procedure TFormNumericTree.DrawTree;
const
   FirstY = 3;
   FirstSeparate = 4;
var
   FirstCircle: TPoint;
   XDelta, YDelta: Byte;
begin
   with pbDrawTree.Canvas do
   begin
      Brush.Color := clWhite;
      FillRect(ClientRect);
      Pen.Width := 3;
   end;
   FirstCircle.X := pbDrawTree.Width div 2 - Radius;
   FirstCircle.Y := FirstY;
   if Head <> nil then
   begin
      if (rbRoot.Checked) or not(rbLeft.Checked or rbRoot.Checked or rbRight.Checked) then
      begin
         with pbDrawTree.Canvas do
         begin
            Pen.Color := clGreen;
            Ellipse(FirstCircle.X, FirstCircle.Y, FirstCircle.X + Diametre,
               FirstCircle.Y + Diametre);
            XDelta := TextWidth(IntToStr(Head^.Key)) div 2;
            YDelta := TextHeight(IntToStr(Head^.Key)) div 2;
            TextOut(FirstCircle.X + Radius - XDelta, FirstCircle.Y + Radius - YDelta,
               IntToStr(Head^.Key));
         end;
      end;
      if (rbLeft.Checked) or not(rbLeft.Checked or rbRoot.Checked or rbRight.Checked) then
         if Head^.Left <> nil then
            DrawElement(Head^.Left, FirstCircle, FirstSeparate, -1);
      if (rbRight.Checked) or not(rbLeft.Checked or rbRoot.Checked or rbRight.Checked) then
         if Head^.Right <> nil then
            DrawElement(Head^.Right, FirstCircle, FirstSeparate, 1);
   end;
end;

procedure TFormNumericTree.DrawElement(CurrElement: Adrzv; PrevCircle: TPoint;
   Depth: Byte; Direction: ShortInt);
var
   NewCircle: TPoint;
   XDelta, YDelta: Byte;
begin
   NewCircle.X := PrevCircle.X + Direction * (CountWidth div Depth);
   NewCircle.Y := PrevCircle.Y + Distance;
   with pbDrawTree.Canvas do
   begin
      Pen.Width := 3;
      Pen.Color := clGreen;
      Brush.Style := bsClear;
      Ellipse(NewCircle.X, NewCircle.Y, NewCircle.X + Diametre, NewCircle.Y + Diametre);
      XDelta := TextWidth(IntToStr(CurrElement^.Key)) div 2;
      YDelta := TextHeight(IntToStr(CurrElement^.Key)) div 2;
      TextOut(NewCircle.X + Radius - XDelta, NewCircle.Y + Radius - YDelta,
         IntToStr(CurrElement^.Key));
      Pen.Color := clBlack;
      MoveTo(PrevCircle.X + Radius, PrevCircle.Y + Diametre);
      LineTo(NewCircle.X + Radius, NewCircle.Y);
   end;
   if CurrElement^.Left <> nil then
      DrawElement(CurrElement^.Left, NewCircle, Depth * 2, -1);
   if CurrElement^.Right <> nil then
      DrawElement(CurrElement^.Right, NewCircle, Depth * 2, 1);
end;