Qwt User's Guide: QwtLegend Class Reference

Qwt User's Guide 6.1.4

Public Slots | Signals | Public Member Functions | Protected Slots | Protected Member Functions | List of all members
QwtLegend Class Reference

The legend widget. More...

`#include <qwt_legend.h>`

Inheritance diagram for QwtLegend:
[legend]

## Public Slots
virtual void | updateLegend (const QVariant &, const QList< QwtLegendData > &)
| Update the entries for an item. More...
Public Slots inherited from QwtAbstractLegend
virtual void | updateLegend (const QVariant &itemInfo, const QList< QwtLegendData > &data)=0
| Update the entries for a plot item. More...

## 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. More...
uint | maxColumns () const
void | setDefaultItemMode (QwtLegendData::Mode)
| Set the default mode for legend labels. More...
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 *)
virtual QSize | sizeHint () const
| Return a size hint.
virtual int | heightForWidth (int width) const
QScrollBar * | horizontalScrollBar () const
QScrollBar * | verticalScrollBar () const
virtual void | renderLegend (QPainter *, const QRectF &, bool fillBackground) const
virtual void | renderItem (QPainter *, const QWidget *, const QRectF &, bool fillBackground) const
virtual bool | isEmpty () const
virtual int | scrollExtent (Qt::Orientation) const
Public Member Functions inherited from QwtAbstractLegend
| QwtAbstractLegend (QWidget *parent=NULL)
virtual | ~QwtAbstractLegend ()
| Destructor.

## 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. More...
virtual void | updateWidget (QWidget *widget, const QwtLegendData &)
| Update the widget. More...

## 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

## Constructor & Destructor Documentation

## ◆ QwtLegend()

QwtLegend::QwtLegend | ( | QWidget * | parent = `NULL` | ) |
| explicit

Constructor

Parameters

  parent | Parent widget

## Member Function Documentation

## ◆ checked

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()

## ◆ clicked

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()

## ◆ contentsWidget() [1/2]

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

## ◆ contentsWidget() [2/2]

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

## ◆ createWidget()

QWidget * QwtLegend::createWidget | ( | const QwtLegendData & | legendData | ) | const
| protectedvirtual

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.

## ◆ defaultItemMode()

QwtLegendData::Mode QwtLegend::defaultItemMode | ( |  | ) | const

Returns
  Default item mode

See also
  setDefaultItemMode()

## ◆ eventFilter()

bool QwtLegend::eventFilter | ( | QObject * | object,
|  | QEvent * | event
| ) |  |
| virtual

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

Parameters

  object | Object to be filtered
  event | Event

Returns
  Forwarded to QwtAbstractLegend::eventFilter()

## ◆ heightForWidth()

int QwtLegend::heightForWidth | ( | int | width | ) | const
| virtual

Returns
  The preferred height, for a width.

Parameters

  width | Width

## ◆ horizontalScrollBar()

QScrollBar * QwtLegend::horizontalScrollBar | ( |  | ) | const

Returns
  Horizontal scrollbar

See also
  verticalScrollBar()

## ◆ isEmpty()

bool QwtLegend::isEmpty | ( |  | ) | const
| virtual

Returns
  True, when no item is inserted

Implements QwtAbstractLegend.

## ◆ itemChecked

void QwtLegend::itemChecked | ( | bool | on | ) |
| protectedslot

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

## ◆ itemClicked

void QwtLegend::itemClicked | ( |  | ) |
| protectedslot

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

## ◆ itemInfo()

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()

## ◆ legendWidget()

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

## ◆ legendWidgets()

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()

## ◆ maxColumns()

uint QwtLegend::maxColumns | ( |  | ) | const

Returns
  Maximum number of entries in a row

See also
  setMaxColumns(), QwtDynGridLayout::maxColumns()

## ◆ renderItem()

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

## ◆ renderLegend()

void QwtLegend::renderLegend | ( | QPainter * | painter,
|  | const QRectF & | rect,
|  | bool | fillBackground
| ) |  | const
| 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.

## ◆ scrollExtent()

int QwtLegend::scrollExtent | ( | Qt::Orientation | orientation | ) | const
| 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.

## ◆ setDefaultItemMode()

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.

## ◆ setMaxColumns()

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()

## ◆ updateLegend

void QwtLegend::updateLegend | ( | const QVariant & | itemInfo,
|  | const QList< QwtLegendData > & | legendData
| ) |  |
| virtualslot

Update the entries for an item.

Parameters

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

## ◆ updateWidget()

void QwtLegend::updateWidget | ( | QWidget * | widget,
|  | const QwtLegendData & | legendData
| ) |  |
| protectedvirtual

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.

## ◆ verticalScrollBar()

QScrollBar * QwtLegend::verticalScrollBar | ( |  | ) | const

Returns
  Vertical scrollbar

See also
  horizontalScrollBar()