• HomeTech SupportElegant GridFeature ArticlesCustom Cell Editors

If the built-in cell editor for a particular cell type is not completely what you are looking for, or if a particular cell type does not feature any cell editor at all, you can implement your own editor by creating a class that implements the ICellEditor interface:

The Elegant Grid knows nothing about the details of the custom editor's implementation, so it is your responsibility to initialize the editor in the ICellEditor.Activate method and destroy it in ICellEditor.Deactivate.

The ICellEditor.Activate method takes one argument of the Cell type, which allows you to get all the information about the edited cell: its layout, a reference to the parent grid object and other cell properties.

The Cell.CommitEdit method allows you to save the changes made to the editor's content. The method takes a single parameter which specifies whether the editor should be closed. To close the editor without saving, call Cell.CancelEdit.

The last thing which deserves to be mentioned here is how to specify the key with which the editor is activated. It is really simple: just use the ActivateByKey attribute class before your editor call declaration. You can specify one or more ActivateByKey attributes for your editor.

The following example illustrates how to implement a custom editor for cells of the ProgressBarCell type.

[C#]
using Elegant.Grid;

[ActivateByKey(Keys.F2)]
[ActivateByKey(Keys.F10)]
[ActivateByKey(Keys.Enter)]
public class ProgressCellCustomEditor : TrackBar, ICellEditor
{
   public ProgressCellCustomEditor()
   {
      Minimum = 0;
      Maximum = 100;
      AutoSize = false;
      Hide();
   }

   public void Activate(Cell cell)
   {
      _EditingCell = cell as ProgressBarCell;
      if(_EditingCell == null)
         return;

      Parent = cell.GridControl;
   
      BackColor = _EditingCell.InheritedStyle.ProgressBarColor1;
      Bounds = _EditingCell.ContentRectangle;
      TickStyle = TickStyle.None;

      Show();
      Focus();
   }

   public void Deactivate()
   {
      Hide();
      _EditingCell = null;
   }

   private ProgressBarCell _EditingCell;

   object ICellEditor.Value
   {
      get
      {
         return base.Value;
      }
      set
      {
         base.Value = Convert.ToInt32(value);
      }
   }

   protected override void OnKeyDown(KeyEventArgs e)
   {
      base.OnKeyDown(e);

      if(_EditingCell == null)
         return;

      if(e.KeyCode == Keys.Escape)
      {
         _EditingCell.CancelEdit();
      }
      else if(e.KeyCode == Keys.Enter)
      {
         _EditingCell.CommitEdit (true);
      }
   }

   protected override void OnLostFocus(EventArgs e)
   {
      base.OnLostFocus(e);
   
      if(_EditingCell != null)
         _EditingCell.CancelEdit();
   }
}

[VB.NET]
Imports Elegant.Grid

< _
   ActivateByKeyAttribute(Keys.F2), _
   ActivateByKey(Keys.F10), _
   ActivateByKey(Keys.Enter) _
> _
Public Class ProgressCellCustomEditor
   Inherits TrackBar
   Implements ICellEditor

   Public Sub New()
      Minimum = 0
      Maximum = 100
      AutoSize = False
      Hide()
   End Sub

   Public Sub Activate(ByVal cell As Cell) Implements ICellEditor.Activate
      _EditingCell = cell
      If (_EditingCell Is Nothing) Then
         Return
      End If

      Parent = cell.GridControl

      BackColor = _EditingCell.InheritedStyle.ProgressBarColor1
      Bounds = _EditingCell.ContentRectangle
      TickStyle = TickStyle.None

      Show()
      Focus()
   End Sub

   Public Sub Deactivate() Implements ICellEditor.Deactivate
      Hide()
      _EditingCell = Nothing
   End Sub

   Private _EditingCell As ProgressBarCell

   Public Shadows Property Value() As Object Implements ICellEditor.Value
      Get
         Return MyBase.Value
      End Get
      Set(ByVal Value)
         MyBase.Value = Convert.ToInt32(Value)
      End Set
   End Property

   Public Shadows Event ValueChanged(ByVal sender As Object, ByVal e As _
   EventArgs) Implements ICellEditor.ValueChanged

   Protected Overridable Sub OnTrackBarValueChanged(ByVal sender As _
   Object, ByVal e As EventArgs) Handles MyBase.ValueChanged
      RaiseEvent ValueChanged(Me, EventArgs.Empty)
   End Sub

   Protected Overrides Sub OnKeyDown(ByVal e As KeyEventArgs)
      MyBase.OnKeyDown(e)

      If (_EditingCell Is Nothing) Then
         Return
      End If

      If (e.KeyCode = Keys.Escape) Then
         _EditingCell.CancelEdit()
      ElseIf (e.KeyCode = Keys.Enter) Then
         _EditingCell.CommitEdit(True)
      End If
End Sub

   Protected Overloads Sub OnLostFocus(ByVal e As EventArgs)
      MyBase.OnLostFocus(e)

      If (Not (_EditingCell Is Nothing)) Then
         _EditingCell.CancelEdit()
      End If
   End Sub
End Class

Here is how to use this custom editor in a grid.

[C#]
using Elegant.Grid;

private void Form1_Load(object sender, System.EventArgs e)
{
   Column nameColumn = new Column();
   nameColumn.HeaderText = "Name";
   nameColumn.DataPropertyName = "[0]";

   Column taskColumn = new Column();
   taskColumn.HeaderText = "Task Name";
   taskColumn.DataPropertyName  = "[1]";

   Column completitionStatusColumn = new Column();
   completitionStatusColumn.HeaderText = "Completion Status";
   completitionStatusColumn.DataPropertyName = "[2]";
   completitionStatusColumn.CellType = typeof(ProgressBarCell);

   boundGridControl1.Columns.AddRange(
      new Column[] 
         {
            nameColumn,
            taskColumn,
            completitionStatusColumn
         }
      );
   boundGridControl1.ColumnsAutoSizeMode = ColumnAutoSizeMode.Fill;

   // 
   // Data source initialization here...
   //

   boundGridControl1.DataSource = dataSource;
}

[VB.NET]
Imports Elegant.Grid

Private Sub Form1_Load(ByVal sender As System.Object, _
   ByVal e As System.EventArgs) Handles MyBase.Load

   Dim nameColumn As New Column
   nameColumn.HeaderText = "Name"
   nameColumn.DataPropertyName = "[0]"

   Dim taskColumn As New Column
   taskColumn.HeaderText = "Task Name"
   taskColumn.DataPropertyName = "[1]"

   Dim completitionStatusColumn As New Column
   completitionStatusColumn.HeaderText = "Completion Status"
   completitionStatusColumn.DataPropertyName = "[2]"
   completitionStatusColumn.CellType = GetType(ProgressBarCell)
   completitionStatusColumn.CellStyles( _
      GetType(ProgressBarCellStyle)).CustomEditorType = _ 
      GetType(ProgressCellCustomEditor)

   BoundGridControl1.Columns.AddRange(New Column() { _
      nameColumn, taskColumn, completitionStatusColumn})
   BoundGridControl1.ColumnsAutoSizeMode = ColumnAutoSizeMode.Fill

   'Data source initialization goes here...

   BoundGridControl1.DataSource = dataSource
End Sub

The implemented custom editor is shown on Figure 1.

Figure 1 Custom editor for the progress bar cell