QwtDateScaleDraw man page

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::TimeSpectimeSpec = 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::IntervalTypeintervalType) 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::IntervalTypeintervalType) 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 (doublevalue) 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::IntervalTypeintervalType, 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::TimeSpectimeSpec)

Set the time specification used for the tick labels

Parameters:

timeSpec Time specification

See Also:

timeSpec(), setUtcOffset(), toDateTime()

void QwtDateScaleDraw::setUtcOffset (intseconds)

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::Week0Typeweek0Type)

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 (doublevalue) 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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Info

Thu Dec 11 2014 Version 6.1.2 Qwt User's Guide