QCPGraph Class Reference

A plottable representing a graph in a plot. More...

Inheritance diagram for QCPGraph:

Public Types
enum	LineStyle {   lsNone , lsLine , lsStepLeft , lsStepRight ,   lsStepCenter , lsImpulse }

Public Member Functions
	QCPGraph (QCPAxis *keyAxis, QCPAxis *valueAxis)
QSharedPointer< QCPGraphDataContainer >	data () const
LineStyle	lineStyle () const
QCPScatterStyle	scatterStyle () const
int	scatterSkip () const
QCPGraph *	channelFillGraph () const
bool	adaptiveSampling () const
void	setData (QSharedPointer< QCPGraphDataContainer > data)
void	setData (const QVector< double > &keys, const QVector< double > &values, bool alreadySorted=false)
void	setLineStyle (LineStyle ls)
void	setScatterStyle (const QCPScatterStyle &style)
void	setScatterSkip (int skip)
void	setChannelFillGraph (QCPGraph *targetGraph)
void	setAdaptiveSampling (bool enabled)
void	addData (const QVector< double > &keys, const QVector< double > &values, bool alreadySorted=false)
void	addData (double key, double value)
virtual double	selectTest (const QPointF &pos, bool onlySelectable, QVariant *details=nullptr) const Q_DECL_OVERRIDE
virtual QCPRange	getKeyRange (bool &foundRange, QCP::SignDomain inSignDomain=QCP::sdBoth) const Q_DECL_OVERRIDE
virtual QCPRange	getValueRange (bool &foundRange, QCP::SignDomain inSignDomain=QCP::sdBoth, const QCPRange &inKeyRange=QCPRange()) const Q_DECL_OVERRIDE
Public Member Functions inherited from QCPAbstractPlottable1D< QCPGraphData >
	QCPAbstractPlottable1D (QCPAxis *keyAxis, QCPAxis *valueAxis)
virtual int	dataCount () const Q_DECL_OVERRIDE
virtual double	dataMainKey (int index) const Q_DECL_OVERRIDE
virtual double	dataSortKey (int index) const Q_DECL_OVERRIDE
virtual double	dataMainValue (int index) const Q_DECL_OVERRIDE
virtual QCPRange	dataValueRange (int index) const Q_DECL_OVERRIDE
virtual QPointF	dataPixelPosition (int index) const Q_DECL_OVERRIDE
virtual bool	sortKeyIsMainKey () const Q_DECL_OVERRIDE
virtual QCPDataSelection	selectTestRect (const QRectF &rect, bool onlySelectable) const Q_DECL_OVERRIDE
virtual int	findBegin (double sortKey, bool expandedRange=true) const Q_DECL_OVERRIDE
virtual int	findEnd (double sortKey, bool expandedRange=true) const Q_DECL_OVERRIDE
virtual QCPPlottableInterface1D *	interface1D () Q_DECL_OVERRIDE
Public Member 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 Member 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 Member Functions
virtual void	draw (QCPPainter *painter) Q_DECL_OVERRIDE
virtual void	drawLegendIcon (QCPPainter *painter, const QRectF &rect) const Q_DECL_OVERRIDE
virtual void	drawFill (QCPPainter *painter, QVector< QPointF > *lines) const
virtual void	drawScatterPlot (QCPPainter *painter, const QVector< QPointF > &scatters, const QCPScatterStyle &style) const
virtual void	drawLinePlot (QCPPainter *painter, const QVector< QPointF > &lines) const
virtual void	drawImpulsePlot (QCPPainter *painter, const QVector< QPointF > &lines) const
virtual void	getOptimizedLineData (QVector< QCPGraphData > *lineData, const QCPGraphDataContainer::const_iterator &begin, const QCPGraphDataContainer::const_iterator &end) const
