//-----------------------------------------------
void DemoBlockAttLED (HANDLE hLcWnd)
{
  static int Addr = 0;
  int StartAddr, EndAddr;
  HANDLE hBlock;

  // get a block, linked with CAD window
  hBlock = lcPropGetHandle( hLcWnd, LC_PROP_WND_VIEWBLOCK );

  StartAddr = 101;
  EndAddr = 125;
  // set lights by LED address
  if (Addr == 0){
    // all LEDs off
    SetLED( hBlock, 0, false );
    Addr = StartAddr;
  }else{
    if (Addr > EndAddr){
      // all LEDs on
      SetLED( hBlock, 0, true );
      Addr = 0;
    }else{
      if (Addr == StartAddr){
        SetLED( hBlock, Addr, true );
      }else{
        SetLED( hBlock, Addr-1, false );
        SetLED( hBlock, Addr, true );
      }
      ++Addr;
    }
  }
  // update view
  lcWndRedraw( hLcWnd ); 
}

//-----------------------------------------------
bool SetLED (HANDLE hBlock, int Addr, bool On)
{
  HANDLE hEnt;
  WCHAR  szValue[32];
  int    Color;

  if (On){
    // color for Light ON
    Color = lcColorRGB( 255, 50, 0 );
  }else{
    // color for Light OFF
    Color = lcColorRGB( 70, 70, 40 );
  }

  if (Addr == 0){
    // select all BlockRefs with Tag "DMXNo"
    hEnt = lcBlockGetBlkRefByTag( hBlock, 0, L"DMXNo", L"", true );
    if (hEnt > 0){
      // set color for selected entities
      hEnt = lcBlockGetFirstSel( hBlock );
      while( hEnt != 0){
        lcPropPutInt( hEnt, LC_PROP_ENT_COLOR, Color );
        hEnt = lcBlockGetNextSel( hBlock );
      }
      // unselect all entities
      lcBlockUnselect( hBlock );
      return true;
    }
    return false;
  }

  swprintf( szValue, L"1.2.%d", Addr );
  // find BlockRef entity by attribute
  hEnt = lcBlockGetBlkRefByTag( hBlock, 0, L"DMXNo", szValue, false );
  if (hEnt){
    lcPropPutInt( hEnt, LC_PROP_ENT_COLOR, Color );
    return true;
  }
  return false;
}