type
 TForm6 = class(TForm)
   Image1: TImage;
   SpinEdit1: TSpinEdit;
   procedure FormCreate(Sender: TObject);
   procedure SpinEdit1Change(Sender: TObject);
   procedure UpdateString;
 private
   { Private declarations }
   FontSize: Integer;
 public
   { Public declarations }
 end;

var
 Form6: TForm6;

implementation

{$R *.dfm}

procedure TForm6.FormCreate(Sender: TObject);
begin
 FontSize := 12;
 SpinEdit1.Value := FontSize;
 UpdateString;
end;

procedure TForm6.SpinEdit1Change(Sender: TObject);
begin
 FontSize := SpinEdit1.Value;
 UpdateString;
end;

procedure TForm6.UpdateString;
var
 ARect: TRect;
 TextStr: string;
 TextHeight: Integer;
begin
 TextStr := 'Июнь 2012';
 Image1.Invalidate;
 Image1.Canvas.Brush.Color := clWhite;
 Image1.Canvas.FillRect(Rect(0,0,Image1.Height, Image1.Width));
 Image1.Canvas.Font := self.Font;
 Image1.Canvas.Font.Size := FontSize;
 TextHeight := Image1.Canvas.TextHeight(TextStr);
 ARect := Rect(0, 0, 200, TextHeight*2);
 Image1.Canvas.Brush.Color := clYellow;
 Image1.Canvas.FillRect(ARect);
 Image1.Canvas.Brush.Color := clLime;
 DrawText(Image1.Canvas.Handle, PWideChar(TextStr), Length(TextStr), ARect, DT_VCENTER);
end;