renderthread.cpp Example File

    /****************************************************************************
     **
     ** 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 "renderthread.hpp"

    RenderThread::RenderThread(QObject *parent)
        : QThread(parent)
    {
        m_abort = false;
    }

    RenderThread::~RenderThread()
    {
        /**
         * If the destructor of the RendererThread is called while the worker
         * thread is still running, we signal the worker thread that it should
         * abort execution and we block execution of this thread (the main thread),
         * until the worker thread has finished, by calling wait().
         */
        mutex.lock();
        m_abort = true;
        mutex.unlock();

        wait();
    }

    void RenderThread::processImage(const QImage &image)
    {
        if (image.isNull())
            return;

        // Store a copy of the image ...
        m_image = image;

        // ... reset the abort flag ...
        m_abort = false;

        // ... and start the execution of the worker thread.
        start();
    }

    void RenderThread::run()
    {
        // Note: The content of this method is executed inside the worker thread!

        // Iterate over the image pixel-by-pixel and calculate the color of the blocks
        int size = qMax(m_image.width() / 20, m_image.height() / 20);
        for (int s = size; s > 10; --s) {
            for (int c = 0; c < 400; ++c) {
                int x1 = qMax(0, (qrand() % m_image.width()) - s / 2);
                int x2 = qMin(x1 + s / 2 + 1, m_image.width());
                int y1 = qMax(0, (qrand() % m_image.height()) - s / 2);
                int y2 = qMin(y1 + s / 2 + 1, m_image.height());
                int n = 0;
                int red = 0;
                int green = 0;
                int blue = 0;
                for (int i = y1; i < y2; ++i) {
                    for (int j = x1; j < x2; ++j) {
                        QRgb pixel = m_image.pixel(j, i);
                        red += qRed(pixel);
                        green += qGreen(pixel);
                        blue += qBlue(pixel);
                        n += 1;
                    }
                }
                if (qAlpha(m_image.pixel(x1, y1)) != 0) { // ignore transparent pixels
                    // Create a corresponding color object
                    const bb::cascades::Color color = bb::cascades::Color::fromRGBA(red / n / 255.0, green / n / 255.0, blue / n / 255.0, 1.0);

                    // Create a block of the current block size
                    Block block(QRect(x1, y1, x2 - x1 + 1, y2 - y1 + 1), color);

                    // Send the result by emitting the signal
                    emit sendBlock(block);
                }

                /**
                 * If the user requested the abort of the worker thread, we simply return from the run() method,
                 * which will cause the termination of the worker thread.
                 */
                if (m_abort)
                    return;

                msleep(10);
            }
        }
    }

    void RenderThread::stopProcess()
    {
        /**
         * If the user requests an abort of the worker thread, we set the m_abort flag
         * protected by the mutex.
         */
        mutex.lock();
        m_abort = true;
        mutex.unlock();
    }