Program Brezenhem;
uses crt,graph,mouse,dos;
const size_set = 40;
type
 SetArray =array[1..100,1..100] of byte;
 BoolArray= array [1..40,1..40] of boolean;
 matrix= array [1..2,1..2]  of Integer;



var q:char;
    selected,select:BoolArray;
    len_x,len_y,len,w:integer;
    flag:boolean;
    gm,gd,i,j,n,z,i1,j1:integer;
    old_mouse, cur_mouse:boolean;
    size_x,size_y:integer;
    c:byte;
    x_,y_:word;
    matr:matrix;

 procedure setka ;
   begin
     size_x:=size_set;
     size_y:=size_set;
     len_x:=480 div size_x;
     len_y:=480 div size_y;
     setcolor(red);

     for i:=1 to size_y  do
       for j:=1 to size_x   do       {risuem setku iz pryamoygolnikov}
         begin
           rectangle((j-1)*len_x,(i-1)*len_y,j*len_x,i*len_y );
         end;
   end;

procedure ResetMouse;
begin
  old_mouse := false;
  cur_mouse := false;
  if initmouse then;
  showmouse;
end;

function GetMouseEvent: byte;
begin
  cur_mouse := (buttonpressed = 1);

  if cur_mouse <> old_mouse then
     begin
       if cur_mouse
          then GetMouseEvent := 1 { mouse pressed once }
          else GetMouseEvent := 2; { mouse released }
     end
  else GetMouseEvent := 0; { Nothing changed }

  old_mouse := cur_mouse;
end;




Procedure Zapolnyaem( selected:Boolarray;var matr:matrix);
var k:boolean;

begin
for i:=1 to n do
for j:=1 to n do
    begin
      selected[i,j]:=false;
    end;
for i:=1 to 2 do
 for j:=1 to 2 do
  matr[i,j]:=0;
repeat      {na4inaem proveryat bil li wel4ok miw'u}
 showmouse;
 z:=GetMouseEvent; {buttonpressed;}
 n:=0;
 for i:=1 to size_y  do
 for j:=1 to size_x do
     begin
       if (mousein((j-1)*len_x,(i-1)*len_y,j*len_x,i*len_y )) and (z=1)  then
          begin
            hidemouse;
            selected[i,j]:=not selected[i,j];
            getmousexy(x_,y_);
            if selected[i,j]  then
               begin
                 setfillstyle(solidfill,lightgray);
               end
            else
               setfillstyle(solidfill,getbkcolor);

            bar ((j-1)*len_x,(i-1)*len_y,j*len_x,i*len_y );
            setcolor(red);
            rectangle((j-1)*len_x,(i-1)*len_y,j*len_x,i*len_y );
          end;
     end;
    for i:=1 to size_x do
      for j:=1 to size_y do
       begin   if selected[i,j] then n:=n+1; end;
 case n of
   1:  begin
      if matr[1,1]=0 then  matr[1,1]:=x_ ;
      if matr[1,2]= 0 then matr[1,2]:=y_;
      end;
   2:  begin
       matr[2,1]:=x_;
       matr[2,2]:=y_;
       end;
 end;
 k:=keypressed;
until k;
 end;

procedure DrawLine4Connected(x1 : Integer; y1 : Integer;x2 : Integer;y2 : Integer);
var q:char;
    x : Integer;
    y : Integer;
    dx : Integer;
    dy : Integer;
    sx : Integer;
    sy : Integer;
    z : Integer;
    e : Integer;
    i : Integer;
    Ch : Boolean;
begin
    x := x1;
    y := y1;
    dx := Abs(x2-x1);
    dy := Abs(y2-y1);
    If ((x2-x1) >0 ) then sx:=1 else sx :=-1;
    If ((y2-x1) >0 ) then sy:=1 else sy :=-1;

    e := 2*dy-dx;
    if dy>=dx then
    begin
        z := dx;
        dx := dy;
        dy := z;
        Ch := True;
    end
    else
    begin
        Ch := False;
    end;
    i := 1;
    repeat
        PutPixel(x, y,10);
        if e<dx then
        begin
            if Ch then
            begin
                y := y+sy;
            end
            else
            begin
                x := x+sx;
            end;
            e := e+2*dy;
        end
        else
        begin
            if Ch then
            begin
                x := x+sx;
            end
            else
            begin
                y := y+sy;
            end;
            e := e-2*dx;
        end;
        i := i+1;
    until  not (i<=dx+dy);
    PutPixel(x, y,10);
 readkey;
end;



 begin
 initmouse;
 gd:=detect;
 initgraph(gd,gm,'');
 repeat
   for i:=1 to 2 do
   for j:=1 to 2 do
   matr[i,j]:=0;
   flag:=false;
   setka;
   zapolnyaem(select,matr);
   setcolor(white);
   circle(matr[1,1],matr[1,2],2);
   circle(matr[2,1],matr[2,2],4);

   DrawLine4Connected(matr[1,1],matr[1,2],matr[2,1],matr[2,2]);
   q:=readkey;
   if q=#32 then  flag:=true;

 until flag;


 end.