Qwt User's Guide
QwtLegend Class Reference

The legend widget. More...

#include <qwt_legend.h>

Inheritance diagram for QwtLegend:

Public Slots

virtual void updateLegend (const QVariant &, const QList< QwtLegendData > &)
 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 *)
virtual QSize sizeHint () const
 Return a size hint.
virtual int heightForWidth (int w) 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

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 *widget, const QwtLegendData &data)
 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

Constructor & Destructor Documentation

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

Constructor

Parameters:
parentParent widget

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:
itemInfoInfo for the item of the selected legend label
indexIndex of the legend label in the list of widgets that are associated with the plot item
onTrue 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:
itemInfoInfo for the item item of the selected legend item
indexIndex 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()

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

Create a widget to be inserted into the legend.

The default implementation returns a QwtLegendLabel.

Parameters:
dataAttributes of the legend entry
Returns:
Widget representing data on the legend
Note:
updateWidget() will called soon after createWidget() with the same attributes.
Returns:
Default item mode
See also:
setDefaultItemMode()
bool QwtLegend::eventFilter ( QObject *  object,
QEvent *  event 
) [virtual]

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

Parameters:
objectObject to be filtered
eventEvent
Returns:
Forwarded to QwtAbstractLegend::eventFilter()
int QwtLegend::heightForWidth ( int  width) const [virtual]
Returns:
The preferred height, for a width.
Parameters:
widthWidth
QScrollBar * QwtLegend::horizontalScrollBar ( ) const
Returns:
Horizontal scrollbar
See also:
verticalScrollBar()
bool QwtLegend::isEmpty ( ) const [virtual]
Returns:
True, when no item is inserted

Implements QwtAbstractLegend.

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

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

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

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

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

Find the item that is associated to a widget

Parameters:
widgetWidget on the legend
Returns:
Associated item info
See also:
legendWidget()
QWidget * QwtLegend::legendWidget ( const QVariant &  itemInfo) const
Returns:
First widget in the list of widgets associated to an item
Parameters:
itemInfoInfo about an item
See also:
itemInfo(), QwtPlot::itemToInfo()
Note:
Almost all types of items have only one widget
QList< QWidget * > QwtLegend::legendWidgets ( const QVariant &  itemInfo) const
Returns:
List of widgets associated to a item
Parameters:
itemInfoInfo about an item
See also:
legendWidget(), itemInfo(), QwtPlot::itemToInfo()
uint QwtLegend::maxColumns ( ) const
Returns:
Maximum number of entries in a row
See also:
setMaxColumns(), QwtDynGridLayout::maxColumns()
void QwtLegend::renderItem ( QPainter *  painter,
const QWidget *  widget,
const QRectF &  rect,
bool  fillBackground 
) const [virtual]

Render a legend entry into a given rectangle.

Parameters:
painterPainter
widgetWidget representing a legend entry
rectBounding rectangle
fillBackgroundWhen true, fill rect with the widget background
Note:
When widget is not derived from QwtLegendLabel renderItem does nothing beside the background
void QwtLegend::renderLegend ( QPainter *  painter,
const QRectF &  rect,
bool  fillBackground 
) const [virtual]

Render the legend into a given rectangle.

Parameters:
painterPainter
rectBounding rectangle
fillBackgroundWhen true, fill rect with the widget background
See also:
renderLegend() is used by QwtPlotRenderer - not by QwtLegend itself

Implements QwtAbstractLegend.

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

Return the extent, that is needed for the scrollbars

Parameters:
orientationOrientation (
Returns:
The width of the vertical scrollbar for Qt::Horizontal and v.v.

Reimplemented from QwtAbstractLegend.

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:
modeDefault item mode
See also:
itemMode(), QwtLegendData::value(), QwtPlotItem::legendData()
Note:
Changing the mode doesn't have any effect on existing labels.
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:
numColumsMaximum number of entries in a row
See also:
maxColumns(), QwtDynGridLayout::setMaxColumns()
void QwtLegend::updateLegend ( const QVariant &  itemInfo,
const QList< QwtLegendData > &  data 
) [virtual, slot]

Update the entries for an item.

Parameters:
itemInfoInfo for an item
dataList of legend entry attributes for the item

Implements QwtAbstractLegend.

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

Update the widget.

Parameters:
widgetUsually a QwtLegendLabel
dataAttributes to be displayed
See also:
createWidget()
Note:
When widget is no QwtLegendLabel updateWidget() does nothing.
QScrollBar * QwtLegend::verticalScrollBar ( ) const
Returns:
Vertical scrollbar
See also:
horizontalScrollBar()

List of all members.

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