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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

Constructor & Destructor Documentation

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

Constructor

Parameters:

parent Parent widget

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.

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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Wed Jan 2 2019 Version 6.1.4