Алгоритм Грэхема / Source / CHILDWIN

unit CHILDWIN;

interface

uses Windows, Classes, Graphics, Forms, Controls, StdCtrls, ExtCtrls,
  ComCtrls,SysUtils,List, RandomForm;

type

  TMDIChild = class(TForm)
    View: TPaintBox;
    ScrollBarHorisontal: TScrollBar;
    ScrollBarVertical: TScrollBar;
    StatusBar: TStatusBar;
    procedure FormClose(Sender: TObject; var Action: TCloseAction);
    procedure FormPaint(Sender: TObject);
    procedure ViewMouseDown(Sender: TObject; Button: TMouseButton;
      Shift: TShiftState; X, Y: Integer);
    procedure ViewMouseMove(Sender: TObject; Shift: TShiftState; X,
      Y: Integer);
    procedure FormCreate(Sender: TObject);
    procedure ScrollBarHorisontalScroll(Sender: TObject;
      ScrollCode: TScrollCode; var ScrollPos: Integer);
    procedure ScrollBarVerticalScroll(Sender: TObject;
      ScrollCode: TScrollCode; var ScrollPos: Integer);
    procedure FormCanResize(Sender: TObject; var NewWidth,
      NewHeight: Integer; var Resize: Boolean);
    procedure ViewMouseUp(Sender: TObject; Button: TMouseButton;
      Shift: TShiftState; X, Y: Integer);
    procedure FormActivate(Sender: TObject);

  private
    { Private declarations }
    a: array[1..1000] of vertex;
    coverTop,coverBottom:array[1..1000] of vertex;
    count,countTopCover,countBottomCover,CountCover: integer;
    coverList:TListVertex;
    ShiftX,ShiftY:integer;
    MaxViewX,CurrentViewX:integer;
    BWidth,BHeight,zX,zY:integer;
    Scale : real;
    filedata : file of integer;
    fStill:boolean;
    f:boolean;
    w:plVertex;
    StillcoverListcurrent:plVertex;
    BitMap:TBitMap;
    al:integer;
    mouseX0,mouseY0,mouseX,mouseY:integer;
    RightBPressed:boolean;
    function CreateCoverAndry():TListVertex;
    function CreateCover():TListVertex;
  public
    { Public declarations }
    procedure SetScale(S:real);
    procedure Zoom(Z:real);
    procedure ReDraw(Sender: TObject);
    procedure Graham(Sender: TObject);
    function StillGraham(Sender: TObject): boolean;
    procedure LoadFromFile(Name:String);
    procedure SaveToFile(Name:String);
    procedure SaveToBMPFile(Name:String);
    procedure RandomVertex(num,xl,yl,xr,yr:integer);
    procedure ClearCover();
    procedure SetAlgorithm(a:integer);
  end;

implementation

uses MAIN;
{$R *.dfm}


procedure TMDIChild.FormClose(Sender: TObject; var Action: TCloseAction);
begin
  Action := caFree;
end;

procedure TMDIChild.LoadFromFile(Name:String);
begin
  AssignFile(filedata,Name);
  {$I-}
  Reset(filedata);
  {$I+}
  if IOResult=0 then
  begin
    count:=0;  Scale:=1;
    MaxViewX:=200;CurrentViewX:=0; CountCover:=0;
    ScrollBarHorisontal.Max:=MaxViewX; ScrollBarHorisontal.Min:=0;
    BWidth:=View.Width; BHeight:=View.Height; zX:=0; zY:=0; count:=0;
    while not EOF(filedata) do
    begin
      inc(count);
      read(filedata,a[count].x);
      read(filedata,a[count].y);
      read(filedata,a[count].number);
    end;
    CloseFile(FileData);
  end;
end;

procedure TMDIChild.SaveToFile(Name:String);
var i:integer;
begin
  AssignFile(filedata,Name);
  {$I-}
  rewrite(filedata);
  {$I+}
  if IOResult=0 then
  begin
    for i:=1 to count do
    begin
      write(filedata,a[i].x);
      write(filedata,a[i].y);
      write(filedata,a[i].number);
    end;
  CloseFile(filedata);
  Caption := Name;
  end;
end;

