Vespucci  1.0.0
QCPItemTracer Class Reference

Item that sticks to QCPGraph data points. More...

#include <qcustomplot.h>

Inheritance diagram for QCPItemTracer:
QCPAbstractItem QCPLayerable

Public Types

enum  TracerStyle {
  tsNone, tsPlus, tsCrosshair, tsCircle,

Public Member Functions

 QCPItemTracer (QCustomPlot *parentPlot)
virtual ~QCPItemTracer ()
QPen pen () const
QPen selectedPen () const
QBrush brush () const
QBrush selectedBrush () const
double size () const
TracerStyle style () const
QCPGraphgraph () const
double graphKey () const
bool interpolating () const
void setPen (const QPen &pen)
void setSelectedPen (const QPen &pen)
void setBrush (const QBrush &brush)
void setSelectedBrush (const QBrush &brush)
void setSize (double size)
void setStyle (TracerStyle style)
void setGraph (QCPGraph *graph)
void setGraphKey (double key)
void setInterpolating (bool enabled)
virtual double selectTest (const QPointF &pos, bool onlySelectable, QVariant *details=0) const
void updatePosition ()
- Public Member Functions inherited from QCPAbstractItem
 QCPAbstractItem (QCustomPlot *parentPlot)
virtual ~QCPAbstractItem ()
bool clipToAxisRect () const
QCPAxisRectclipAxisRect () const
bool selectable () const
bool selected () const
void setClipToAxisRect (bool clip)
void setClipAxisRect (QCPAxisRect *rect)
Q_SLOT void setSelectable (bool selectable)
Q_SLOT void setSelected (bool selected)
QList< QCPItemPosition * > positions () const
QList< QCPItemAnchor * > anchors () const
QCPItemPositionposition (const QString &name) const
QCPItemAnchoranchor (const QString &name) const
bool hasAnchor (const QString &name) const
- Public Member Functions inherited from QCPLayerable
 QCPLayerable (QCustomPlot *plot, QString targetLayer=QString(), QCPLayerable *parentLayerable=0)
 ~QCPLayerable ()
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

Public Attributes

QCPItemPosition *const position

Protected Member Functions

virtual void draw (QCPPainter *painter)
QPen mainPen () const
QBrush mainBrush () const
- Protected Member Functions inherited from QCPAbstractItem
virtual QCP::Interaction selectionCategory () const
virtual QRect clipRect () const
virtual void applyDefaultAntialiasingHint (QCPPainter *painter) const
virtual void selectEvent (QMouseEvent *event, bool additive, const QVariant &details, bool *selectionStateChanged)
virtual void deselectEvent (bool *selectionStateChanged)
virtual QPointF anchorPixelPoint (int anchorId) const
double distSqrToLine (const QPointF &start, const QPointF &end, const QPointF &point) const
double rectSelectTest (const QRectF &rect, const QPointF &pos, bool filledRect) const
QCPItemPositioncreatePosition (const QString &name)
QCPItemAnchorcreateAnchor (const QString &name, int anchorId)
- Protected Member Functions inherited from QCPLayerable
virtual void parentPlotInitialized (QCustomPlot *parentPlot)
void initializeParentPlot (QCustomPlot *parentPlot)
void setParentLayerable (QCPLayerable *parentLayerable)
bool moveToLayer (QCPLayer *layer, bool prepend)
void applyAntialiasingHint (QCPPainter *painter, bool localAntialiased, QCP::AntialiasedElement overrideElement) const

Protected Attributes

QPen mPen
QPen mSelectedPen
QBrush mBrush
QBrush mSelectedBrush
double mSize
TracerStyle mStyle
double mGraphKey
bool mInterpolating
- Protected Attributes inherited from QCPAbstractItem
bool mClipToAxisRect
QPointer< QCPAxisRectmClipAxisRect
QList< QCPItemPosition * > mPositions
QList< QCPItemAnchor * > mAnchors
bool mSelectable
bool mSelected
- Protected Attributes inherited from QCPLayerable
bool mVisible
QPointer< QCPLayerablemParentLayerable
bool mAntialiased

Additional Inherited Members

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

Detailed Description

Item that sticks to QCPGraph data points.

