Qt with Cascades UI Examples Documentation

GameController.cpp Example File

scriptgame/src/GameController.cpp
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     ** Portions Copyright (C) 2012 Research In Motion Limited.
     ** Copyright (C) 2011 Nokia Corporation and/or its subsidiary(-ies).
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    #include "GameController.hpp"

    #include "Board.hpp"
    #include "Player.hpp"

    #include <QScriptEngine>

    /**
     * This function is called by the script engine if the user creates new Player objects from
     * within the script. (e.g. 'var p = new Player(board)')
     */
    static QScriptValue constructNewPlayer(QScriptContext *context, QScriptEngine *engine)
    {
        /**
         * Since the Player class expects a Board object as parameter to the constructor we
         * have to pass it in the script and extract it here again.
         */
        Board *board = qobject_cast<Board*>(context->argument(0).toQObject());
        if (!board) {
            // If no valid Board object was passed, we throw an error...
            return context->throwError("Missing Board parameter in ctor");
        }

        // ... otherwise we return a new Player object whose lifetime is managed by the script engine
        return engine->newQObject(new Player(board), QScriptEngine::ScriptOwnership);
    }

    GameController::GameController(QObject *parent)
        : QObject(parent)
        , m_boardContainer(0)
        , m_board(0)
        , m_player(0)
        , m_scriptEngine(0)
    {
    }

    QString GameController::scriptError() const
    {
        return m_scriptError;
    }

    void GameController::setBoard(bb::cascades::Container *board)
    {
        /**
         * Now that we know on which Container we are supposed to work, create
         * our Board and Player objects that handle the business logic.
         */
        m_boardContainer = board;
        m_board = new Board(m_boardContainer, this);
        m_board->reset();

        m_player = new Player(m_board, this);
        m_player->reset();

        reset();
    }

    void GameController::reset()
    {
        // Reset the script engine

        /**
         * We have to delete the script engine with deleteLater() here, because this method is called
         * by the script engine itself, so we should not call 'delete m_scriptEngine' while it is used.
         */
        m_scriptEngine->deleteLater();
        m_scriptEngine = new QScriptEngine(this);

        /**
         * Create a wrapper object for the GameController itself since we want to
         * access its reset() method from within the scripts.
         */
        QScriptValue scriptController = m_scriptEngine->newQObject(this);

        // Export it to the script engine environment
        m_scriptEngine->globalObject().setProperty("controller", scriptController);

        // Create a wrapper object for the Board object...
        QScriptValue scriptBoard = m_scriptEngine->newQObject(m_board);

        // ... and export it to the script engine environment
        m_scriptEngine->globalObject().setProperty("board", scriptBoard);

        // Create a wrapper object for the Player object...
        QScriptValue scriptPlayer = m_scriptEngine->newQObject(m_player);

        // ... and export it to the script engine environment as well
        m_scriptEngine->globalObject().setProperty("player", scriptPlayer);

        // Make the constructor function for new Player objects known to the script engine environment
        QScriptValue createPlayerFunc = m_scriptEngine->newFunction(constructNewPlayer);
        m_scriptEngine->globalObject().setProperty("Player", createPlayerFunc);
    }

    void GameController::run(const QString &script)
    {
        // Run the script that is passed in from the UI
        const QScriptValue result = m_scriptEngine->evaluate(script);

        // Update the scriptError property
        if (result.isError()) {
            m_scriptError = QString::fromLatin1("%1: %2").arg(result.property("lineNumber").toInt32())
                                                         .arg(result.toString());
        } else {
            m_scriptError.clear();
        }

        emit scriptErrorChanged();

        /**
         * We call collectGarbage() explicitly here to ensure that Player objects are deleted immediately
         * and their tiles will disappear from the UI.
         */
        m_scriptEngine->collectGarbage();
    }