QCPErrorBars Class Reference
Author: Emanuel Eichhammer

· · · ·
Public Types | Public Functions | Protected Functions
QCPErrorBars Class Reference

A plottable that adds a set of error bars to other plottables. More...

Inheritance diagram for QCPErrorBars:

## Public Types
enum | ErrorType

## Public Functions
| QCPErrorBars (QCPAxis *keyAxis, QCPAxis *valueAxis)
QSharedPointer< QCPErrorBarsDataContainer > | data () const
QCPAbstractPlottable * | dataPlottable () const
ErrorType | errorType () const
double | whiskerWidth () const
double | symbolGap () const
void | setData (QSharedPointer< QCPErrorBarsDataContainer > data)
void | setData (const QVector< double > &error)
void | setData (const QVector< double > &errorMinus, const QVector< double > &errorPlus)
void | setDataPlottable (QCPAbstractPlottable *plottable)
void | setErrorType (ErrorType type)
void | setWhiskerWidth (double pixels)
void | setSymbolGap (double pixels)
void | addData (const QVector< double > &error)
void | addData (const QVector< double > &errorMinus, const QVector< double > &errorPlus)
void | addData (double error)
void | addData (double errorMinus, double errorPlus)
virtual int | dataCount () const
virtual double | dataMainKey (int index) const
virtual double | dataSortKey (int index) const
virtual double | dataMainValue (int index) const
virtual QCPRange | dataValueRange (int index) const
virtual QPointF | dataPixelPosition (int index) const
virtual bool | sortKeyIsMainKey () const
virtual QCPDataSelection | selectTestRect (const QRectF &rect, bool onlySelectable) const
virtual int | findBegin (double sortKey, bool expandedRange=true) const
virtual int | findEnd (double sortKey, bool expandedRange=true) const
virtual double | selectTest (const QPointF &pos, bool onlySelectable, QVariant *details=nullptr) const
virtual QCPPlottableInterface1D * | interface1D ()
Public Functions inherited from QCPAbstractPlottable
| QCPAbstractPlottable (QCPAxis *keyAxis, QCPAxis *valueAxis)
QString | name () const
bool | antialiasedFill () const
bool | antialiasedScatters () const
QPen | pen () const
QBrush | brush () const
QCPAxis * | keyAxis () const
QCPAxis * | valueAxis () const
QCP::SelectionType | selectable () const
bool | selected () const
QCPDataSelection | selection () const
QCPSelectionDecorator * | selectionDecorator () const
void | setName (const QString &name)
void | setAntialiasedFill (bool enabled)
void | setAntialiasedScatters (bool enabled)
void | setPen (const QPen &pen)
void | setBrush (const QBrush &brush)
void | setKeyAxis (QCPAxis *axis)
void | setValueAxis (QCPAxis *axis)
Q_SLOT void | setSelectable (QCP::SelectionType selectable)
Q_SLOT void | setSelection (QCPDataSelection selection)
void | setSelectionDecorator (QCPSelectionDecorator *decorator)
void | coordsToPixels (double key, double value, double &x, double &y) const
const QPointF | coordsToPixels (double key, double value) const
void | pixelsToCoords (double x, double y, double &key, double &value) const
void | pixelsToCoords (const QPointF &pixelPos, double &key, double &value) const
void | rescaleAxes (bool onlyEnlarge=false) const
void | rescaleKeyAxis (bool onlyEnlarge=false) const
void | rescaleValueAxis (bool onlyEnlarge=false, bool inKeyRange=false) const
bool | addToLegend (QCPLegend *legend)
bool | addToLegend ()
bool | removeFromLegend (QCPLegend *legend) const
bool | removeFromLegend () const
Public Functions inherited from QCPLayerable
| QCPLayerable (QCustomPlot *plot, QString targetLayer=QString(), QCPLayerable *parentLayerable=nullptr)
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)
bool | realVisibility () const

