Firemonkey FillEllipse Problem

[CHackbart]

Hi,

hat jemand eventuell eine Idee warum unter Android und iOS eine Ellipse aus so wenigen Polygonen besteht?
Anbei mal ein Beispiel einer Control die lediglich einen Aufnahmeknopf zeichnet. Was unter Windows ausschaut wie es soll, wirkt auf den Mobilgeräten nicht wirklich attraktiv:

Delphi-Quellcode:

unit URecordButton;

interface

uses System.SysUtils, System.Classes, System.Types, System.UITypes,
  FMX.Graphics, FMX.Types, FMX.Controls, FMX.Objects;

type
  TRecordButton = class(TShape)
  protected
    FRecording: Boolean;
    FDiameter: single;

    procedure Paint; override;
    procedure SetDiameter(const Value: single);
  public
    constructor Create(AOwner: TComponent); override;
  published
    property Diameter: single read FDiameter write SetDiameter;
    property Recording: Boolean read FRecording write FRecording;
    property Align;
    property Anchors;
    property ClipChildren default false;
    property ClipParent default false;
    property DesignVisible default True;
    property Enabled default True;
    property Locked default false;
    property Height;
    property HitTest default True;
    property Padding;
    property Opacity;
    property Margins;
    property PopupMenu;
    property position;
    property RotationAngle;
    property RotationCenter;
    property Scale;
    property Visible default True;
    property Width;

    { Mouse events }
    property OnClick;
    property OnDblClick;

    property OnMouseDown;
    property OnMouseMove;
    property OnMouseUp;
    property OnMouseWheel;
    property OnMouseEnter;
    property OnMouseLeave;

    property OnPainting;
    property OnPaint;
    property OnResize;
  end;

implementation

constructor TRecordButton.Create(AOwner: TComponent);
begin
  inherited;

  Fill.color := $FFFF0000;
  Stroke.color := $FFFFFFFF;
  Stroke.Kind := TBrushKind.bkSolid;
  Diameter := 32;
end;

procedure TRecordButton.SetDiameter(const Value: single);
begin
  FDiameter := Value;
  Stroke.Thickness := FDiameter / 20;
end;

procedure TRecordButton.Paint;
var
  perc, w: single;
  xp, yp: single;
  color: TAlphaColor;
begin
  if FRecording then
    perc := 0.4
  else
    perc := 0.85;

  w := perc * FDiameter;
  xp := (Width - w) / 2;
  yp := (FDiameter - w) / 2;

  if FRecording then
    canvas.FillRect(RectF(xp, yp, xp + w, yp + w), 0.2 * w, 0.2 * w,
      AllCorners, 1, Fill)
  else
    canvas.FillEllipse(RectF(xp, yp, xp + w, yp + w), 1, Fill);

  xp := (Width - FDiameter) / 2;
  yp := 0;

  canvas.DrawEllipse(RectF(xp, yp, xp + Diameter, yp + Diameter), 1, Stroke);
end;

end.

Christian