Исправленный код для Берлина и выше:
procedure TForm2.FormPaint(Sender: TObject; Canvas: TCanvas; const ARect: TRectF);
var path : TPathData;
begin
path := TPathData.Create;
try
path.MoveTo(TPointF.Create (10,100));
path.CurveTo (TPointF.Create(100,10),TPointF.Create(150,150),
TPointF.Create(200,100));
Canvas.Stroke.Thickness := 2;
Canvas.Stroke.Kind := TBrushKind.Solid;
Canvas.Stroke.Color := TAlphaColorRec.Red;
Canvas.BeginScene;
Canvas.DrawPath(path, 1.0);
Canvas.EndScene;
finally
path.Free;
end;
end;