## Protected Functions
virtual void | draw (QCPPainter *painter)
virtual void | drawLegendIcon (QCPPainter *painter, const QRectF &rect) const
virtual QCPRange | getKeyRange (bool &foundRange, QCP::SignDomain inSignDomain=QCP::sdBoth) const
virtual QCPRange | getValueRange (bool &foundRange, QCP::SignDomain inSignDomain=QCP::sdBoth, const QCPRange &inKeyRange=QCPRange()) const
void | getErrorBarLines (QCPErrorBarsDataContainer::const_iterator it, QVector< QLineF > &backbones, QVector< QLineF > &whiskers) const
void | getVisibleDataBounds (QCPErrorBarsDataContainer::const_iterator &begin, QCPErrorBarsDataContainer::const_iterator &end, const QCPDataRange &rangeRestriction) const
double | pointDistance (const QPointF &pixelPoint, QCPErrorBarsDataContainer::const_iterator &closestData) const
void | getDataSegments (QList< QCPDataRange > &selectedSegments, QList< QCPDataRange > &unselectedSegments) const
bool | errorBarVisible (int index) const
bool | rectIntersectsLine (const QRectF &pixelRect, const QLineF &line) const
Protected Functions inherited from QCPAbstractPlottable
virtual QRect | clipRect () const
virtual QCP::Interaction | selectionCategory () const
void | applyDefaultAntialiasingHint (QCPPainter *painter) const
virtual void | selectEvent (QMouseEvent *event, bool additive, const QVariant &details, bool *selectionStateChanged)
virtual void | deselectEvent (bool *selectionStateChanged)
void | applyFillAntialiasingHint (QCPPainter *painter) const
void | applyScattersAntialiasingHint (QCPPainter *painter) const
Protected Functions inherited from QCPLayerable
virtual void | parentPlotInitialized (QCustomPlot *parentPlot)
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
Signals inherited from QCPAbstractPlottable
void | selectionChanged (bool selected)
void | selectionChanged (const QCPDataSelection &selection)
void | selectableChanged (QCP::SelectionType selectable)
Signals inherited from QCPLayerable
void | layerChanged (QCPLayer *newLayer)

## Detailed Description

A plottable that adds a set of error bars to other plottables.

The QCPErrorBars plottable can be attached to other one-dimensional plottables (e.g. QCPGraph, QCPCurve, QCPBars, etc.) and equips them with error bars.

Use setDataPlottable to define for which plottable the QCPErrorBars shall display the error bars. The orientation of the error bars can be controlled with setErrorType.

By using setData, you can supply the actual error data, either as symmetric error or plus/minus asymmetric errors. QCPErrorBars only stores the error data. The absolute key/value position of each error bar will be adopted from the configured data plottable. The error data of the QCPErrorBars are associated one-to-one via their index to the data points of the data plottable. You can directly access and manipulate the error bar data via data.

Set either of the plus/minus errors to NaN (`qQNaN()` or `std::numeric_limits<double>::quiet_NaN()`) to not show the respective error bar on the data point at that index.

# Changing the appearance

The appearance of the error bars is defined by the pen (setPen), and the width of the whiskers (setWhiskerWidth). Further, the error bar backbones may leave a gap around the data point center to prevent that error bars are drawn too close to or even through scatter points. This gap size can be controlled via setSymbolGap.

## Member Enumeration Documentation

## § ErrorType

enum QCPErrorBars::ErrorType

Defines in which orientation the error bars shall appear. If your data needs both error dimensions, create two QCPErrorBars with different ErrorType.

See also
  setErrorType

Enumerator
etKeyError | The errors are for the key dimension (bars appear parallel to the key axis)
etValueError | The errors are for the value dimension (bars appear parallel to the value axis)

## Constructor & Destructor Documentation

## § QCPErrorBars()

QCPErrorBars::QCPErrorBars | ( | QCPAxis * | keyAxis,
|  | QCPAxis * | valueAxis
| ) |  |
| explicit

Constructs an error bars plottable which uses keyAxis as its key axis ("x") and valueAxis as its value axis ("y"). keyAxis and valueAxis must reside in the same QCustomPlot instance and not have the same orientation. If either of these restrictions is violated, a corresponding message is printed to the debug output (qDebug), the construction is not aborted, though.

It is also important that the keyAxis and valueAxis are the same for the error bars plottable and the data plottable that the error bars shall be drawn on (setDataPlottable).

