Probleme mit Sinus Darstellung

[Chris211183]

Delphi-Quellcode:

type
   TFxFunction = function(const x: Extended): Extended;
   TPointDynArray = array of TPoint;




function CalculatePointView
(AFunc: TFxFunction; const ARect: TRect; x0, y0, dx, dy: double): TPointDynArray;
var
  x, y: double;
  i : integer;
begin                                                                           // für jede Spalte einen Punkt
   SetLength(Result, ARect.Right - ARect.Left +1);                              // Punkte berechnen
   x := x0;
   for i := Low(Result) to High(Result) do
   begin
   y := AFunc(x);
   y := -y;                                                                     // Canvas Nullpunkt obere linke Ecke mit Y- Achse nach unten !!!
   y := y0 + y;                                                                 // oberen Rand Addieren
   y := y / dy;                                                                 // Skalieren
   Result[i].x := ARect.Left +1;
   Result[i].Y := ARect.Top + Round(y);                                         // runden
   x := x + dx;
   end;                                                                         // nächster Punkt
end;

procedure DrawPointView
(ACanvas: TCanvas; const ARect: TRect; const APoints : TPointDynArray);
var
  h : Thandle;
   begin
   h:= SaveDC(ACanvas.Handle);
   try
   IntersectClipRect(ACanvas.Handle, ARect.Left, ARect.Top, ARect.Right, ARect.Bottom);
   Polyline(ACanvas.Handle, APoints[0], Length(APoints));
   finally
      RestoreDC(ACanvas.Handle, h);
   end;
end;

procedure THixHistoGraph.DrawFunction;
var
  R :TRect;
  x0, y0, dx, dy :double;
  P: TPointDynArray;
  begin
   R := Rect (GapLeft,
              GapTop,
              Width - GapRight + 2,
              Height - GapBottom);
   Canvas.Brush.Color := FHistoBkColor;
   Canvas.Pen.Color   := FHistoBkColor;
   Canvas.Pen.Style   := psSolid;
   Canvas.FillRect(R);
   InflateRect(R, -1, -1);
   x0 := 0;
   y0 := 3;
   dx := 0.05;
   dy := 0.05;
   P := CalculatePointView(sin, R, x0, y0, dx, dy));
   Canvas.Pen.Color := cllime;
   CalculatePointView(Canvas, R, P);
end;