[Dublin]

без разбиения на процедуры

Код:

unit MainUnit;

interface

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

type
  TForm1 = class(TForm)
    PB1: TPaintBox;
    procedure FormClick(Sender: TObject);
    procedure FormCreate(Sender: TObject);
    procedure FormMouseMove(Sender: TObject; Shift: TShiftState; X,
      Y: Integer);
    procedure FormDbClick(Sender: TObject);

  private
    { Private declarations }
    OldPenMode:TPenMode;
    StartX, StartY, OldX, OldY:Integer;
    dragging:Boolean;
  public
    { Public declarations }
  end;
const
x1=0;
y1=0;

var
  Form1: TForm1;
implementation
{$R *.dfm}

procedure TForm1.FormCreate(Sender: TObject);
begin
 dragging:=false;
end;

procedure TForm1.FormClick(Sender: TObject);
begin
 dragging:=true;
end;

procedure TForm1.FormMouseMove(Sender: TObject; Shift: TShiftState; X,
  Y: Integer);
var    a,b,t: integer;
 Xn1,Xn2,Yn1,Yn2:variant;
 A1,B1,C1,D,x11,x22,y11,y22:extended;
  begin
 StartX:=X;
 StartY:=Y;
 if dragging=false then exit;
     PB1.Canvas.Brush.Color:=clBlack;
 PB1.Canvas.Rectangle(0, 0,1400, 1400 );
  PB1.Canvas.Pen.Color:=clBlack;
 PB1.Canvas.Rectangle(0, 0,1400, 1400 );
   PB1.Canvas.Pen.Color:=clWhite;
 PB1.Canvas.Ellipse(StartX-140, StartY-140,OldX+140, OldY+140 );

 A1:=sqr(x1)-2*x1*startx+sqr(startx)+sqr(y1)-2*y1*starty+sqr(starty);
  B1:=2*sqr(140)*startx-2*sqr(140)*x1-2*sqr(x1)*startx+4*x1*sqr(startx)-2*sqr(startx)*startx-2*sqr(y1)*startx+4*y1*starty*startx-2*startx*sqr(starty);
  C1:=sqr(140*140)+2*sqr(140)*x1*startx-2*sqr(140)*sqr(startx)+sqr(x1)*sqr(startx)-2*sqr(startx)*startx*x1+sqr(startx*startx)-sqr(140)*sqr(y1)+sqr(y1)*sqr(startx)+2*y1*starty*sqr(140)-2*y1*starty*sqr(startx)-sqr(140)*sqr(starty)+sqr(startx*starty);
  D:=sqr(B1)-4*A1*C1;
  x11:=sqrt(abs(D))-B1;
  x22:=-B1-sqrt(abs(D)); 
  xn1:=x11/(2*A1);
  xn2:=x22/(2*A1);
 yn1:=starty+(sqr(140)-(xn1-startx)*(x1-startx))/(y1-starty);
  yn2:=starty+(sqr(140)-(xn2-startx)*(x1-startx))/(y1-starty);
   PB1.Canvas.Polyline([Point(x1,y1),Point(xn1,yn1)]);
   PB1.Canvas.Polyline([Point(xn1,yn1),Point(xn2,yn2)]);
   PB1.Canvas.Polyline([Point(x1,y1),Point(xn2,yn2)]);
   yt1:=(yn1+140);
   yt2:=yn2+140;
   xt1:=(starty+140)*xn1/yn1;
   PB1.Canvas.Polyline([Point(xt1,yt1),Point(400,400)]);
   xt2:=(starty+140)*xn2/yn2;
   PB1.Canvas.Polyline([Point(xt2,yt2),Point(400,400)]);
end;

procedure TForm1.FormDbClick(Sender: TObject);
begin
 dragging:=false;
end;

end.

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