The created QCPErrorBars is automatically registered with the QCustomPlot instance inferred from keyAxis. This QCustomPlot instance takes ownership of the QCPErrorBars, so do not delete it manually but use QCustomPlot::removePlottable() instead.

## Member Function Documentation

## § data()

QSharedPointer< QCPErrorBarsDataContainer > QCPErrorBars::data | ( |  | ) | const
| inline

Returns a shared pointer to the internal data storage of type QCPErrorBarsDataContainer. You may use it to directly manipulate the error values, which may be more convenient and faster than using the regular setData methods.

## § setData() [1/3]

void QCPErrorBars::setData | ( | QSharedPointer< QCPErrorBarsDataContainer > | data | ) |

This is an overloaded function.

Replaces the current data container with the provided data container.

Since a QSharedPointer is used, multiple QCPErrorBars instances may share the same data container safely. Modifying the data in the container will then affect all QCPErrorBars instances that share the container. Sharing can be achieved by simply exchanging the data containers wrapped in shared pointers:

errorBars2->setData(errorBars1->data()); // errorBars1 and errorBars2 now share data container

If you do not wish to share containers, but create a copy from an existing container, assign the data containers directly:

*errorBars2->data() = *errorBars1->data(); // errorBars2 now has copy of errorBars1's data in its container

(This uses different notation compared with other plottables, because the QCPErrorBars uses a `QVector<QCPErrorBarsData>` as its data container, instead of a QCPDataContainer.)

See also
  addData

## § setData() [2/3]

void QCPErrorBars::setData | ( | const QVector< double > & | error | ) |

This is an overloaded function.

Sets symmetrical error values as specified in error. The errors will be associated one-to-one by the data point index to the associated data plottable (setDataPlottable).

You can directly access and manipulate the error bar data via data.

See also
  addData

## § setData() [3/3]

void QCPErrorBars::setData | ( | const QVector< double > & | errorMinus,
|  | const QVector< double > & | errorPlus
| ) |  |

This is an overloaded function.

Sets asymmetrical errors as specified in errorMinus and errorPlus. The errors will be associated one-to-one by the data point index to the associated data plottable (setDataPlottable).

You can directly access and manipulate the error bar data via data.

See also
  addData

## § setDataPlottable()

void QCPErrorBars::setDataPlottable | ( | QCPAbstractPlottable * | plottable | ) |

Sets the data plottable to which the error bars will be applied. The error values specified e.g. via setData will be associated one-to-one by the data point index to the data points of plottable. This means that the error bars will adopt the key/value coordinates of the data point with the same index.

The passed plottable must be a one-dimensional plottable, i.e. it must implement the QCPPlottableInterface1D. Further, it must not be a QCPErrorBars instance itself. If either of these restrictions is violated, a corresponding qDebug output is generated, and the data plottable of this QCPErrorBars instance is set to zero.

For proper display, care must also be taken that the key and value axes of the plottable match those configured for this QCPErrorBars instance.

## § setErrorType()

void QCPErrorBars::setErrorType | ( | ErrorType | type | ) |

Sets in which orientation the error bars shall appear on the data points. If your data needs both error dimensions, create two QCPErrorBars with different type.

## § setWhiskerWidth()

void QCPErrorBars::setWhiskerWidth | ( | double | pixels | ) |

Sets the width of the whiskers (the short bars at the end of the actual error bar backbones) to pixels.

## § setSymbolGap()

void QCPErrorBars::setSymbolGap | ( | double | pixels | ) |

Sets the gap diameter around the data points that will be left out when drawing the error bar backbones. This gap prevents that error bars are drawn too close to or even through scatter points.

## § addData() [1/4]

void QCPErrorBars::addData | ( | const QVector< double > & | error | ) |

This is an overloaded function.

Adds symmetrical error values as specified in error. The errors will be associated one-to-one by the data point index to the associated data plottable (setDataPlottable).

You can directly access and manipulate the error bar data via data.

See also
  setData

## § addData() [2/4]

void QCPErrorBars::addData | ( | const QVector< double > & | errorMinus,
|  | const QVector< double > & | errorPlus
| ) |  |

This is an overloaded function.

