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

#include <qwt_date_scale_engine.h>

Inheritance diagram for QwtDateScaleEngine:

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

virtual	~QwtDateScaleEngine ()
	Destructor.

void	setTimeSpec (Qt::TimeSpec)

Qt::TimeSpec	timeSpec () const

void	setUtcOffset (int seconds)

int	utcOffset () const

void	setWeek0Type (QwtDate::Week0Type)

QwtDate::Week0Type	week0Type () const

void	setMaxWeeks (int)

int	maxWeeks () const

virtual void	autoScale (int maxNumSteps, double &x1, double &x2, double &stepSize) const override

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

QDateTime	toDateTime (double) const

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

virtual	~QwtLinearScaleEngine ()
	Destructor.

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

virtual	~QwtScaleEngine ()
	Destructor.

void	setBase (uint base)

uint	base () const

void	setAttribute (Attribute, bool on=true)

bool	testAttribute (Attribute) const

void	setAttributes (Attributes)

Attributes	attributes () const

void	setReference (double)
	Specify a reference point.

double	reference () const

void	setMargins (double lower, double upper)
	Specify margins at the scale's endpoints.

double	lowerMargin () const

double	upperMargin () const

void	setTransformation (QwtTransform *)

QwtTransform *	transformation () const

Protected Member Functions
virtual QDateTime	alignDate (const QDateTime &, double stepSize, QwtDate::IntervalType, bool up) const

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

QList< double >	strip (const QList< double > &, const QwtInterval &) const

double	divideInterval (double intervalSize, int numSteps) const

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 }

typedef QFlags< Attribute >	Attributes

Detailed Description

A scale engine for date/time values.

QwtDateScaleEngine builds scales from a 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()

Definition at line 42 of file qwt_date_scale_engine.h.

Constructor & Destructor Documentation

◆ QwtDateScaleEngine()

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

explicit

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

timeSpec Time specification

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

Definition at line 747 of file qwt_date_scale_engine.cpp.

◆ ~QwtDateScaleEngine()

QwtDateScaleEngine::~QwtDateScaleEngine ( )

virtual

Destructor.

Definition at line 754 of file qwt_date_scale_engine.cpp.

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

Definition at line 1108 of file qwt_date_scale_engine.cpp.

◆ 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

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

See also: QwtScaleEngine::setAttribute()

Reimplemented from QwtLinearScaleEngine.

Definition at line 925 of file qwt_date_scale_engine.cpp.

◆ 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

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

Returns: Calculated scale division

Reimplemented from QwtLinearScaleEngine.

Definition at line 992 of file qwt_date_scale_engine.cpp.

◆ intervalType()

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

virtual

Classification of a date/time interval division

Parameters

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

Returns: Interval classification

Definition at line 865 of file qwt_date_scale_engine.cpp.

◆ maxWeeks()

int QwtDateScaleEngine::maxWeeks ( ) const

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

See also: setMaxWeeks(), week0Type()

Definition at line 851 of file qwt_date_scale_engine.cpp.

◆ setMaxWeeks()

void QwtDateScaleEngine::setMaxWeeks ( int weeks )

Set a upper limit for the number of weeks, when an interval can be classified as Qt::Week.

The default setting is 4 weeks.

Parameters

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()

Definition at line 841 of file qwt_date_scale_engine.cpp.

◆ setTimeSpec()

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

Set the time specification used by the engine

Parameters

timeSpec Time specification

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

Definition at line 765 of file qwt_date_scale_engine.cpp.

◆ setUtcOffset()

void QwtDateScaleEngine::setUtcOffset ( int seconds )

Set the offset in seconds from Coordinated Universal Time

Parameters

seconds Offset in seconds

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

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

Definition at line 789 of file qwt_date_scale_engine.cpp.

◆ setWeek0Type()

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

Sets how to identify the first week of a year.

Parameters

week0Type Mode how to identify the first week of a year

See also: week0Type(), setMaxWeeks()

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

Definition at line 815 of file qwt_date_scale_engine.cpp.

◆ timeSpec()

Qt::TimeSpec QwtDateScaleEngine::timeSpec ( ) const

Returns: Time specification used by the engine

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

Definition at line 774 of file qwt_date_scale_engine.cpp.

◆ 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()

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

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

Definition at line 1298 of file qwt_date_scale_engine.cpp.

◆ utcOffset()

int QwtDateScaleEngine::utcOffset ( ) const

Returns: Offset in seconds from Coordinated Universal Time

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

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

Definition at line 801 of file qwt_date_scale_engine.cpp.

◆ week0Type()

QwtDate::Week0Type QwtDateScaleEngine::week0Type ( ) const

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

See also: setWeek0Type(), maxWeeks()

Definition at line 824 of file qwt_date_scale_engine.cpp.

Public Member Functions

Protected Member Functions

Additional Inherited Members

Detailed Description

Constructor & Destructor Documentation

◆ QwtDateScaleEngine()

◆ ~QwtDateScaleEngine()

Member Function Documentation

◆ alignDate()

◆ autoScale()

◆ divideScale()

◆ intervalType()

◆ maxWeeks()

◆ setMaxWeeks()

◆ setTimeSpec()

◆ setUtcOffset()

◆ setWeek0Type()

◆ timeSpec()

◆ toDateTime()

◆ utcOffset()

◆ week0Type()