[marcoszorrilla]

unit Main;

interface

uses
  Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
  StdCtrls, Grids;

type
  TfrmMain = class(TForm)
    StringGrid1: TStringGrid;
    cbInplaceComboBox: TComboBox;
    btnClose: TButton;
    MemoDescription: TMemo;
    procedure FormCreate(Sender: TObject);
    procedure cbInplaceComboBoxChange(Sender: TObject);
    procedure StringGrid1SelectCell(Sender: TObject; Col, Row: Integer;
      var CanSelect: Boolean);
    procedure StringGrid1DrawCell(Sender: TObject; Col, Row: Integer;
      Rect: TRect; State: TGridDrawState);
    procedure btnCloseClick(Sender: TObject);
  private
    { Private declarations }
    procedure CMDialogKey(var msg: TCMDialogKey); message CM_DIALOGKEY;
  public
    { Public declarations }
  end;

var
  frmMain: TfrmMain;

implementation

{$R *.DFM}

procedure TfrmMain.FormCreate(Sender: TObject);
var i: Integer;
begin
  StringGrid1.DefaultRowHeight := cbInplaceComboBox.Height;
  cbInplaceComboBox.Visible := False;

  StringGrid1.Cells[0, 0] := 'Row No';
  StringGrid1.Cells[1, 0] := 'Values (from Combobox)';
  for i := 1 to StringGrid1.RowCount-1 do
    StringGrid1.Cells[0, i] := IntToStr(i);
end;

procedure TfrmMain.CMDialogKey(var msg: TCMDialogKey);
begin
  if (ActiveControl = cbInplaceComboBox) then
  begin
    if (msg.CharCode = VK_TAB) then
    begin
      //set focus back to the grid and pass the tab key to it
      cbInplaceComboBox.SetFocus;
      cbInplaceComboBox.Perform(WM_KEYDOWN, msg.CharCode, msg.KeyData);
      // swallow this message
      msg.result := 1;
      Exit;
    end;
  end;

  inherited;
end;

procedure TfrmMain.cbInplaceComboBoxChange(Sender: TObject);
var intRow: Integer;
begin
  inherited;

  {Obtener la selección del ComboBox y colocarla en la Rejilla}
  with cbInplaceComboBox do
  begin
    intRow := StringGrid1.Row;
    if (StringGrid1.Col = 2) then
      StringGrid1.Cells[2, intRow] := Items[ItemIndex]
    else
      StringGrid1.Cells[StringGrid1.Col, intRow] := Items[ItemIndex];
    Visible := False;
  end;
  StringGrid1.SetFocus;
end;

procedure TfrmMain.StringGrid1SelectCell(Sender: TObject; Col, Row: Integer;
  var CanSelect: Boolean);
var R: TRect;
begin
  if ((Col = 1) and (Row <> 0)) then
  begin
    {Tamaño y posición del ComboBox para llenar la celdilla}
    R := StringGrid1.CellRect(Col, Row);
    R.Left := R.Left + StringGrid1.Left;
    R.Right := R.Right + StringGrid1.Left;
    R.Top := R.Top + StringGrid1.Top;
    R.Bottom := R.Bottom + StringGrid1.Top;

    {Mostrar el CombBox}
    with cbInplaceComboBox do
    begin
      Left := R.Left + 1;
      Top := R.Top + 1;
      Width := (R.Right + 1) - R.Left;
      Height := (R.Bottom + 1) - R.Top;

      ItemIndex := Items.IndexOf(StringGrid1.Cells[Col, Row]);
      Visible := True;
      SetFocus;
    end;
  end;
  CanSelect := True;
end;

procedure TfrmMain.StringGrid1DrawCell(Sender: TObject; Col, Row: Integer;
  Rect: TRect; State: TGridDrawState);
const
  AlignFlags: array [TAlignment] of Integer =
     (DT_LEFT or DT_VCENTER or DT_WORDBREAK or DT_EXPANDTABS or DT_NOPREFIX,
      DT_RIGHT or DT_VCENTER or DT_WORDBREAK or DT_EXPANDTABS or DT_NOPREFIX,
      DT_CENTER or DT_VCENTER or DT_WORDBREAK or DT_EXPANDTABS or DT_NOPREFIX);
var s: string;
begin
  inherited;

  with Rect do
  begin
    Left := Left + 2;
    Top := Top + 2;
    Right := Right - 5
  end;

  s := StringGrid1.Cells[Col, Row];

  if (Row = 0) and (Col < StringGrid1.ColCount) then
  begin
    StringGrid1.Canvas.Font.Style := StringGrid1.Canvas.Font.Style + [fsBold];
    StringGrid1.Canvas.Brush.Color := StringGrid1.FixedColor;
    StringGrid1.Canvas.FillRect(Rect);

    DrawText(StringGrid1.Canvas.Handle,
             PChar(s), Length(s),
             Rect, AlignFlags[taCenter]);
  end
  else
    if (Col = 0) and (Row > 0) and (Row < StringGrid1.RowCount) then
    begin
      StringGrid1.Canvas.FillRect(Rect);
      DrawText(StringGrid1.Canvas.Handle,
               PChar(s), Length(s),
               Rect, AlignFlags[taRightJustify]);
    end;
end;

procedure TfrmMain.btnCloseClick(Sender: TObject);
begin
  Close
end;

end.

Saludos.