QwtPlotLegendItem - Man Page

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 Member Functions

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

Protected Member Functions

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

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.

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.

Member Function Documentation

Qt::Alignment QwtPlotLegendItem::alignment () const

Returns

Alignment flags

See also

setAlignment()

QBrush QwtPlotLegendItem::backgroundBrush () const

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()

int QwtPlotLegendItem::borderDistance () const

Returns

Margin between the legend and the canvas border

See also

margin()

QPen QwtPlotLegendItem::borderPen () const

Returns

Pen for drawing the border

See also

setBorderPen(), backgroundBrush()

double QwtPlotLegendItem::borderRadius () const

Returns

Radius of the border

See also

setBorderRadius(), setBorderPen()

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

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()

void QwtPlotLegendItem::drawLegendData (QPainter * painter, const QwtPlotItem * 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

QFont QwtPlotLegendItem::font () const

Returns

Font used for drawing the text label

See also

setFont()

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

Calculate the geometry of the legend on the canvas

Parameters

canvasRect Geometry of the canvas

Returns

Geometry of the legend

int QwtPlotLegendItem::heightForWidth (const QwtLegendData & data, int width) const [virtual]

Returns

The preferred height, for a width.

Parameters

data Attributes of the legend entry
width Width

int QwtPlotLegendItem::itemMargin () const

Returns

Margin around each item

See also

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

int QwtPlotLegendItem::itemSpacing () const

Returns

Spacing inside of each item

See also

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

QList< QRect > QwtPlotLegendItem::legendGeometries (const QwtPlotItem * plotItem) const

Returns

Geometries of the items of a plot item

Note

Usually a plot item has only one entry on the legend

int QwtPlotLegendItem::margin () const

Returns

Margin around the legend items

See also

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

uint QwtPlotLegendItem::maxColumns () const

Returns

Maximum number of columns

See also

maxColumns(), QwtDynGridLayout::maxColumns()

QSize QwtPlotLegendItem::minimumSize (const QwtLegendData & data) const [virtual]

Minimum size hint needed to display an entry

Parameters

data Attributes of the legend entry

Returns

Minimum size

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

int QwtPlotLegendItem::rtti () const [virtual]

Returns

QwtPlotItem::Rtti_PlotLegend

Reimplemented from QwtPlotItem.

void QwtPlotLegendItem::setAlignment (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

alignment(), setMaxColumns()

Note

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

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()

void QwtPlotLegendItem::setBackgroundMode (BackgroundMode mode)

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()

void QwtPlotLegendItem::setBorderDistance (int distance)

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()

void QwtPlotLegendItem::setBorderPen (const QPen & pen)

Set the pen for drawing the border

Parameters

pen Border pen

See also

borderPen(), setBackgroundBrush()

void QwtPlotLegendItem::setBorderRadius (double radius)

Set the radius for the border

Parameters

radius A value <= 0 defines a rectangular border

See also

borderRadius(), setBorderPen()

void QwtPlotLegendItem::setFont (const QFont & font)

Change the font used for drawing the text label

Parameters

font Legend font

See also

font()

void QwtPlotLegendItem::setItemMargin (int margin)

Set the margin around each item

Parameters

margin Margin

See also

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

void QwtPlotLegendItem::setItemSpacing (int spacing)

Set the spacing inside of each item

Parameters

spacing Spacing

See also

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

void QwtPlotLegendItem::setMargin (int margin)

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

void QwtPlotLegendItem::setMaxColumns (uint maxColumns)

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()

void QwtPlotLegendItem::setSpacing (int spacing)

Set the spacing between the legend items.

Parameters

spacing Spacing in pixels

See also

spacing(), setMargin()

void QwtPlotLegendItem::setTextPen (const QPen & pen)

Set the pen for drawing text labels.

Parameters

pen Text pen

See also

textPen(), setFont()

int QwtPlotLegendItem::spacing () const

Returns

Spacing between the legend items

See also

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

QPen QwtPlotLegendItem::textPen () const

Returns

Pen for drawing text labels

See also

setTextPen(), font()

void QwtPlotLegendItem::updateLegend (const QwtPlotItem * plotItem, const QList< QwtLegendData > & data) [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.

Author

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Info

Mon Jun 1 2020 Version 6.1.5 Qwt User's Guide