Convert Date From Solar (Gregorian) to Lunar (Hijri) Using C#

Introduction

The Lunar (Hijri) calendar is very important for Muslims as is the Solar (Gregorian) calendar important because the Lunar calendar was related to some elements of worship, so I looked at many sites on the internet to understand how to calculate the age of the moon in any given day. I found many sites offering various ways and I took what I found to provide results closer to the truth.

I've noticed that most sites agree on the expense of the Julian date but don't agree on how to calculate the age of the moon and found the difference among these sites to be up to one day and when the moon's age is 30 days, the result is zero in some sites.

In this program I calculate the approximate age of the moon in days and did not give attention to the parts of the day of the hours and minutes.

For the program to be more useful, I added a PictureBox control to display the lighted part of the moon and darkness part of the moon commensurate with the age of the moon.

There is a small probability of a one-day error for any calculation to convert a date.

Note: You can read Months by its name or by its number.

Code

Best Calculation to Get Number Approximation

private double getInt(double fNumber)
{
    double intPart;
    if (fNumber < -0.0000001)
    {
        intPart = Math.Ceiling(fNumber - 0.0000001);
    }
    else
    {
        intPart = Math.Floor(fNumber + 0.0000001);
    }
    return intPart;
}

Convert Solar (Gregorian) Date to Lunar (Hijri) Date

private void SolarToLunar()
{
    //convert Solar year from 622 to 2500
    double jd;
    double j, L, n;
    int d, m, y;
    int theDay;
    //Solar day
    d = int.Parse(SolarDay.Text);
    //get the number of Solar month
    m = SolarMonth.SelectedIndex + 1;
    // Solar year
    y = int.Parse(SolarYear.Text);
    if ((y > 1582) || ((y == 1582) && (m > 10)) || ((y == 1582) && (m == 10) && (d > 14)))
    {
jd = getInt((1461 * (y + 4800 + getInt((m - 14) / 12))) / 4) + getInt((367 * (m - 2 - 12 * (getInt((m - 14) / 12)))) / 12) - getInt((3 * (getInt((y + 4900 + getInt((m - 14) / 12)) / 100))) / 4) + d - 32075;
    }
    else
    {
    jd = 367 * y - getInt((7 * (y + 5001 + getInt((m - 9) / 7))) / 4) + getInt((275 * m) / 9) + d + 1729777;
    }
    //Solar year >= 622
    if (jd < 1948440)
    {
    DateMinError();
    return;
    }
    //Solar year <= 2500
    if (jd > 2621734)
    {
    DateMaxError();
    return;
    }
    //day of the week
    theDay = (int)(jd%7);
    lblDay.Text = WeekDays[theDay];
    L = jd - 1948440 + 10632;
    n = getInt((L - 1) / 10631);
    L = L - 10631 * n + 354;
    j = (getInt((10985 - L) / 5316)) * (getInt((50 * L) / 17719)) + (getInt(L / 5670)) * (getInt((43 * L) / 15238));
    L = L - (getInt((30 - j) / 15)) * (getInt((17719 * j) / 50)) - (getInt(j / 16)) * (getInt((15238 * j) / 43)) + 29;
    m = (int)(getInt((24 * L) / 709));
    d = (int)(L - getInt((709 * m) / 24));
    y = (int)(30 * n + j - 30);
    //display Lunar date
    LunarDay.Text = d.ToString();
    LunarMonth.Text = LunarMonths[m - 1];
    LunarYear.Text = y.ToString();
    ShowMoonPhase();
    if (d == 1)
    {
    lblAge.Text = d.ToString() + " day";
    }
    else
    {
    lblAge.Text = d.ToString() + " days";
    }
}