Adds asymmetrical errors as specified in errorMinus and errorPlus. The errors will be associated one-to-one by the data point index to the associated data plottable (setDataPlottable).

You can directly access and manipulate the error bar data via data.

See also
  setData

## § addData() [3/4]

void QCPErrorBars::addData | ( | double | error | ) |

This is an overloaded function.

Adds a single symmetrical error bar as specified in error. The errors will be associated one-to-one by the data point index to the associated data plottable (setDataPlottable).

You can directly access and manipulate the error bar data via data.

See also
  setData

## § addData() [4/4]

void QCPErrorBars::addData | ( | double | errorMinus,
|  | double | errorPlus
| ) |  |

This is an overloaded function.

Adds a single asymmetrical error bar as specified in errorMinus and errorPlus. The errors will be associated one-to-one by the data point index to the associated data plottable (setDataPlottable).

You can directly access and manipulate the error bar data via data.

See also
  setData

## § dataCount()

int QCPErrorBars::dataCount | ( |  | ) | const
| virtual

Returns the number of data points of the plottable.

Implements QCPPlottableInterface1D.

## § dataMainKey()

double QCPErrorBars::dataMainKey | ( | int | index | ) | const
| virtual

Returns the main key of the data point at the given index.

What the main key is, is defined by the plottable's data type. See the QCPDataContainer DataType documentation for details about this naming convention.

Implements QCPPlottableInterface1D.

## § dataSortKey()

double QCPErrorBars::dataSortKey | ( | int | index | ) | const
| virtual

Returns the sort key of the data point at the given index.

What the sort key is, is defined by the plottable's data type. See the QCPDataContainer DataType documentation for details about this naming convention.

Implements QCPPlottableInterface1D.

## § dataMainValue()

double QCPErrorBars::dataMainValue | ( | int | index | ) | const
| virtual

Returns the main value of the data point at the given index.

What the main value is, is defined by the plottable's data type. See the QCPDataContainer DataType documentation for details about this naming convention.

Implements QCPPlottableInterface1D.

## § dataValueRange()

QCPRange QCPErrorBars::dataValueRange | ( | int | index | ) | const
| virtual

Returns the value range of the data point at the given index.

What the value range is, is defined by the plottable's data type. See the QCPDataContainer DataType documentation for details about this naming convention.

Implements QCPPlottableInterface1D.

## § dataPixelPosition()

QPointF QCPErrorBars::dataPixelPosition | ( | int | index | ) | const
| virtual

Returns the pixel position on the widget surface at which the data point at the given index appears.

Usually this corresponds to the point of dataMainKey/dataMainValue, in pixel coordinates. However, depending on the plottable, this might be a different apparent position than just a coord-to-pixel transform of those values. For example, QCPBars apparent data values can be shifted depending on their stacking, bar grouping or configured base value.

Implements QCPPlottableInterface1D.

## § sortKeyIsMainKey()

bool QCPErrorBars::sortKeyIsMainKey | ( |  | ) | const
| virtual

Returns whether the sort key (dataSortKey) is identical to the main key (dataMainKey).

What the sort and main keys are, is defined by the plottable's data type. See the QCPDataContainer DataType documentation for details about this naming convention.

Implements QCPPlottableInterface1D.

## § selectTestRect()

QCPDataSelection QCPErrorBars::selectTestRect | ( | const QRectF & | rect,
|  | bool | onlySelectable
| ) |  | const
| virtual

Returns a data selection containing all the data points of this plottable which are contained (or hit by) rect. This is used mainly in the selection rect interaction for data selection (data selection mechanism).

If onlySelectable is true, an empty QCPDataSelection is returned if this plottable is not selectable (i.e. if QCPAbstractPlottable::setSelectable is QCP::stNone).

Note
  rect must be a normalized rect (positive or zero width and height). This is especially important when using the rect of QCPSelectionRect::accepted, which is not necessarily normalized. Use `QRect::normalized()` when passing a rect which might not be normalized.

Implements QCPPlottableInterface1D.

## § findBegin()

int QCPErrorBars::findBegin | ( | double | sortKey,
|  | bool | expandedRange = `true`
| ) |  | const
| virtual

Returns the index of the data point with a (sort-)key that is equal to, just below, or just above sortKey. If expandedRange is true, the data point just below sortKey will be considered, otherwise the one just above.

