C# DataGridView + OpenFileDialog แบบบ้านๆ

using System.Drawing;
using System.Windows.Forms;

    #region _DataGridViewFilePathColumn




    /// <summary>
    /// Hosts a collection of DataGridViewTextBoxCell cells.
    /// </summary>
    public class DataGridViewFilePathColumn : DataGridViewColumn
    {

        public enum PathType { directory, file };
        public PathType pathtype = PathType.file;

        public DataGridViewFilePathColumn()
            : base(new DataGridViewFilePathCell())
        {

        }
        public override DataGridViewCell CellTemplate
        {
            get
            {
                return base.CellTemplate;
            }
            set
            {
                if (null != value &&
                    !value.GetType().IsAssignableFrom(typeof(DataGridViewFilePathCell)))
                {
                    throw new InvalidCastException("must be a DataGridViewFilePathCell");
                }
                base.CellTemplate = value;
            }
        }
    }

    /// <summary>
    /// Displays editable text information in a DataGridView control. Uses
    /// PathEllipsis formatting if the column is smaller than the width of a
    /// displayed filesystem path.
    /// </summary>
    public class DataGridViewFilePathCell : DataGridViewTextBoxCell
    {
        Button browseButton;

        Dictionary<Color, SolidBrush> brushes = new Dictionary<Color, SolidBrush>();
        protected virtual SolidBrush GetCachedBrush(Color color)
        {
            if (this.brushes.ContainsKey(color))
                return this.brushes[color];
            SolidBrush brush = new SolidBrush(color);
            this.brushes.Add(color, brush);
            return brush;
        }

        protected virtual bool RightToLeftInternal
        {
            get
            {
                return this.DataGridView.RightToLeft == RightToLeft.Yes;
            }
        }
protected override void OnClick(DataGridViewCellEventArgs e)
        {
            base.OnClick(e);
            if (this.DataGridView.CurrentCell == this )
            {
                string file = Convert.ToString(base.Value);
                if (!System.IO.File.Exists(file))
                {
                    MessageBox.Show("ไม่พบไฟล์ " + file);
                }
                else
                {
                    System.Diagnostics.Process.Start(file);
                }
            }
        }
        protected override void Paint(Graphics graphics, Rectangle clipBounds, Rectangle cellBounds, int rowIndex, DataGridViewElementStates cellState, object value, object formattedValue, string errorText, DataGridViewCellStyle cellStyle, DataGridViewAdvancedBorderStyle advancedBorderStyle, DataGridViewPaintParts paintParts)
        {
            if (cellStyle == null) { throw new ArgumentNullException("cellStyle"); }
            this.PaintPrivate(graphics, clipBounds, cellBounds, rowIndex, cellState, formattedValue, errorText, cellStyle, advancedBorderStyle, paintParts);
        }

        protected Rectangle PaintPrivate(Graphics graphics, Rectangle clipBounds, Rectangle cellBounds, int rowIndex, DataGridViewElementStates cellState, object formattedValue, string errorText, DataGridViewCellStyle cellStyle, DataGridViewAdvancedBorderStyle advancedBorderStyle, DataGridViewPaintParts paintParts)
        {
            System.Diagnostics.Debug.WriteLine(string.Format("Painting Cell row {0} for rowindex {2} with rectangle {1}", this.RowIndex, cellBounds, rowIndex));
            SolidBrush cachedBrush;
            Rectangle empty = Rectangle.Empty;
            if (((paintParts & DataGridViewPaintParts.Border) != DataGridViewPaintParts.None)) { this.PaintBorder(graphics, clipBounds, cellBounds, cellStyle, advancedBorderStyle); }
            Rectangle rectangle2 = this.BorderWidths(advancedBorderStyle);
            Rectangle borderedCellRectangle = cellBounds;
            borderedCellRectangle.Offset(rectangle2.X, rectangle2.Y);
            borderedCellRectangle.Width -= rectangle2.Right;
            borderedCellRectangle.Height -= rectangle2.Bottom;
            Point currentCellAddress = base.DataGridView.CurrentCellAddress;
            bool isFirstCell = (currentCellAddress.X == base.ColumnIndex) && (currentCellAddress.Y == rowIndex);
            bool flagisFirstCellAndNotEditing = isFirstCell && (base.DataGridView.EditingControl != null);
            bool thisCellIsSelected = (cellState & DataGridViewElementStates.Selected) != DataGridViewElementStates.None;
            cachedBrush = ((((paintParts & DataGridViewPaintParts.SelectionBackground) != DataGridViewPaintParts.None) && thisCellIsSelected) && !flagisFirstCellAndNotEditing) ? GetCachedBrush(cellStyle.SelectionBackColor) : GetCachedBrush(cellStyle.BackColor);

