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Public Functions | Signals | Protected Functions
QCPLayerable Class Reference

Base class for all drawable objects. More...

Inheritance diagram for QCPLayerable:

## Public Functions
| QCPLayerable (QCustomPlot *plot, QString targetLayer="", QCPLayerable *parentLayerable=0)
bool | visible () const
QCustomPlot * | parentPlot () const
QCPLayerable * | parentLayerable () const
QCPLayer * | layer () const
bool | antialiased () const
void | setVisible (bool on)
Q_SLOT bool | setLayer (QCPLayer *layer)
bool | setLayer (const QString &layerName)
void | setAntialiased (bool enabled)
virtual double | selectTest (const QPointF &pos, bool onlySelectable, QVariant *details=0) const
bool | realVisibility () const

## Signals
void | layerChanged (QCPLayer *newLayer)

## Protected Functions
virtual void | parentPlotInitialized (QCustomPlot *parentPlot)
virtual QCP::Interaction | selectionCategory () const
virtual QRect | clipRect () const
virtual void | applyDefaultAntialiasingHint (QCPPainter *painter) const =0
virtual void | draw (QCPPainter *painter)=0
virtual void | selectEvent (QMouseEvent *event, bool additive, const QVariant &details, bool *selectionStateChanged)
virtual void | deselectEvent (bool *selectionStateChanged)
void | initializeParentPlot (QCustomPlot *parentPlot)
void | setParentLayerable (QCPLayerable *parentLayerable)
bool | moveToLayer (QCPLayer *layer, bool prepend)
void | applyAntialiasingHint (QCPPainter *painter, bool localAntialiased, QCP::AntialiasedElement overrideElement) const

## Detailed Description

Base class for all drawable objects.

This is the abstract base class most visible objects derive from, e.g. plottables, axes, grid etc.

Every layerable is on a layer (QCPLayer) which allows controlling the rendering order by stacking the layers accordingly.

For details about the layering mechanism, see the QCPLayer documentation.

## Constructor & Destructor Documentation

QCPLayerable::QCPLayerable | ( | QCustomPlot * | plot,
|  | QString | targetLayer = `""`,
|  | QCPLayerable * | parentLayerable = `0`
| ) |  |

Creates a new QCPLayerable instance.

Since QCPLayerable is an abstract base class, it can't be instantiated directly. Use one of the derived classes.

If plot is provided, it automatically places itself on the layer named targetLayer. If targetLayer is an empty string, it places itself on the current layer of the plot (see QCustomPlot::setCurrentLayer).

It is possible to provide 0 as plot. In that case, you should assign a parent plot at a later time with initializeParentPlot.

The layerable's parent layerable is set to parentLayerable, if provided. Direct layerable parents are mainly used to control visibility in a hierarchy of layerables. This means a layerable is only drawn, if all its ancestor layerables are also visible. Note that parentLayerable does not become the QObject-parent (for memory management) of this layerable, plot does.

## Member Function Documentation

QCPLayerable * QCPLayerable::parentLayerable | ( |  | ) | const
| inline

Returns the parent layerable of this layerable. The parent layerable is used to provide visibility hierarchies in conjunction with the method realVisibility. This way, layerables only get drawn if their parent layerables are visible, too.

Note that a parent layerable is not necessarily also the QObject parent for memory management. Further, a layerable doesn't always have a parent layerable, so this function may return 0.

A parent layerable is set implicitly with when placed inside layout elements and doesn't need to be set manually by the user.

void QCPLayerable::setVisible | ( | bool | on | ) |

Sets the visibility of this layerable object. If an object is not visible, it will not be drawn on the QCustomPlot surface, and user interaction with it (e.g. click and selection) is not possible.

bool QCPLayerable::setLayer | ( | QCPLayer * | layer | ) |

Sets the layer of this layerable object. The object will be placed on top of the other objects already on layer.

Returns true on success, i.e. if layer is a valid layer.

bool QCPLayerable::setLayer | ( | const QString & | layerName | ) |

This is an overloaded function.

Sets the layer of this layerable object by name

Returns true on success, i.e. if layerName is a valid layer name.

void QCPLayerable::setAntialiased | ( | bool | enabled | ) |

Sets whether this object will be drawn antialiased or not.