This can be used in conjunction with findEnd to iterate over data points within a given key range, including or excluding the bounding data points that are just beyond the specified range.

If expandedRange is true but there are no data points below sortKey, 0 is returned.

If the container is empty, returns 0 (in that case, findEnd will also return 0, so a loop using these methods will not iterate over the index 0).

See also
  findEnd, QCPDataContainer::findBegin

Implements QCPPlottableInterface1D.

## § findEnd()

int QCPErrorBars::findEnd | ( | double | sortKey,
|  | bool | expandedRange = `true`
| ) |  | const
| virtual

Returns the index one after the data point with a (sort-)key that is equal to, just above, or just below sortKey. If expandedRange is true, the data point just above sortKey will be considered, otherwise the one just below.

This can be used in conjunction with findBegin to iterate over data points within a given key range, including the bounding data points that are just below and above the specified range.

If expandedRange is true but there are no data points above sortKey, the index just above the highest data point is returned.

If the container is empty, returns 0.

See also
  findBegin, QCPDataContainer::findEnd

Implements QCPPlottableInterface1D.

## § selectTest()

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

Implements a selectTest specific to this plottable's point geometry.

If details is not 0, it will be set to a QCPDataSelection, describing the closest data point to pos.

For general information about this virtual method, see the base class implementation. QCPAbstractPlottable::selectTest

Implements QCPAbstractPlottable.

## § interface1D()

virtual QCPPlottableInterface1D* QCPErrorBars::interface1D | ( |  | ) |
| inlinevirtual

If this plottable is a one-dimensional plottable, i.e. it implements the QCPPlottableInterface1D, returns the this pointer with that type. Otherwise (e.g. in the case of a QCPColorMap) returns zero.

You can use this method to gain read access to data coordinates while holding a pointer to the abstract base class only.

Reimplemented from QCPAbstractPlottable.

## § draw()

void QCPErrorBars::draw | ( | QCPPainter * | painter | ) |
| protectedvirtual

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.

Implements QCPAbstractPlottable.

## § drawLegendIcon()

void QCPErrorBars::drawLegendIcon | ( | QCPPainter * | painter,
|  | const QRectF & | rect
| ) |  | const
| protectedvirtual

called by QCPLegend::draw (via QCPPlottableLegendItem::draw) to create a graphical representation of this plottable inside rect, next to the plottable name.

The passed painter has its cliprect set to rect, so painting outside of rect won't appear outside the legend icon border.

Implements QCPAbstractPlottable.

## § getKeyRange()

QCPRange QCPErrorBars::getKeyRange | ( | bool & | foundRange,
|  | QCP::SignDomain | inSignDomain = `QCP::sdBoth`
| ) |  | const
| protectedvirtual

Returns the coordinate range that all data in this plottable span in the key axis dimension. For logarithmic plots, one can set inSignDomain to either QCP::sdNegative or QCP::sdPositive in order to restrict the returned range to that sign domain. E.g. when only negative range is wanted, set inSignDomain to QCP::sdNegative and all positive points will be ignored for range calculation. For no restriction, just set inSignDomain to QCP::sdBoth (default). foundRange is an output parameter that indicates whether a range could be found or not. If this is false, you shouldn't use the returned range (e.g. no points in data).

Note that foundRange is not the same as QCPRange::validRange, since the range returned by this function may have size zero (e.g. when there is only one data point). In this case foundRange would return true, but the returned range is not a valid range in terms of QCPRange::validRange.

See also
  rescaleAxes, getValueRange

Implements QCPAbstractPlottable.

## § getValueRange()

QCPRange QCPErrorBars::getValueRange | ( | bool & | foundRange,
|  | QCP::SignDomain | inSignDomain = `QCP::sdBoth`,
|  | const QCPRange & | inKeyRange = `QCPRange()`
| ) |  | const
| protectedvirtual

Returns the coordinate range that the data points in the specified key range (inKeyRange) span in the value axis dimension. For logarithmic plots, one can set inSignDomain to either QCP::sdNegative or QCP::sdPositive in order to restrict the returned range to that sign domain. E.g. when only negative range is wanted, set inSignDomain to QCP::sdNegative and all positive points will be ignored for range calculation. For no restriction, just set inSignDomain to QCP::sdBoth (default). foundRange is an output parameter that indicates whether a range could be found or not. If this is false, you shouldn't use the returned range (e.g. no points in data).

