DBGrid - problem with DrawColumnCell
lazarus / 39-Graphics

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tanguy · 2013-07-29 07:43

Hello,
My goal is to color a cell in a DBGrid
The color is depending of value  of field in the same column

i use ondrawcolumncell  :

     if Column.FieldName='TEST1' then
     begin
          val_test:= column.Field.AsInteger;
          case val_test of
               -1 : Column.Color:= clGray;
               0 : Column.Color:= clGreen;
               1 : Column.Color:= clYellow;
               2 : Column.Color:= clRed;
          end;
     end;

but i don't have the good result
lines
 Value of column  - Color of column
   0      : Green
   2      : Green
  -1      :  Red
  -1      : Gray
  -1      : Gray
   2      : Gray
   2      : Red
   1     :  Red
   0     : Yellow
....

I think i don't use the good method ...
if you have any idea

Many thanks

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howardpc · 2013-07-29 10:41

You need to use the OnPrepareCanvas event, and not try to repeatedly
change the Color of the entire column, just the individual cell.
Something like this:
Code: [Select]procedure TForm1.DBGrid1PrepareCanvas(sender: TObject;
DataCol: Integer;
  Column: TColumn; AState: TGridDrawState);
const ColumnToColour = 1; //change this to appropriate value
begin
  if DataCol = ColumnToColour
  then begin
    case Column.Field.AsInteger of
     1: DBGrid1.Canvas.Brush.Color := clBlue;
     2: DBGrid1.Canvas.Brush.Color := clRed;
     3: DBGrid1.Canvas.Brush.Color := clGreen;
     // 4: ... etc.
    end;
  end;
end;

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tanguy · 2013-07-29 11:59

Many thanks
it's working nice