How to Host a Color Picker Combobox in Windows Forms DataGridView Cells

using System;
using System.Collections.Generic;
using System.Text;
using System.Windows.Forms;


namespace ColorPickerCombo
{
    public class CalendarColumn : DataGridViewColumn
    {
        public CalendarColumn()
            : base(new CalendarCell())
        {
        }

        public override DataGridViewCell CellTemplate
        {
            get
            {
                return base.CellTemplate;
            }
            set
            {
                // Ensure that the cell used for the template is a CalendarCell.
                if (value != null &&
                    !value.GetType().IsAssignableFrom(typeof(CalendarCell)))
                {
                    throw new InvalidCastException("Must be a CalendarCell");
                }
                base.CellTemplate = value;
            }
        }
    }

    public class CalendarCell : DataGridViewTextBoxCell
    {

        public CalendarCell()
            : base()
        {
            // Use the short date format.
            this.Style.Format = "d";
        }

        public override void InitializeEditingControl(int rowIndex, object
            initialFormattedValue, DataGridViewCellStyle dataGridViewCellStyle)
        {
            // Set the value of the editing control to the current cell value.
            base.InitializeEditingControl(rowIndex, initialFormattedValue,
                dataGridViewCellStyle);
            CalendarEditingControl ctl =
                DataGridView.EditingControl as CalendarEditingControl;
            ctl.Value = (DateTime)this.Value;
        }

        public override Type EditType
        {
            get
            {
                // Return the type of the editing contol that CalendarCell uses.
                return typeof(CalendarEditingControl);
            }
        }

        public override Type ValueType
        {
            get
            {
                // Return the type of the value that CalendarCell contains.
                return typeof(DateTime);
            }
        }

        public override object DefaultNewRowValue
        {
            get
            {
                // Use the current date and time as the default value.
                return DateTime.Now;
            }
        }
    }

    class CalendarEditingControl : DateTimePicker, IDataGridViewEditingControl
    {
        DataGridView dataGridView;
        private bool valueChanged = false;
        int rowIndex;

        public CalendarEditingControl()
        {
            this.Format = DateTimePickerFormat.Short;
        }

        // Implements the IDataGridViewEditingControl.EditingControlFormattedValue 
        // property.
        public object EditingControlFormattedValue
        {
            get
            {
                return this.Value.ToShortDateString();
            }
            set
            {
                if (value is String)
                {
                    this.Value = DateTime.Parse((String)value);
                }
            }
        }

        // Implements the 
        // IDataGridViewEditingControl.GetEditingControlFormattedValue method.
        public object GetEditingControlFormattedValue(
            DataGridViewDataErrorContexts context)
        {
            return EditingControlFormattedValue;
        }

        // Implements the 
        // IDataGridViewEditingControl.ApplyCellStyleToEditingControl method.
        public void ApplyCellStyleToEditingControl(
            DataGridViewCellStyle dataGridViewCellStyle)
        {
            this.Font = dataGridViewCellStyle.Font;
            this.CalendarForeColor = dataGridViewCellStyle.ForeColor;
            this.CalendarMonthBackground = dataGridViewCellStyle.BackColor;
        }

        // Implements the IDataGridViewEditingControl.EditingControlRowIndex 
        // property.
        public int EditingControlRowIndex
        {
            get
            {
                return rowIndex;
            }
            set
            {
                rowIndex = value;
            }
        }

        // Implements the IDataGridViewEditingControl.EditingControlWantsInputKey 
        // method.
        public bool EditingControlWantsInputKey(
            Keys key, bool dataGridViewWantsInputKey)
        {
            // Let the DateTimePicker handle the keys listed.
            switch (key & Keys.KeyCode)
            {
                case Keys.Left:
                case Keys.Up:
                case Keys.Down:
                case Keys.Right:
                case Keys.Home:
                case Keys.End:
                case Keys.PageDown:
                case Keys.PageUp:
                    return true;
                default:
                    return !dataGridViewWantsInputKey;
            }
        }

        // Implements the IDataGridViewEditingControl.PrepareEditingControlForEdit 
        // method.
        public void PrepareEditingControlForEdit(bool selectAll)
        {
            // No preparation needs to be done.
        }

        // Implements the IDataGridViewEditingControl
        // .RepositionEditingControlOnValueChange property.
        public bool RepositionEditingControlOnValueChange
        {
            get
            {
                return false;
            }
        }

        // Implements the IDataGridViewEditingControl
        // .EditingControlDataGridView property.
        public DataGridView EditingControlDataGridView
        {
            get
            {
                return dataGridView;
            }
            set
            {
                dataGridView = value;
            }
        }

        // Implements the IDataGridViewEditingControl
        // .EditingControlValueChanged property.
        public bool EditingControlValueChanged
        {
            get
            {
                return valueChanged;
            }
            set
            {
                valueChanged = value;
            }
        }

        // Implements the IDataGridViewEditingControl
        // .EditingPanelCursor property.
        public Cursor EditingPanelCursor
        {
            get
            {
                return base.Cursor;
            }
        }

        protected override void OnValueChanged(EventArgs eventargs)
        {
            // Notify the DataGridView that the contents of the cell
            // have changed.
            valueChanged = true;
            this.EditingControlDataGridView.NotifyCurrentCellDirty(true);
            base.OnValueChanged(eventargs);
        }
    }
}