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

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

#include <qwt_plot_legenditem.h>

Inherits QwtPlotItem.


enum BackgroundMode { LegendBackground, ItemBackground }
Background mode.


QwtPlotLegendItem ()
Constructor. virtual ~QwtPlotLegendItem ()
Destructor. virtual int rtti () const
void setAlignment (Qt::Alignment)
Set the alignmnet. Qt::Alignment alignment () 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 setBorderDistance (int)
Set the margin between the legend and the canvas border. int borderDistance () 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
void clearLegend ()
Remove all items from the legend. virtual void updateLegend (const QwtPlotItem *, const QList< QwtLegendData > &)
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


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

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.

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

The legend has a background.
Each item has a background.

Returns:

Alignment flags

See also:

setAlignment()

Returns:

Brush is used to fill the background

See also:

setBackgroundBrush(), backgroundMode(), drawBackground()

QwtPlotLegendItem::BackgroundMode QwtPlotLegendItem::backgroundMode () const

Returns:

backgroundMode

See also:

setBackgroundMode(), backgroundBrush(), drawBackground()

Returns:

Margin between the legend and the canvas border

See also:

margin()

Returns:

Pen for drawing the border

See also:

setBorderPen(), backgroundBrush()

Returns:

Radius of the border

See also:

setBorderRadius(), setBorderPen()

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.

Draw a rounded rect

Parameters:

painter Painter
rect Bounding rectangle

See also:

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

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

Returns:

Font used for drawing the text label

See also:

setFont()

Calculate the geometry of the legend on the canvas

Parameters:

canvasRect Geometry of the canvas

Returns:

Geometry of the legend

Returns:

The preferred height, for a width.

Parameters:

data Attributes of the legend entry
width Width

Returns:

Margin around each item

See also:

setItemMargin(), itemSpacing(), margin(), spacing()

Returns:

Spacing inside of each item

See also:

setItemSpacing(), itemMargin(), margin(), spacing()

Returns:

Geometries of the items of a plot item

Note:

Usually a plot item has only one entry on the legend

Returns:

Margin around the legend items

See also:

setMargin(), spacing(), itemMargin(), itemSpacing()

Returns:

Maximum number of columns

See also:

maxColumns(), QwtDynGridLayout::maxColumns()

Minimum size hint needed to display an entry

Parameters:

data Attributes of the legend entry

Returns:

Minimum size

Returns:

All plot items with an entry on the legend

Note:

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

Returns:

QwtPlotItem::Rtti_PlotLegend

Reimplemented from QwtPlotItem.

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

Parameters:

alignment Alignment flags

See also:

alignment(), setMaxColumns()

Note:

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

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

Parameters:

brush Brush

See also:

backgroundBrush(), setBackgroundMode(), drawBackground()

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

The default setting is LegendBackground.

See also:

backgroundMode(), setBackgroundBrush(), drawBackground()

Set the margin between the legend and the canvas border. The default setting for the margin is 10 pixels.

Parameters:

distance Margin in pixels

See also:

setMargin()

Set the pen for drawing the border

Parameters:

pen Border pen

See also:

borderPen(), setBackgroundBrush()

Set the radius for the border

Parameters:

radius A value <= 0 defines a rectangular border

See also:

borderRadius(), setBorderPen()

Change the font used for drawing the text label

Parameters:

font Legend font

See also:

font()

Set the margin around each item

Parameters:

margin Margin

See also:

itemMargin(), setItemSpacing(), setMargin(), setSpacing()

Set the spacing inside of each item

Parameters:

spacing Spacing

See also:

itemSpacing(), setItemMargin(), setMargin(), setSpacing()

Set the margin around legend items. The default setting for the margin is 0.

Parameters:

margin Margin in pixels

See also:

margin(), setSpacing(), setItemMargin(), setItemSpacing

Limit the number of columns. When aligning the legend horizontally ( Qt::AlignLeft, Qt::AlignRight ) the number of columns needs to be limited to avoid, that the width of the legend grows with an increasing number of entries.

Parameters:

maxColumns Maximum number of columns. 0 means unlimited.

See also:

maxColumns(), QwtDynGridLayout::setMaxColumns()

Set the spacing between the legend items.

Parameters:

spacing Spacing in pixels

See also:

spacing(), setMargin()

Set the pen for drawing text labels.

Parameters:

pen Text pen

See also:

textPen(), setFont()

Returns:

Spacing between the legend items

See also:

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

Returns:

Pen for drawing text labels

See also:

setTextPen(), font()

Update the legend items according to modifications of a plot item

Parameters:

plotItem Plot item
data Attributes of the legend entries

Reimplemented from QwtPlotItem.

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Wed Jan 2 2019 Version 6.1.4