{************************************************}

procedure TMDIChild.SaveToBMPFile(Name:String);
var  MyRect: TRect;
begin
  BitMap:= TBitmap.Create;
  BitMap.Height:=View.height;
  BitMap.Width:=View.Width;
  MyRect := Rect(0,0,View.width,View.height);
  Bitmap.Canvas.CopyRect(MyRect,View.Canvas,MyRect);
  BitMap.SaveToFile(Name);
end;


procedure TMDIChild.RandomVertex(num,xl,yl,xr,yr:integer);
var i,x,y:integer;
begin
  if (num>0) and (count+num<1000) then
  begin
    Randomize;
    for i:=1 to num do
    begin
      x:=random(xr-xl)+xl;
      y:=random(yr-yl)+yl;
      a[count+i].x:=x;
      a[count+i].y:=y;
      a[count+i].number:=i+count;
    end;
    count:=count+num; CountCover:=0; fstill:=false;
    CountTopCover:=0; CountBottomCover:=0;
  end;
end;

procedure TMDIChild.ClearCover();
begin
  fstill:=false;
  if CountCover>0 then  CoverList.Free();
  countTopCover:=0;
  countBottomCover:=0;
  CountCover:=0;
end;

procedure TMDIChild.FormPaint(Sender: TObject);
var i,x,y:integer;
begin
  // Очистка области рисования
  canvas.Brush.Color:=clWhite;
  canvas.Pen.Style:=psSolid;
  View.canvas.Pen.Width := 1;
  View.canvas.Pen.Style:=psSolid;
  View.canvas.Rectangle(0,0,View.Width,View.Height);

  if (countTopCover>0) then
  begin
    View.Canvas.Pen.Color:=clSilver;
    x:=round((CoverTop[1].x-View.Width/2+ShiftX)*Scale+View.Width/2);
    y:=round((CoverTop[1].y-View.Height/2+ShiftY)*Scale+View.Height/2);
    View.Canvas.MoveTo(x,y);
    for i:=1 to countTopCover do
    begin
      x:=round((CoverTop[i].x-View.Width/2+ShiftX)*Scale+View.Width/2);
      y:=round((CoverTop[i].y-View.Height/2+ShiftY)*Scale+View.Height/2);
      View.Canvas.LineTo(x,y);
    end;
    View.Canvas.Pen.Style:=psDashDot;
    View.Canvas.MoveTo(x,y);
    x:=round((CoverTop[1].x-View.Width/2+ShiftX)*Scale+View.Width/2);
    y:=round((CoverTop[1].y-View.Height/2+ShiftY)*Scale+View.Height/2);
    View.Canvas.LineTo(x,y);
  end;


  View.Canvas.Pen.Style:=psSolid;
  if (countBottomCover>0) then
  begin
    x:=round((CoverBottom[1].x-View.Width/2+ShiftX)*Scale+View.Width/2);
    y:=round((CoverBottom[1].y-View.Height/2+ShiftY)*Scale+View.Height/2);
    View.Canvas.MoveTo(x,y);
    for i:=1 to countBottomCover do
    begin
      x:=round((CoverBottom[i].x-View.Width/2+ShiftX)*Scale+View.Width/2);
      y:=round((CoverBottom[i].y-View.Height/2+ShiftY)*Scale+View.Height/2);
      View.Canvas.LineTo(x,y);
    end;
  end;

  if (countCover>0) then
  begin
    CoverList.current:=CoverList.beginList;
    View.Canvas.Pen.Color:=clRed;
    x:=round((CoverList.current.x-View.Width/2+ShiftX)*Scale+View.Width/2);
    y:=round((CoverList.current.y-View.Height/2+ShiftY)*Scale+View.Height/2);
    View.Canvas.MoveTo(x,y);
    repeat
      CoverList.current:=CoverList.current.next;
      x:=round((CoverList.current.x-View.Width/2+ShiftX)*Scale+View.Width/2);
      y:=round((CoverList.current.y-View.Height/2+ShiftY)*Scale+View.Height/2);
      View.Canvas.Pen.Style:=psSolid;
      if (CoverList.current^.next.used=3) then
      begin
        View.Canvas.Pen.Width:=2; //2
        View.Canvas.Pen.Color:=$000000FF;//$0000FF00;
        View.Canvas.Ellipse(x-5,y-5,x+5,y+5);
        View.Canvas.Pen.Width:=1;//1
      end;

      if (CoverList.current^.used=1) then View.Canvas.Pen.Color:=clRed
        else
        if (CoverList.current^.used=2) then View.Canvas.Pen.Color:=$000000FF //$0000FF00
        else
          if (CoverList.current^.used=0) then View.Canvas.Pen.Color:=clGray
          else
            begin
              View.Canvas.Pen.Width:=2; //2
              View.Canvas.Pen.Color:=$000000FF;//$0000FF00;
              View.Canvas.Ellipse(x-4,y-4,x+5,y+5);
              View.Canvas.Pen.Style:=psDot;
              View.Canvas.Pen.Width:=1; //1
            end;
      View.Canvas.LineTo(x,y);
      View.Canvas.Pen.Style:=psSolid;
    until (CoverList.current=CoverList.beginList);
  end;

