

updateLegend()

Definition at line 355 of file qwt_polar_item.cpp.

void QwtPolarItem::legendChanged () [virtual]

Update the legend of the parent plot.

See also

QwtPolarPlot::updateLegend(), itemChanged()

Definition at line 365 of file qwt_polar_item.cpp.

QList< QwtLegendData > QwtPolarItem::legendData () const [virtual]

Return all information, that is needed to represent the item on the legend. Most items are represented by one entry on the legend showing an icon and a text.

QwtLegendData is basically a list of QVariants that makes it possible to overload and reimplement legendData() to return almost any type of information, that is understood by the receiver that acts as the legend.

The default implementation returns one entry with the title() of the item and the legendIcon().

See also

title(), legendIcon(), QwtLegend

Definition at line 428 of file qwt_polar_item.cpp.

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

Returns

Icon representing the item on the legend

The default implementation returns an invalid icon

Parameters

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

See also

setLegendIconSize(), legendData()

Reimplemented in QwtPolarCurve.

Definition at line 462 of file qwt_polar_item.cpp.

QSize QwtPolarItem::legendIconSize () const

Returns

Legend icon size

See also

setLegendIconSize(), legendIcon()

Definition at line 308 of file qwt_polar_item.cpp.

int QwtPolarItem::marginHint () const [virtual]

Some items like to display something (f.e. the azimuth axis) outside of the area of the interval of the radial scale. The default implementation returns 0 pixels

Returns

Hint for the margin

Reimplemented in QwtPolarGrid.

Definition at line 478 of file qwt_polar_item.cpp.

QwtPolarPlot * QwtPolarItem::plot () const

Returns

Attached plot

Definition at line 118 of file qwt_polar_item.cpp.

uint QwtPolarItem::renderThreadCount () const

Returns

Number of threads to be used for rendering. If numThreads() is set to 0, the system specific ideal thread count is used.

Definition at line 282 of file qwt_polar_item.cpp.

int QwtPolarItem::rtti () const [virtual]

Return rtti for the specific class represented. QwtPolarItem is simply a virtual interface class, and base classes will implement this method with specific rtti values so a user can differentiate them.

The rtti value is useful for environments, where the runtime type information is disabled and it is not possible to do a dynamic_cast<...>.

Returns

rtti value

See also

RttiValues

Reimplemented in QwtPolarCurve, QwtPolarGrid, QwtPolarMarker, and QwtPolarSpectrogram.

Definition at line 112 of file qwt_polar_item.cpp.

void QwtPolarItem::setItemAttribute (ItemAttribute attribute, bool on =true)

Toggle an item attribute

Parameters

attribute Attribute type
on true/false

See also

testItemAttribute(), ItemAttribute

Definition at line 201 of file qwt_polar_item.cpp.

void QwtPolarItem::setLegendIconSize (const QSize & size)

Set the size of the legend icon

The default setting is 8x8 pixels

Parameters

size Size

See also

legendIconSize(), legendIcon()

Definition at line 295 of file qwt_polar_item.cpp.

void QwtPolarItem::setRenderHint (RenderHint hint, bool on = true)

Toggle an render hint

Parameters

hint Render hint
on true/false

See also

testRenderHint(), RenderHint

Definition at line 234 of file qwt_polar_item.cpp.

void QwtPolarItem::setRenderThreadCount (uint numThreads)

On multi core systems rendering of certain plot item ( f.e QwtPolarSpectrogram ) can be done in parallel in several threads.

The default setting is set to 1.

Parameters

numThreads Number of threads to be used for rendering. If numThreads is set to 0, the system specific ideal thread count is used.

The default thread count is 1 ( = no additional threads )

Definition at line 272 of file qwt_polar_item.cpp.

void QwtPolarItem::setTitle (const QString & title)

Set a new title

Parameters

title Title

See also

title()

Definition at line 164 of file qwt_polar_item.cpp.

void QwtPolarItem::setTitle (const QwtText & title)

Set a new title

Parameters

title Title

See also

title()

Definition at line 175 of file qwt_polar_item.cpp.

void QwtPolarItem::setVisible (bool on) [virtual]

Show/Hide the item

Parameters

on Show if true, otherwise hide

See also

isVisible(), show(), hide()

Definition at line 331 of file qwt_polar_item.cpp.

void QwtPolarItem::setZ (double z)

Set the z value. Plot items are painted in increasing z-order.

Parameters

z Z-value

See also

z(), QwtPolarItemDict::itemList()

Definition at line 142 of file qwt_polar_item.cpp.

void QwtPolarItem::show ()

Show the item.

Definition at line 314 of file qwt_polar_item.cpp.

bool QwtPolarItem::testItemAttribute (ItemAttribute attribute) const

Test an item attribute

Parameters

attribute Attribute type

Returns

true/false

See also

setItemAttribute(), ItemAttribute

Definition at line 221 of file qwt_polar_item.cpp.

bool QwtPolarItem::testRenderHint (RenderHint hint) const

Test a render hint

Parameters

hint Render hint

Returns

true/false

See also

setRenderHint(), RenderHint

Definition at line 254 of file qwt_polar_item.cpp.

const QwtText & QwtPolarItem::title () const

Returns

Title of the item

See also

setTitle()

Definition at line 188 of file qwt_polar_item.cpp.

void QwtPolarItem::updateScaleDiv (const QwtScaleDiv & azimuthScaleDiv,const QwtScaleDiv & radialScaleDiv, const QwtInterval & interval)[virtual]

Update the item to changes of the axes scale division. Update the item, when the axes of plot have changed. The default implementation does nothing, but items that depend on the scale division (like QwtPolarGrid()) have to reimplement updateScaleDiv()

Parameters

azimuthScaleDiv Scale division of the azimuth-scale
radialScaleDiv Scale division of the radius-axis
interval The interval of the radius-axis, that is visible on the canvas

See also

QwtPolarPlot::updateAxes()

Reimplemented in QwtPolarGrid.

Definition at line 403 of file qwt_polar_item.cpp.

double QwtPolarItem::z () const

Plot items are painted in increasing z-order.

Returns

Z value

See also

setZ(), QwtPolarItemDict::itemList()

Definition at line 129 of file qwt_polar_item.cpp.

Author

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