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.

virtual	~QwtDateScaleEngine ()
	Destructor.

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

Qt::TimeSpec	timeSpec () const

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

int	utcOffset () const

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

QwtDate::Week0Type	week0Type () const

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

int	maxWeeks () const

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

virtual QwtScaleDiv	divideScale (double x1, double x2, int maxMajorSteps, int maxMinorSteps, double stepSize=0.0) const QWT_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.

virtual	~QwtLinearScaleEngine ()
	Destructor.

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

virtual	~QwtScaleEngine ()
	Destructor.

void	setBase (uint base)
	Set the base of the scale engine.

uint	base () const

void	setAttribute (Attribute, bool on=true)
	Change a scale attribute.

bool	testAttribute (Attribute) const

void	setAttributes (Attributes)
	Change the scale attribute.

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 *)
	Assign a 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
	Remove ticks from a list, that are not inside an interval.

double	divideInterval (double intervalSize, int numSteps) const
	Calculate a step size for an interval size.

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/布局属性 More...

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()

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()

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

virtual

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.

◆ divideScale()

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

virtual

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.

◆ 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

◆ 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()

◆ 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()

◆ setTimeSpec()

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

Set the time specification used by the engine.

Parameters

timeSpec Time specification

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

◆ 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()

◆ 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.

◆ timeSpec()

Qt::TimeSpec QwtDateScaleEngine::timeSpec ( ) const

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()

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

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

◆ 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()

◆ week0Type()

QwtDate::Week0Type QwtDateScaleEngine::week0Type ( ) const

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/qwt_date_scale_engine.h
/home/runner/work/QWT/QWT/src/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()