tictactoe.cpp Example File

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  #include "tictactoe.h"

  #include <QMouseEvent>
  #include <QPainter>

  TicTacToe::TicTacToe(QWidget *parent)
      : QWidget(parent)
      , turnNumber(0)
  {
  }

  QSize TicTacToe::minimumSizeHint() const
  {
      return QSize(200, 200);
  }

  QSize TicTacToe::sizeHint() const
  {
      return QSize(200, 200);
  }

  void TicTacToe::setState(const QString &newState)
  {
      turnNumber = 0;
      myState = "---------";
      int position = 0;
      while (position < 9 && position < newState.length()) {
          QChar mark = newState.at(position);
          if (mark == Cross || mark == Nought) {
              ++turnNumber;
              myState.replace(position, 1, mark);
          }
          position++;
      }
      update();
  }

  QString TicTacToe::state() const
  {
      return myState;
  }

  void TicTacToe::clearBoard()
  {
      myState = "---------";
      turnNumber = 0;
      update();
  }

  void TicTacToe::mousePressEvent(QMouseEvent *event)
  {
      if (turnNumber == 9) {
          clearBoard();
          update();
      } else {
          for (int position = 0; position < 9; ++position) {
              QRect cell = cellRect(position / 3, position % 3);
              if (cell.contains(event->pos())) {
                  if (myState.at(position) == Empty) {
                      if (turnNumber % 2 == 0)
                          myState.replace(position, 1, Cross);
                      else
                          myState.replace(position, 1, Nought);
                      ++turnNumber;
                      update();
                  }
              }
          }
      }
  }

  void TicTacToe::paintEvent(QPaintEvent * /* event */)
  {
      QPainter painter(this);
      painter.setRenderHint(QPainter::Antialiasing);

      painter.setPen(QPen(Qt::darkGreen, 1));
      painter.drawLine(cellWidth(), 0, cellWidth(), height());
      painter.drawLine(2 * cellWidth(), 0, 2 * cellWidth(), height());
      painter.drawLine(0, cellHeight(), width(), cellHeight());
      painter.drawLine(0, 2 * cellHeight(), width(), 2 * cellHeight());

      painter.setPen(QPen(Qt::darkBlue, 2));

      for (int position = 0; position < 9; ++position) {
          QRect cell = cellRect(position / 3, position % 3);

          if (myState.at(position) == Cross) {
              painter.drawLine(cell.topLeft(), cell.bottomRight());
              painter.drawLine(cell.topRight(), cell.bottomLeft());
          } else if (myState.at(position) == Nought) {
              painter.drawEllipse(cell);
          }
      }

      painter.setPen(QPen(Qt::yellow, 3));

      for (int position = 0; position < 9; position = position + 3) {
          if (myState.at(position) != Empty
                  && myState.at(position + 1) == myState.at(position)
                  && myState.at(position + 2) == myState.at(position)) {
              int y = cellRect((position / 3), 0).center().y();
              painter.drawLine(0, y, width(), y);
              turnNumber = 9;
          }
      }

      for (int position = 0; position < 3; ++position) {
          if (myState.at(position) != Empty
                  && myState.at(position + 3) == myState.at(position)
                  && myState.at(position + 6) == myState.at(position)) {
              int x = cellRect(0, position).center().x();
              painter.drawLine(x, 0, x, height());
              turnNumber = 9;
          }
      }
      if (myState.at(0) != Empty && myState.at(4) == myState.at(0)
              && myState.at(8) == myState.at(0)) {
          painter.drawLine(0, 0, width(), height());
          turnNumber = 9;
      }
      if (myState.at(2) != Empty && myState.at(4) == myState.at(2)
              && myState.at(6) == myState.at(2)) {
          painter.drawLine(0, height(), width(), 0);
          turnNumber = 9;
      }
  }

  QRect TicTacToe::cellRect(int row, int column) const
  {
      const int HMargin = width() / 30;
      const int VMargin = height() / 30;
      return QRect(column * cellWidth() + HMargin,
                   row * cellHeight() + VMargin,
                   cellWidth() - 2 * HMargin,
                   cellHeight() - 2 * VMargin);
  }