QCPAxisTickerLog Class Reference

Inheritance diagram for QCPAxisTickerLog:

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

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

Protected Attributes
double	mLogBase
double	mLogBaseLnInv
int	mSubTickCount
Protected Attributes inherited from QCPAxisTicker
int	mTickCount
double	mTickOrigin
TickStepStrategy	mTickStepStrategy

Additional Inherited Members
Public Types inherited from QCPAxisTicker
enum	TickStepStrategy { tssReadability , tssMeetTickCount }

Detailed Description

Specialized axis ticker suited for logarithmic axes.

This QCPAxisTicker subclass generates ticks with unequal tick intervals suited for logarithmic axis scales. The ticks are placed at powers of the specified log base (setLogBase).

Especially in the case of a log base equal to 10 (the default), it might be desirable to have tick labels in the form of powers of ten without mantissa display. To achieve this, set the number precision (QCPAxis::setNumberPrecision) to zero and the number format (QCPAxis::setNumberFormat) to scientific (exponential) display with beautifully typeset decimal powers, so a format string of "eb". This will result in the following axis tick labels:

The ticker can be created and assigned to an axis like this:

Note that the nature of logarithmic ticks imply that there exists a smallest possible tick step, corresponding to one multiplication by the log base. If the user zooms in further than that, no new ticks would appear, leading to very sparse or even no axis ticks on the axis. To prevent this situation, this ticker falls back to regular tick generation if the axis range would be covered by too few logarithmically placed ticks.

Definition at line 1980 of file qcustomplot.h.

Constructor & Destructor Documentation

QCPAxisTickerLog()

QCPAxisTickerLog::QCPAxisTickerLog

(

)

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.

Definition at line 7712 of file qcustomplot.cpp.

Member Function Documentation

createTickVector()

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

overrideprotectedvirtual

Creates ticks with a spacing given by the logarithm base and an increasing integer power in the provided range. The step in which the power increases tick by tick is chosen in order to keep the total number of ticks as close as possible to the tick count (setTickCount).

The parameter tickStep is ignored for the normal logarithmic ticker generation. Only when zoomed in very far such that not enough logarithmically placed ticks would be visible, this function falls back to the regular QCPAxisTicker::createTickVector, which then uses tickStep.

\seebaseclassmethod

Reimplemented from QCPAxisTicker.

Definition at line 7776 of file qcustomplot.cpp.

getSubTickCount()

int QCPAxisTickerLog::getSubTickCount ( double tickStep )

overrideprotectedvirtual

Returns the sub tick count specified in setSubTickCount. For QCPAxisTickerLog, there is no automatic sub tick count calculation necessary.

\seebaseclassmethod

Reimplemented from QCPAxisTicker.

Definition at line 7758 of file qcustomplot.cpp.

logBase()

double QCPAxisTickerLog::logBase ( ) const

inline

Definition at line 1986 of file qcustomplot.h.

setLogBase()

void QCPAxisTickerLog::setLogBase

(

double

base

)

Sets the logarithm base used for tick coordinate generation. The ticks will be placed at integer powers of base.

Definition at line 7723 of file qcustomplot.cpp.

setSubTickCount()

void QCPAxisTickerLog::setSubTickCount

(

int

subTicks

)

Sets the number of sub ticks in a tick interval. Within each interval, the sub ticks are spaced linearly to provide a better visual guide, so the sub tick density increases toward the higher tick.

Note that subTicks is the number of sub ticks (not sub intervals) in one tick interval. So in the case of logarithm base 10 an intuitive sub tick spacing would be achieved with eight sub ticks (the default). This means e.g. between the ticks 10 and 100 there will be eight ticks, namely at 20, 30, 40, 50, 60, 70, 80 and 90.

Definition at line 7743 of file qcustomplot.cpp.

subTickCount()

int QCPAxisTickerLog::subTickCount ( ) const

inline

Definition at line 1987 of file qcustomplot.h.

Member Data Documentation

mLogBase

double QCPAxisTickerLog::mLogBase

protected

Definition at line 1995 of file qcustomplot.h.

mLogBaseLnInv

double QCPAxisTickerLog::mLogBaseLnInv

protected

Definition at line 1999 of file qcustomplot.h.

mSubTickCount

int QCPAxisTickerLog::mSubTickCount

protected

Definition at line 1996 of file qcustomplot.h.

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

• qcustomplot.h
• qcustomplot.cpp