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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