DBGrid

Also you can get the width of a character using this
x:=Form1.Canvas.TextWidth('A');
Where the font is the default used font on the canvas.

Hi!

The widh of the text depends of the font settings, screen resolution, etc, and... the width of 'iiiiiii' is less than the width of 'WWWWWW' for example...

So... you must get the width of the text using the function TextWidth of the destination canvas to paint.

For example, the canvas DBGrid1 is DBGrid1.Canvas so... for get the width of any text painted in DBGrid you must use:

WidthOfTheText:=DBGrid1.Canvas.TextWidth('The example text');

For an automatic resizing of the columns, you must calculate the max width of the showed data...and for this work, there are several methods:

- Iterate trought all records of your table and calculate the Canvas.Textwidth of each value and get the max of them
This method is not valid for a large amount of data... its slow...

- Calculate the column width just getting the width of it column title:
This is faster, but very innacurate...

- Calculate the max width just of the records showed in the screen, not in all the table
This is faster than calculate the whole able but... its slow too because you must recalculate the max widths on every scroll of the grid...

- Calculate the max width 'On The Fly', while the DBGrid paints the cells:
This is fast and accurate.

The procedure is:
- Create a global array of integers for store the Max Widths while we calculate them
- In the OnDrawColumnCell of the DBGrid, calculate the max width of each column
- Later, when you want apply the automatic calculated sizes, pass the values of the dinamic array to the columns widths... globally (all the columns with just one click)  or in the OnClick of each column... as you wish.

Here you have the full unit of my testing project:

Has a TTable, a Ddatasource a DBGrid and a TButton

The button pass the calculated max widths to the columns widths.

//--------------------------------------------------------------------------------------------
unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls, Grids, DBGrids, DB, DBTables;

type
  TForm1 = class(TForm)
    DBGrid1: TDBGrid;
    Table1: TTable;
    DataSource1: TDataSource;
    Button4: TButton;
    procedure DBGrid1DrawColumnCell(Sender: TObject; const Rect: TRect;
      DataCol: Integer; Column: TColumn; State: TGridDrawState);
    procedure FormCreate(Sender: TObject);
    procedure Button4Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1  : TForm1;
  Cw     : array of integer;
implementation

{$R *.dfm}

procedure TForm1.DBGrid1DrawColumnCell(Sender: TObject; const Rect: TRect;
  DataCol: Integer; Column: TColumn; State: TGridDrawState);
var
  iTemp  : integer;
begin
  iTemp:=DBGrid1.Canvas.TextWidth( Column.Field.AsString );
  if iTemp> Cw[Column.Index] then begin
    Cw[Column.Index]:=iTemp;
  end;
end;

procedure TForm1.FormCreate(Sender: TObject);
begin
  SetLength(Cw, DBGrid1.Columns.Count);
end;

procedure TForm1.Button4Click(Sender: TObject);
const
  MARGIN = 8;
var
  n  : integer;
begin
  //Let the calculated sizes to the columns
   for n:=0 to Pred(DBGrid1.Columns.Count) do begin
     DBGrid1.Columns[n].Width:=Cw[n]+MARGIN;
     //Cw[n]:=0; //Uncomment if you want recalculate again in the next paint event of the grid
   end;
end;

end.