QwtDateScaleDraw(3)

NAME
QwtDateScaleDraw - A class for drawing datetime scales.

SYNOPSIS

#include <qwt_date_scale_draw.h>

Inherits QwtScaleDraw.

  Public Member Functions

QwtDateScaleDraw (Qt::TimeSpec=Qt::LocalTime)
Constructor.
virtual ~QwtDateScaleDraw ()
Destructor.
void setDateFormat (QwtDate::IntervalType, const QString &)
QString dateFormat (QwtDate::IntervalType) const
void setTimeSpec (Qt::TimeSpec)
Qt::TimeSpec timeSpec () const
void setUtcOffset (int seconds)
int utcOffset () const
void setWeek0Type (QwtDate::Week0Type)
QwtDate::Week0Type week0Type () const
virtual QwtText label (double) const
Convert a value into its representing label.
QDateTime toDateTime (double) const

  Protected Member Functions

virtual QwtDate::IntervalType intervalType (const QwtScaleDiv &) const
virtual QString dateFormatOfDate (const QDateTime &, QwtDate::IntervalType) const

  Additional Inherited Members

Detailed Description

A class for drawing datetime scales.

QwtDateScaleDraw displays values as datetime labels. The format of the labels depends on the alignment of the major tick labels.

The default format strings are:

•   Millisecond
     'hh:mm:ss:zzz\nddd dd MMM yyyy'

•   Second
     'hh:mm:ss\nddd dd MMM yyyy'

•   Minute
     'hh:mm\nddd dd MMM yyyy'

•   Hour
     'hh:mm\nddd dd MMM yyyy'

•   Day
     'ddd dd MMM yyyy'

•   Week
     'Www yyyy'

•   Month
     'MMM yyyy'

•   Year
     'yyyy'

The format strings can be modified using setDateFormat() or individually for each tick label by overloading dateFormatOfDate(),

Usually QwtDateScaleDraw is used in combination with QwtDateScaleEngine, that calculates scales for datetime intervals.

See also:
    QwtDateScaleEngine, QwtPlot::setAxisScaleDraw()

Constructor & Destructor Documentation

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

Constructor. The default setting is to display tick labels for the given time specification. The first week of a year is defined like for QwtDate::FirstThursday.

Parameters:
    timeSpec Time specification

See also:
    setTimeSpec(), setWeek0Type()

Member Function Documentation

  QString QwtDateScaleDraw::dateFormat (QwtDate::IntervalType intervalType) const

Parameters:
    intervalType Interval type

Returns:
    Default format string for an datetime interval type

See also:
    setDateFormat(), dateFormatOfDate()

  QString QwtDateScaleDraw::dateFormatOfDate (const QDateTime & dateTime, QwtDate::IntervalType intervalType) const [protected], [virtual]
Format string for the representation of a datetime

dateFormatOfDate() is intended to be overloaded for situations, where formats are individual for specific datetime values.

The default setting ignores dateTime and return the default format for the interval type.

Parameters:
    dateTime Datetime value
    intervalType Interval type

Returns:
    Format string

See also:
    setDateFormat(), QwtDate::toString()

  QwtDate::IntervalType QwtDateScaleDraw::intervalType (const QwtScaleDiv & scaleDiv) const [protected], [virtual]
Find the less detailed datetime unit, where no rounding errors happen.

Parameters:
    scaleDiv Scale division

Returns:
    Interval type

See also:
    dateFormatOfDate()

  QwtText QwtDateScaleDraw::label (double value) const [virtual]

Convert a value into its representing label. The value is converted to a datetime value using toDateTime() and converted to a plain text using QwtDate::toString().

Parameters:
    value Value

Returns:
    Label string.

See also:
    dateFormatOfDate()

Reimplemented from QwtAbstractScaleDraw.

  void QwtDateScaleDraw::setDateFormat (QwtDate::IntervalType intervalType, const QString & format)
Set the default format string for an datetime interval type

Parameters:
    intervalType Interval type
    format Default format string

See also:
    dateFormat(), dateFormatOfDate(), QwtDate::toString()

  void QwtDateScaleDraw::setTimeSpec (Qt::TimeSpec timeSpec)
Set the time specification used for the tick labels

Parameters:
    timeSpec Time specification

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

  void QwtDateScaleDraw::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()

  void QwtDateScaleDraw::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().

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

  Qt::TimeSpec QwtDateScaleDraw::timeSpec () const

Returns:
    Time specification used for the tick labels

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

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

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

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

  int QwtDateScaleDraw::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()

  QwtDate::Week0Type QwtDateScaleDraw::week0Type () const

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

See also:
    setWeek0Type()

Author

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