            if (((((paintParts & DataGridViewPaintParts.Background) != DataGridViewPaintParts.None)) && ((cachedBrush.Color.A == 0xff) && (borderedCellRectangle.Width > 0))) && (borderedCellRectangle.Height > 0))
            {
                graphics.FillRectangle(cachedBrush, borderedCellRectangle);
            }
            if (cellStyle.Padding != Padding.Empty)
            {
                if (RightToLeftInternal)
                {
                    borderedCellRectangle.Offset(cellStyle.Padding.Right, cellStyle.Padding.Top);
                }
                else
                {
                    borderedCellRectangle.Offset(cellStyle.Padding.Left, cellStyle.Padding.Top);
                }
                borderedCellRectangle.Width -= cellStyle.Padding.Horizontal;
                borderedCellRectangle.Height -= cellStyle.Padding.Vertical;
            }
            if (((isFirstCell) && (!flagisFirstCellAndNotEditing && ((paintParts & DataGridViewPaintParts.Focus) != DataGridViewPaintParts.None))) && ((ShowFocusCues && base.DataGridView.Focused) && ((borderedCellRectangle.Width > 0) && (borderedCellRectangle.Height > 0))))
            {
                ControlPaint.DrawFocusRectangle(graphics, borderedCellRectangle, Color.Empty, cachedBrush.Color);
            }
            Rectangle cellValueBounds = borderedCellRectangle;
            string text = formattedValue as string;
            if ((text != null) && (!flagisFirstCellAndNotEditing))
            {
                int y = (cellStyle.WrapMode == DataGridViewTriState.True) ? 1 : 2;
                borderedCellRectangle.Offset(0, y);
                borderedCellRectangle.Width = borderedCellRectangle.Width;
                borderedCellRectangle.Height -= y + 1;
                if ((borderedCellRectangle.Width > 0) && (borderedCellRectangle.Height > 0))
                {
                    TextFormatFlags flags = TextFormatFlags.PathEllipsis;

                    if (((paintParts & DataGridViewPaintParts.ContentForeground) != DataGridViewPaintParts.None))
                    {
                        if ((flags & TextFormatFlags.SingleLine) != TextFormatFlags.GlyphOverhangPadding) { flags |= TextFormatFlags.EndEllipsis; }
                        DataGridViewFilePathColumn filePathColumn = (DataGridViewFilePathColumn)this.DataGridView.Columns[ColumnIndex];

