Qwt User's Guide  6.2.0
QwtAbstractLegend Class Referenceabstract

Abstract base class for legend widgets. More...

#include <qwt_abstract_legend.h>

Inheritance diagram for QwtAbstractLegend:

Public Slots

virtual void updateLegend (const QVariant &itemInfo, const QList< QwtLegendData > &data)=0
 Update the entries for a plot item. More...
 

Public Member Functions

 QwtAbstractLegend (QWidget *parent=NULL)
 
virtual ~QwtAbstractLegend ()
 Destructor.
 
virtual void renderLegend (QPainter *painter, const QRectF &rect, bool fillBackground) const =0
 
virtual bool isEmpty () const =0
 
virtual int scrollExtent (Qt::Orientation) const
 

Detailed Description

Abstract base class for legend widgets.

Legends, that need to be under control of the QwtPlot layout system need to be derived from QwtAbstractLegend.

Note
Other type of legends can be implemented by connecting to the QwtPlot::legendDataChanged() signal. But as these legends are unknown to the plot layout system the layout code ( on screen and for QwtPlotRenderer ) need to be organized in application code.
See also
QwtLegend

Definition at line 34 of file qwt_abstract_legend.h.

Constructor & Destructor Documentation

◆ QwtAbstractLegend()

QwtAbstractLegend::QwtAbstractLegend ( QWidget *  parent = NULL)
explicit

Constructor

Parameters
parentParent widget

Definition at line 18 of file qwt_abstract_legend.cpp.

Member Function Documentation

◆ isEmpty()

virtual bool QwtAbstractLegend::isEmpty ( ) const
pure virtual
Returns
True, when no plot item is inserted

Implemented in QwtLegend.

◆ renderLegend()

virtual void QwtAbstractLegend::renderLegend ( QPainter *  painter,
const QRectF &  rect,
bool  fillBackground 
) const
pure virtual

Render the legend into a given rectangle.

Parameters
painterPainter
rectBounding rectangle
fillBackgroundWhen true, fill rect with the widget background
See also
renderLegend() is used by QwtPlotRenderer

Implemented in QwtLegend.

◆ scrollExtent()

int QwtAbstractLegend::scrollExtent ( Qt::Orientation  orientation) const
virtual

Return the extent, that is needed for elements to scroll the legend ( usually scrollbars ),

Parameters
orientationOrientation
Returns
Extent of the corresponding scroll element

Reimplemented in QwtLegend.

Definition at line 35 of file qwt_abstract_legend.cpp.

◆ updateLegend

virtual void QwtAbstractLegend::updateLegend ( const QVariant &  itemInfo,
const QList< QwtLegendData > &  data 
)
pure virtualslot

Update the entries for a plot item.

Parameters
itemInfoInfo about an item
dataList of legend entry attributes for the item