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

NAME

QwtLegend - The legend widget.

SYNOPSIS

#include <qwt_legend.h>

Inherits QwtAbstractLegend.

Public Slots


virtual void updateLegend (const QVariant &, const QList< QwtLegendData > &) override
Update the entries for an item.

Signals


void clicked (const QVariant &itemInfo, int index)
void checked (const QVariant &itemInfo, bool on, int index)

Public Member Functions


QwtLegend (QWidget *parent=NULL)
virtual ~QwtLegend ()
Destructor. void setMaxColumns (uint numColums)
Set the maximum number of entries in a row. uint maxColumns () const
void setDefaultItemMode (QwtLegendData::Mode)
Set the default mode for legend labels. QwtLegendData::Mode defaultItemMode () const
QWidget * contentsWidget ()
const QWidget * contentsWidget () const
QWidget * legendWidget (const QVariant &) const
QList< QWidget * > legendWidgets (const QVariant &) const
QVariant itemInfo (const QWidget *) const
virtual bool eventFilter (QObject *, QEvent *) override
virtual QSize sizeHint () const override
Return a size hint. virtual int heightForWidth (int w) const override
QScrollBar * horizontalScrollBar () const
QScrollBar * verticalScrollBar () const
virtual void renderLegend (QPainter *, const QRectF &, bool fillBackground) const override
virtual void renderItem (QPainter *, const QWidget *, const QRectF &, bool fillBackground) const
virtual bool isEmpty () const override
virtual int scrollExtent (Qt::Orientation) const override

Protected Slots


void itemClicked ()
void itemChecked (bool)

Protected Member Functions


virtual QWidget * createWidget (const QwtLegendData &) const
Create a widget to be inserted into the legend. virtual void updateWidget (QWidget *, const QwtLegendData &)
Update the widget.

Detailed Description

The legend widget.

The QwtLegend widget is a tabular arrangement of legend items. Legend items might be any type of widget, but in general they will be a QwtLegendLabel.

See also

QwtLegendLabel, QwtPlotItem, QwtPlot

Definition at line 31 of file qwt_legend.h.

Constructor & Destructor Documentation

QwtLegend::QwtLegend (QWidget * parent = NULL) [explicit]

Constructor

Parameters

parent Parent widget

Definition at line 258 of file qwt_legend.cpp.

Member Function Documentation

void QwtLegend::checked (const QVariant & itemInfo, bool on, int index) [signal]

A signal which is emitted when the user has clicked on a legend label, which is in QwtLegendData::Checkable mode

Parameters

itemInfo Info for the item of the selected legend label
index Index of the legend label in the list of widgets that are associated with the plot item
on True when the legend label is checked

Note

clicks are disabled as default

See also

setDefaultItemMode(), defaultItemMode(), QwtPlot::itemToInfo()

void QwtLegend::clicked (const QVariant & itemInfo, int index) [signal]

A signal which is emitted when the user has clicked on a legend label, which is in QwtLegendData::Clickable mode.

Parameters

itemInfo Info for the item item of the selected legend item
index Index of the legend label in the list of widgets that are associated with the plot item

Note

clicks are disabled as default

See also

setDefaultItemMode(), defaultItemMode(), QwtPlot::itemToInfo()

QWidget * QwtLegend::contentsWidget ()

The contents widget is the only child of the viewport of the internal QScrollArea and the parent widget of all legend items.

Returns

Container widget of the legend items

Definition at line 355 of file qwt_legend.cpp.

const QWidget * QwtLegend::contentsWidget () const

The contents widget is the only child of the viewport of the internal QScrollArea and the parent widget of all legend items.

Returns

Container widget of the legend items

Definition at line 385 of file qwt_legend.cpp.

QWidget * QwtLegend::createWidget (const QwtLegendData & legendData) const [protected], [virtual]

Create a widget to be inserted into the legend. The default implementation returns a QwtLegendLabel.

Parameters

legendData Attributes of the legend entry

Returns

Widget representing data on the legend

Note

updateWidget() will called soon after createWidget() with the same attributes.

Definition at line 467 of file qwt_legend.cpp.

QwtLegendData::Mode QwtLegend::defaultItemMode () const

Returns

Default item mode

See also

setDefaultItemMode()

Definition at line 344 of file qwt_legend.cpp.

bool QwtLegend::eventFilter (QObject * object, QEvent * event) [override], [virtual]

Handle QEvent::ChildRemoved and QEvent::LayoutRequest events for the contentsWidget().

Parameters

object Object to be filtered
event Event

Returns

Forwarded to QwtAbstractLegend::eventFilter()

Definition at line 559 of file qwt_legend.cpp.

int QwtLegend::heightForWidth (int width) const [override], [virtual]

Returns

The preferred height, for a width.

