Qt with Cascades UI Examples Documentation

FileLoaderProxy.cpp Example File

sharedmemory/src/FileLoaderProxy.cpp
    /****************************************************************************
     **
     ** Portions Copyright (C) 2012 Research In Motion Limited.
     ** Copyright (C) 2011 Nokia Corporation and/or its subsidiary(-ies).
     ** All rights reserved.
     ** Contact: Research In Motion Ltd. (http://www.rim.com/company/contact/)
     ** Contact: Nokia Corporation (qt-info@nokia.com)
     **
     ** This file is part of the examples of the BB10 Platform and is derived
     ** from a similar file that is part of the Qt Toolkit.
     **
     ** You may use this file under the terms of the BSD license as follows:
     **
     ** "Redistribution and use in source and binary forms, with or without
     ** modification, are permitted provided that the following conditions are
     ** met:
     **   * Redistributions of source code must retain the above copyright
     **     notice, this list of conditions and the following disclaimer.
     **   * Redistributions in binary form must reproduce the above copyright
     **     notice, this list of conditions and the following disclaimer in
     **     the documentation and/or other materials provided with the
     **     distribution.
     **   * Neither the name of Research In Motion, nor the name of Nokia
     **     Corporation and its Subsidiary(-ies), nor the names of its
     **     contributors may be used to endorse or promote products
     **     derived from this software without specific prior written
     **     permission.
     **
     ** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
     ** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
     ** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
     ** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
     ** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
     ** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
     ** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
     ** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
     ** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     ** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
     ** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
     **
     ****************************************************************************/

    #include "FileLoaderProxy.hpp"

    // The key that is used for the shared memory segment
    static const char *s_sharedKey = "fileloader_shm_key";

    // The size of the shared memory segment
    static const int s_memorySize = 10 * 1024; // 10kB

    FileLoaderProxy::FileLoaderProxy(QObject *parent)
        : QObject(parent)
    {
        // Define the key that identifies this shared memory segment
        m_sharedMemory.setKey(QString::fromLatin1(s_sharedKey));

        // Create the shared memory segment with the given size
        m_sharedMemory.create(s_memorySize);
    }

    QString FileLoaderProxy::fileContent() const
    {
        // Before we access the content of the shared memory we should lock it
        m_sharedMemory.lock();

        // Read out all data
        QString content = QString::fromUtf8(static_cast<char*>(m_sharedMemory.data()));
        if (content.isEmpty())
            content = tr("No file loaded yet, please use sharedmemory_loader sample application to load one.");

        // Unlock the shared memory again
        m_sharedMemory.unlock();

        return content;
    }

    void FileLoaderProxy::loadFile()
    {
        /**
         * We expect that the user has started the sharedmemory_loader example and loaded
         * a file into the shared memory already, so just trigger to read the data from the
         * shared memory.
         */
        emit fileContentChanged();
    }