QwtDateScaleEngine(3)

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version 6.3.0 · 4 versions
, in alpine 3.24

💅 QwtDateScaleEngine(3) — Library Functions Manual ✨

okay bestie, welcome to the QwtDateScaleEngine(3) page from the Library Functions Manual. it’s giving “date/time scale engine main character energy,” and we’re gonna go through literally every detail together. 🫶

🌸 NAME

QwtDateScaleEngine — a scale engine for date/time values. 💖

✨ SYNOPSIS

#include <qwt_date_scale_engine.h>

Inherits QwtLinearScaleEngine.

💅 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

Okay so: A scale engine for date/time values. That’s the whole vibe. 💅

QwtDateScaleEngine builds scales from a time intervals — yes, that’s the original wording, bestie — and 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. Slay. ✨

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. important detail, no cap.

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 (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 () [virtual]

Destructor. bye bestie 💖

Definition at line 754 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 1108 of file qwt_date_scale_engine.cpp.

void QwtDateScaleEngine::autoScale (int maxNumSteps, double & x1, double & x2, double & stepSize) const [override], [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(). lowkey important caveat.

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.

QwtScaleDiv QwtDateScaleEngine::divideScale (double x1, double x2, int maxMajorSteps, int maxMinorSteps, double stepSize = 0.0) const [override], [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 992 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 865 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 851 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 divided into weeks [1-52]

See also: maxWeeks(), setWeek0Type()

Definition at line 841 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 765 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 789 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 815 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 774 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 1298 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 801 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 824 of file qwt_date_scale_engine.cpp.

👑 Author

Generated automatically by Doxygen for Qwt User’s Guide from the source code. ✨

💖 and that’s the whole page, bestie — generated automatically by Doxygen for Qwt User’s Guide from the source code. Footer vibe: Qwt User’s Guide / QwtDateScaleEngine(3), no date shown on this one, so I’m not inventing one. byeee 🌈💅

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