Parameters

width Width

Definition at line 538 of file qwt_legend.cpp.

QScrollBar * QwtLegend::horizontalScrollBar () const

Returns

Horizontal scrollbar

See also

verticalScrollBar()

Definition at line 364 of file qwt_legend.cpp.

bool QwtLegend::isEmpty () const [override], [virtual]

Returns

True, when no item is inserted

Implements QwtAbstractLegend.

Definition at line 810 of file qwt_legend.cpp.

void QwtLegend::itemChecked (bool on) [protected], [slot]

Called internally when the legend has been checked Emits a checked() signal.

Definition at line 638 of file qwt_legend.cpp.

void QwtLegend::itemClicked () [protected], [slot]

Called internally when the legend has been clicked on. Emits a clicked() signal.

Definition at line 616 of file qwt_legend.cpp.

QVariant QwtLegend::itemInfo (const QWidget * widget) const

Find the item that is associated to a widget

Parameters

widget Widget on the legend

Returns

Associated item info

See also

legendWidget()

Definition at line 804 of file qwt_legend.cpp.

QWidget * QwtLegend::legendWidget (const QVariant & itemInfo) const

Returns

First widget in the list of widgets associated to an item

Parameters

itemInfo Info about an item

See also

itemInfo(), QwtPlot::itemToInfo()

Note

Almost all types of items have only one widget

Definition at line 788 of file qwt_legend.cpp.

QList< QWidget * > QwtLegend::legendWidgets (const QVariant & itemInfo) const

Returns

List of widgets associated to a item

Parameters

itemInfo Info about an item

See also

legendWidget(), itemInfo(), QwtPlot::itemToInfo()

Definition at line 777 of file qwt_legend.cpp.

uint QwtLegend::maxColumns () const

Returns

Maximum number of entries in a row

See also

setMaxColumns(), QwtDynGridLayout::maxColumns()

Definition at line 310 of file qwt_legend.cpp.

void QwtLegend::renderItem (QPainter * painter, const QWidget * widget, const QRectF & rect, bool fillBackground) const [virtual]

Render a legend entry into a given rectangle.

Parameters

painter Painter
widget Widget representing a legend entry
rect Bounding rectangle
fillBackground When true, fill rect with the widget background

Note

When widget is not derived from QwtLegendLabel renderItem does nothing beside the background

Definition at line 727 of file qwt_legend.cpp.

void QwtLegend::renderLegend (QPainter * painter, const QRectF & rect, bool fillBackground) const [override], [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 - not by QwtLegend itself

Implements QwtAbstractLegend.

Definition at line 665 of file qwt_legend.cpp.

int QwtLegend::scrollExtent (Qt::Orientation orientation) const [override], [virtual]

Return the extent, that is needed for the scrollbars

Parameters

orientation Orientation

Returns

The width of the vertical scrollbar for Qt::Horizontal and v.v.

Reimplemented from QwtAbstractLegend.

Definition at line 821 of file qwt_legend.cpp.

void QwtLegend::setDefaultItemMode (QwtLegendData::Mode mode)

Set the default mode for legend labels. Legend labels will be constructed according to the attributes in a QwtLegendData object. When it doesn't contain a value for the QwtLegendData::ModeRole the label will be initialized with the default mode of the legend.

Parameters

mode Default item mode

See also

itemMode(), QwtLegendData::value(), QwtPlotItem::legendData()

Note

Changing the mode doesn't have any effect on existing labels.

Definition at line 335 of file qwt_legend.cpp.

void QwtLegend::setMaxColumns (uint numColums)

Set the maximum number of entries in a row. F.e when the maximum is set to 1 all items are aligned vertically. 0 means unlimited

Parameters

numColums Maximum number of entries in a row

See also

maxColumns(), QwtDynGridLayout::setMaxColumns()

Definition at line 296 of file qwt_legend.cpp.

void QwtLegend::updateLegend (const QVariant & itemInfo, const QList< QwtLegendData > & legendData) [override], [virtual], [slot]

Update the entries for an item.

Parameters

itemInfo Info for an item
legendData List of legend entry attributes for the item

Definition at line 396 of file qwt_legend.cpp.

void QwtLegend::updateWidget (QWidget * widget, const QwtLegendData & legendData) [protected], [virtual]

Update the widget.

Parameters

widget Usually a QwtLegendLabel
legendData Attributes to be displayed

See also

createWidget()

Note

When widget is no QwtLegendLabel updateWidget() does nothing.

Definition at line 489 of file qwt_legend.cpp.

QScrollBar * QwtLegend::verticalScrollBar () const

Returns

Vertical scrollbar

See also

horizontalScrollBar()

Definition at line 373 of file qwt_legend.cpp.

Author

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Sun Jul 18 2021 Version 6.2.0