                        if (this.RowIndex >= 0)
                        {

                            bool changed = false;
                            if ((browseButton.Width != Math.Max(10, borderedCellRectangle.Width / 4)) && (browseButton.Width != 20))
                            {
                                System.Diagnostics.Trace.WriteLine(string.Format("browseButton Width was incorrect:{0} for given rectangle:{1}", browseButton.Width, borderedCellRectangle));
                                browseButton.Width = Math.Max(10, borderedCellRectangle.Width / 4);
                                browseButton.Width = Math.Min(browseButton.Width, 20);
                                changed = true;
                            }
                            if (browseButton.Height != (borderedCellRectangle.Height + 4))
                            {
                                System.Diagnostics.Trace.WriteLine(string.Format("browseButton Height was incorrect:{0} for given rectangle:{1}", browseButton.Height, borderedCellRectangle));
                                browseButton.Height = borderedCellRectangle.Height + 4;
                                changed = true;
                            }
                            Point loc = new Point();
                            loc.X = borderedCellRectangle.X + borderedCellRectangle.Width - browseButton.Width;
                            loc.Y = borderedCellRectangle.Y - 4;
                            if (browseButton.Location != loc)
                            {
                                System.Diagnostics.Trace.WriteLine(string.Format("browseButton location was incorrect:{0} for given rectangle:{1} with loc: {2}", browseButton.Location, borderedCellRectangle, loc));
                                browseButton.Location = loc;
                                changed = true;
                            }
                            if (changed)
                                browseButton.Invalidate();
                            if (!this.DataGridView.Controls.Contains(browseButton))
                                this.DataGridView.Controls.Add(browseButton);
                            borderedCellRectangle.Width -= browseButton.Width;
                        }
                    }
                    TextRenderer.DrawText(graphics, text, cellStyle.Font, borderedCellRectangle, thisCellIsSelected ? cellStyle.SelectionForeColor : cellStyle.ForeColor, flags);


                }
            }
            if ((base.DataGridView.ShowCellErrors) && ((paintParts & DataGridViewPaintParts.ErrorIcon) != DataGridViewPaintParts.None))
            {
                if ((!string.IsNullOrEmpty(errorText) && (cellValueBounds.Width >= 20)) && (cellValueBounds.Height >= 0x13))
                {
                    Rectangle iconBounds = this.GetErrorIconBounds(graphics, cellStyle, rowIndex);
                    if ((iconBounds.Width >= 4) && (iconBounds.Height >= 11))
                    {
                        iconBounds.X += cellBounds.X;
                        iconBounds.Y += cellBounds.Y;
                        Bitmap errorBitmap = new Bitmap(typeof(DataGridViewCell), "DataGridViewRow.error.bmp");
                        errorBitmap.MakeTransparent();
                        if (errorBitmap != null)
                        {
                            lock (errorBitmap)
                            {
                                graphics.DrawImage(errorBitmap, iconBounds, 0, 0, 12, 11, GraphicsUnit.Pixel);
                            }
                        }
                    }
                }

            }
            return empty;
        }

        public bool ShowFocusCues
        {
            get { return true; }
        }

        protected bool ApplyVisualStylesToHeaders
        {
            get
            {
                if (Application.RenderWithVisualStyles)
                {
                    return this.DataGridView.EnableHeadersVisualStyles;
                }
                return false;
            }
        }
        private void DataGridView_CellClick(object sender, DataGridViewCellEventArgs e)
        {
            if (base.Value.ToString().Length > 0)
            {
                System.Diagnostics.Process.Start(base.Value.ToString());
            }
        }
        void browseButton_Click(object sender, EventArgs e)
        {
            DataGridViewFilePathColumn filePathColumn = (DataGridViewFilePathColumn)this.DataGridView.Columns[ColumnIndex];
            if (filePathColumn.pathtype == DataGridViewFilePathColumn.PathType.file)
            {
                OpenFileDialog fdg = new OpenFileDialog();
                fdg.ShowDialog();
                base.Value = (fdg.FileName.Length > 0) ? fdg.FileName : base.Value;
            }
            else
            {
                FolderBrowserDialog fdg = new FolderBrowserDialog();
                fdg.ShowDialog();
                base.Value = (fdg.SelectedPath.Length > 0) ? fdg.SelectedPath : base.Value;
            }
        }
        public DataGridViewFilePathCell()
            : base()
        {
            browseButton = new Button();
            browseButton.Text = "…";
            browseButton.Click += new EventHandler(browseButton_Click); 
        }
    }

    #endregion