A scale engine for date/time values. More...

#include <qwt_date_scale_engine.h>

Inheritance diagram for QwtDateScaleEngine:

Classes
class	PrivateData

Public Member Functions
	QwtDateScaleEngine (Qt::TimeSpec=Qt::LocalTime)
	Constructor with time specification.

	~QwtDateScaleEngine () override
	Destructor.

void	setTimeSpec (Qt::TimeSpec)
	Set the time specification used by the engine.

Qt::TimeSpec	timeSpec () const
	Get the time specification used by the engine.

void	setUtcOffset (int seconds)
	Set the offset in seconds from Coordinated Universal Time.

int	utcOffset () const
	Get the offset in seconds from Coordinated Universal Time.

void	setWeek0Type (QwtDate::Week0Type)
	Set how to identify the first week of a year.

QwtDate::Week0Type	week0Type () const
	Get how to identify the first week of a year.

void	setMaxWeeks (int)
	Set upper limit for the number of weeks.

int	maxWeeks () const
	Get upper limit for the number of weeks.

virtual void	autoScale (int maxNumSteps, double &x1, double &x2, double &stepSize) const override
	Align and divide an interval.

virtual QwtScaleDiv	divideScale (double x1, double x2, int maxMajorSteps, int maxMinorSteps, double stepSize=0.0) const override
	Calculate a scale division for a date/time interval.

virtual QwtDate::IntervalType	intervalType (const QDateTime &, const QDateTime &, int maxSteps) const
	Classification of a date/time interval division.

QDateTime	toDateTime (double) const
	Translate a double value into a QDateTime object.

Public Member Functions inherited from QwtLinearScaleEngine
	QwtLinearScaleEngine (uint base=10)
	Constructor.

	~QwtLinearScaleEngine () override
	Destructor.

Public Member Functions inherited from QwtScaleEngine
	QwtScaleEngine (uint base=10)
	Constructor.

void	setBase (uint base)
	Set the base.

uint	base () const
	Return base of the scale engine.

void	setAttribute (Attribute, bool on=true)
	Set an attribute.

bool	testAttribute (Attribute) const
	Test if an attribute is enabled.

void	setAttributes (Attributes)
	Set attributes.

Attributes	attributes () const
	Return scale attributes.

void	setReference (double)
	Set the reference value.

double	reference () const
	Return the reference value.

void	setMargins (double lower, double upper)
	Set the margins.

double	lowerMargin () const
	Return the margin at the lower end of the scale.

double	upperMargin () const
	Return the margin at the upper end of the scale.

void	setTransformation (QwtTransform *)
	Set the transformation.

QwtTransform *	transformation () const
	Create and return a clone of the transformation of the engine.

Protected Member Functions
virtual QDateTime	alignDate (const QDateTime &, double stepSize, QwtDate::IntervalType, bool up) const
	Align a date/time value for a step size.

Protected Member Functions inherited from QwtLinearScaleEngine
QwtInterval	align (const QwtInterval &, double stepSize) const
	Align an interval to a step size.

void	buildTicks (const QwtInterval &, double stepSize, int maxMinorSteps, QList< double > ticks[QwtScaleDiv::NTickTypes]) const
	Calculate ticks for an interval.

QList< double >	buildMajorTicks (const QwtInterval &interval, double stepSize) const
	Calculate major ticks for an interval.

void	buildMinorTicks (const QList< double > &majorTicks, int maxMinorSteps, double stepSize, QList< double > &minorTicks, QList< double > &mediumTicks) const
	Calculate minor/medium ticks for major ticks.

Protected Member Functions inherited from QwtScaleEngine
bool	contains (const QwtInterval &, double value) const
	Check if an interval contains a value.

QList< double >	strip (const QList< double > &, const QwtInterval &) const
	Strip values outside an interval.

double	divideInterval (double intervalSize, int numSteps) const
	Divide an interval.

QwtInterval	buildInterval (double value) const
	Build an interval around a value.

