QwtPlotLegendItem - A class which draws a legend inside the plot canvas.

NAME

QwtPlotLegendItem − A class which draws a legend inside the plot canvas.

SYNOPSIS

#include <qwt_plot_legenditem.h>

Inherits QwtPlotItem.

Public Types

enum BackgroundMode { LegendBackground, ItemBackground }
Background mode.

Public Types inherited from QwtPlotItem

enum RttiValues { Rtti_PlotItem = 0, Rtti_PlotGrid, Rtti_PlotScale, Rtti_PlotLegend, Rtti_PlotMarker, Rtti_PlotCurve, Rtti_PlotSpectroCurve, Rtti_PlotIntervalCurve, Rtti_PlotHistogram, Rtti_PlotSpectrogram, Rtti_PlotGraphic, Rtti_PlotTradingCurve, Rtti_PlotBarChart, Rtti_PlotMultiBarChart, Rtti_PlotShape, Rtti_PlotTextLabel, Rtti_PlotZone, Rtti_PlotVectorField, Rtti_PlotUserItem = 1000 }
Runtime type information.
enum ItemAttribute { Legend = 0x01, AutoScale = 0x02, Margins = 0x04 }
Plot Item Attributes.
enum ItemInterest { ScaleInterest = 0x01, LegendInterest = 0x02 }
Plot Item Interests.
enum RenderHint { RenderAntialiased = 0x1 }
Render hints.
typedef QFlags< ItemAttribute > ItemAttributes
typedef QFlags< ItemInterest > ItemInterests
typedef QFlags< RenderHint > RenderHints

Public Member Functions

QwtPlotLegendItem ()
Constructor.
virtual ˜QwtPlotLegendItem ()
Destructor.
virtual int rtti () const override
void setAlignmentInCanvas (Qt::Alignment)
Set the alignmnet.
Qt::Alignment alignmentInCanvas () const
void setOffsetInCanvas (Qt::Orientations, int numPixels)
Set the distance between the legend and the canvas border.
int offsetInCanvas (Qt::Orientation) const
void setMaxColumns (uint)
Limit the number of columns.
uint maxColumns () const
void setMargin (int)
Set the margin around legend items.
int margin () const
void setSpacing (int)
Set the spacing between the legend items.
int spacing () const
void setItemMargin (int)
int itemMargin () const
void setItemSpacing (int)
int itemSpacing () const
void setFont (const QFont &)
QFont font () const
void setBorderRadius (double)
double borderRadius () const
void setBorderPen (const QPen &)
QPen borderPen () const
void setBackgroundBrush (const QBrush &)
Set the background brush.
QBrush backgroundBrush () const
void setBackgroundMode (BackgroundMode)
Set the background mode.
BackgroundMode backgroundMode () const
void setTextPen (const QPen &)
Set the pen for drawing text labels.
QPen textPen () const
virtual void draw (QPainter *, const QwtScaleMap &xMap, const QwtScaleMap &yMap, const QRectF &canvasRect) const override
void clearLegend ()
Remove all items from the legend.
virtual void updateLegend (const QwtPlotItem *, const QList< QwtLegendData > &) override
virtual QRect geometry (const QRectF &canvasRect) const
virtual QSize minimumSize (const QwtLegendData &) const
virtual int heightForWidth (const QwtLegendData &, int width) const
QList< const QwtPlotItem * > plotItems () const
QList< QRect > legendGeometries (const QwtPlotItem *) const

Public Member Functions inherited from QwtPlotItem

QwtPlotItem ()
QwtPlotItem (const QString &title)
QwtPlotItem (const QwtText &title)
virtual ˜QwtPlotItem ()
Destroy the QwtPlotItem.
void attach (QwtPlot *plot)
Attach the item to a plot.
void detach ()
This method detaches a QwtPlotItem from any QwtPlot it has been associated with.
QwtPlot * plot () const
Return attached plot.
void setTitle (const QString &title)
void setTitle (const QwtText &title)
const QwtText & title () const
void setItemAttribute (ItemAttribute, bool on=true)
bool testItemAttribute (ItemAttribute) const
void setItemInterest (ItemInterest, bool on=true)
bool testItemInterest (ItemInterest) const
void setRenderHint (RenderHint, bool on=true)
bool testRenderHint (RenderHint) const
void setRenderThreadCount (uint numThreads)
uint renderThreadCount () const
void setLegendIconSize (const QSize &)
QSize legendIconSize () const
double z () const
void setZ (double z)
Set the z value.
void show ()
Show the item.
void hide ()
Hide the item.
virtual void setVisible (bool)
bool isVisible () const
void setAxes (QwtAxisId xAxis, QwtAxisId yAxis)
void setXAxis (QwtAxisId)
QwtAxisId xAxis () const
Return xAxis.
void setYAxis (QwtAxisId)
QwtAxisId yAxis () const
Return yAxis.
virtual void itemChanged ()
virtual void legendChanged ()
virtual QRectF boundingRect () const
virtual void getCanvasMarginHint (const QwtScaleMap &xMap, const QwtScaleMap &yMap, const QRectF &canvasRect, double &left, double &top, double &right, double &bottom) const
Calculate a hint for the canvas margin.
virtual void updateScaleDiv (const QwtScaleDiv &, const QwtScaleDiv &)
Update the item to changes of the axes scale division.
QRectF scaleRect (const QwtScaleMap &, const QwtScaleMap &) const
Calculate the bounding scale rectangle of 2 maps.
QRectF paintRect (const QwtScaleMap &, const QwtScaleMap &) const
Calculate the bounding paint rectangle of 2 maps.
virtual QList< QwtLegendData > legendData () const
Return all information, that is needed to represent the item on the legend.
virtual QwtGraphic legendIcon (int index, const QSizeF &) const

Protected Member Functions

virtual void drawLegendData (QPainter *, const QwtPlotItem *, const QwtLegendData &, const QRectF &) const
virtual void drawBackground (QPainter *, const QRectF &rect) const

Protected Member Functions inherited from QwtPlotItem

QwtGraphic defaultIcon (const QBrush &, const QSizeF &) const
Return a default icon from a brush.