   View.Canvas.Pen.Color:=clBlack;
   for i:=1 to count do
    with View.canvas do
    begin
      x:=round((a[i].x-View.Width/2+ShiftX)*Scale+View.Width/2);
      y:=round((a[i].y-View.Height/2+ShiftY)*Scale+View.Height/2);
      View.Canvas.Font.Name:='Arial';
      View.Canvas.Font.Size:=7;

              View.Canvas.Pen.Width:=2; //2
              View.Canvas.Pen.Color:=clTeal	;
              View.Canvas.Ellipse(x-2,y-2,x+3,y+3);
              View.Canvas.Pen.Style:=psDot;


      View.Canvas.TextOut(x+1,y+1,IntToStr(a[i].number)) ;
    end;
end;

procedure TMDIChild.ViewMouseDown(Sender: TObject; Button: TMouseButton;
  Shift: TShiftState; X, Y: Integer);
begin
  if (Button=mbLeft) then
  begin
    with View.canvas do
    begin
      View.Canvas.Font.Name:='Arial';
      View.Canvas.Font.Size:=7;
      {Pixels[x,y]:=clBlack;
      Pixels[x+1,y]:=clSilver;
      Pixels[x-1,y]:=clSilver;
      Pixels[x,y+1]:=clSilver;
      Pixels[x,y-1]:=clSilver;}

              View.Canvas.Pen.Width:=2; //2
              View.Canvas.Pen.Color:=clTeal	;
              View.Canvas.Ellipse(x-2,y-2,x+3,y+3);
              View.Canvas.Pen.Style:=psDot;
      inc(count);
      a[count].x:=round((x-View.Width/2)/Scale+View.Width/2-ShiftX);
      a[count].y:=round((y-View.Height/2)/Scale+View.Height/2-ShiftY);
      a[count].number:=count;
      View.Canvas.TextOut(x+1,y+1,IntToStr(a[count].number)) ;
     end;
    fstill:=false;
  end;
  if (Button=mbRight) then
  begin
    RightBPressed:=true; MouseX0:=x; MouseY0:=y;
    MouseX:=x;MouseY:=y;
  end;
end;

procedure TMDIChild.ViewMouseMove(Sender: TObject; Shift: TShiftState; X,
  Y: Integer);
var XX,YY:integer;
begin
  if RightBPressed then
  begin
    {FormPaint(Sender);
    Update();}

    View.Canvas.Pen.Width:=1;
    View.Canvas.Pen.Style:=psDot;
    View.Canvas.Pen.Mode:=pmNotXor;
    View.Canvas.Brush.Style := bsClear;
    View.Canvas.Pen.Color:=clBlack;
    View.Canvas.Polygon([point(MouseX0,MouseY0),point(MouseX0,MouseY),
                 point(MouseX,MouseY),point(Mousex,MouseY0)]);

    //View.Canvas.Pen.Mode:=pmMaskNotPen;
    View.Canvas.Pen.Color:=clBlack;
    View.Canvas.Polygon([point(MouseX0,MouseY0),point(MouseX0,Y),
                 point(X,Y),point(x,MouseY0)]);
    MouseX:=x;MouseY:=y;
    View.Canvas.Pen.Mode:=pmCopy;
    View.Canvas.Brush.Style := bsSolid;
  end;
  {
  XX:=round((X-View.Width/2)/Scale+View.Width/2-ShiftX);
  YY:=round((Y-View.Height/2)/Scale+View.Height/2-ShiftY);
  }