Additional Inherited Members
Public Types inherited from QwtScaleEngine
enum	Attribute { NoAttribute = 0x00 , IncludeReference = 0x01 , Symmetric = 0x02 , Floating = 0x04 , Inverted = 0x08 }
	Layout attributes. More...

Detailed Description

A scale engine for date/time values.

QwtDateScaleEngine builds scales from time intervals. Together with QwtDateScaleDraw it can be used for axes according to date/time values.

Years, months, weeks, days, hours and minutes are organized in steps with non constant intervals. QwtDateScaleEngine classifies intervals and aligns the boundaries and tick positions according to this classification.

QwtDateScaleEngine supports representations depending on Qt::TimeSpec specifications. The valid range for scales is limited by the range of QDateTime, that differs between Qt4 and Qt5.

Datetime values are expected as the number of milliseconds since 1970-01-01T00:00:00 Universal Coordinated Time - also known as "The Epoch", that can be converted to QDateTime using QwtDate::toDateTime().

See also: QwtDate, QwtPlot::setAxisScaleEngine(), QwtAbstractScale::setScaleEngine()

Constructor & Destructor Documentation

◆ QwtDateScaleEngine()

QwtDateScaleEngine::QwtDateScaleEngine ( Qt::TimeSpec timeSpec = Qt::LocalTime )

explicit

Constructor with time specification.

Constructor.

The engine is initialized to build scales for the given time specification. It classifies intervals > 4 weeks as >= Qt::Month. The first week of a year is defined like for QwtDate::FirstThursday.

Parameters

[in] timeSpec Time specification

See also: setTimeSpec(), setMaxWeeks(), setWeek0Type()

Member Function Documentation

◆ alignDate()

QDateTime QwtDateScaleEngine::alignDate	(	const QDateTime &	dateTime,
		double	stepSize,
		QwtDate::IntervalType	intervalType,
		bool	up
	)		const

protectedvirtual

Align a date/time value for a step size.

For Qt::Day alignments there is no "natural day 0" - instead the first day of the year is used to avoid jumping major ticks positions when panning a scale. For other alignments ( f.e according to the first day of the month ) alignDate() has to be overloaded.

Parameters

dateTime	Date/time value
stepSize	Step size
intervalType	Interval type
up	When true dateTime is ceiled - otherwise it is floored

Returns: Aligned date/time value

◆ autoScale()

void QwtDateScaleEngine::autoScale	(	int	maxNumSteps,
		double &	x1,
		double &	x2,
		double &	stepSize
	)		const

overridevirtual

Align and divide an interval.

The algorithm aligns and divides the interval into steps. Datetime interval divisions are usually not equidistant and the calculated stepSize can only be used as an approximation for the steps calculated by divideScale().

Parameters

[in]	maxNumSteps	Max. number of steps
[out]	x1	First limit of the interval (In/Out)
[out]	x2	Second limit of the interval (In/Out)
[out]	stepSize	Step size (Out)

See also: QwtScaleEngine::setAttribute()

Reimplemented from QwtLinearScaleEngine.

◆ divideScale()

QwtScaleDiv QwtDateScaleEngine::divideScale	(	double	x1,
		double	x2,
		int	maxMajorSteps,
		int	maxMinorSteps,
		double	stepSize = `0.0`
	)		const

overridevirtual

Calculate a scale division for a date/time interval.

Parameters

[in]	x1	First interval limit
[in]	x2	Second interval limit
[in]	maxMajorSteps	Maximum for the number of major steps
[in]	maxMinorSteps	Maximum number of minor steps
[in]	stepSize	Step size. If stepSize == 0, the scaleEngine calculates one.

Returns: Calculated scale division

Reimplemented from QwtLinearScaleEngine.

◆ intervalType()

QwtDate::IntervalType QwtDateScaleEngine::intervalType	(	const QDateTime &	minDate,
		const QDateTime &	maxDate,
		int	maxSteps
	)		const

virtual

Classification of a date/time interval division.

