Q.   How can I determine the Length in pixels of a string after a specific font has been applied to it?

A.    The two methods, TextHeigh and TextWidth, can be used to determine both the text height and width of a string in pixels.  These methods can only be accessed through components that have a Canvas property such as TForm.  The TPanel component does not have access to its Canvas property by default because it is protected.

      If a component doesn't have a Canvas property then The following function will return the text width based on the font passed.

  function GetTextWidth(CanvasOWner: TForm; Text : String; TextFont :  TFont): Integer;
  var
     OldFont : TFont;
  begin
    OldFont := TFont.Create;
    try
      OldFont.Assign( CanvasOWner.Font );
      CanvasOWner.Font.Assign( TextFont );
      Result := CanvasOWner.Canvas.TextWidth(Text);
      CanvasOWner.Font.Assign( OldFont );
    finally
      OldFont.Free;
    end;
  end;