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QCPAbstractLegendItem Class Referenceabstract

The abstract base class for all entries in a QCPLegend. More...

Inheritance diagram for QCPAbstractLegendItem:
Inheritance graph

Public Functions

 QCPAbstractLegendItem (QCPLegend *parent)
QCPLegendparentLegend () const
QFont font () const
QColor textColor () const
QFont selectedFont () const
QColor selectedTextColor () const
bool selectable () const
bool selected () const
void setFont (const QFont &font)
void setTextColor (const QColor &color)
void setSelectedFont (const QFont &font)
void setSelectedTextColor (const QColor &color)
Q_SLOT void setSelectable (bool selectable)
Q_SLOT void setSelected (bool selected)
virtual double selectTest (const QPointF &pos, bool onlySelectable, QVariant *details=nullptr) const
- Public Functions inherited from QCPLayoutElement
 QCPLayoutElement (QCustomPlot *parentPlot=nullptr)
QCPLayoutlayout () const
QRect rect () const
QRect outerRect () const
QMargins margins () const
QMargins minimumMargins () const
QCP::MarginSides autoMargins () const
QSize minimumSize () const
QSize maximumSize () const
SizeConstraintRect sizeConstraintRect () const
QCPMarginGroupmarginGroup (QCP::MarginSide side) const
QHash< QCP::MarginSide, QCPMarginGroup * > marginGroups () const
void setOuterRect (const QRect &rect)
void setMargins (const QMargins &margins)
void setMinimumMargins (const QMargins &margins)
void setAutoMargins (QCP::MarginSides sides)
void setMinimumSize (const QSize &size)
void setMinimumSize (int width, int height)
void setMaximumSize (const QSize &size)
void setMaximumSize (int width, int height)
void setSizeConstraintRect (SizeConstraintRect constraintRect)
void setMarginGroup (QCP::MarginSides sides, QCPMarginGroup *group)
virtual void update (UpdatePhase phase)
virtual QSize minimumOuterSizeHint () const
virtual QSize maximumOuterSizeHint () const
virtual QList< QCPLayoutElement * > elements (bool recursive) const
- Public Functions inherited from QCPLayerable
 QCPLayerable (QCustomPlot *plot, QString targetLayer=QString(), QCPLayerable *parentLayerable=nullptr)
bool visible () const
QCustomPlotparentPlot () const
QCPLayerableparentLayerable () const
QCPLayerlayer () const
bool antialiased () const
void setVisible (bool on)
Q_SLOT bool setLayer (QCPLayer *layer)
bool setLayer (const QString &layerName)
void setAntialiased (bool enabled)
bool realVisibility () const


void selectionChanged (bool selected)
void selectableChanged (bool selectable)
- Signals inherited from QCPLayerable
void layerChanged (QCPLayer *newLayer)

Protected Functions

virtual QCP::Interaction selectionCategory () const
virtual void applyDefaultAntialiasingHint (QCPPainter *painter) const
virtual QRect clipRect () const
virtual void draw (QCPPainter *painter)=0
virtual void selectEvent (QMouseEvent *event, bool additive, const QVariant &details, bool *selectionStateChanged)
virtual void deselectEvent (bool *selectionStateChanged)
- Protected Functions inherited from QCPLayoutElement
virtual int calculateAutoMargin (QCP::MarginSide side)
virtual void layoutChanged ()
virtual void parentPlotInitialized (QCustomPlot *parentPlot)
- Protected Functions inherited from QCPLayerable
virtual void mousePressEvent (QMouseEvent *event, const QVariant &details)
virtual void mouseMoveEvent (QMouseEvent *event, const QPointF &startPos)
virtual void mouseReleaseEvent (QMouseEvent *event, const QPointF &startPos)
virtual void mouseDoubleClickEvent (QMouseEvent *event, const QVariant &details)
virtual void wheelEvent (QWheelEvent *event)
void initializeParentPlot (QCustomPlot *parentPlot)
void setParentLayerable (QCPLayerable *parentLayerable)
bool moveToLayer (QCPLayer *layer, bool prepend)
void applyAntialiasingHint (QCPPainter *painter, bool localAntialiased, QCP::AntialiasedElement overrideElement) const

Additional Inherited Members

- Public Types inherited from QCPLayoutElement
enum  UpdatePhase
enum  SizeConstraintRect

Detailed Description

The abstract base class for all entries in a QCPLegend.

