QCPAxisTicker Class Reference

The base class tick generator used by QCPAxis to create tick positions and tick labels. More...

Inheritance diagram for QCPAxisTicker:

Public Types
enum	TickStepStrategy { tssReadability , tssMeetTickCount }

Public Member Functions
	QCPAxisTicker ()
TickStepStrategy	tickStepStrategy () const
int	tickCount () const
double	tickOrigin () const
void	setTickStepStrategy (TickStepStrategy strategy)
void	setTickCount (int count)
void	setTickOrigin (double origin)
virtual void	generate (const QCPRange &range, const QLocale &locale, QChar formatChar, int precision, QVector< double > &ticks, QVector< double > *subTicks, QVector< QString > *tickLabels)

Protected Member Functions
virtual double	getTickStep (const QCPRange &range)
virtual int	getSubTickCount (double tickStep)
virtual QString	getTickLabel (double tick, const QLocale &locale, QChar formatChar, int precision)
virtual QVector< double >	createTickVector (double tickStep, const QCPRange &range)
virtual QVector< double >	createSubTickVector (int subTickCount, const QVector< double > &ticks)
virtual QVector< QString >	createLabelVector (const QVector< double > &ticks, const QLocale &locale, QChar formatChar, int precision)
void	trimTicks (const QCPRange &range, QVector< double > &ticks, bool keepOneOutlier) const
double	pickClosest (double target, const QVector< double > &candidates) const
double	getMantissa (double input, double *magnitude=nullptr) const
double	cleanMantissa (double input) const

Protected Attributes
TickStepStrategy	mTickStepStrategy
int	mTickCount
double	mTickOrigin

Detailed Description

The base class tick generator used by QCPAxis to create tick positions and tick labels.

Each QCPAxis has an internal QCPAxisTicker (or a subclass) in order to generate tick positions and tick labels for the current axis range. The ticker of an axis can be set via QCPAxis::setTicker. Since that method takes a QSharedPointer<QCPAxisTicker>, multiple axes can share the same ticker instance.

This base class generates normal tick coordinates and numeric labels for linear axes. It picks a reasonable tick step (the separation between ticks) which results in readable tick labels. The number of ticks that should be approximately generated can be set via setTickCount. Depending on the current tick step strategy (setTickStepStrategy), the algorithm either sacrifices readability to better match the specified tick count (QCPAxisTicker::tssMeetTickCount) or relaxes the tick count in favor of better tick steps (QCPAxisTicker::tssReadability), which is the default.

The following more specialized axis ticker subclasses are available, see details in the respective class documentation:

QCPAxisTickerFixed
QCPAxisTickerLog
QCPAxisTickerPi
QCPAxisTickerText
QCPAxisTickerDateTime
QCPAxisTickerTime

Creating own axis tickers

Creating own axis tickers can be achieved very easily by sublassing QCPAxisTicker and reimplementing some or all of the available virtual methods.

In the simplest case you might wish to just generate different tick steps than the other tickers, so you only reimplement the method getTickStep. If you additionally want control over the string that will be shown as tick label, reimplement getTickLabel.

If you wish to have complete control, you can generate the tick vectors and tick label vectors yourself by reimplementing createTickVector and createLabelVector. The default implementations use the previously mentioned virtual methods getTickStep and getTickLabel, but your reimplementations don't necessarily need to do so. For example in the case of unequal tick steps, the method getTickStep loses its usefulness and can be ignored.

The sub tick count between major ticks can be controlled with getSubTickCount. Full sub tick placement control is obtained by reimplementing createSubTickVector.

See the documentation of all these virtual methods in QCPAxisTicker for detailed information about the parameters and expected return values.

Member Enumeration Documentation

TickStepStrategy

enum QCPAxisTicker::TickStepStrategy

Defines the strategies that the axis ticker may follow when choosing the size of the tick step.

See also

setTickStepStrategy

Enumerator
tssReadability	A nicely readable tick step is prioritized over matching the requested number of ticks (see setTickCount)
tssMeetTickCount	Less readable tick steps are allowed which in turn facilitates getting closer to the requested tick count.

Constructor & Destructor Documentation

QCPAxisTicker()

QCPAxisTicker::QCPAxisTicker

(

)

Constructs the ticker and sets reasonable default values. Axis tickers are commonly created managed by a QSharedPointer, which then can be passed to QCPAxis::setTicker.

Member Function Documentation

createTickVector()

QVector< double > QCPAxisTicker::createTickVector ( double tickStep, const QCPRange & range )

protectedvirtual

Reimplemented in QCPAxisTickerText.

generate()

void QCPAxisTicker::generate ( const QCPRange & range, const QLocale & locale, QChar formatChar, int precision, QVector< double > & ticks, QVector< double > * subTicks, QVector< QString > * tickLabels )

virtual

This is the method called by QCPAxis in order to actually generate tick coordinates (ticks), tick label strings (tickLabels) and sub tick coordinates (subTicks).

The ticks are generated for the specified range. The generated labels typically follow the specified locale, formatChar and number precision, however this might be different (or even irrelevant) for certain QCPAxisTicker subclasses.

The output parameter ticks is filled with the generated tick positions in axis coordinates. The output parameters subTicks and tickLabels are optional (set them to nullptr if not needed) and are respectively filled with sub tick coordinates, and tick label strings belonging to ticks by index.

getSubTickCount()

int QCPAxisTicker::getSubTickCount ( double tickStep )

protectedvirtual

Reimplemented in QCPAxisTickerText.

getTickLabel()

QString QCPAxisTicker::getTickLabel ( double tick, const QLocale & locale, QChar formatChar, int precision )

protectedvirtual

Reimplemented in QCPAxisTickerText.

getTickStep()

double QCPAxisTicker::getTickStep ( const QCPRange & range )

protectedvirtual

Reimplemented in QCPAxisTickerText.

setTickCount()

void QCPAxisTicker::setTickCount

(

int

count

)

Sets how many ticks this ticker shall aim to generate across the axis range. Note that count is not guaranteed to be matched exactly, as generating readable tick intervals may conflict with the requested number of ticks.

Whether the readability has priority over meeting the requested count can be specified with setTickStepStrategy.

setTickOrigin()

void QCPAxisTicker::setTickOrigin

(

double

origin

)

Sets the mathematical coordinate (or "offset") of the zeroth tick. This tick coordinate is just a concept and doesn't need to be inside the currently visible axis range.

By default origin is zero, which for example yields ticks {-5, 0, 5, 10, 15,...} when the tick step is five. If origin is now set to 1 instead, the correspondingly generated ticks would be {-4, 1, 6, 11, 16,...}.

setTickStepStrategy()

void QCPAxisTicker::setTickStepStrategy

(

QCPAxisTicker::TickStepStrategy

strategy

)

Sets which strategy the axis ticker follows when choosing the size of the tick step. For the available strategies, see TickStepStrategy.

---

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

• app/NaFCSE/qcustomplot.h
• app/NaFCSE/qcustomplot.cpp