Tracer example. Blue dotted circles are anchors, solid blue discs are positions.

The tracer can be connected with a QCPGraph via setGraph. Then it will automatically adopt the coordinate axes of the graph and update its position to be on the graph's data. This means the key stays controllable via setGraphKey, but the value will follow the graph data. If a QCPGraph is connected, note that setting the coordinates of the tracer item directly via position will have no effect because they will be overriden in the next redraw (this is when the coordinate update happens).

If the specified key in setGraphKey is outside the key bounds of the graph, the tracer will stay at the corresponding end of the graph.

With setInterpolating you may specify whether the tracer may only stay exactly on data points or whether it interpolates data points linearly, if given a key that lies between two data points of the graph.

The tracer has different visual styles, see setStyle. It is also possible to make the tracer have no own visual appearance (set the style to tsNone), and just connect other item positions to the tracer position (used as an anchor) via QCPItemPosition::setParentAnchor.

The tracer position is only automatically updated upon redraws. So when the data of the graph changes and immediately afterwards (without a redraw) the a position coordinates of the tracer are retrieved, they will not reflect the updated data of the graph. In this case updatePosition must be called manually, prior to reading the tracer coordinates.

Definition at line 3683 of file qcustomplot.h.

Member Enumeration Documentation

The different visual appearances a tracer item can have. Some styles size may be controlled with setSize.

See also

The tracer is not visible.


A plus shaped crosshair with limited size.


A plus shaped crosshair which spans the complete axis rect.


A circle.


A square.

Definition at line 3703 of file qcustomplot.h.

Constructor & Destructor Documentation

QCPItemTracer::QCPItemTracer ( QCustomPlot parentPlot)

Creates a tracer item and sets default values.

The constructed item can be added to the plot with QCustomPlot::addItem.

Definition at line 23411 of file qcustomplot.cpp.

QCPItemTracer::~QCPItemTracer ( )

Definition at line 23428 of file qcustomplot.cpp.

Member Function Documentation

QBrush QCPItemTracer::brush ( ) const

Definition at line 3717 of file qcustomplot.h.

void QCPItemTracer::draw ( QCPPainter painter)

Implements QCPAbstractItem.

Definition at line 23608 of file qcustomplot.cpp.

QCPGraph* QCPItemTracer::graph ( ) const

Definition at line 3721 of file qcustomplot.h.

double QCPItemTracer::graphKey ( ) const

Definition at line 3722 of file qcustomplot.h.

bool QCPItemTracer::interpolating ( ) const

Definition at line 3723 of file qcustomplot.h.

QBrush QCPItemTracer::mainBrush ( ) const

Definition at line 23729 of file qcustomplot.cpp.

QPen QCPItemTracer::mainPen ( ) const

Definition at line 23719 of file qcustomplot.cpp.

QPen QCPItemTracer::pen ( ) const

Definition at line 3715 of file qcustomplot.h.

QBrush QCPItemTracer::selectedBrush ( ) const

Definition at line 3718 of file qcustomplot.h.

QPen QCPItemTracer::selectedPen ( ) const

Definition at line 3716 of file qcustomplot.h.

double QCPItemTracer::selectTest ( const QPointF &  pos,
bool  onlySelectable,
QVariant *  details = 0 
) const

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

Implements QCPAbstractItem.

Definition at line 23551 of file qcustomplot.cpp.

void QCPItemTracer::setBrush ( const QBrush &  brush)

Sets the brush that will be used to draw any fills of the tracer

See also
setSelectedBrush, setPen

Definition at line 23457 of file qcustomplot.cpp.

void QCPItemTracer::setGraph ( QCPGraph graph)

Sets the QCPGraph this tracer sticks to. The tracer position will be set to type QCPItemPosition::ptPlotCoords and the axes will be set to the axes of graph.

To free the tracer from any graph, set graph to 0. The tracer position can then be placed freely like any other item position. This is the state the tracer will assume when its graph gets deleted while still attached to it.