It defines a very basic interface for entries in a QCPLegend. For representing plottables in the legend, the subclass QCPPlottableLegendItem is more suitable.

Only derive directly from this class when you need absolute freedom (e.g. a custom legend entry that's not even associated with a plottable).

You must implement the following pure virtual functions:

You inherit the following members you may use:

QCPLegend *mParentLegend A pointer to the parent QCPLegend.
QFont mFont The generic font of the item. You should use this font for all or at least the most prominent text of the item.

Constructor & Destructor Documentation

§ QCPAbstractLegendItem()

QCPAbstractLegendItem::QCPAbstractLegendItem ( QCPLegend parent)

Constructs a QCPAbstractLegendItem and associates it with the QCPLegend parent. This does not cause the item to be added to parent, so QCPLegend::addItem must be called separately.

Member Function Documentation

§ setFont()

void QCPAbstractLegendItem::setFont ( const QFont &  font)

Sets the default font of this specific legend item to font.

See also
setTextColor, QCPLegend::setFont

§ setTextColor()

void QCPAbstractLegendItem::setTextColor ( const QColor &  color)

Sets the default text color of this specific legend item to color.

See also
setFont, QCPLegend::setTextColor

§ setSelectedFont()

void QCPAbstractLegendItem::setSelectedFont ( const QFont &  font)

When this legend item is selected, font is used to draw generic text, instead of the normal font set with setFont.

See also
setFont, QCPLegend::setSelectedFont

§ setSelectedTextColor()

void QCPAbstractLegendItem::setSelectedTextColor ( const QColor &  color)

When this legend item is selected, color is used to draw generic text, instead of the normal color set with setTextColor.

See also
setTextColor, QCPLegend::setSelectedTextColor

§ setSelectable()

void QCPAbstractLegendItem::setSelectable ( bool  selectable)

Sets whether this specific legend item is selectable.

See also
setSelectedParts, QCustomPlot::setInteractions

§ setSelected()

void QCPAbstractLegendItem::setSelected ( bool  selected)

Sets whether this specific legend item is selected.

It is possible to set the selection state of this item by calling this function directly, even if setSelectable is set to false.

See also
setSelectableParts, QCustomPlot::setInteractions

§ selectTest()

double QCPAbstractLegendItem::selectTest ( const QPointF &  pos,
bool  onlySelectable,
QVariant *  details = nullptr 
) const

Layout elements are sensitive to events inside their outer rect. If pos is within the outer rect, this method returns a value corresponding to 0.99 times the parent plot's selection tolerance. However, layout elements are not selectable by default. So if onlySelectable is true, -1.0 is returned.

See QCPLayerable::selectTest for a general explanation of this virtual method.

QCPLayoutElement subclasses may reimplement this method to provide more specific selection test behaviour.

Reimplemented from QCPLayoutElement.

§ selectionChanged

void QCPAbstractLegendItem::selectionChanged ( bool  selected)

This signal is emitted when the selection state of this legend item has changed, either by user interaction or by a direct call to setSelected.

§ selectionCategory()

QCP::Interaction QCPAbstractLegendItem::selectionCategory ( ) const

Returns the selection category this layerable shall belong to. The selection category is used in conjunction with QCustomPlot::setInteractions to control which objects are selectable and which aren't.

Subclasses that don't fit any of the normal QCP::Interaction values can use QCP::iSelectOther. This is what the default implementation returns.

See also

Reimplemented from QCPLayerable.

§ applyDefaultAntialiasingHint()

void QCPAbstractLegendItem::applyDefaultAntialiasingHint ( QCPPainter painter) const

This function applies the default antialiasing setting to the specified painter, using the function applyAntialiasingHint. It is the antialiasing state the painter is put in, when draw is called on the layerable. If the layerable has multiple entities whose antialiasing setting may be specified individually, this function should set the antialiasing state of the most prominent entity. In this case however, the draw function usually calls the specialized versions of this function before drawing each entity, effectively overriding the setting of the default antialiasing hint.

