qwt_date.h

/******************************************************************************
 * Qwt Widget Library
 * Copyright (C) 1997   Josef Wilgen
 * Copyright (C) 2002   Uwe Rathmann
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the Qwt License, Version 1.0
 *
 * Modified by ChenZongYan in 2024 <czy.t@163.com>
 *   Summary of major modifications (see ChangeLog.md for full history):
 *   1. CMake build system & C++11 throughout.
 *   2. Core panner/ zoomer refactored:
 *        - QwtPanner → QwtCachePanner (pixmap-cache version)
 *        - New real-time QwtPlotPanner derived from QwtPicker.
 *   3. Zoomer supports multi-axis.
 *   4. Parasite-plot framework:
 *        - QwtFigure, QwtPlotParasiteLayout, QwtPlotTransparentCanvas,
 *        - QwtPlotScaleEventDispatcher, built-in pan/zoom on axis.
 *   5. New picker: QwtPlotSeriesDataPicker (works with date axis).
 *   6. Raster & color-map extensions:
 *        - QwtGridRasterData (2-D table + interpolation)
 *        - QwtLinearColorMap::stopColors(), stopPos() API rename.
 *   7. Bar-chart: expose pen/brush control.
 *   8. Amalgamated build: single QwtPlot.h / QwtPlot.cpp pair in src-amalgamate.
 *****************************************************************************/
 
#ifndef QWT_DATE_H
#define QWT_DATE_H
 
#include "qwtcore_global.h"
#include <qdatetime.h>
#include <QTimeZone>
 
class QWTCORE_EXPORT QwtDate
{
public:
    enum Week0Type
    {
        FirstThursday,
 
        FirstDay
    };
 
    enum IntervalType
    {
        Millisecond,
 
        Second,
 
        Minute,
 
        Hour,
 
        Day,
 
        Week,
 
        Month,
 
        Year
    };
 
    enum
    {
        JulianDayForEpoch = 2440588
    };
 
    // Get minimum date
    static QDate minDate();
    // Get maximum date
    static QDate maxDate();
 
    // Convert Qt::TimeSpec to QTimeZone
    static QTimeZone toTimeZone(Qt::TimeSpec timeSpec, int offsetSeconds = 0);
 
    // Convert double to QDateTime
    static QDateTime toDateTime(double value, Qt::TimeSpec = Qt::UTC);
 
    // Convert double to QDateTime with a specific time zone
    static QDateTime toDateTime(double value, const QTimeZone& timeZone);
 
    // Convert QDateTime to double
    static double toDouble(const QDateTime&);
 
    // Ceil datetime to interval type
    static QDateTime ceil(const QDateTime&, IntervalType);
    // Floor datetime to interval type
    static QDateTime floor(const QDateTime&, IntervalType);
 
    // Get date of week 0
    static QDate dateOfWeek0(int year, Week0Type);
    // Get week number
    static int weekNumber(const QDate&, Week0Type);
 
    // Get UTC offset in seconds
    static int utcOffset(const QDateTime&);
 
    // Format datetime to string
    static QString toString(const QDateTime&, const QString& format, Week0Type);
};
 
#endif