unit Sinikayra;

interface

uses
  Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
  ExtCtrls;

type
  TSinikayra = class(TPaintBox)
  private
    FAkselinLeveys: double;
    FVali: integer;
    FapuAkseli: integer;
    procedure SetAkselinLeveys(const Value: double);
    procedure SetVali(Value: integer);
  protected
  public
    constructor Create(AOwner:TComponent); Override;
    property apuAkseli : integer read FapuAkseli write FapuAkseli default 2;
  published
    { x-akselin leveys kuvassa, default -2*pi, 2*pi }
    property AkselinLeveys : double read FAkselinLeveys write SetAkselinLeveys;
    property Vali : integer read FVali write SetVali default 5 ;
    procedure piirra;
  end;

procedure Register;

implementation

procedure Register;
begin
  RegisterComponents('Samples', [TSinikayra]);
end;

{ TSinikayra }

constructor TSinikayra.Create(AOwner: TComponent);
begin
  inherited;
  Canvas.Pen.Style := psSolid;
  Canvas.Pen.Color := clBlack;
  Canvas.Pen.Width := 1;
  { x-akseli }
  Canvas.MoveTo(0,ClientHeight div 2);
  Canvas.LineTo(ClientWidth,ClientHeight);
  { y-akseli }
  Canvas.MoveTo(ClientWidth div 2, 0);
  Canvas.LineTo(ClientWidth div 2,ClientHeight);
  Canvas.Pen.Width := 3;
  Canvas.Pen.Color := clRed;
  apuAkseli := 2;
  AkselinLeveys := apuAkseli;
  Vali := 5;
end;


procedure TSinikayra.piirra;
  var x,y,kork2,leve2, I : integer;
begin
  kork2 := ClientHeight div 2;
  leve2 := ClientWidth  div 2;
  { alkutila, laitetaan kynä vasemmaisimpaan laitaan oikeaan kohtaan }
  y := StrToInt(
         FloatToStrF( (sin(AkselinLeveys*pi) * kork2), ffFixed, 7, 0)
       ) + kork2;
  x := 0;
  Canvas.MoveTo(x,y);

  for I := 0 to ClientWidth do
  begin
    if (( I mod vali ) <> 0 ) then continue;
    { sinin arvo skaalataan kuvaan sopivaksi }
    AkselinLeveys := 2 * ( I - leve2 ) / leve2;
    { Pisteen paikka y-akselilla }
    y := StrToInt(
           FloatToStrF( (sin(AkselinLeveys*pi) * kork2), ffFixed, 7, 0)
         ) + kork2;
    x := I;
  Canvas.LineTo(x,y);
  end;

end;

procedure TSinikayra.SetAkselinLeveys(const Value: double);
begin
  FAkselinLeveys := Value;
end;

procedure TSinikayra.SetVali(Value: integer);
begin
  if (Value <= 0) then Value := 1;
  FVali := Value;
end;

end.