Mouse Listener for the Game of Fifteen tutorial on the SSaurel's Channel

MouseListener.java

addMouseListener(new MouseAdapter() {
  @Override
  public void mousePressed(MouseEvent e) {
    // used to let users to interact on the grid by clicking
    // it's time to implement interaction with users to move tiles to solve the game !
    if (gameOver) {
      newGame();
    } else {
      // get position of the click
      int ex = e.getX() - margin;
      int ey = e.getY() - margin;

      // click in the grid ?
      if (ex < 0 || ex > gridSize  || ey < 0  || ey > gridSize)
        return;

      // get position in the grid
      int c1 = ex / tileSize;
      int r1 = ey / tileSize;

      // get position of the blank cell
      int c2 = blankPos % size;
      int r2 = blankPos / size;

      // we convert in the 1D coord 
      int clickPos = r1 * size + c1;

      int dir = 0;

      // we search direction for multiple tile moves at once
      if (c1 == c2  &&  Math.abs(r1 - r2) > 0)
        dir = (r1 - r2) > 0 ? size : -size;
      else if (r1 == r2 && Math.abs(c1 - c2) > 0)
        dir = (c1 - c2) > 0 ? 1 : -1;

      if (dir != 0) {
        // we move tiles in the direction
        do {
          int newBlankPos = blankPos + dir;
          tiles[blankPos] = tiles[newBlankPos];
          blankPos = newBlankPos;
        } while(blankPos != clickPos);

        tiles[blankPos] = 0;
      }

      // we check if game is solved
      gameOver = isSolved();
    }

    // we repaint panel
    repaint();
  }
});