 Convert Lunar (Hijri) Date to Solar (Gregorian) Date

private void LunarToSolar()
{
    //convert Lunar year from 1 to 1900
    double jd;
    double i, j, k, L, n;
    int d, m, y;
    int theDay;
    //Lunar day
    d = int.Parse(LunarDay.Text);
    if (d == 1)
    {
    lblAge.Text = d.ToString() + " day";
    }
    else
   {
    lblAge.Text = d.ToString() + " days";
    }
    //get the number of Lunar month
    m = LunarMonth.SelectedIndex + 1;
    //Lunar year
    y = int.Parse(LunarYear.Text);
    jd = getInt((11 * y + 3) / 30) + 354 * y + 30 * m - getInt((m - 1) / 2) + d + 1948440 – 3
    //day of the week
    theDay = (int)(jd%7);
    lblDay.Text = WeekDays[theDay];
    if (jd > 2299160)
    {
    L = jd + 68569;
    n = getInt((4 * L) / 146097);
    L = L - getInt((146097 * n + 3) / 4);
    i = getInt((4000 * (L + 1)) / 1461001);
    L = L - getInt((1461 * i) / 4) + 31;
    j = getInt((80 * L) / 2447);
    d = (int)(L - getInt((2447 * j) / 80));
    L = getInt(j / 11);
    m = (int)(j + 2 - 12 * L);
    y = (int)(100 * (n - 49) + i + L);
    }
    else
    {
    j = jd + 1402;
    k = getInt((j - 1) / 1461);
    L = j - 1461 * k;
    n = getInt((L - 1) / 365) - getInt(L / 1461);
    i = L - 365 * n + 30;
    j = getInt((80 * i) / 2447);
    d = (int)(i - getInt((2447 * j) / 80));
    i = getInt(j / 11);
    m = (int)(j + 2 - 12 * i);
    y = (int)(4 * k + n + i - 4716);
    }
    //display Solar date
    SolarDay.Text = d.ToString();
    SolarMonth.Text = SolarMonths[m - 1];
    SolarYear.Text = y.ToString();
    ShowMoonPhase();
}

Draw the Moon at Selected Date

private void ShowMoonPhase()
{
    int ag  = int.Parse(LunarDay.Text);
    double Phase = ag / 29.530588853;
    int Xpos, Ypos, Rpos;
    int Xpos1, Xpos2;
    this.ClearDraw(); //clear PicMoon PictureBox
    //Width of 'ImageToDraw' Object = Width of 'PicMoon' control
    int PageWidth = this.MoonShape.Width;
    //Height of 'ImageToDraw' Object = Height of 'PicMoon' control
    int PageHeight = this.MoonShape.Height;
    //Initiate 'ImageToDraw' Object with size = size of control 'PicMoon' control
    Bitmap ImageToDraw = new Bitmap(PageWidth, PageHeight);
    //Create graphics object for alteration.
    Graphics newGraphics = Graphics.FromImage(ImageToDraw);
    Pen PenW = new Pen(Color.White); //For lighted part of the moon
    Pen PenB = new Pen(Color.Black); //For darkness part of the moon
    for (Ypos = 0; Ypos <=45; Ypos++)
    {
    Xpos = (int)(Math.Sqrt(45 * 45 - Ypos * Ypos));
    //Draw darkness part of the moon
    Point pB1 = new Point(90 - Xpos, Ypos + 90);
    Point pB2 = new Point(Xpos + 90, Ypos + 90);
    Point pB3 = new Point(90 - Xpos, 90 - Ypos);
    Point pB4 = new Point(Xpos + 90, 90 - Ypos);
    newGraphics.DrawLine(PenW, pB1, pB2);
    newGraphics.DrawLine(PenW, pB3, pB4);
    //Determine the edges of the lighted part of the moon
    Rpos = 2 * Xpos;
    if (Phase < 0.5)
    {
        Xpos1 = -Xpos;
        Xpos2 = (int)(Rpos - 2 * Phase * Rpos - Xpos);
    }
    else
    {
        Xpos1 = Xpos;
        Xpos2 = (int)(Xpos - 2 * Phase * Rpos + Rpos);
    }
    //Draw the lighted part of the moon
    Point pW1 = new Point(Xpos1 + 90, 90 - Ypos);
    Point pW2 = new Point(Xpos2 + 90, 90 - Ypos);
    Point pW3 = new Point(Xpos1 + 90, Ypos + 90);
    Point pW4 = new Point(Xpos2 + 90, Ypos + 90);
    newGraphics.DrawLine(PenB, pW1, pW2);
    newGraphics.DrawLine(PenB, pW3, pW4);
    }
    //Display the bitmap in the picture box.
    this.MoonShape.Image = ImageToDraw;
    //Release graphics object
    PenW.Dispose();
    PenB.Dispose();
    newGraphics.Dispose();
    ImageToDraw = null;
}

 You can go to the source file to read the code, if you have any idea or find another code to convert dates then please tell me:

Mostafa Kaisoun
[email protected]