Base class for items on the plot canvas. More...

#include <qwt_plot_item.h>

Inheritance diagram for QwtPlotItem:

Classes
class	PrivateData
Public Types
enum	ItemAttribute { Legend = 0x01, AutoScale = 0x02, Margins = 0x04 }
	Plot Item Attributes. More...
typedef QFlags< ItemAttribute >	ItemAttributes
	Plot Item Attributes.
enum	ItemInterest { ScaleInterest = 0x01, LegendInterest = 0x02 }
	Plot Item Interests. More...
typedef QFlags< ItemInterest >	ItemInterests
	Plot Item Interests.
enum	RenderHint { RenderAntialiased = 0x1 }
	Render hints. More...
typedef QFlags< RenderHint >	RenderHints
	Render hints.
enum	RttiValues { Rtti_PlotItem = 0, Rtti_PlotGrid, Rtti_PlotScale, Rtti_PlotLegend, Rtti_PlotMarker, Rtti_PlotCurve, Rtti_PlotSpectroCurve, Rtti_PlotIntervalCurve, Rtti_PlotHistogram, Rtti_PlotSpectrogram, Rtti_PlotSVG, Rtti_PlotTradingCurve, Rtti_PlotBarChart, Rtti_PlotMultiBarChart, Rtti_PlotShape, Rtti_PlotTextLabel, Rtti_PlotZone, Rtti_PlotUserItem = 1000 }
	Runtime type information. More...
Public Member Functions
void	attach (QwtPlot *plot)
	Attach the item to a plot.
virtual QRectF	boundingRect () const
void	detach ()
	This method detaches a QwtPlotItem from any QwtPlot it has been associated with.
virtual void	draw (QPainter *painter, const QwtScaleMap &xMap, const QwtScaleMap &yMap, const QRectF &canvasRect) const =0
	Draw the item.
virtual void	getCanvasMarginHint (const QwtScaleMap &xMap, const QwtScaleMap &yMap, const QRectF &canvasSize, double &left, double &top, double &right, double &bottom) const
	Calculate a hint for the canvas margin.
void	hide ()
	Hide the item.
bool	isVisible () const
virtual void	itemChanged ()
virtual void	legendChanged ()
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
QSize	legendIconSize () const
QRectF	paintRect (const QwtScaleMap &, const QwtScaleMap &) const
	Calculate the bounding paint rectangle of 2 maps.
QwtPlot *	plot () const
	Return attached plot.
	QwtPlotItem (const QwtText &title=QwtText())
uint	renderThreadCount () const
virtual int	rtti () const
QRectF	scaleRect (const QwtScaleMap &, const QwtScaleMap &) const
	Calculate the bounding scale rectangle of 2 maps.
void	setAxes (int xAxis, int yAxis)
void	setItemAttribute (ItemAttribute, bool on=true)
void	setItemInterest (ItemInterest, bool on=true)
void	setLegendIconSize (const QSize &)
void	setRenderHint (RenderHint, bool on=true)
void	setRenderThreadCount (uint numThreads)
void	setTitle (const QString &title)
void	setTitle (const QwtText &title)
virtual void	setVisible (bool)
void	setXAxis (int axis)
void	setYAxis (int axis)
void	setZ (double z)
	Set the z value.
void	show ()
	Show the item.
bool	testItemAttribute (ItemAttribute) const
bool	testItemInterest (ItemInterest) const
bool	testRenderHint (RenderHint) const
const QwtText &	title () const
virtual void	updateLegend (const QwtPlotItem *, const QList< QwtLegendData > &)
	Update the item to changes of the legend info.
virtual void	updateScaleDiv (const QwtScaleDiv &, const QwtScaleDiv &)
	Update the item to changes of the axes scale division.
int	xAxis () const
	Return xAxis.
int	yAxis () const
	Return yAxis.
double	z () const
virtual	~QwtPlotItem ()
	Destroy the QwtPlotItem.
Protected Member Functions
QwtGraphic	defaultIcon (const QBrush &, const QSizeF &) const
	Return a default icon from a brush.
Private Attributes
PrivateData *	d_data

Detailed Description

Base class for items on the plot canvas.

A plot item is "something", that can be painted on the plot canvas, or only affects the scales of the plot widget. They can be categorized as:

Representator
A "Representator" is an item that represents some sort of data on the plot canvas. The different representator classes are organized according to the characteristics of the data:
- QwtPlotMarker Represents a point or a horizontal/vertical coordinate
- QwtPlotCurve Represents a series of points
- QwtPlotSpectrogram ( QwtPlotRasterItem ) Represents raster data
- ...

Decorators
A "Decorator" is an item, that displays additional information, that is not related to any data:
- QwtPlotGrid
- QwtPlotScaleItem
- QwtPlotSvgItem
- ...

Depending on the QwtPlotItem::ItemAttribute flags, an item is included into autoscaling or has an entry on the legend.

Before misusing the existing item classes it might be better to implement a new type of plot item ( don't implement a watermark as spectrogram ). Deriving a new type of QwtPlotItem primarily means to implement the YourPlotItem::draw() method.

See also:: The cpuplot example shows the implementation of additional plot items.

Definition at line 64 of file qwt_plot_item.h.

Member Typedef Documentation

typedef QFlags<ItemAttribute> QwtPlotItem::ItemAttributes

Plot Item Attributes.

Definition at line 163 of file qwt_plot_item.h.

typedef QFlags<ItemInterest> QwtPlotItem::ItemInterests

Plot Item Interests.

Definition at line 197 of file qwt_plot_item.h.

typedef QFlags<RenderHint> QwtPlotItem::RenderHints

Render hints.

Definition at line 207 of file qwt_plot_item.h.

Member Enumeration Documentation

enum QwtPlotItem::ItemAttribute

Plot Item Attributes.

Various aspects of a plot widget depend on the attributes of the attached plot items. If and how a single plot item participates in these updates depends on its attributes.

See also:: setItemAttribute(), testItemAttribute(), ItemInterest

Enumerator:

Legend

The item is represented on the legend.

AutoScale

The boundingRect() of the item is included in the autoscaling calculation as long as its width or height is >= 0.0.

Margins

The item needs extra space to display something outside its bounding rectangle.

See also:: getCanvasMarginHint()

Definition at line 142 of file qwt_plot_item.h.

enum QwtPlotItem::ItemInterest

Plot Item Interests.

Plot items might depend on the situation of the corresponding plot widget. By enabling an interest the plot item will be notified, when the corresponding attribute of the plot widgets has changed.

See also:: setItemAttribute(), testItemAttribute(), ItemInterest

Enumerator:

ScaleInterest

The item is interested in updates of the scales

See also:: updateScaleDiv()

LegendInterest

The item is interested in updates of the legend ( of other items ) This flag is intended for items, that want to implement a legend for displaying entries of other plot item.

Note:: If the plot item wants to be represented on a legend enable QwtPlotItem::Legend instead.

See also:: updateLegend()

Definition at line 175 of file qwt_plot_item.h.

enum QwtPlotItem::RenderHint

Render hints.

Enumerator:

RenderAntialiased

Enable antialiasing.

Definition at line 200 of file qwt_plot_item.h.

enum QwtPlotItem::RttiValues

Runtime type information.

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

Enumerator:

Rtti_PlotItem	Unspecific value, that can be used, when it doesn't matter.
Rtti_PlotGrid	For QwtPlotGrid.
Rtti_PlotScale	For QwtPlotScaleItem.
Rtti_PlotLegend	For QwtPlotLegendItem.
Rtti_PlotMarker	For QwtPlotMarker.
Rtti_PlotCurve	For QwtPlotCurve.
Rtti_PlotSpectroCurve	For QwtPlotSpectroCurve.
Rtti_PlotIntervalCurve	For QwtPlotIntervalCurve.
Rtti_PlotHistogram	For QwtPlotHistogram.
Rtti_PlotSpectrogram	For QwtPlotSpectrogram.
Rtti_PlotSVG	For QwtPlotSvgItem.
Rtti_PlotTradingCurve	For QwtPlotTradingCurve.
Rtti_PlotBarChart	For QwtPlotBarChart.
Rtti_PlotMultiBarChart	For QwtPlotMultiBarChart.
Rtti_PlotShape	For QwtPlotShapeItem.
Rtti_PlotTextLabel	For QwtPlotTextLabel.
Rtti_PlotZone	For QwtPlotZoneItem.
Rtti_PlotUserItem	Values >= Rtti_PlotUserItem are reserved for plot items not implemented in the Qwt library.

Definition at line 73 of file qwt_plot_item.h.

Constructor & Destructor Documentation

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

Constructor

Parameters:

title Title of the item

Definition at line 58 of file qwt_plot_item.cpp.

QwtPlotItem::~QwtPlotItem ( ) [virtual]

Destroy the QwtPlotItem.

Definition at line 65 of file qwt_plot_item.cpp.

Member Function Documentation

void QwtPlotItem::attach ( QwtPlot * plot )

Attach the item to a plot.

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

Parameters:

plot	Plot widget

See also:: detach()

Definition at line 82 of file qwt_plot_item.cpp.

QRectF QwtPlotItem::boundingRect ( ) const [virtual]

Returns:: An invalid bounding rect: QRectF(1.0, 1.0, -2.0, -2.0)

Note:: A width or height < 0.0 is ignored by the autoscaler

Reimplemented in QwtPlotTradingCurve, QwtPlotMarker, QwtPlotIntervalCurve, QwtPlotHistogram, QwtPlotRasterItem, QwtPlotShapeItem, QwtPlotBarChart, QwtPlotMultiBarChart, QwtPlotZoneItem, QwtPlotSeriesItem, and QwtPlotSvgItem.

Definition at line 537 of file qwt_plot_item.cpp.

QwtGraphic QwtPlotItem::defaultIcon	(	const QBrush &	brush,
		const QSizeF &	size
	)		const `[protected]`

Return a default icon from a brush.

The default icon is a filled rectangle used in several derived classes as legendIcon().

Parameters:

brush	Fill brush
size	Icon size

Returns:: A filled rectangle

Definition at line 391 of file qwt_plot_item.cpp.

void QwtPlotItem::detach ( )

This method detaches a QwtPlotItem from any QwtPlot it has been associated with.

detach() is equivalent to calling attach( NULL )

See also:: attach()

Definition at line 103 of file qwt_plot_item.cpp.

virtual void QwtPlotItem::draw	(	QPainter *	painter,
		const QwtScaleMap &	xMap,
		const QwtScaleMap &	yMap,
		const QRectF &	canvasRect
	)		const `[pure virtual]`

Draw the item.

Parameters:

painter	Painter
xMap	Maps x-values into pixel coordinates.
yMap	Maps y-values into pixel coordinates.
canvasRect	Contents rect of the canvas in painter coordinates

Implemented in QwtPlotMarker, QwtPlotLegendItem, QwtPlotRasterItem, QwtPlotShapeItem, QwtPlotSpectrogram, QwtPlotScaleItem, QwtPlotGrid, QwtPlotTextLabel, QwtPlotZoneItem, QwtPlotSvgItem, and QwtPlotSeriesItem.

void QwtPlotItem::getCanvasMarginHint	(	const QwtScaleMap &	xMap,
		const QwtScaleMap &	yMap,
		const QRectF &	canvasRect,
		double &	left,
		double &	top,
		double &	right,
		double &	bottom
	)		const `[virtual]`

Calculate a hint for the canvas margin.

When the QwtPlotItem::Margins flag is enabled the plot item indicates, that it needs some margins at the borders of the canvas. This is f.e. used by bar charts to reserve space for displaying the bars.

The margins are in target device coordinates ( pixels on screen )

Parameters:

xMap	Maps x-values into pixel coordinates.
yMap	Maps y-values into pixel coordinates.
canvasRect	Contents rectangle of the canvas in painter coordinates
left	Returns the left margin
top	Returns the top margin
right	Returns the right margin
bottom	Returns the bottom margin

Returns:: The default implementation returns 0 for all margins

See also:: QwtPlot::getCanvasMarginsHint(), QwtPlot::updateCanvasMargins()

Reimplemented in QwtPlotAbstractBarChart.

Definition at line 564 of file qwt_plot_item.cpp.

void QwtPlotItem::hide ( )

Hide the item.

Definition at line 415 of file qwt_plot_item.cpp.

bool QwtPlotItem::isVisible ( ) const

Returns:: true if visible

See also:: setVisible(), show(), hide()

Definition at line 439 of file qwt_plot_item.cpp.

void QwtPlotItem::itemChanged ( ) [virtual]

Update the legend and call QwtPlot::autoRefresh() for the parent plot.

