QwtPlotItem Class Reference

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

#include <qwt_plot_item.h>

Inheritance diagram for QwtPlotItem:
Inheritance graph
[legend]

List of all members.

Public Types

enum  RttiValues {
  Rtti_PlotItem = 0,
  Rtti_PlotGrid,
  Rtti_PlotScale,
  Rtti_PlotMarker,
  Rtti_PlotCurve,
  Rtti_PlotHistogram,
  Rtti_PlotSpectrogram,
  Rtti_PlotSVG,
  Rtti_PlotUserItem = 1000
}
enum  ItemAttribute {
  Legend = 1,
  AutoScale = 2
}
enum  RenderHint { RenderAntialiased = 1 }

Public Member Functions

 QwtPlotItem (const QwtText &title=QwtText())
virtual ~QwtPlotItem ()
void attach (QwtPlot *plot)
void detach ()
QwtPlotplot () const
void setTitle (const QString &title)
void setTitle (const QwtText &title)
const QwtTexttitle () 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 setAxis (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 QRect &canvasRect) const =0
virtual QwtDoubleRect boundingRect () const
virtual void updateLegend (QwtLegend *) const
virtual void updateScaleDiv (const QwtScaleDiv &, const QwtScaleDiv &)
virtual QWidget * legendItem () const
QwtDoubleRect scaleRect (const QwtScaleMap &, const QwtScaleMap &) const
QRect paintRect (const QwtScaleMap &, const QwtScaleMap &) const
QRect transform (const QwtScaleMap &, const QwtScaleMap &, const QwtDoubleRect &) const
QwtDoubleRect invTransform (const QwtScaleMap &, const QwtScaleMap &, const QRect &) 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:

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

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()

Render hints.

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:
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, QwtPlotGrid, QwtPlotMarker, QwtPlotRasterItem, QwtPlotScaleItem, QwtPlotSpectrogram, and QwtPlotSvgItem.

void QwtPlotItem::hide (  ) 

Hide the item.

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
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, QwtPlotMarker, QwtPlotScaleItem, QwtPlotSpectrogram, and QwtPlotSvgItem.

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 ( int  xAxis,
int  yAxis 
)

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 ( ItemAttribute  attribute,
bool  on = true 
)

Toggle an item attribute

Parameters:
attribute Attribute type
on true/false
See also:
testItemAttribute(), ItemAttribute
void QwtPlotItem::setRenderHint ( RenderHint  hint,
bool  on = true 
)

Toggle an render hint

Parameters:
hint Render hint
on true/false
See also:
testRenderHint(), RenderHint
void QwtPlotItem::setTitle ( const QwtText title  ) 

Set a new title

Parameters:
title Title
See also:
title()
void QwtPlotItem::setTitle ( const QString &  title  ) 

Set a new title

Parameters:
title Title
See also:
title()
void QwtPlotItem::setVisible ( bool  on  )  [virtual]

Show/Hide the item

Parameters:
on Show if true, otherwise hide
See also:
isVisible(), show(), hide()
void QwtPlotItem::setXAxis ( int  axis  ) 

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 ( int  axis  ) 

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 ( double  z  ) 

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 ( ItemAttribute  attribute  )  const

Test an item attribute

Parameters:
attribute Attribute type
Returns:
true/false
See also:
setItemAttribute(), ItemAttribute
bool QwtPlotItem::testRenderHint ( RenderHint  hint  )  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 QwtPlotGrid, and QwtPlotScaleItem.

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()
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