DataGridView custom column accessing design time parameters at run time

问题

I have been playing with some sample code which implements a datepicker column for a DataGridView.

Where I'm struggling is in how to appropriately access design time parameters (thanks to Bradley Smith for the tip on overriding the Clone method) in the CalendarEditingControl where I want to set the Format to the DateFormat.

I've provided the complete sample below and to see where I want to use DateFormat if you just scan for the comment: //*********** I'd like to set the Format to the design time value provided inDataGridViewCalendarColumn.DateFormat here ***********//

thanks

Matt

using System; using System.Windows.Forms;

namespace MyApplication.Components { public class DataGridViewCalendarColumn : DataGridViewColumn { public DataGridViewCalendarColumn() : 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 DateTimePickerFormat DateFormat { get; set; }

    public override object Clone()
    {
        DataGridViewCalendarColumn clone = (DataGridViewCalendarColumn)base.Clone();
        clone.DateFormat = this.DateFormat;
        return clone;
    }

}

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;
        // Use the default row value when Value property is null. 
        if (this.Value == null)
        {
            ctl.Value = (DateTime)this.DefaultNewRowValue;
        }
        else
        {
            ctl.Value = (DateTime)this.Value;
        }
    }

    public override Type EditType
    {
        get
        {
            // Return the type of the editing control 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()
    {
        //*********************** I'd like to set the Format to the design time value provided inDataGridViewCalendarColumn.DateFormat here ***********************//
        //(instead of hard coding it to DateTimePickerFormat.Short)
        this.Format = DateTimePickerFormat.Short;
    }

    // Implements the IDataGridViewEditingControl.EditingControlFormattedValue  
    // property. 
    public object EditingControlFormattedValue
    {
        get
        {
            return this.Value.ToShortDateString();
        }
        set
        {
            if (value is String)
            {
                try
                {
                    // This will throw an exception of the string is  
                    // null, empty, or not in the format of a date. 
                    this.Value = DateTime.Parse((String)value);
                }
                catch
                {
                    // In the case of an exception, just use the  
                    // default value so we're not left with a null 
                    // value. 
                    this.Value = DateTime.Now;
                }
            }
        }
    }

    // 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);
    }
}

}

回答1:

All you need to do is apply the DateFormat property from the column onto the editing control. In the InitializeEditingControl method, add the following line:

ctl.Format = (OwningColumn as DataGridViewCalendarColumn).DateFormat;

That should do the trick.

回答2:

In WinForms (and WebForms, and WPF...) you don't get access to the design-time values in the constructor. Instead, the Framework invokes your no-arg constructor, then uses the appropriate property setters on your object to finish initializing it.

Setting default values for your object's properties in the constructor is a sensible thing to do in case the designer-user doesn't specify at design time what all the property values should be. So your constructor is good as-is.

来源：https://stackoverflow.com/questions/17711964/datagridview-custom-column-accessing-design-time-parameters-at-run-time