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QwtAbstractLegend(3) Qwt User's Guide QwtAbstractLegend(3)

NAME

QwtAbstractLegend - Abstract base class for legend widgets.

SYNOPSIS

#include <qwt_abstract_legend.h>

Inherits QFrame.

Inherited by QwtLegend.

Public Slots


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

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 (QWidget * parent = NULL) [explicit]

Constructor

Parameters

parent Parent widget

Definition at line 18 of file qwt_abstract_legend.cpp.

Member Function Documentation

virtual bool QwtAbstractLegend::isEmpty () const [pure virtual]

Returns

True, when no plot item is inserted

Implemented in QwtLegend.

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

Render the legend into a given rectangle.

Parameters

painter Painter
rect Bounding rectangle
fillBackground When true, fill rect with the widget background

See also

renderLegend() is used by QwtPlotRenderer

Implemented in QwtLegend.

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

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

Parameters

orientation Orientation

Returns

Extent of the corresponding scroll element

Reimplemented in QwtLegend.

Definition at line 35 of file qwt_abstract_legend.cpp.

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

Update the entries for a plot item.

Parameters

itemInfo Info about an item
data List of legend entry attributes for the item

Author

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Sun Jul 18 2021 Version 6.2.0