Provided by: libqwt5-doc_5.2.3-1_all 
NAME
QwtPlotItem -
SYNOPSIS
#include <qwt_plot_item.h>
Inherits QwtLegendItemManager.
Inherited by QwtPlotCurve, QwtPlotGrid, QwtPlotMarker, QwtPlotRasterItem,
QwtPlotScaleItem, and QwtPlotSvgItem.
Public Types
enum ItemAttribute { Legend = 1, AutoScale = 2 }
enum RenderHint { RenderAntialiased = 1 }
enum RttiValues { Rtti_PlotItem = 0, Rtti_PlotGrid, Rtti_PlotScale, Rtti_PlotMarker,
Rtti_PlotCurve, Rtti_PlotHistogram, Rtti_PlotSpectrogram, Rtti_PlotSVG,
Rtti_PlotUserItem = 1000 }
Public Member Functions
QwtPlotItem (const QwtText &title=QwtText())
virtual ~QwtPlotItem ()
void attach (QwtPlot *plot)
virtual QwtDoubleRect boundingRect () const
void detach ()
virtual void draw (QPainter *painter, const QwtScaleMap &xMap, const QwtScaleMap &yMap,
const QRect &canvasRect) const =0
void hide ()
QwtDoubleRect invTransform (const QwtScaleMap &, const QwtScaleMap &, const QRect &) const
bool isVisible () const
virtual void itemChanged ()
virtual QWidget * legendItem () const
QRect paintRect (const QwtScaleMap &, const QwtScaleMap &) const
QwtPlot * plot () const
virtual int rtti () const
QwtDoubleRect scaleRect (const QwtScaleMap &, const QwtScaleMap &) const
void setAxis (int xAxis, int yAxis)
void setItemAttribute (ItemAttribute, bool on=true)
void setRenderHint (RenderHint, bool on=true)
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)
void show ()
bool testItemAttribute (ItemAttribute) const
bool testRenderHint (RenderHint) const
const QwtText & title () const
QRect transform (const QwtScaleMap &, const QwtScaleMap &, const QwtDoubleRect &) const
virtual void updateLegend (QwtLegend *) const
virtual void updateScaleDiv (const QwtScaleDiv &, const QwtScaleDiv &)
int xAxis () const
int yAxis () const
double z () 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 Enumeration Documentation
enum QwtPlotItem::ItemAttribute
Plot Item Attributes
• Legend
The item is represented on the legend.
• AutoScale
The boundingRect() of the item is included in the autoscaling calculation.
See also:
setItemAttribute(), testItemAttribute()
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
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:
QwtPlotItem::detach()
QwtDoubleRect QwtPlotItem::boundingRect () const [virtual]
Returns:
An invalid bounding rect: QwtDoubleRect(1.0, 1.0, -2.0, -2.0)
Reimplemented in QwtPlotCurve, QwtPlotMarker, QwtPlotSpectrogram, and QwtPlotSvgItem.
void QwtPlotItem::detach () [inline]
This method detaches a QwtPlotItem from any QwtPlot it has been associated with. detach()
is equivalent to calling attach( NULL )
See also:
attach( QwtPlot* plot )
virtual void QwtPlotItem::draw (QPainter *painter, const QwtScaleMap &xMap, const QwtScaleMap
&yMap, const QRect &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 QwtPlotCurve, QwtPlotMarker, QwtPlotScaleItem, QwtPlotSpectrogram,
QwtPlotRasterItem, QwtPlotGrid, and QwtPlotSvgItem.
QwtDoubleRect QwtPlotItem::invTransform (const QwtScaleMap &xMap, const QwtScaleMap &yMap,
const QRect &rect) const
Transform a rectangle from paint to scale coordinates
Parameters:
xMap X map
yMap Y map
rect Rectangle in paint coordinates
Returns:
Rectangle in scale coordinates
See also:
transform()
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 is
made for QwtPlotCurve and 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.
QRect 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 rect of the scale maps
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, QwtPlotSpectrogram, QwtPlotMarker, QwtPlotScaleItem,
QwtPlotSvgItem, and QwtPlotGrid.
QwtDoubleRect 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 rect of the scale maps
void QwtPlotItem::setAxis (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:
setAxis(), 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:
setAxis(), 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()
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()
QRect QwtPlotItem::transform (const QwtScaleMap &xMap, const QwtScaleMap &yMap, const
QwtDoubleRect &rect) const
Transform a rectangle
Parameters:
xMap X map
yMap Y map
rect Rectangle in scale coordinates
Returns:
Rectangle in paint coordinates
See also:
invTransform()
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 is made for QwtPlotCurve and 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.
void QwtPlotItem::updateScaleDiv (const QwtScaleDiv &, const QwtScaleDiv &) [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 QwtPlotScaleItem, and QwtPlotGrid.
double QwtPlotItem::z () const
Plot items are painted in increasing z-order.
Returns:
setZ(), QwtPlotDict::itemList()
Author
Generated automatically by Doxygen for Qwt User's Guide from the source code.