Note that antialiasing settings may be overridden by QCustomPlot::setAntialiasedElements and QCustomPlot::setNotAntialiasedElements.

double QCPLayerable::selectTest | ( | const QPointF & | pos,
|  | bool | onlySelectable,
|  | QVariant * | details = `0`
| ) |  | const
| virtual

This function is used to decide whether a click hits a layerable object or not.

pos is a point in pixel coordinates on the QCustomPlot surface. This function returns the shortest pixel distance of this point to the object. If the object is either invisible or the distance couldn't be determined, -1.0 is returned. Further, if onlySelectable is true and the object is not selectable, -1.0 is returned, too.

If the item is represented not by single lines but by an area like QCPItemRect or QCPItemText, a click inside the area returns a constant value greater zero (typically the selectionTolerance of the parent QCustomPlot multiplied by 0.99). If the click lies outside the area, this function returns -1.0.

Providing a constant value for area objects allows selecting line objects even when they are obscured by such area objects, by clicking close to the lines (i.e. closer than 0.99*selectionTolerance).

The actual setting of the selection state is not done by this function. This is handled by the parent QCustomPlot when the mouseReleaseEvent occurs, and the finally selected object is notified via the selectEvent/deselectEvent methods.

details is an optional output parameter. Every layerable subclass may place any information in details. This information will be passed to selectEvent when the parent QCustomPlot decides on the basis of this selectTest call, that the object was successfully selected. The subsequent call to selectEvent will carry the details. This is useful for multi-part objects (like QCPAxis). This way, a possibly complex calculation to decide which part was clicked is only done once in selectTest. The result (i.e. the actually clicked part) can then be placed in details. So in the subsequent selectEvent, the decision which part was selected doesn't have to be done a second time for a single selection operation.

You may pass 0 as details to indicate that you are not interested in those selection details.

See Also
  selectEvent, deselectEvent, QCustomPlot::setInteractions

Reimplemented in QCPAxis, QCPLayoutInset, QCPLegend, QCPAbstractItem, QCPGraph, QCPColorMap, QCPLayoutElement, QCPCurve, QCPBars, QCPStatisticalBox, QCPItemTracer, QCPItemText, QCPAbstractPlottable, QCPAbstractLegendItem, QCPPlotTitle, QCPItemBracket, QCPItemPixmap, QCPItemCurve, QCPItemLine, QCPItemEllipse, QCPItemRect, and QCPItemStraightLine.

bool QCPLayerable::realVisibility | ( |  | ) | const

Returns whether this layerable is visible, taking the visibility of the layerable parent and the visibility of the layer this layerable is on into account. This is the method that is consulted to decide whether a layerable shall be drawn or not.

If this layerable has a direct layerable parent (usually set via hierarchies implemented in subclasses, like in the case of QCPLayoutElement), this function returns true only if this layerable has its visibility set to true and the parent layerable's realVisibility returns true.

If this layerable doesn't have a direct layerable parent, returns the state of this layerable's visibility.

void QCPLayerable::layerChanged | ( | QCPLayer * | newLayer | ) |
| signal

This signal is emitted when the layer of this layerable changes, i.e. this layerable is moved to a different layer.

See Also
  setLayer

void QCPLayerable::parentPlotInitialized | ( | QCustomPlot * | parentPlot | ) |
| protected virtual

This function is called by initializeParentPlot, to allow subclasses to react on the setting of a parent plot. This is the case when 0 was passed as parent plot in the constructor, and the parent plot is set at a later time.

For example, QCPLayoutElement/QCPLayout hierarchies may be created independently of any QCustomPlot at first. When they are then added to a layout inside the QCustomPlot, the top level element of the hierarchy gets its parent plot initialized with initializeParentPlot. To propagate the parent plot to all the children of the hierarchy, the top level element then uses this function to pass the parent plot on to its child elements.

The default implementation does nothing.

See Also
  initializeParentPlot

Reimplemented in QCPLegend, and QCPLayoutElement.

QCP::Interaction QCPLayerable::selectionCategory | ( |  | ) | const
| protected virtual

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
  QCustomPlot::setInteractions

Reimplemented in QCPAxis, QCPLegend, QCPAbstractItem, QCPAbstractPlottable, and QCPAbstractLegendItem.