See also:: QwtPlot::legendChanged(), QwtPlot::autoRefresh()

Definition at line 450 of file qwt_plot_item.cpp.

void QwtPlotItem::legendChanged ( ) [virtual]

Update the legend of the parent plot.

See also:: QwtPlot::updateLegend(), itemChanged()

Definition at line 460 of file qwt_plot_item.cpp.

QList< QwtLegendData > QwtPlotItem::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, but f.e. QwtPlotMultiBarChart displays one entry for each bar.

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().

Returns:: Data, that is needed to represent the item on the legend

See also:: title(), legendIcon(), QwtLegend, QwtPlotLegendItem

Reimplemented in QwtPlotBarChart, and QwtPlotMultiBarChart.

Definition at line 595 of file qwt_plot_item.cpp.

QwtGraphic QwtPlotItem::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 QwtPlotCurve, QwtPlotTradingCurve, QwtPlotMarker, QwtPlotBarChart, QwtPlotIntervalCurve, QwtPlotHistogram, QwtPlotShapeItem, and QwtPlotMultiBarChart.

Definition at line 371 of file qwt_plot_item.cpp.

QSize QwtPlotItem::legendIconSize ( ) const

Returns:: Legend icon size

See also:: setLegendIconSize(), legendIcon()

Definition at line 355 of file qwt_plot_item.cpp.

QRectF QwtPlotItem::paintRect	(	const QwtScaleMap &	xMap,
		const QwtScaleMap &	yMap
	)		const

Calculate the bounding paint rectangle of 2 maps.

Parameters:

xMap	Maps x-values into pixel coordinates.
yMap	Maps y-values into pixel coordinates.

Returns:: Bounding paint rectangle of the scale maps, not normalized

Definition at line 691 of file qwt_plot_item.cpp.

QwtPlot * QwtPlotItem::plot ( ) const

Return attached plot.

Definition at line 126 of file qwt_plot_item.cpp.

uint QwtPlotItem::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 329 of file qwt_plot_item.cpp.

int QwtPlotItem::rtti ( ) const [virtual]

Return rtti for the specific class represented. QwtPlotItem 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 QwtPlotCurve, QwtPlotTradingCurve, QwtPlotShapeItem, QwtPlotSpectrogram, QwtPlotIntervalCurve, QwtPlotHistogram, QwtPlotMarker, QwtPlotBarChart, QwtPlotMultiBarChart, QwtPlotLegendItem, QwtPlotScaleItem, QwtPlotTextLabel, QwtPlotSpectroCurve, QwtPlotSvgItem, QwtPlotGrid, and QwtPlotZoneItem.

Definition at line 120 of file qwt_plot_item.cpp.

QRectF QwtPlotItem::scaleRect	(	const QwtScaleMap &	xMap,
		const QwtScaleMap &	yMap
	)		const

Calculate the bounding scale rectangle of 2 maps.

Parameters:

xMap	Maps x-values into pixel coordinates.
yMap	Maps y-values into pixel coordinates.

Returns:: Bounding scale rect of the scale maps, not normalized

Definition at line 676 of file qwt_plot_item.cpp.

void QwtPlotItem::setAxes	(	int	xAxis,
		int	yAxis
	)

Set X and Y axis

The item will painted according to the coordinates of its Axes.

Parameters:

xAxis	X Axis ( QwtPlot::xBottom or QwtPlot::xTop )
yAxis	Y Axis ( QwtPlot::yLeft or QwtPlot::yRight )

See also:: setXAxis(), setYAxis(), xAxis(), yAxis(), QwtPlot::Axis

Definition at line 476 of file qwt_plot_item.cpp.

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

Toggle an item attribute

Parameters:

attribute	Attribute type
on	true/false

See also:: testItemAttribute(), ItemInterest

Definition at line 212 of file qwt_plot_item.cpp.

void QwtPlotItem::setItemInterest	(	ItemInterest	interest,
		bool	on = `true`
	)

Toggle an item interest

Parameters:

interest	Interest type
on	true/false

See also:: testItemInterest(), ItemAttribute

Definition at line 248 of file qwt_plot_item.cpp.

void QwtPlotItem::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 342 of file qwt_plot_item.cpp.

