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A pair is a tuple where n is 2 - so yes it is a tuple

If there can be multiple users modifying the same database then this task becomes very challenging.

I develop only VCL for Windows and my target are almost exclusively Win10 e Win11 (and Win2012 server+). Windows 7 practically disappeared from my customer PCs and Windows 8 never appeared. In my scenario I'm happily using styles: with latest Alexandria 11.x EMB provide at least 4 default VCL styles HIDPI compliant 2 for Win10 and 2 for Win11 (2 = light + dark). I decide in real time the style to use based on the SysOp and the user's choice to use the light or dark theme of Windows and I get an acceptable result and an UI compliant with that of the SysOp. Without styles in VCL its impossibile to create dark apps.

I started from scratch (had in plan to trim some fat anyway) and now I'm accessing the database directly from the TThread, inspired by the example from Embarcadero: https://docwiki.embarcadero.com/RADStudio/Sydney/en/Multithreading_(FireDAC) The service now works very well, no more access violations. I wish I had the time and patience to actually find exactly what exactly caused the problem, but the problem only appeared in production and I was pressed to fix it fast so I pretty much made it from scratch.

Here's an example: uses Skia; function MakeCubicSplineInterpolation(const APoints: TArray<TPointF>): ISkPath; var LPathBuilder: ISkPathBuilder; LSegments: Integer; I: Integer; mx: Single; my: Single; LScratches: array of record a, b, c, r, p: TPointF; end; begin LPathBuilder := TSkPathBuilder.Create; if Length(APoints) < 2 then Exit(LPathBuilder.Detach); if Length(APoints) = 2 then begin LPathBuilder.MoveTo(APoints[0]); LPathBuilder.LineTo(APoints[1]); Exit(LPathBuilder.Detach); end; LSegments := Length(APoints) - 1; SetLength(LScratches, LSegments); LScratches[0].a := PointF(0, 0); LScratches[0].b := PointF(2, 2); LScratches[0].c := PointF(1, 1); LScratches[0].r := PointF(APoints[0].X + 2 * APoints[1].X, APoints[0].Y + 2 * APoints[1].Y); for I := 1 to LSegments - 2 do begin LScratches[I].a := PointF(1, 1); LScratches[I].b := PointF(4, 4); LScratches[I].c := PointF(1, 1); LScratches[I].r := PointF(4 * APoints[i].X + 2 * APoints[I + 1].X, 4 * APoints[I].Y + 2 * APoints[I + 1].Y); end; LScratches[LSegments - 1].a := PointF(2, 2); LScratches[LSegments - 1].b := PointF(7, 7); LScratches[LSegments - 1].c := PointF(0, 0); LScratches[LSegments - 1].r := PointF(8 * APoints[LSegments - 1].X + APoints[LSegments].X, 8 * APoints[LSegments - 1].Y + APoints[LSegments].Y); for I := 1 to LSegments - 1 do begin mx := LScratches[I].a.X / LScratches[I - 1].b.X; my := LScratches[I].a.Y / LScratches[I - 1].b.Y; LScratches[I].b := LScratches[I].b - PointF(mx * LScratches[I - 1].c.X, my * LScratches[I - 1].c.Y); LScratches[I].r := LScratches[I].r - PointF(mx * LScratches[I - 1].r.X, my * LScratches[I - 1].r.Y); end; LScratches[LSegments - 1].p := PointF(LScratches[LSegments - 1].r.X / LScratches[LSegments - 1].b.X, LScratches[LSegments - 1].r.Y / LScratches[LSegments - 1].b.Y); for I := Length(APoints) - 3 downto 0 do begin LScratches[I].p := PointF((LScratches[I].r.X - LScratches[I].c.X * LScratches[I + 1].p.X) / LScratches[I].b.X, (LScratches[I].r.Y - LScratches[I].c.Y * LScratches[I + 1].p.Y) / LScratches[I].b.Y); end; LPathBuilder.MoveTo(APoints[0]); for I := 0 to LSegments - 2 do begin LPathBuilder.CubicTo(LScratches[I].p, PointF(2 * APoints[I + 1].X - LScratches[I + 1].p.X, 2 * APoints[I + 1].Y - LScratches[I + 1].p.Y), APoints[I + 1]); end; LPathBuilder.CubicTo(LScratches[LSegments - 1].p, PointF(0.5 * (APoints[LSegments].X + LScratches[LSegments - 1].p.X), 0.5 * (APoints[LSegments].Y + LScratches[LSegments - 1].p.Y)), APoints[LSegments]); Result := LPathBuilder.Detach; end; procedure TForm1.SkPaintBox1Draw(ASender: TObject; const ACanvas: ISkCanvas; const ADest: TRectF; const AOpacity: Single); var LPaint: ISkPaint; LMyPoints: TArray<TPointF>; begin LMyPoints := [PointF(62, 511), PointF(162, 605), PointF(262, 610), PointF(362, 402), PointF(462, 959), PointF(562, 58), PointF(662, 272), PointF(762, 99), PointF(862, 759), PointF(962, 945)]; LPaint := TSkPaint.Create(TSkPaintStyle.Stroke); LPaint.Color := TAlphaColors.Red; LPaint.AntiAlias := True; LPaint.StrokeWidth := 3; LPaint.StrokeCap := TSkStrokeCap.Round; ACanvas.DrawPath(MakeCubicSplineInterpolation(LMyPoints), LPaint); LPaint.StrokeWidth := 10; LPaint.Color := TAlphaColors.Black; ACanvas.DrawPoints(TSkDrawPointsMode.Points, LMyPoints, LPaint); end; Result: Note: You don't need to use Skia, it was just a facilitator for the example.

If you don't mind third-party solutions, Skia has an effect that applies rounded edges automatically and works for Console, Vcl and FMX: https://github.com/skia4delphi/skia4delphi/blob/eed4afbf8a34137a9bfa308bcb5ef87cee84abcb/Samples/Demo/FMX/Source/Sample.Form.PathsAndEffects.pas#L193 Result: