procedure TForm1.Button1Click(Sender: TObject);
var
  MyRect: TRectF;
begin
  MyRect:=TRectF.Create(0,0,300,500);
  Image1.Bitmap.Clear($FFFFFF);
  Image1.Bitmap.Canvas.Font.Size:=120;
  Image1.Bitmap.Canvas.Fill.Kind:=TBrushKind.bkSolid;
  Image1.Bitmap.Canvas.Fill.Color:=TAlphaColorRec.Blue;
  Image1.Bitmap.Canvas.BeginScene;
  Image1.Bitmap.Canvas.FillText(MyRect,'FillText', false, 1,
      [TFillTextFlag.RightToLeft], TTextAlign.Center, TTextAlign.Center);
  Image1.Bitmap.Canvas.EndScene;
end;

procedure TForm1.FormCreate(Sender: TObject);
begin
Image1.Bitmap := TBitmap.Create(317, 530);
end;