If inKeyRange has both lower and upper bound set to zero (is equal to `QCPRange()`), all data points are considered, without any restriction on the keys.

Note that foundRange is not the same as QCPRange::validRange, since the range returned by this function may have size zero (e.g. when there is only one data point). In this case foundRange would return true, but the returned range is not a valid range in terms of QCPRange::validRange.

See also
  rescaleAxes, getKeyRange

Implements QCPAbstractPlottable.

## § getErrorBarLines()

void QCPErrorBars::getErrorBarLines | ( | QCPErrorBarsDataContainer::const_iterator | it,
|  | QVector< QLineF > & | backbones,
|  | QVector< QLineF > & | whiskers
| ) |  | const
| protected

Calculates the lines that make up the error bar belonging to the data point it.

The resulting lines are added to backbones and whiskers. The vectors are not cleared, so calling this method with different it but the same backbones and whiskers allows to accumulate lines for multiple data points.

This method assumes that it is a valid iterator within the bounds of this QCPErrorBars instance and within the bounds of the associated data plottable.

## § getVisibleDataBounds()

void QCPErrorBars::getVisibleDataBounds | ( | QCPErrorBarsDataContainer::const_iterator & | begin,
|  | QCPErrorBarsDataContainer::const_iterator & | end,
|  | const QCPDataRange & | rangeRestriction
| ) |  | const
| protected

This method outputs the currently visible data range via begin and end. The returned range will also never exceed rangeRestriction.

Since error bars with type etKeyError may extend to arbitrarily positive and negative key coordinates relative to their data point key, this method checks all outer error bars whether they truly don't reach into the visible portion of the axis rect, by calling errorBarVisible. On the other hand error bars with type etValueError that are associated with data plottables whose sort key is equal to the main key (see QCPDataContainer DataType) can be handled very efficiently by finding the visible range of error bars through binary search (QCPPlottableInterface1D::findBegin and QCPPlottableInterface1D::findEnd).

If the plottable's sort key is not equal to the main key, this method returns the full data range, only restricted by rangeRestriction. Drawing optimization then has to be done on a point-by-point basis in the draw method.

## § pointDistance()

double QCPErrorBars::pointDistance | ( | const QPointF & | pixelPoint,
|  | QCPErrorBarsDataContainer::const_iterator & | closestData
| ) |  | const
| protected

Calculates the minimum distance in pixels the error bars' representation has from the given pixelPoint. This is used to determine whether the error bar was clicked or not, e.g. in selectTest. The closest data point to pixelPoint is returned in closestData.

## § getDataSegments()

void QCPErrorBars::getDataSegments | ( | QList< QCPDataRange > & | selectedSegments,
|  | QList< QCPDataRange > & | unselectedSegments
| ) |  | const
| protected

Note
  This method is identical to QCPAbstractPlottable1D::getDataSegments but needs to be reproduced here since the QCPErrorBars plottable, as a special case that doesn't have its own key/value data coordinates, doesn't derive from QCPAbstractPlottable1D. See the documentation there for details.

## § errorBarVisible()

bool QCPErrorBars::errorBarVisible | ( | int | index | ) | const
| protected

Returns whether the error bar at the specified index is visible within the current key axis range.

This method assumes for performance reasons without checking that the key axis, the value axis, and the data plottable (setDataPlottable) are not `nullptr` and that index is within valid bounds of this QCPErrorBars instance and the bounds of the data plottable.

## § rectIntersectsLine()

bool QCPErrorBars::rectIntersectsLine | ( | const QRectF & | pixelRect,
|  | const QLineF & | line
| ) |  | const
| protected

Returns whether line intersects (or is contained in) pixelRect.

line is assumed to be either perfectly horizontal or perfectly vertical, as is the case for error bar lines.

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

- src/plottables/plottable-errorbar.h
- src/plottables/plottable-errorbar.cpp