Detailed Description

A class which draws a legend inside the plot canvas.

QwtPlotLegendItem can be used to draw a inside the plot canvas. It can be used together with a QwtLegend or instead of it to have more space for the plot canvas.

In opposite to QwtLegend the legend item is not interactive. To identify mouse clicks on a legend item an event filter needs to be installed catching mouse events ob the plot canvas. The geometries of the legend items are available using legendGeometries().

The legend item is aligned to plot canvas according to its alignment() flags. It might have a background for the complete legend ( usually semi transparent ) or for each legend item.

Note

An external QwtLegend with a transparent background on top the plot canvas might be another option with a similar effect.

Definition at line 41 of file qwt_plot_legenditem.h.

Member Enumeration Documentation

enum QwtPlotLegendItem::BackgroundMode

Background mode. Depending on the mode the complete legend or each item might have an background.

The default setting is LegendBackground.

See also

setBackgroundMode(), setBackgroundBrush(), drawBackground()

Enumerator
LegendBackground

The legend has a background.

ItemBackground

Each item has a background.

Definition at line 54 of file qwt_plot_legenditem.h.

Constructor & Destructor Documentation

QwtPlotLegendItem::QwtPlotLegendItem () [explicit]

Constructor.

Definition at line 175 of file qwt_plot_legenditem.cpp.

QwtPlotLegendItem::˜QwtPlotLegendItem () [virtual]

void QwtPlotLegendItem::draw (QPainter * painter, const QwtScaleMap & xMap,const QwtScaleMap & yMap, const QRectF & canvasRect) const [override],[virtual]

Draw the legend

Parameters

painter Painter
xMap x Scale Map
yMap y Scale Map
canvasRect Contents rectangle of the canvas in painter coordinates

Implements QwtPlotItem.

Definition at line 587 of file qwt_plot_legenditem.cpp.

void QwtPlotLegendItem::drawBackground (QPainter * painter, const QRectF &rect) const [protected], [virtual]

Draw a rounded rect

Parameters

painter Painter
rect Bounding rectangle

See also

setBorderRadius(), setBorderPen(), setBackgroundBrush(), setBackgroundMode()

Definition at line 630 of file qwt_plot_legenditem.cpp.

void QwtPlotLegendItem::drawLegendData (QPainter * painter, constQwtPlotItem * plotItem, const QwtLegendData & data, const QRectF &rect) const [protected], [virtual]

Draw an entry on the legend

Parameters

painter Qt Painter
plotItem Plot item, represented by the entry
data Attributes of the legend entry
rect Bounding rectangle for the entry

Definition at line 780 of file qwt_plot_legenditem.cpp.

QFont QwtPlotLegendItem::font () const

Returns

Font used for drawing the text label

See also

setFont()

Definition at line 389 of file qwt_plot_legenditem.cpp.

QRect QwtPlotLegendItem::geometry (const QRectF & canvasRect) const[virtual]

Calculate the geometry of the legend on the canvas

int QwtPlotLegendItem::offsetInCanvas (Qt::Orientation orientation) const

Parameters

orientation Qt::Horizontal is for the left/right, Qt::Vertical for the top/bottom padding.

Returns

Distance between the legend and the canvas border

See also

setOffsetInCanvas()

Definition at line 444 of file qwt_plot_legenditem.cpp.

QList< const QwtPlotItem * > QwtPlotLegendItem::plotItems () const

Returns

All plot items with an entry on the legend

Note

A plot item might have more than one entry on the legend

Definition at line 886 of file qwt_plot_legenditem.cpp.

int QwtPlotLegendItem::rtti () const [override], [virtual]

Returns

QwtPlotItem::Rtti_PlotLegend

Reimplemented from QwtPlotItem.

Definition at line 192 of file qwt_plot_legenditem.cpp.

void QwtPlotLegendItem::setAlignmentInCanvas (Qt::Alignment alignment)

Set the alignmnet. Alignment means the position of the legend relative to the geometry of the plot canvas.

Parameters

alignment Alignment flags

See also

alignmentInCanvas(), setMaxColumns()

Note

To align a legend with many items horizontally the number of columns need to be limited

Definition at line 210 of file qwt_plot_legenditem.cpp.

void QwtPlotLegendItem::setBackgroundBrush (const QBrush & brush)

Set the background brush. The brush is used to fill the background

Parameters

brush Brush

See also

backgroundBrush(), setBackgroundMode(), drawBackground()

Definition at line 509 of file qwt_plot_legenditem.cpp.

Returns

Spacing between the legend items

See also

setSpacing(), margin(), itemSpacing(), itemMargin()

Definition at line 308 of file qwt_plot_legenditem.cpp.

QPen QwtPlotLegendItem::textPen () const

Returns

Pen for drawing text labels

See also

setTextPen(), font()

Definition at line 574 of file qwt_plot_legenditem.cpp.

void QwtPlotLegendItem::updateLegend (const QwtPlotItem * plotItem, constQList< QwtLegendData > & data) [override], [virtual]

Update the legend items according to modifications of a plot item

Parameters

plotItem Plot item
data Attributes of the legend entries

Reimplemented from QwtPlotItem.

Definition at line 697 of file qwt_plot_legenditem.cpp.

Author

Generated automatically by Doxygen for Qwt User’s Guide from the source code.

Updated 2026-06-01 - jenkler.se | uex.se