virtual void	getOptimizedScatterData (QVector< QCPGraphData > *scatterData, QCPGraphDataContainer::const_iterator begin, QCPGraphDataContainer::const_iterator end) const
void	getVisibleDataBounds (QCPGraphDataContainer::const_iterator &begin, QCPGraphDataContainer::const_iterator &end, const QCPDataRange &rangeRestriction) const
void	getLines (QVector< QPointF > *lines, const QCPDataRange &dataRange) const
void	getScatters (QVector< QPointF > *scatters, const QCPDataRange &dataRange) const
QVector< QPointF >	dataToLines (const QVector< QCPGraphData > &data) const
QVector< QPointF >	dataToStepLeftLines (const QVector< QCPGraphData > &data) const
QVector< QPointF >	dataToStepRightLines (const QVector< QCPGraphData > &data) const
QVector< QPointF >	dataToStepCenterLines (const QVector< QCPGraphData > &data) const
QVector< QPointF >	dataToImpulseLines (const QVector< QCPGraphData > &data) const
QVector< QCPDataRange >	getNonNanSegments (const QVector< QPointF > *lineData, Qt::Orientation keyOrientation) const
QVector< QPair< QCPDataRange, QCPDataRange > >	getOverlappingSegments (QVector< QCPDataRange > thisSegments, const QVector< QPointF > *thisData, QVector< QCPDataRange > otherSegments, const QVector< QPointF > *otherData) const
bool	segmentsIntersect (double aLower, double aUpper, double bLower, double bUpper, int &bPrecedence) const
QPointF	getFillBasePoint (QPointF matchingDataPoint) const
const QPolygonF	getFillPolygon (const QVector< QPointF > *lineData, QCPDataRange segment) const
const QPolygonF	getChannelFillPolygon (const QVector< QPointF > *thisData, QCPDataRange thisSegment, const QVector< QPointF > *otherData, QCPDataRange otherSegment) const
int	findIndexBelowX (const QVector< QPointF > *data, double x) const
int	findIndexAboveX (const QVector< QPointF > *data, double x) const
int	findIndexBelowY (const QVector< QPointF > *data, double y) const
int	findIndexAboveY (const QVector< QPointF > *data, double y) const
double	pointDistance (const QPointF &pixelPoint, QCPGraphDataContainer::const_iterator &closestData) const
Protected Member Functions inherited from QCPAbstractPlottable1D< QCPGraphData >
void	getDataSegments (QList< QCPDataRange > &selectedSegments, QList< QCPDataRange > &unselectedSegments) const
void	drawPolyline (QCPPainter *painter, const QVector< QPointF > &lineData) const
Protected Member Functions inherited from QCPAbstractPlottable
virtual QRect	clipRect () const Q_DECL_OVERRIDE
virtual QCP::Interaction	selectionCategory () const Q_DECL_OVERRIDE
void	applyDefaultAntialiasingHint (QCPPainter *painter) const Q_DECL_OVERRIDE
virtual void	selectEvent (QMouseEvent *event, bool additive, const QVariant &details, bool *selectionStateChanged) Q_DECL_OVERRIDE
virtual void	deselectEvent (bool *selectionStateChanged) Q_DECL_OVERRIDE
void	applyFillAntialiasingHint (QCPPainter *painter) const
void	applyScattersAntialiasingHint (QCPPainter *painter) const
Protected Member 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