  XX:=round((X-View.Width/2-ShiftX)/Scale+View.Width/2);
  YY:=round((Y-View.Height/2-ShiftY)/Scale+View.Height/2);
  StatusBar.SimpleText:='X:'+IntToStr(XX)+'  Y:'+IntToStr(YY);
end;

procedure TMDIChild.FormCreate(Sender: TObject);
begin
  RightBPressed:=false;
  count:=0;  Scale:=1;
  MaxViewX:=200;CurrentViewX:=0; CountCover:=0;
  ScrollBarHorisontal.Max:=MaxViewX; ScrollBarHorisontal.Min:=0;
  BWidth:=View.Width; BHeight:=View.Height; zX:=0; zY:=0;
end;

procedure TMDIChild.ScrollBarHorisontalScroll(Sender: TObject;
  ScrollCode: TScrollCode; var ScrollPos: Integer);
begin
  ShiftX:=round(-ScrollPos); ShiftX:=ShiftX+zX;
  FormPaint(Sender);
end;

procedure TMDIChild.ScrollBarVerticalScroll(Sender: TObject;
  ScrollCode: TScrollCode; var ScrollPos: Integer);
begin
  ShiftY:=round(-ScrollPos); ShiftY:=ShiftY+zY;
  FormPaint(Sender);
end;

procedure TMDIChild.SetScale(S:real);
begin
  Scale:=S;
end;

procedure TMDIChild.Zoom(Z:real);
begin
  if (((Z<1) and (Scale>0.4)) or
      ((Z>1) and (Scale<100)))
   then
  begin
    Scale:=Scale*Z;
  end;
end;

procedure TMDIChild.ReDraw(Sender: TObject);
begin
  FormPaint(Sender);
end;

function isAngleLeft(V1,V2,V3:plVertex):boolean;
var ax,ay,bx,by:integer;
begin
  ax:=V3.x-V2.x; ay:=V3.y-V2.y;
  bx:=V1.x-V2.x; by:=V1.y-V2.y;
  if (ax*by-ay*bx<=0) then  isAngleLeft:=true
    else isAngleLeft:=false;
end;

function isAngleLeftInt(x1,y1,x2,y2,x3,y3:integer):boolean;
var ax,ay,bx,by:integer;
begin
  ax:=x3-x2; ay:=y3-y2;
  bx:=x1-x2; by:=y1-y2;
  if (ax*by-ay*bx<0) then  isAngleLeftInt:=true
    else isAngleLeftInt:=false;
end;

function TMDIChild.CreateCover():TListVertex;
var i,j,minY,minCount,tx,ty,tn:integer;
    list : TListVertex;
begin
  countBottomCover:=Count;CountTopCover:=1;
  CountCover:=Count;
  for i:=1 to count do
  begin
    coverBottom[i].x:=a[i].x;
    coverBottom[i].y:=a[i].y;
    coverBottom[i].number:=a[i].number;
  end;
{======= Поиск нижней точки - ищем и записываем ее на первое место ====}
  minY:=a[1].y; minCount:=1;
  for i:=2 to count do
    if coverBottom[i].y<minY then
    begin
      minY:=coverBottom[i].y; minCount:=i;
    end;
  coverBottom[minCount].y:=coverBottom[1].y; coverBottom[1].y:=minY;
  i:=coverBottom[minCount].x; coverBottom[minCount].x:=coverBottom[1].x;
  coverBottom[1].x:=i;
  coverTop[1].x:=coverBottom[1].x;  coverTop[1].y:=coverBottom[1].y;
  coverTop[1].number:=coverBottom[1].number;
{======= Сортировка массива точек по углу отн. нижней точки ===========}
  for i:=1 to CountBottomCover-1 do
    for j:=i+1 to CountBottomCover do
    begin
      if (isAngleLeftInt(coverBottom[i].x,coverBottom[i].y,
                         coverBottom[1].x,coverBottom[1].y,
                         coverBottom[j].x,coverBottom[j].y)) then
      begin
        tx:=coverBottom[i].x; ty:=coverBottom[i].y; tn:=coverBottom[i].number;
        coverBottom[i].x:=coverBottom[j].x; coverBottom[i].y:=coverBottom[j].y;
        coverBottom[i].number:=coverBottom[j].number;
        coverBottom[j].x:=tx; coverBottom[j].y:=ty;
        coverBottom[j].number:=tn;
      end;
    end;

  list:=TListVertex.Create;
  for i:=1 to countBottomCover
    do list.AddVector(coverBottom[i].x,coverBottom[i].y,coverBottom[i].number);
  CreateCover:=list;
end;

