Abstract base class for legend widgets.  
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#include <qwt_abstract_legend.h>
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 
  
  | 
        
          | QwtAbstractLegend::QwtAbstractLegend | ( | QWidget * | parent = NULL | ) |  |  | explicit | 
 
 
  
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          | virtual bool QwtAbstractLegend::isEmpty | ( |  | ) | const |  | pure virtual | 
 
- Returns
- True, when no plot item is inserted 
Implemented in QwtLegend.
 
 
  
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          | 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.
 
 
  
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          | int QwtAbstractLegend::scrollExtent | ( | Qt::Orientation | orientation | ) | const |  | virtual | 
 
Return the extent, that is needed for elements to scroll the legend ( usually scrollbars ),
- Parameters
- 
  
  
- Returns
- Extent of the corresponding scroll element 
Reimplemented in QwtLegend.
 
 
  
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          | virtual void QwtAbstractLegend::updateLegend | ( | const QVariant & | itemInfo, |  
          |  |  | const QList< QwtLegendData > & | data |  
          |  | ) |  |  |  | pure virtualslot | 
 
Update the entries for a plot item. 
- Parameters
- 
  
    | itemInfo | Info about an item |  | data | List of legend entry attributes for the item |