unit Unit1;

interface

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

type
  TForm1 = class(TForm)
    Image1: TImage;
    OpenDialog1: TOpenDialog;
    OpenPictureDialog1: TOpenPictureDialog;
    GroupBox1: TGroupBox;
    Edit1: TEdit;
    Edit2: TEdit;
    Edit3: TEdit;
    Edit4: TEdit;
    GroupBox2: TGroupBox;
    Button1: TButton;
    Button3: TButton;
    Button2: TButton;
    procedure Button1Click(Sender: TObject);
    procedure Button2Click(Sender: TObject);
    procedure Button3Click(Sender: TObject);
  private
    { Private declarations }
  public
      xmax,ymax:integer;
      fajl:string;
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.Button1Click(Sender: TObject);
Var x,y,yteto,yalj,maxx,maxy,maxr,ry,sy,r:integer;
    alapszin:Tcolor; {Ezen lehetne még javítani?}

  Function kore(x,ry,r:integer):boolean;
    Var ok:boolean;
        svy:integer;
        svx:integer;
    Begin
        svx:=0;
        ok:=true;
        While ok and (svx<r) do
                Begin
                  svY:=Round(sqrt(r*r-svx*svx));
                  if Canvas.Pixels[svX+X, svY+rY]=alapszin then ok:=false;
                  if Canvas.Pixels[svX+X, -svY+rY]=alapszin then ok:=false;
                  if Canvas.Pixels[-svX+X, svY+rY]=alapszin then ok:=false;
                  if Canvas.Pixels[-svX+X, -svY+rY]=alapszin then ok:=false;
                  inc(svx);
                End;
        kore:=ok;
      End;

   Procedure Korrajz (x,ry,r:integer; szin:Tcolor);
    var svx,svy:integer;
     Begin
          For svx:=0 to r do
           Begin
                svY:=Round(sqrt(r*r-svx*svx));
                Canvas.Pixels[svX+X, svY+rY]:=szin;
                Canvas.Pixels[svX+X, -svY+rY]:=szin;
                Canvas.Pixels[-svX+X, svY+rY]:=szin;
                Canvas.Pixels[-svX+X, -svY+rY]:=szin;
           End;
     End;

   BEGIN
     xmax:=Image1.Picture.Width-1; {512}
     ymax:=Image1.Picture.Height-1;{384}
     x:=0;
     y:=0;
     maxx:=0;
     maxy:=0;
     maxr:=0;
     alapszin:=canvas.pixels[0,0];
     Repeat
        inc(x);
        if x>=xmax then
                    Begin
                      x:=0;
                      inc(y);
                    End;
        While (canvas.pixels[x,y]=alapszin) and (y<=Ymax) do
          Begin
            x:=x+1;
            If x>=xmax then
                         Begin
                           x:=0;
                           inc(y);
                         End;
          End;

        If y<=ymax then
          Begin
            yteto:=y;
            sy:=y;
            y:=y+1;
            While (canvas.pixels[x,y]<>alapszin) and (y<ymax) do inc(y);
            yalj:=y-1;
            r:=round((yalj-sy)/2);
            ry:=sy+r;
            if r>maxr then
              Begin
                 if kore(x,ry,r) then
                   Begin
                     if maxr<r then
                         Begin
                           maxr:=r;
                           maxx:=x;
                           maxy:=ry;
                           edit1.text:='X= '+IntToStr(maxx);
                           edit2.Text:='Y= '+IntToStr(maxy);
                           edit3.text:='R= '+IntToStr(maxr);
                         End;
                   End;
                 y:=yteto;
              End;
          End;
     until y>=ymax;
     if maxr>0 Then
                Begin
                  korrajz(maxx,maxy,maxr,ClRed);
                  ShowMessage('Megtaláltam!');
                End
               Else ShowMessage('Nincs kör!');
END;

procedure TForm1.Button2Click(Sender: TObject);
begin
  if OpenPictureDialog1.Execute then
        Begin
          Fajl:=OpenPictureDialog1.Filename;
          Image1.Picture.LoadFromFile(Fajl);
{         xmax:=Image1.Picture.Width;
          ymax:=Image1.Picture.Height;}
        End;
end;

procedure TForm1.Button3Click(Sender: TObject);
begin
  Form1.Close;
end;

end.