function TMDIChild.CreateCoverAndry(): TListVertex;
var k,b : real;
    i,j,tx,ty,tn  : integer;
    minX,minCountX,maxX,maxCountX:integer;
    list : TListVertex;
begin
{======= Поиск минимальной и максимальной по х точек ===================}
  minX:=a[1].x ;minCountX:=1;
  maxX:=a[1].x ;maxCountX:=1;
  for i:=2 to count do
  begin
    if (a[i].x<minX) then
    begin
      minX:=a[i].x; minCountX:=i;
    end;
    if (a[i].x>maxX) then
    begin
      maxX:=a[i].x; maxCountX:=i;
    end;
  end;
{======== Вычисление параметров прямой через точки min и max ===========}
  if (a[maxCountX].x-a[minCountX].x)<>0 then
  begin
    k:=(a[maxCountX].y-a[minCountX].y)/(a[maxCountX].x-a[minCountX].x);
    b:=a[maxCountX].y-k*a[maxCountX].x;
{======== Создание неупорядоченной верхней и нижней оболочки ===========}
    coverTop[1].x:=a[minCountX].x;
    coverTop[1].y:=a[minCountX].y;
    coverTop[1].number:=a[minCountX].number;
    coverBottom[1].x:=a[minCountX].x;
    coverBottom[1].y:=a[minCountX].y;
    coverBottom[1].number:=a[minCountX].number;
    countTopCover:=1; countBottomCover:=1;
    for i:=1 to count do
      if ((i<>maxCountX) and (i<>minCountX)) then
      begin
        if (a[i].y>=k*a[i].x+b) then
        begin
          inc(countTopCover);
          coverTop[countTopCover].x:=a[i].x;
          coverTop[countTopCover].y:=a[i].y;
          coverTop[countTopCover].number:=a[i].number;
        end
        else
        begin
          inc(countBottomCover);
          coverBottom[countBottomCover].x:=a[i].x;
          coverBottom[countBottomCover].y:=a[i].y;
          coverBottom[countBottomCover].number:=a[i].number;
        end;
      end;
    inc(countTopCover); inc(countBottomCover);
    coverTop[countTopCover].x:=a[maxCountX].x;
    coverTop[countTopCover].y:=a[maxCountX].y;
    coverTop[countTopCover].number:=a[maxCountX].number;
    coverBottom[countBottomCover].x:=a[maxCountX].x;
    coverBottom[countBottomCover].y:=a[maxCountX].y;
    coverBottom[countBottomCover].number:=a[maxCountX].number;
  end;
{============== Сортировка верхней оболочки =================}
  for i:=1 to CountTopCover-2 do
    for j:=i+1 to CountTopCover-1 do
    begin
      if (coverTop[i].x>coverTop[j].x) then
      begin
        tx:=coverTop[i].x; ty:=coverTop[i].y;
        tn:=coverTop[i].number;
        coverTop[i].x:=coverTop[j].x;
        coverTop[i].y:=coverTop[j].y;
        coverTop[i].number:=coverTop[j].number;
        coverTop[j].x:=tx; coverTop[j].y:=ty;
        coverTop[j].number:=tn;
      end;
    end;
{============== Сортировка нижней оболочки =================}
  for i:=1 to CountBottomCover-2 do
    for j:=i+1 to CountBottomCover-1 do
    begin
      if (coverBottom[i].x>coverBottom[j].x) then
      begin
        tx:=coverBottom[i].x; ty:=coverBottom[i].y; tn:=coverBottom[i].number;
        coverBottom[i].x:=coverBottom[j].x; coverBottom[i].y:=coverBottom[j].y;
        coverBottom[i].number:=coverBottom[j].number;
        coverBottom[j].x:=tx; coverBottom[j].y:=ty;
        coverBottom[j].number:=tn;
      end;
    end;
{=============== Переводим массив в список =================}
//  if (CountCover<>0) then list.Free;
  list:=TListVertex.Create;
  for i:=1 to countTopCover
    do list.AddVector(coverTop[i].x,coverTop[i].y,coverTop[i].number);
  for i:=countBottomCover-1 downto 2
    do list.AddVector(coverBottom[i].x,coverBottom[i].y,coverBottom[i].number);
  CountCover:=CountTopCover+CountBottomCover;
  CreateCoverAndry:=list;
end;

procedure TMDIChild.Graham(Sender: TObject);
var f:boolean;
    w:plVertex;
begin
  if (Count>1) then
  begin
    if (al=1) then
    coverList:=CreateCover
    else
    coverList:=CreateCoverAndry;
    
    coverList.current:=coverList.beginList;
    w:=coverList.current.previos;
    f:=false;
    while ((CoverList.current.next<>CoverList.beginList) or (f=false)) do
    begin
      if (Coverlist.current.next=w)
      then f:=true;
      if (isAngleLeft(CoverList.current,CoverList.current.next,
                     CoverList.current.next.next))
        then CoverList.current:=CoverList.current.next
        else
          begin
            CoverList.DeleteVector(CoverList.current.next);
            CoverList.current:=CoverList.current.previos;
          end;
    end;
    coverList.current:=coverList.beginList;
    repeat
      coverList.current.used:=1;
      coverList.current:=coverList.current^.next;
    until coverList.current=coverList.beginList;
  end;
end;

function TMDIChild.StillGraham(Sender: TObject):boolean;
begin
  if (Count>1) then
  if (not fstill) then
  begin
    if (al=1) then
    coverList:=CreateCover
    else
    coverList:=CreateCoverAndry;