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

Toggle an render hint

Parameters:

hint	Render hint
on	true/false

See also:: testRenderHint(), RenderHint

Definition at line 281 of file qwt_plot_item.cpp.

void QwtPlotItem::setRenderThreadCount ( uint numThreads )

On multi core systems rendering of certain plot item ( f.e QwtPlotRasterItem ) 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 319 of file qwt_plot_item.cpp.

void QwtPlotItem::setTitle ( const QString & title )

Set a new title

Parameters:

title Title

See also:: title()

Definition at line 171 of file qwt_plot_item.cpp.

void QwtPlotItem::setTitle ( const QwtText & title )

Set a new title

Parameters:

title Title

See also:: title()

Definition at line 182 of file qwt_plot_item.cpp.

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

Show/Hide the item

Parameters:

on	Show if true, otherwise hide

See also:: isVisible(), show(), hide()

Definition at line 426 of file qwt_plot_item.cpp.

void QwtPlotItem::setXAxis ( int axis )

Set the X axis

The item will painted according to the coordinates its Axes.

Parameters:

axis	X Axis ( QwtPlot::xBottom or QwtPlot::xTop )

See also:: setAxes(), setYAxis(), xAxis(), QwtPlot::Axis

Definition at line 495 of file qwt_plot_item.cpp.

void QwtPlotItem::setYAxis ( int axis )

Set the Y axis

The item will painted according to the coordinates its Axes.

Parameters:

axis	Y Axis ( QwtPlot::yLeft or QwtPlot::yRight )

See also:: setAxes(), setXAxis(), yAxis(), QwtPlot::Axis

Definition at line 512 of file qwt_plot_item.cpp.

void QwtPlotItem::setZ ( double z )

Set the z value.

Plot items are painted in increasing z-order.

Parameters:

z Z-value

See also:: z(), QwtPlotDict::itemList()

Definition at line 149 of file qwt_plot_item.cpp.

void QwtPlotItem::show ( )

Show the item.

Definition at line 409 of file qwt_plot_item.cpp.

bool QwtPlotItem::testItemAttribute ( ItemAttribute attribute ) const

Test an item attribute

Parameters:

attribute Attribute type

Returns:: true/false

See also:: setItemAttribute(), ItemInterest

Definition at line 235 of file qwt_plot_item.cpp.

bool QwtPlotItem::testItemInterest ( ItemInterest interest ) const

Test an item interest

Parameters:

interest Interest type

Returns:: true/false

See also:: setItemInterest(), ItemAttribute

Definition at line 268 of file qwt_plot_item.cpp.

bool QwtPlotItem::testRenderHint ( RenderHint hint ) const

Test a render hint

Parameters:

hint	Render hint

Returns:: true/false

See also:: setRenderHint(), RenderHint

Definition at line 301 of file qwt_plot_item.cpp.

const QwtText & QwtPlotItem::title ( ) const

Returns:: Title of the item

See also:: setTitle()

Definition at line 199 of file qwt_plot_item.cpp.

void QwtPlotItem::updateLegend	(	const QwtPlotItem *	item,
		const QList< QwtLegendData > &	data
	)		`[virtual]`

Update the item to changes of the legend info.

Plot items that want to display a legend ( not those, that want to be displayed on a legend ! ) will have to implement updateLegend().

updateLegend() is only called when the LegendInterest interest is enabled. The default implementation does nothing.

Parameters:

item	Plot item to be displayed on a legend
data	Attributes how to display item on the legend

See also:: QwtPlotLegendItem

Note:: Plot items, that want to be displayed on a legend need to enable the QwtPlotItem::Legend flag and to implement legendData() and legendIcon()

Reimplemented in QwtPlotLegendItem.

Definition at line 661 of file qwt_plot_item.cpp.

void QwtPlotItem::updateScaleDiv	(	const QwtScaleDiv &	xScaleDiv,
		const QwtScaleDiv &	yScaleDiv
	)		`[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 QwtPlotGrid()) have to reimplement updateScaleDiv()

updateScaleDiv() is only called when the ScaleInterest interest is enabled. The default implementation does nothing.

Parameters: