Provided by: libqwt-doc_6.0.0-1.2_all 
NAME
QwtPlotItem -
Base class for items on the plot canvas.
SYNOPSIS
#include <qwt_plot_item.h>
Inherits QwtLegendItemManager.
Inherited by QwtPlotAbstractSeriesItem, QwtPlotGrid, QwtPlotMarker, QwtPlotRasterItem, QwtPlotScaleItem,
and QwtPlotSvgItem.
Public Types
enum RttiValues { Rtti_PlotItem = 0, Rtti_PlotGrid, Rtti_PlotScale, Rtti_PlotMarker, Rtti_PlotCurve,
Rtti_PlotSpectroCurve, Rtti_PlotIntervalCurve, Rtti_PlotHistogram, Rtti_PlotSpectrogram,
Rtti_PlotSVG, Rtti_PlotUserItem = 1000 }
enum ItemAttribute { Legend = 0x01, AutoScale = 0x02 }
enum RenderHint { RenderAntialiased = 1 }
typedef QFlags< ItemAttribute > ItemAttributes
typedef QFlags< RenderHint > RenderHints
Public Member Functions
QwtPlotItem (const QwtText &title=QwtText())
virtual ~QwtPlotItem ()
void attach (QwtPlot *plot)
void detach ()
QwtPlot * 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
double z () const
void setZ (double z)
void show ()
void hide ()
virtual void setVisible (bool)
bool isVisible () const
void setAxes (int xAxis, int yAxis)
void setXAxis (int axis)
int xAxis () const
void setYAxis (int axis)
int yAxis () const
virtual void itemChanged ()
virtual void draw (QPainter *painter, const QwtScaleMap &xMap, const QwtScaleMap &yMap, const QRectF
&canvasRect) const =0
virtual QRectF boundingRect () const
virtual void updateLegend (QwtLegend *) const
virtual void updateScaleDiv (const QwtScaleDiv &, const QwtScaleDiv &)
virtual QWidget * legendItem () const
QRectF scaleRect (const QwtScaleMap &, const QwtScaleMap &) const
QRectF paintRect (const QwtScaleMap &, const QwtScaleMap &) const
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 legnd.
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.
Member Typedef Documentation
typedef QFlags<ItemAttribute> QwtPlotItem::ItemAttributes
Plot Item Attributes.
typedef QFlags<RenderHint> QwtPlotItem::RenderHints
Render hints.
Member Enumeration Documentation
enum QwtPlotItem::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.
enum QwtPlotItem::RenderHint
Render hints.
Enumerator:
RenderAntialiased
Enable antialiasing.
enum QwtPlotItem::RttiValues
Runtime type information. RttiValues is used to cast plot items, without having to enable runtime type
information of the compiler.
Constructor & Destructor Documentation
QwtPlotItem::QwtPlotItem (const QwtText &title = QwtText()) [explicit] Constructor
Parameters:
title Title of the item
QwtPlotItem::~QwtPlotItem () [virtual]
Destroy the QwtPlotItem.
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()
QRectF QwtPlotItem::boundingRect () const [virtual] Returns:
An invalid bounding rect: QRectF(1.0, 1.0, -2.0, -2.0)
Reimplemented in QwtPlotHistogram, QwtPlotIntervalCurve, QwtPlotMarker, QwtPlotRasterItem,
QwtPlotSeriesItem< T >, QwtPlotSvgItem, QwtPlotSeriesItem< QwtIntervalSample >, QwtPlotSeriesItem<
QPointF >, and QwtPlotSeriesItem< QwtPoint3D >.
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()
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 QwtPlotGrid, QwtPlotMarker, QwtPlotRasterItem, QwtPlotScaleItem,
QwtPlotAbstractSeriesItem, QwtPlotSpectrogram, and QwtPlotSvgItem.
void QwtPlotItem::hide ()
Hide the item.
bool QwtPlotItem::isVisible () const Returns:
true if visible
See also:
setVisible(), show(), hide()
void QwtPlotItem::itemChanged () [virtual] Update the legend and call QwtPlot::autoRefresh for the parent
plot.
See also:
updateLegend()
QWidget * QwtPlotItem::legendItem () const [virtual]
Allocate the widget that represents the item on the legend. The default implementation returns a
QwtLegendItem(), but an item could be represented by any type of widget, by overloading legendItem() and
updateLegend().
Returns:
QwtLegendItem()
See also:
updateLegend() QwtLegend()
Implements QwtLegendItemManager.
QRectF QwtPlotItem::paintRect (const QwtScaleMap &xMap, const QwtScaleMap &yMap) const
Calculate the bounding paint rect of 2 maps. Parameters:
xMap X map
yMap X map
Returns:
Bounding paint rect of the scale maps, normalized
QwtPlot * QwtPlotItem::plot () const
Return attached plot.
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, QwtPlotGrid, QwtPlotHistogram, QwtPlotIntervalCurve, QwtPlotMarker,
QwtPlotScaleItem, QwtPlotSpectroCurve, QwtPlotSpectrogram, and QwtPlotSvgItem.
QRectF QwtPlotItem::scaleRect (const QwtScaleMap &xMap, const QwtScaleMap &yMap) const
Calculate the bounding scale rect of 2 maps. Parameters:
xMap X map
yMap X map
Returns:
Bounding scale rect of the scale maps, normalized
void QwtPlotItem::setAxes (intxAxis, intyAxis) Set X and Y axis
The item will painted according to the coordinates its Axes.
Parameters:
xAxis X Axis
yAxis Y Axis
See also:
setXAxis(), setYAxis(), xAxis(), yAxis()
void QwtPlotItem::setItemAttribute (ItemAttributeattribute, boolon = true) Toggle an item attribute
Parameters:
attribute Attribute type
on true/false
See also:
testItemAttribute(), ItemAttribute
void QwtPlotItem::setRenderHint (RenderHinthint, boolon = true) Toggle an render hint
Parameters:
hint Render hint
on true/false
See also:
testRenderHint(), RenderHint
void QwtPlotItem::setTitle (const QString &title) Set a new title
Parameters:
title Title
See also:
title()
void QwtPlotItem::setTitle (const QwtText &title) Set a new title
Parameters:
title Title
See also:
title()
void QwtPlotItem::setVisible (boolon) [virtual] Show/Hide the item
Parameters:
on Show if true, otherwise hide
See also:
isVisible(), show(), hide()
void QwtPlotItem::setXAxis (intaxis) Set the X axis
The item will painted according to the coordinates its Axes.
Parameters:
axis X Axis
See also:
setAxes(), setYAxis(), xAxis()
void QwtPlotItem::setYAxis (intaxis) Set the Y axis
The item will painted according to the coordinates its Axes.
Parameters:
axis Y Axis
See also:
setAxes(), setXAxis(), yAxis()
void QwtPlotItem::setZ (doublez)
Set the z value. Plot items are painted in increasing z-order.
Parameters:
z Z-value
See also:
z(), QwtPlotDict::itemList()
void QwtPlotItem::show ()
Show the item.
bool QwtPlotItem::testItemAttribute (ItemAttributeattribute) const Test an item attribute
Parameters:
attribute Attribute type
Returns:
true/false
See also:
setItemAttribute(), ItemAttribute
bool QwtPlotItem::testRenderHint (RenderHinthint) const Test a render hint
Parameters:
hint Render hint
Returns:
true/false
See also:
setRenderHint(), RenderHint
const QwtText & QwtPlotItem::title () const Returns:
Title of the item
See also:
setTitle()
void QwtPlotItem::updateLegend (QwtLegend *legend) const [virtual]
Update the widget that represents the item on the legend. updateLegend() is called from itemChanged() to
adopt the widget representing the item on the legend to its new configuration.
The default implementation updates a QwtLegendItem(), but an item could be represented by any type of
widget, by overloading legendItem() and updateLegend().
Parameters:
legend Legend
See also:
legendItem(), itemChanged(), QwtLegend()
Implements QwtLegendItemManager.
Reimplemented in QwtPlotCurve, and QwtPlotMarker.
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()
Parameters:
xScaleDiv Scale division of the x-axis
yScaleDiv Scale division of the y-axis
See also:
QwtPlot::updateAxes()
Reimplemented in QwtPlotGrid, QwtPlotScaleItem, QwtPlotSeriesItem< T >, QwtPlotSeriesItem<
QwtIntervalSample >, QwtPlotSeriesItem< QPointF >, and QwtPlotSeriesItem< QwtPoint3D >.
int QwtPlotItem::xAxis () const
Return xAxis.
int QwtPlotItem::yAxis () const
Return yAxis.
double QwtPlotItem::z () const Plot items are painted in increasing z-order.
Returns:
setZ(), QwtPlotDict::itemList()
Author
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