Parameters

[in]	minDate	Minimum ( = earlier ) of the interval
[in]	maxDate	Maximum ( = later ) of the interval
[in]	maxSteps	Maximum for the number of steps

Returns: Interval classification

◆ maxWeeks()

int QwtDateScaleEngine::maxWeeks ( ) const

Get upper limit for the number of weeks.

Get the upper limit for the number of weeks.

Returns: Upper limit for the number of weeks, when an interval can be classified as Qt::Week

See also: setMaxWeeks(), week0Type()

◆ setMaxWeeks()

void QwtDateScaleEngine::setMaxWeeks ( int weeks )

Set upper limit for the number of weeks.

Set an upper limit for the number of weeks.

Set an upper limit for the number of weeks, when an interval can be classified as Qt::Week. The default setting is 4 weeks.

Parameters

[in] weeks Upper limit for the number of weeks

Note: In business charts a year is often divided into weeks [1-52]

See also: maxWeeks(), setWeek0Type()

◆ setTimeSpec()

void QwtDateScaleEngine::setTimeSpec ( Qt::TimeSpec timeSpec )

Set the time specification used by the engine.

Parameters

[in] timeSpec Time specification

See also: timeSpec(), setUtcOffset(), toDateTime()

◆ setUtcOffset()

void QwtDateScaleEngine::setUtcOffset ( int seconds )

Set the offset in seconds from Coordinated Universal Time.

Parameters

[in] seconds Offset in seconds

Note: The offset has no effect beside for the time specification Qt::OffsetFromUTC.

See also: utcOffset(), setTimeSpec(), toDateTime()

◆ setWeek0Type()

void QwtDateScaleEngine::setWeek0Type ( QwtDate::Week0Type week0Type )

Set how to identify the first week of a year.

Parameters

[in] week0Type Mode how to identify the first week of a year

Note: week0Type has no effect beside for intervals classified as QwtDate::Week.

See also: week0Type(), setMaxWeeks()

◆ timeSpec()

Qt::TimeSpec QwtDateScaleEngine::timeSpec ( ) const

Get the time specification used by the engine.

Returns: Time specification used by the engine

See also: setTimeSpec(), utcOffset(), toDateTime()

◆ toDateTime()

QDateTime QwtDateScaleEngine::toDateTime ( double value ) const

Translate a double value into a QDateTime object.

For QDateTime result is bounded by QwtDate::minDate() and QwtDate::maxDate()

Parameters

[in] value Double value to convert

Returns: QDateTime object initialized with timeSpec() and utcOffset()

See also: timeSpec(), utcOffset(), QwtDate::toDateTime()

◆ utcOffset()

int QwtDateScaleEngine::utcOffset ( ) const

Get the offset in seconds from Coordinated Universal Time.

Returns: Offset in seconds from Coordinated Universal Time

Note: The offset has no effect beside for the time specification Qt::OffsetFromUTC.

See also: setUtcOffset(), setTimeSpec(), toDateTime()

◆ week0Type()

QwtDate::Week0Type QwtDateScaleEngine::week0Type ( ) const

Get how to identify the first week of a year.

Returns: Setting how to identify the first week of a year

See also: setWeek0Type(), maxWeeks()

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

/home/runner/work/QWT/QWT/src/plot/qwt_date_scale_engine.h
/home/runner/work/QWT/QWT/src/plot/qwt_date_scale_engine.cpp

Classes

Public Member Functions

Protected Member Functions

Additional Inherited Members

Detailed Description

Constructor & Destructor Documentation

◆ QwtDateScaleEngine()

Member Function Documentation

◆ alignDate()

◆ autoScale()

◆ divideScale()

◆ intervalType()

◆ maxWeeks()

◆ setMaxWeeks()

◆ setTimeSpec()

◆ setUtcOffset()

◆ setWeek0Type()

◆ timeSpec()

◆ toDateTime()

◆ utcOffset()

◆ week0Type()