Make calendar in datagridview c#

Question

Good day!

Please take a look the image below.

I want to input day from June to July but no color displayed from start to end date.

And here my code.

int offset = 4;
                foreach (DataGridViewRow row in dataGridView1.Rows)
                {
                    if (!row.IsNewRow)
                    {
                        if (row.Cells.Count >= 4)
                        {
                            DateTime startBook;
                            DateTime endBook;
                            if (DateTime.TryParse(row.Cells[2].Value?.ToString(), out startBook) &&
                                DateTime.TryParse(row.Cells[3].Value?.ToString(), out endBook))
                            {
                                int startBook_C = startBook.Day;
                                int endBook_C = endBook.Day;
                                int TotalDays = endBook_C - startBook_C;
                                for (int a = 0; a <= TotalDays; a++)
                                {
                                    dataGridView1.Rows[row.Index].Cells[offset + startBook_C - 1 + a].Style.BackColor = Color.Blue;
                                }
                            }
                        }
                    }
                }

Thank you very much to those can fix my problem.

Answer 1

Previous question: https://learn.microsoft.com/en-us/answers/questions/1658584/calendar-booking-using-datagridview

View_CellPainting method from my answer can be used as is by defining it as follows:

public partial class Form1 : Form
{
    private DataGridView view { get => dataGridView1; }
    private DataGridViewColumn startTimeColumn { get => view.Columns[2]; }
    private DataGridViewColumn endTimeColumn { get => view.Columns[3]; }
    public int gridYear { get => monthCalendar1.SelectionStart.Year; }
    public int gridMonth { get => monthCalendar1.SelectionStart.Month; }
    private readonly Brush brush = new SolidBrush(Color.Blue);

    const int offset = 4;

    public Form1() {
        InitializeComponent();
        view.CellPainting += View_CellPainting;
    }

    private void View_CellPainting(object sender, DataGridViewCellPaintingEventArgs e) {
        if (e.RowIndex < 0 || e.ColumnIndex <= endTimeColumn.Index) return;
        if (view.Rows[e.RowIndex].IsNewRow) return;

        object startValue = view[startTimeColumn.Index, e.RowIndex].Value;
        object endValue = view[endTimeColumn.Index, e.RowIndex].Value;
        if (!(startValue is DateTime) || !(endValue is DateTime)) return;
        DateTime startTime = (DateTime)startValue;
        DateTime endTime = (DateTime)endValue;

        int day = int.Parse(view.Columns[e.ColumnIndex].HeaderText);
        DateTime dayStart = new DateTime(gridYear, gridMonth, day);
        DateTime dayEnd = dayStart.AddDays(1);
        TimeSpan daySpan = dayEnd - dayStart;

        if (startTime < dayEnd && endTime >= dayStart) {
            e.Paint(e.CellBounds, DataGridViewPaintParts.All);

            int top = e.CellBounds.Top + 4;
            int bottom = e.CellBounds.Bottom - 4;

            int left = (int)(e.CellBounds.Width * (startTime - dayStart).TotalMinutes / daySpan.TotalMinutes);
            if (left < 0) left = 0;
            left = e.CellBounds.Left + left;

            int right = (int)(e.CellBounds.Width * (dayEnd - endTime).TotalMinutes / daySpan.TotalMinutes);
            if (right < 0) right = 0;
            right = e.CellBounds.Right - right;

            Rectangle face = Rectangle.FromLTRB(left, top, right, bottom);
            e.Graphics.FillRectangle(brush, face);

            e.Handled = true;
        }
    }

Answer 2

Try something like this:

if( DateTime.TryParse ... )
{
    int last_column = row.Cells.Count - 1;

    for( int c = offset; c <= last_column; c++ )
    {
        DateTime d = startBook.Date.AddDays( -startBook.Day + (c - offset) + 1 );
        row.Cells[c].Style.BackColor = d >= startBook.Date && d <= endBook.Date ? Color.Blue : Color.White;
    }
}