First example: QCPGraph has multiple entities that have an antialiasing setting: The graph line, fills and scatters. Those can be configured via QCPGraph::setAntialiased, QCPGraph::setAntialiasedFill and QCPGraph::setAntialiasedScatters. Consequently, there isn't only the QCPGraph::applyDefaultAntialiasingHint function (which corresponds to the graph line's antialiasing), but specialized ones like QCPGraph::applyFillAntialiasingHint and QCPGraph::applyScattersAntialiasingHint. So before drawing one of those entities, QCPGraph::draw calls the respective specialized applyAntialiasingHint function.

Second example: QCPItemLine consists only of a line so there is only one antialiasing setting which can be controlled with QCPItemLine::setAntialiased. (This function is inherited by all layerables. The specialized functions, as seen on QCPGraph, must be added explicitly to the respective layerable subclass.) Consequently it only has the normal QCPItemLine::applyDefaultAntialiasingHint. The QCPItemLine::draw function doesn't need to care about setting any antialiasing states, because the default antialiasing hint is already set on the painter when the draw function is called, and that's the state it wants to draw the line with.

Reimplemented from QCPLayoutElement.

§ clipRect()

QRect QCPAbstractLegendItem::clipRect ( ) const

Returns the clipping rectangle of this layerable object. By default, this is the viewport of the parent QCustomPlot. Specific subclasses may reimplement this function to provide different clipping rects.

The returned clipping rect is set on the painter before the draw function of the respective object is called.

Reimplemented from QCPLayerable.

§ draw()

virtual void QCPAbstractLegendItem::draw ( QCPPainter painter)
protectedpure virtual

This function draws the layerable with the specified painter. It is only called by QCustomPlot, if the layerable is visible (setVisible).

Before this function is called, the painter's antialiasing state is set via applyDefaultAntialiasingHint, see the documentation there. Further, the clipping rectangle was set to clipRect.

Reimplemented from QCPLayoutElement.

Implemented in QCPPlottableLegendItem, and QCPPolarLegendItem.

§ selectEvent()

void QCPAbstractLegendItem::selectEvent ( QMouseEvent *  event,
bool  additive,
const QVariant &  details,
bool *  selectionStateChanged 

This event is called when the layerable shall be selected, as a consequence of a click by the user. Subclasses should react to it by setting their selection state appropriately. The default implementation does nothing.

event is the mouse event that caused the selection. additive indicates, whether the user was holding the multi-select-modifier while performing the selection (see QCustomPlot::setMultiSelectModifier). if additive is true, the selection state must be toggled (i.e. become selected when unselected and unselected when selected).

Every selectEvent is preceded by a call to selectTest, which has returned positively (i.e. returned a value greater than 0 and less than the selection tolerance of the parent QCustomPlot). The details data you output from selectTest is fed back via details here. You may use it to transport any kind of information from the selectTest to the possibly subsequent selectEvent. Usually details is used to transfer which part was clicked, if it is a layerable that has multiple individually selectable parts (like QCPAxis). This way selectEvent doesn't need to do the calculation again to find out which part was actually clicked.

selectionStateChanged is an output parameter. If the pointer is non-null, this function must set the value either to true or false, depending on whether the selection state of this layerable was actually changed. For layerables that only are selectable as a whole and not in parts, this is simple: if additive is true, selectionStateChanged must also be set to true, because the selection toggles. If additive is false, selectionStateChanged is only set to true, if the layerable was previously unselected and now is switched to the selected state.

See also
selectTest, deselectEvent

Reimplemented from QCPLayerable.

§ deselectEvent()

void QCPAbstractLegendItem::deselectEvent ( bool *  selectionStateChanged)

This event is called when the layerable shall be deselected, either as consequence of a user interaction or a call to QCustomPlot::deselectAll. Subclasses should react to it by unsetting their selection appropriately.

just as in selectEvent, the output parameter selectionStateChanged (if non-null), must return true or false when the selection state of this layerable has changed or not changed, respectively.

See also
selectTest, selectEvent

Reimplemented from QCPLayerable.

The documentation for this class was generated from the following files: