Custom DBGrid cell formatting
lazarus / 31-LCL

----------------------------------------------------------------------
tatamata · 2010-01-26 13:43

I tried to program custom formatting for a cell in a DBGrid, so if the
value is >0 that the font becomes bold and red and the background
yellow. I disabled the DefaultDrawing property and wrote the following
code:
Code: [Select]procedure
TFormMain.DBGridMultipleMRPComponentsDrawColumnCell(Sender: TObject;
  const Rect: TRect; DataCol: Integer; Column: TColumn; State:
TGridDrawState);
begin
  if Column.FieldName='ComponentShortageQuantity' then begin
    if Column.Field.AsFloat>=0 then begin
      with (Sender As TDBGrid) do begin
        //Custom drawing
        Canvas.Brush.Color:=clYellow;
        Canvas.Font.Color:=clRed;
        Canvas.Font.Style:=[fsBold];
      end;
    end;
  end;
  //Call default drawing
  (Sender As
TDBGrid).DefaultDrawColumnCell(Rect,DataCol,Column,State);
end;Unfortunately, it doesn't work as I expected. All the rows and all
the cells are now bolded, and font in the cell is red for all the
rows.
What is wrong with my code?

Thanks.

----------------------------------------------------------------------
theo · 2010-01-26 13:49

Without knowing exactly the method you use, it seems obvious:
You change the canvas properties but never reset them.
Imho you need an else case where you set font back to normal etc.

----------------------------------------------------------------------
tatamata · 2010-01-26 14:07

What exactly DefaultDrawColumnCell(Rect,DataCol,Column,State) do?

----------------------------------------------------------------------
theo · 2010-01-26 14:18

As I said, I don't know.
But it seems obvious that it is not resetting the dbgrid canvas
properties you have set before, so you have to do it yourself.

----------------------------------------------------------------------
JD · 2010-01-26 17:04

Try these tips. They are for Delphi but can be adapted to work in
Lazarus

http://delphi.about.com/od/usedbvcl/l/aa031699.htm

----------------------------------------------------------------------
paweld · 2010-01-26 17:09

use OnPrepareCanvas event:

Code: [Select]procedure TForm1.DBGrid1PrepareCanvas(sender: TObject;
DataCol: Integer;
  Column: TColumn; AState: TGridDrawState);
begin
  if Column.FieldName='pole1' then
  begin
    if Column.Field.AsString='test' then
    begin
      with (Sender As TDBGrid) do
      begin
        //Custom drawing
        Canvas.Brush.Color:=clYellow;
        Canvas.Font.Color:=clRed;
        Canvas.Font.Style:=[fsBold];
      end;
    end;
  end;
end;
this work.

Best regards
paweld

----------------------------------------------------------------------
tatamata · 2010-01-26 18:05

Thank you, Paweld! It works.

What if I want to yellow brush for the whole row, instead of only the
current cell?

----------------------------------------------------------------------
paweld · 2010-01-26 18:36

retrieves the value from ZQuery field:

Code: [Select]procedure TForm1.DBGrid1PrepareCanvas(sender: TObject;
DataCol: Integer;
  Column: TColumn; AState: TGridDrawState);
begin
  {if Column.FieldName='pole1' then
  begin
    if Column.Field.AsString='test' then }
    if ZQuery1.FieldByName('pole1').AsString='test' then
    begin
      with (Sender As TDBGrid) do
      begin
        //Custom drawing
        Canvas.Brush.Color:=clYellow;
        Canvas.Font.Color:=clRed;
        Canvas.Font.Style:=[fsBold];
      end;
    end;
  //end;
end;
sorry for my English

Best regards
paweld

----------------------------------------------------------------------
tatamata · 2010-01-26 19:20

Yeah, that's it. Thanks.
The same is described in the article that JD linked...

----------------------------------------------------------------------
Fortuna1 · 2011-02-04 13:26

How   brush  if    ButtonStyle is                    cbsButtonColumn??

HOW change color  cbsButtonColumn in dbgrid   ??

Thanks

----------------------------------------------------------------------
darmawan · 2011-09-21 09:24

because if DefaultDrawing is set false, PrepareCanvas don't set canvas
properties so you must declare it self. In the Grids unit u can see
that..
Quoteprocedure TCustomGrid.PrepareCanvas(aCol, aRow: Integer; aState:
TGridDrawState);
var
  AColor: TColor;
  CurrentTextStyle: TTextStyle;
  IsSelected: boolean;
begin
  if DefaultDrawing then begin
    Canvas.Pen.Mode := pmCopy;
.
.
.