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

#include <qwt_date_scale_engine.h>

Inheritance diagram for QwtDateScaleEngine:

Classes
class	PrivateData
Public Member Functions
virtual void	autoScale (int maxNumSteps, double &x1, double &x2, double &stepSize) const
virtual QwtScaleDiv	divideScale (double x1, double x2, int maxMajorSteps, int maxMinorSteps, double stepSize=0.0) const
	Calculate a scale division for a date/time interval.
virtual QwtDate::IntervalType	intervalType (const QDateTime &, const QDateTime &, int maxSteps) const
int	maxWeeks () const
	QwtDateScaleEngine (Qt::TimeSpec=Qt::LocalTime)
	Constructor.
void	setMaxWeeks (int)
void	setTimeSpec (Qt::TimeSpec)
void	setUtcOffset (int seconds)
void	setWeek0Type (QwtDate::Week0Type)
Qt::TimeSpec	timeSpec () const
QDateTime	toDateTime (double) const
int	utcOffset () const
QwtDate::Week0Type	week0Type () const
virtual	~QwtDateScaleEngine ()
	Destructor.
Protected Member Functions
virtual QDateTime	alignDate (const QDateTime &, double stepSize, QwtDate::IntervalType, bool up) const
Private Member Functions
QwtScaleDiv	buildScaleDiv (const QDateTime &, const QDateTime &, int maxMajorSteps, int maxMinorSteps, QwtDate::IntervalType) const
Private Attributes
PrivateData *	d_data

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 41 of file qwt_date_scale_engine.h.

Constructor & Destructor Documentation

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 751 of file qwt_date_scale_engine.cpp.

QwtDateScaleEngine::~QwtDateScaleEngine ( ) [virtual]

Destructor.

Definition at line 758 of file qwt_date_scale_engine.cpp.

Member Function Documentation

QDateTime QwtDateScaleEngine::alignDate	(	const QDateTime &	dateTime,
		double	stepSize,
		QwtDate::IntervalType	intervalType,
		bool	up
	)		const `[protected, virtual]`

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 1112 of file qwt_date_scale_engine.cpp.

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.

Definition at line 929 of file qwt_date_scale_engine.cpp.

QwtScaleDiv QwtDateScaleEngine::buildScaleDiv	(	const QDateTime &	minDate,
		const QDateTime &	maxDate,
		int	maxMajorSteps,
		int	maxMinorSteps,
		QwtDate::IntervalType	intervalType
	)		const `[private]`

Definition at line 1052 of file qwt_date_scale_engine.cpp.

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.

Definition at line 996 of file qwt_date_scale_engine.cpp.

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 869 of file qwt_date_scale_engine.cpp.

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 855 of file qwt_date_scale_engine.cpp.

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 devided into weeks [1-52]

See also:: maxWeeks(), setWeek0Type()

Definition at line 845 of file qwt_date_scale_engine.cpp.

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 769 of file qwt_date_scale_engine.cpp.

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 793 of file qwt_date_scale_engine.cpp.

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 819 of file qwt_date_scale_engine.cpp.

Qt::TimeSpec QwtDateScaleEngine::timeSpec ( ) const

Returns:: Time specification used by the engine

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

Definition at line 778 of file qwt_date_scale_engine.cpp.

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 1294 of file qwt_date_scale_engine.cpp.

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 805 of file qwt_date_scale_engine.cpp.

QwtDate::Week0Type QwtDateScaleEngine::week0Type ( ) const

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

See also:: setWeek0Type(), maxWeeks()

Definition at line 828 of file qwt_date_scale_engine.cpp.

Member Data Documentation

PrivateData* QwtDateScaleEngine::d_data [private]

Reimplemented from QwtScaleEngine.

Definition at line 82 of file qwt_date_scale_engine.h.

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

Classes

Public Member Functions

Protected Member Functions

Private Member Functions

Private Attributes

Detailed Description

Constructor & Destructor Documentation

Member Function Documentation

Member Data Documentation