Protected Attributes
LineStyle	mLineStyle
QCPScatterStyle	mScatterStyle
int	mScatterSkip
QPointer< QCPGraph >	mChannelFillGraph
bool	mAdaptiveSampling
Protected Attributes inherited from QCPAbstractPlottable1D< QCPGraphData >
QSharedPointer< QCPDataContainer< QCPGraphData > >	mDataContainer
Protected Attributes inherited from QCPAbstractPlottable
QString	mName
bool	mAntialiasedFill
bool	mAntialiasedScatters
QPen	mPen
QBrush	mBrush
QPointer< QCPAxis >	mKeyAxis
QPointer< QCPAxis >	mValueAxis
QCP::SelectionType	mSelectable
QCPDataSelection	mSelection
QCPSelectionDecorator *	mSelectionDecorator
Protected Attributes inherited from QCPLayerable
bool	mVisible
QCustomPlot *	mParentPlot
QPointer< QCPLayerable >	mParentLayerable
QCPLayer *	mLayer
bool	mAntialiased

Friends
class	QCustomPlot
class	QCPLegend

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 representing a graph in a plot.

Usually you create new graphs by calling QCustomPlot::addGraph. The resulting instance can be accessed via QCustomPlot::graph.

To plot data, assign it with the setData or addData functions. Alternatively, you can also access and modify the data via the data method, which returns a pointer to the internal QCPGraphDataContainer.

Graphs are used to display single-valued data. Single-valued means that there should only be one data point per unique key coordinate. In other words, the graph can't have loops. If you do want to plot non-single-valued curves, rather use the QCPCurve plottable.

Gaps in the graph line can be created by adding data points with NaN as value (qQNaN() or std::numeric_limits<double>::quiet_NaN()) in between the two data points that shall be separated.

Changing the appearance

The appearance of the graph is mainly determined by the line style, scatter style, brush and pen of the graph (setLineStyle, setScatterStyle, setBrush, setPen).

Filling under or between graphs

QCPGraph knows two types of fills: Normal graph fills towards the zero-value-line parallel to the key axis of the graph, and fills between two graphs, called channel fills. To enable a fill, just set a brush with setBrush which is neither Qt::NoBrush nor fully transparent.

By default, a normal fill towards the zero-value-line will be drawn. To set up a channel fill between this graph and another one, call setChannelFillGraph with the other graph as parameter.

See also

QCustomPlot::addGraph, QCustomPlot::graph

Member Enumeration Documentation

LineStyle

enum QCPGraph::LineStyle

Defines how the graph's line is represented visually in the plot. The line is drawn with the current pen of the graph (setPen).

See also

setLineStyle

Enumerator
lsNone	data points are not connected with any lines (e.g. data only represented with symbols according to the scatter style, see setScatterStyle)
lsLine	data points are connected by a straight line
lsStepLeft	line is drawn as steps where the step height is the value of the left data point
lsStepRight	line is drawn as steps where the step height is the value of the right data point
lsStepCenter	line is drawn as steps where the step is in between two data points
lsImpulse	each data point is represented by a line parallel to the value axis, which reaches from the data point to the zero-value-line

Constructor & Destructor Documentation

QCPGraph()

QCPGraph::QCPGraph ( QCPAxis * keyAxis, QCPAxis * valueAxis )

explicit

Constructs a graph 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.

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

To directly create a graph inside a plot, you can also use the simpler QCustomPlot::addGraph function.

Member Function Documentation

addData() [1/2]

void QCPGraph::addData	(	const QVector< double > &	keys,
		const QVector< double > &	values,
		bool	alreadySorted = false )

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

Adds the provided points in keys and values to the current data. The provided vectors should have equal length. Else, the number of added points will be the size of the smallest vector.

If you can guarantee that the passed data points are sorted by keys in ascending order, you can set alreadySorted to true, to improve performance by saving a sorting run.

Alternatively, you can also access and modify the data directly via the data method, which returns a pointer to the internal data container.

addData() [2/2]

void QCPGraph::addData	(	double	key,
		double	value )

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

Adds the provided data point as key and value to the current data.

Alternatively, you can also access and modify the data directly via the data method, which returns a pointer to the internal data container.

data()

QSharedPointer< QCPGraphDataContainer > QCPGraph::data ( ) const

inline

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

draw()

void QCPGraph::draw ( QCPPainter * painter )

protectedvirtual

Implements QCPAbstractPlottable.

drawLegendIcon()

void QCPGraph::drawLegendIcon ( QCPPainter * painter, const QRectF & rect ) const

protectedvirtual

Implements QCPAbstractPlottable.

getKeyRange()

QCPRange QCPGraph::getKeyRange ( bool & foundRange, QCP::SignDomain inSignDomain = QCP::sdBoth ) const

virtual

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 QCPGraph::getValueRange ( bool & foundRange, QCP::SignDomain inSignDomain = QCP::sdBoth, const QCPRange & inKeyRange = QCPRange() ) const

virtual

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.

getVisibleDataBounds()

void QCPGraph::getVisibleDataBounds ( QCPGraphDataContainer::const_iterator & begin, QCPGraphDataContainer::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.

