how to color DBGrid special cell?

Question

I have a column which have only "yes" and "no" values. I want if column value is "yes" then only that cell background color is red else "no" then background color is yellow but this code colors whole row :

if ADOTable1.FieldByName('Clubs').AsString = 'yes' then
begin
  DBGrid1.Canvas.Brush.Color := clRed;
  DBGrid1.DefaultDrawColumnCell(Rect, DataCol, Column, State);
end;

EDIT

Thanks for your replies. My real code look like that. The "netice" column only have "L, D, W,".

if Column.FieldName = 'netice' then
 begin
 if ADOTable1.FieldByName('netice').AsString = 'L' then
 DBGrid1.Canvas.Brush.Color := clgreen ;
 if ADOTable1.FieldByName('netice').AsString = 'D' then
 DBGrid1.Canvas.Brush.Color := clRed ;
 if ADOTable1.FieldByName('netice').AsString = 'W' then
 DBGrid1.Canvas.Brush.Color := clYellow ;
 end;
 DBGrid1.DefaultDrawColumnCell(Rect, DataCol, Column, State);
 end;

but I need L--green, D--red, W--yellow I am using Delphi 2010.

Lifeanddeath

Thanks for your reply. This code colors the row . but I need to color only cells in which value "yes" or "no" – Lifeanddeath

Are you sure Adotable1 is the Dataset bound to the grid, or might there be anonther one, you should better use: var ADS:TDataset; begin Ads := TDBGrid(Sender).DataSource.DataSet; if Column.FieldName = 'netice' then begin if Ads.FieldByName('netice').AsString = 'L' then DBGrid1.Canvas.Brush.Color := clgreen ; ......... – Buckish

@bummi, Column.Field gives you the exact linked dataset field. Hence I've used it in my code below. But here I'm not feeling much safe from that FieldName comparison (the OP used first capital in the first case, not in the latter). Maybe something like this might work. – Glower

Answer 1

You need to add a condition to restrict changing of the brush color only to the column of your choice. In code it could be:

procedure TForm1.DBGrid1DrawColumnCell(Sender: TObject; const Rect: TRect;
  DataCol: Integer; Column: TColumn; State: TGridDrawState);
var
  Field: TField;
begin
  // store the currently rendered cell's column assigned field reference
  // (if any) to the local variable (there's quite expensive getter)
  Field := Column.Field;
  // if the rendered cell's column has assigned a field and this field's
  // name is 'Clubs' (compared without case sensitivity), then, and only
  // then change the brush color...
  if Assigned(Field) and SameText(Field.FieldName, 'Clubs') then
  begin
    if Field.AsString = 'yes' then
      DBGrid1.Canvas.Brush.Color := clRed
    else
      DBGrid1.Canvas.Brush.Color := clYellow;
  end;
  DBGrid1.DefaultDrawColumnCell(Rect, DataCol, Column, State);
end;

I'd prefer this before Column.FieldName because Column.FieldName does not yet guarantee that there is such field in the linked dataset. Accessing the field directly is therefore safer in this manner.

Glower

P.S. try to choose a different DB column type. String is not an optimal choice for storing boolean values. – Glower

Answer 2

You can do it this way:

if Column.FieldName = 'Clubs' then
begin
  if ADOTable1.FieldByName('Clubs').AsString = 'yes' then
    DBGrid1.Canvas.Brush.Color := clRed
  else
    DBGrid1.Canvas.Brush.Color := clYellow;
end;
DBGrid1.DefaultDrawColumnCell(Rect, DataCol, Column, State);

Lipcombe