QRect QCPLayerable::clipRect | ( |  | ) | const
| protected virtual

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 in QCPAbstractItem, QCPAbstractPlottable, and QCPAbstractLegendItem.

void QCPLayerable::applyDefaultAntialiasingHint | ( | QCPPainter * | painter | ) | const
| protected pure virtual

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, scatters and error bars. Those can be configured via QCPGraph::setAntialiased, QCPGraph::setAntialiasedFill, QCPGraph::setAntialiasedScatters etc. 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.

Implemented in QCPAxis, QCPLegend, QCPAbstractItem, QCPLayoutElement, QCPAxisRect, QCPColorScale, QCPAbstractPlottable, QCPAbstractLegendItem, QCPPlotTitle, and QCPGrid.

void QCPLayerable::draw | ( | QCPPainter * | painter | ) |
| protected pure 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.

Implemented in QCPAxis, QCPLegend, QCPAbstractItem, QCPGraph, QCPColorMap, QCPLayoutElement, QCPAxisRect, QCPAbstractPlottable, QCPPlottableLegendItem, QCPItemText, QCPCurve, QCPItemTracer, QCPBars, QCPStatisticalBox, QCPAbstractLegendItem, QCPPlotTitle, QCPItemPixmap, QCPGrid, QCPItemEllipse, QCPItemBracket, QCPItemRect, QCPItemCurve, QCPItemLine, and QCPItemStraightLine.

void QCPLayerable::selectEvent | ( | QMouseEvent * | event,
|  | bool | additive,
|  | const QVariant & | details,
|  | bool * | selectionStateChanged
| ) |  |
| protected virtual

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 in QCPAxis, QCPLegend, QCPAbstractItem, QCPAbstractPlottable, QCPPlotTitle, and QCPAbstractLegendItem.

void QCPLayerable::deselectEvent | ( | bool * | selectionStateChanged | ) |
| protected virtual

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 in QCPAxis, QCPLegend, QCPAbstractItem, QCPAbstractPlottable, QCPPlotTitle, and QCPAbstractLegendItem.

void QCPLayerable::initializeParentPlot | ( | QCustomPlot * | parentPlot | ) |
| protected

Sets the parent plot of this layerable. Use this function once to set the parent plot if you have passed 0 in the constructor. It can not be used to move a layerable from one QCustomPlot to another one.

Note that, unlike when passing a non-null parent plot in the constructor, this function does not make parentPlot the QObject-parent of this layerable. If you want this, call QObject::setParent(parentPlot) in addition to this function.

Further, you will probably want to set a layer (setLayer) after calling this function, to make the layerable appear on the QCustomPlot.

The parent plot change will be propagated to subclasses via a call to parentPlotInitialized so they can react accordingly (e.g. also initialize the parent plot of child layerables, like QCPLayout does).

void QCPLayerable::setParentLayerable | ( | QCPLayerable * | parentLayerable | ) |
| protected

Sets the parent layerable of this layerable to parentLayerable. Note that parentLayerable does not become the QObject-parent (for memory management) of this layerable.

The parent layerable has influence on the return value of the realVisibility method. Only layerables with a fully visible parent tree will return true for realVisibility, and thus be drawn.

See Also
  realVisibility

bool QCPLayerable::moveToLayer | ( | QCPLayer * | layer,
|  | bool | prepend
| ) |  |
| protected

Moves this layerable object to layer. If prepend is true, this object will be prepended to the new layer's list, i.e. it will be drawn below the objects already on the layer. If it is false, the object will be appended.

Returns true on success, i.e. if layer is a valid layer.

void QCPLayerable::applyAntialiasingHint | ( | QCPPainter * | painter,
|  | bool | localAntialiased,
|  | QCP::AntialiasedElement | overrideElement
| ) |  | const
| protected

Sets the QCPainter::setAntialiasing state on the provided painter, depending on the localAntialiased value as well as the overrides QCustomPlot::setAntialiasedElements and QCustomPlot::setNotAntialiasedElements. Which override enum this function takes into account is controlled via overrideElement.

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

- src/layer.h
- src/layer.cpp

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