Delphi Skia：从ISKSurface复制到TSkPaintBox的抗锯齿问题求助

我正在将一个使用TBitmap和TImage的Delphi程序改用Skia，以实现抗锯齿绘图。原程序逻辑是先在TBitmap上完成绘制，再通过image.canvas.copyrect复制到TImage。

现在我尝试用ISKSurface替代TBitmap，TSkPaintBox替代TImage：直接在TSkPaintBox画布上绘制时抗锯齿效果正常，但先在ISKSurface绘制完成后再复制到TSkPaintBox时，结果却没有抗锯齿效果。

测试代码如下：

procedure TfrmMain.drawTest(canvasA: ISkCanvas; targetRect: TRectF);
var
  paint: ISkPaint;
  LSurface: ISKSurface;
  LFont1:ISkFont;
  LTypeface:ISkTypeface;
  rot:single;
  tempimg:ISKImage;
  RWidth,RHeight:integer;
  
begin
  RWidth := round(targetRect.Right);
  RHeight := round(targetRect.Height);

  LSurface := TSkSurface.MakeRaster(RWidth, RHeight);//


  // Set canvas color
  LSurface.canvas.drawColor(TAlphaColors.Aqua);
  LSurface.canvas.Clear(TAlphaColors.Aqua); // refresh canvas

  paint := TSKPaint.Create;
  Paint.SetColorF(TAlphaColorF.Create(TALphaColorRec.Blue));
  paint.AntiAlias := true;
  paint.StrokeWidth := 1;
  paint.Style := TSkPaintStyle.Stroke; // .fill .strokeandfill

  LSurface.canvas.DrawLine(0, 0, 200, 700, paint);
  LSurface.canvas.drawcircle(500,500,200,paint);

  LTypeface := TSkTypeface.MakeFromName('Arial',tskFontStyle.normal);
  LFont1 := TSkFont.Create(LTypeface, 66, 1);
  LFont1.Edging := TSkFontEdging.AntiAlias;
  Paint.Style := TSkPaintStyle.Fill;
  rot := -90;
  LSurface.canvas.Rotate(rot);
  LSurface.canvas.DrawSimpleText('234.4', -500,500,LFont1,paint);
  LSurface.canvas.Rotate(-rot);
  LSurface.canvas.DrawSimpleText('789', 500,500,LFont1,paint);
  
  tempimg := lsurface.MakeImageSnapshot; //only way I can see to get a copy of
                                         //LSurface.canvas to TSKPaintBox.canvas
  
  canvasA.DrawImageRect(tempimg,targetRect,targetRect); //result is not antialiased.

end;

补充说明：将ISKSurface的快照保存为PNG图片时，图片是带有抗锯齿的，因此推测问题出在从ISKSurface复制到TSkPaintBox的缩放环节。

我想了解问题出在哪里，或是该查阅哪些相关资料。

内容的提问来源于stack exchange，提问作者Martincg