    StillcoverListcurrent:=coverList.beginList;
    w:=coverList.current.previos;
    f:=false; fstill:=true;

    coverList.current:=coverList.beginList;
    repeat
      coverList.current.used:=0;
      coverList.current:=coverList.current^.next;
    until coverList.current=coverList.beginList;
    FormPaint(Sender);
  end
  else
  begin
    if ( (al = 2) and (StillCoverListcurrent^.next^.x = coverTop[countTopCover].x) and (StillCoverListcurrent^.next^.y = coverTop[countTopCover].y) ) then
      StillGraham := true
    else
      StillGraham := false;

    if ((StillCoverListcurrent^.next<>CoverList.beginList) or (f=false)) then
      begin
        if (StillCoverlistcurrent^.next=w)
          then f:=true;
        if (StillCoverListCurrent^.used=3) then
            StillCoverListCurrent^.used:=2;
        StillCoverListCurrent^.next^.used:=3;
        StillCoverListCurrent^.next^.next.used:=3;
        FormPaint(Sender);

        if (isAngleLeft(StillCoverListcurrent,StillCoverListcurrent^.next,
                        StillCoverListcurrent^.next.next))
        then
        begin
          StillCoverListcurrent:=StillCoverListcurrent^.next;
        end
        else
        begin
          CoverList.DeleteVector(StillCoverListcurrent^.next);
          StillCoverListcurrent:=StillCoverListcurrent^.previos;
        end;
      end
    else
    begin
      coverList.current:=coverList.beginList;
      repeat
        coverList.current.used:=1;
        coverList.current:=coverList.current^.next;
      until coverList.current=coverList.beginList;
      FormPaint(Sender);
    end;
  end;
end;


procedure TMDIChild.FormCanResize(Sender: TObject; var NewWidth,
  NewHeight: Integer; var Resize: Boolean);
begin
  zX:=zX+round((View.Width-BWidth)/2);
  zY:=zY+round((View.Height-BHeight)/2);
  ShiftX:=ShiftX+round((View.Width-BWidth)/2);
  ShiftY:=ShiftY+round((View.Height-BHeight)/2);
  BWidth:=View.Width; BHeight:=View.Height;
end;

procedure TMDIChild.SetAlgorithm(a:integer);
begin
  al:=a;

  if ( al = 1 ) then
      MainForm.N3.Checked := true
  else
      MainForm.N4.Checked := true;

end;

procedure TMDIChild.ViewMouseUp(Sender: TObject; Button: TMouseButton;
  Shift: TShiftState; X, Y: Integer);
var XX,YY,XX2,YY2,tmp:integer;
begin
  if Button=mbRight then
  begin
    RightBPressed:=false;
    XX:=round((mouseX0-View.Width/2)/Scale+View.Width/2-ShiftX);
    YY:=round((mouseY0-View.Height/2)/Scale+View.Height/2-ShiftY);
    XX2:=round((X-View.Width/2)/Scale+View.Width/2-ShiftX);
    YY2:=round((Y-View.Height/2)/Scale+View.Height/2-ShiftY);

    if(XX > XX2) then
    begin
      tmp := XX2;
      XX2 := XX;
      XX :=tmp;
    end;

    if(YY > YY2) then
    begin
      tmp := YY2; 
      YY2 := YY;
      YY :=tmp;
    end;

    RandForm.ShowModal;
    if ((RandForm.ModalResult=1) and (RandForm.EditNumRND.Text<>'')) then
      RandomVertex(StrToInt(RandForm.EditNumRND.Text), XX, YY, XX2, YY2);
    FormPaint(Sender);
  end;
end;

procedure TMDIChild.FormActivate(Sender: TObject);
begin
    if ( al = 1 ) then
        MainForm.N3.Checked := true
    else
        MainForm.N4.Checked := true;
end;

end.