// ----- #pragma endregion ----------------------------------------------------

  Bitmap^ bitmapa;
  int kulaX,kulaY,kulaR;
  bool WTrakciePrzesuwania;


// ----- Form1_Load() ---------------------------------------------------------

  bitmapa = gcnew Bitmap(1200, 800, Imaging::PixelFormat::Format24bppRgb);
  Graphics^ grafBMP = Graphics::FromImage(bitmapa); 
  grafBMP->Clear(Color::White);
  WTrakciePrzesuwania=false;
  kulaR=10;


// ----- pictureBox1_MouseDown() ----------------------------------------------

  if(e->Button==Windows::Forms::MouseButtons::Left)
  {
    int px=e->X-kulaX;
    int py=e->Y-kulaY;
    if(px*px+py*py<=kulaR*kulaR)
      WTrakciePrzesuwania=true;
  }   


// ----- pictureBox1_MouseMove() ----------------------------------------------

  if(e->Button==Windows::Forms::MouseButtons::Left && WTrakciePrzesuwania==true)
  {
    kulaX=e->X;
    kulaY=e->Y;
    pictureBox1->Invalidate();
  }
  else 
    WTrakciePrzesuwania=false;


// ----- pictureBox1_Paint() --------------------------------------------------

  static int lastMX=0,lastMY=0;
  Graphics^ grafBMP = Graphics::FromImage(bitmapa); 
  grafBMP->DrawLine(Pens::Black, lastMX, lastMY, kulaX, kulaY);
 
  Graphics^ grafika = e->Graphics;
  grafika->DrawImage(bitmapa,0,0);
  grafika->FillEllipse(Brushes::Green, kulaX-kulaR,kulaY-kulaR,2*kulaR,2*kulaR);
  lastMX=kulaX; 
  lastMY=kulaY;