This method takes into account that the drawing of data lines at the axis rect border always requires the points just outside the visible axis range. So begin and end may actually indicate a range that contains one additional data point to the left and right of the visible axis range.

selectTest()

double QCPGraph::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.

\seebaseclassmethod QCPAbstractPlottable::selectTest

Reimplemented from QCPAbstractPlottable1D< QCPGraphData >.

setAdaptiveSampling()

void QCPGraph::setAdaptiveSampling

(

bool

enabled

)

Sets whether adaptive sampling shall be used when plotting this graph. QCustomPlot's adaptive sampling technique can drastically improve the replot performance for graphs with a larger number of points (e.g. above 10,000), without notably changing the appearance of the graph.

By default, adaptive sampling is enabled. Even if enabled, QCustomPlot decides whether adaptive sampling shall actually be used on a per-graph basis. So leaving adaptive sampling enabled has no disadvantage in almost all cases.

A line plot of 500,000 points without and with adaptive sampling

As can be seen, line plots experience no visual degradation from adaptive sampling. Outliers are reproduced reliably, as well as the overall shape of the data set. The replot time reduces dramatically though. This allows QCustomPlot to display large amounts of data in realtime.

A scatter plot of 100,000 points without and with adaptive sampling

Care must be taken when using high-density scatter plots in combination with adaptive sampling. The adaptive sampling algorithm treats scatter plots more carefully than line plots which still gives a significant reduction of replot times, but not quite as much as for line plots. This is because scatter plots inherently need more data points to be preserved in order to still resemble the original, non-adaptive-sampling plot. As shown above, the results still aren't quite identical, as banding occurs for the outer data points. This is in fact intentional, such that the boundaries of the data cloud stay visible to the viewer. How strong the banding appears, depends on the point density, i.e. the number of points in the plot.

For some situations with scatter plots it might thus be desirable to manually turn adaptive sampling off. For example, when saving the plot to disk. This can be achieved by setting enabled to false before issuing a command like QCustomPlot::savePng, and setting enabled back to true afterwards.

setChannelFillGraph()

void QCPGraph::setChannelFillGraph

(

QCPGraph *

targetGraph

)

Sets the target graph for filling the area between this graph and targetGraph with the current brush (setBrush).

When targetGraph is set to 0, a normal graph fill to the zero-value-line will be shown. To disable any filling, set the brush to Qt::NoBrush.

See also

setBrush

setData() [1/2]

void QCPGraph::setData	(	const QVector< double > &	keys,
		const QVector< double > &	values,
		bool	alreadySorted = false )

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

Replaces the current data with the provided points in keys and values. The provided vectors should have equal length. Else, the number of added points will be the size of the smallest vector.

If you can guarantee that the passed data points are sorted by keys in ascending order, you can set alreadySorted to true, to improve performance by saving a sorting run.

See also

addData

setData() [2/2]

void QCPGraph::setData

(

QSharedPointer< QCPGraphDataContainer >

data

)

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

Replaces the current data container with the provided data container.

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

If you do not wish to share containers, but create a copy from an existing container, rather use the QCPDataContainer<DataType>::set method on the graph's data container directly:

See also

addData

setLineStyle()

void QCPGraph::setLineStyle

(

LineStyle

ls

)

Sets how the single data points are connected in the plot. For scatter-only plots, set ls to lsNone and setScatterStyle to the desired scatter style.

See also

setScatterStyle

setScatterSkip()

void QCPGraph::setScatterSkip

(

int

skip

)

If scatters are displayed (scatter style not QCPScatterStyle::ssNone), skip number of scatter points are skipped/not drawn after every drawn scatter point.

This can be used to make the data appear sparser while for example still having a smooth line, and to improve performance for very high density plots.

If skip is set to 0 (default), all scatter points are drawn.

See also

setScatterStyle

setScatterStyle()

void QCPGraph::setScatterStyle

(

const QCPScatterStyle &

style

)

Sets the visual appearance of single data points in the plot. If set to QCPScatterStyle::ssNone, no scatter points are drawn (e.g. for line-only-plots with appropriate line style).

See also

QCPScatterStyle, setLineStyle

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

• qcustomplot.h
• qcustomplot.cpp