See also

Definition at line 23502 of file qcustomplot.cpp.

void QCPItemTracer::setGraphKey ( double  key)

Sets the key of the graph's data point the tracer will be positioned at. This is the only free coordinate of a tracer when attached to a graph.

Depending on setInterpolating, the tracer will be either positioned on the data point closest to key, or will stay exactly at key and interpolate the value linearly.

See also
setGraph, setInterpolating

Definition at line 23529 of file qcustomplot.cpp.

void QCPItemTracer::setInterpolating ( bool  enabled)

Sets whether the value of the graph's data points shall be interpolated, when positioning the tracer.

If enabled is set to false and a key is given with setGraphKey, the tracer is placed on the data point of the graph which is closest to the key, but which is not necessarily exactly there. If enabled is true, the tracer will be positioned exactly at the specified key, and the appropriate value will be interpolated from the graph's data points linearly.

See also
setGraph, setGraphKey

Definition at line 23545 of file qcustomplot.cpp.

void QCPItemTracer::setPen ( const QPen &  pen)

Sets the pen that will be used to draw the line of the tracer

See also
setSelectedPen, setBrush

Definition at line 23437 of file qcustomplot.cpp.

void QCPItemTracer::setSelectedBrush ( const QBrush &  brush)

Sets the brush that will be used to draw any fills of the tracer, when selected.

See also
setBrush, setSelected

Definition at line 23467 of file qcustomplot.cpp.

void QCPItemTracer::setSelectedPen ( const QPen &  pen)

Sets the pen that will be used to draw the line of the tracer when selected

See also
setPen, setSelected

Definition at line 23447 of file qcustomplot.cpp.

void QCPItemTracer::setSize ( double  size)

Sets the size of the tracer in pixels, if the style supports setting a size (e.g. tsSquare does, tsCrosshair does not).

Definition at line 23476 of file qcustomplot.cpp.

void QCPItemTracer::setStyle ( QCPItemTracer::TracerStyle  style)

Sets the style/visual appearance of the tracer.

If you only want to use the tracer position as an anchor for other items, set style to tsNone.

Definition at line 23487 of file qcustomplot.cpp.

double QCPItemTracer::size ( ) const

Definition at line 3719 of file qcustomplot.h.

TracerStyle QCPItemTracer::style ( ) const

Definition at line 3720 of file qcustomplot.h.

void QCPItemTracer::updatePosition ( )

If the tracer is connected with a graph (setGraph), this function updates the tracer's position to reside on the graph data, depending on the configured key (setGraphKey).

It is called automatically on every redraw and normally doesn't need to be called manually. One exception is when you want to read the tracer coordinates via position and are not sure that the graph's data (or the tracer key with setGraphKey) hasn't changed since the last redraw. In that situation, call this function before accessing position, to make sure you don't get out-of-date coordinates.

If there is no graph set on this tracer, this function does nothing.

Definition at line 23666 of file qcustomplot.cpp.

Member Data Documentation

QBrush QCPItemTracer::mBrush

Definition at line 3747 of file qcustomplot.h.

QCPGraph* QCPItemTracer::mGraph

Definition at line 3750 of file qcustomplot.h.

double QCPItemTracer::mGraphKey

Definition at line 3751 of file qcustomplot.h.

bool QCPItemTracer::mInterpolating

Definition at line 3752 of file qcustomplot.h.

QPen QCPItemTracer::mPen

Definition at line 3746 of file qcustomplot.h.

QBrush QCPItemTracer::mSelectedBrush

Definition at line 3747 of file qcustomplot.h.

QPen QCPItemTracer::mSelectedPen

Definition at line 3746 of file qcustomplot.h.

double QCPItemTracer::mSize

Definition at line 3748 of file qcustomplot.h.

TracerStyle QCPItemTracer::mStyle

Definition at line 3749 of file qcustomplot.h.

QCPItemPosition* const QCPItemTracer::position

Definition at line 3742 of file qcustomplot.h.

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