/******************************************************************************** Copyright (C) 2004-2006 Trolltech ASA. All rights reserved.**** This file is part of the example classes of the Qt Toolkit.**** This file may be used under the terms of the GNU General Public** License version 2.0 as published by the Free Software Foundation** and appearing in the file LICENSE.GPL included in the packaging of** this file.  Please review the following information to ensure GNU** General Public Licensing requirements will be met:** http://www.trolltech.com/products/qt/opensource.html**** If you are unsure which license is appropriate for your use, please** review the following information:** http://www.trolltech.com/products/qt/licensing.html or contact the** sales department at sales@trolltech.com.**** This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE** WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.******************************************************************************/#include <QtGui>#include <math.h>#include "renderthread.h"RenderThread::RenderThread(QObject *parent)    : QThread(parent){    restart = false;    abort = false;    for (int i = 0; i < ColormapSize; ++i)        colormap[i] = rgbFromWaveLength(380.0 + (i * 400.0 / ColormapSize));}RenderThread::~RenderThread(){    mutex.lock();    abort = true;    condition.wakeOne();    mutex.unlock();    wait();}void RenderThread::render(double centerX, double centerY, double scaleFactor,                          QSize resultSize){    QMutexLocker locker(&mutex);    this->centerX = centerX;    this->centerY = centerY;    this->scaleFactor = scaleFactor;    this->resultSize = resultSize;    if (!isRunning()) {        start(LowPriority);    } else {        restart = true;        condition.wakeOne();    }}void RenderThread::run(){    forever {        mutex.lock();        QSize resultSize = this->resultSize;        double scaleFactor = this->scaleFactor;        double centerX = this->centerX;        double centerY = this->centerY;        mutex.unlock();        int halfWidth = resultSize.width() / 2;        int halfHeight = resultSize.height() / 2;        QImage image(resultSize, QImage::Format_RGB32);        const int NumPasses = 8;        int pass = 0;        while (pass < NumPasses) {            const int MaxIterations = (1 << (2 * pass + 6)) + 32;            const int Limit = 4;            bool allBlack = true;            for (int y = -halfHeight; y < halfHeight; ++y) {                if (restart)                    break;                if (abort)                    return;                uint *scanLine =                        reinterpret_cast<uint *>(image.scanLine(y + halfHeight));                double ay = centerY + (y * scaleFactor);                for (int x = -halfWidth; x < halfWidth; ++x) {                    double ax = centerX + (x * scaleFactor);                    double a1 = ax;                    double b1 = ay;                    int numIterations = 0;                    do {                        ++numIterations;                        double a2 = (a1 * a1) - (b1 * b1) + ax;                        double b2 = (2 * a1 * b1) + ay;                        if ((a2 * a2) + (b2 * b2) > Limit)                            break;                        ++numIterations;                        a1 = (a2 * a2) - (b2 * b2) + ax;                        b1 = (2 * a2 * b2) + ay;                        if ((a1 * a1) + (b1 * b1) > Limit)                            break;                    } while (numIterations < MaxIterations);                    if (numIterations < MaxIterations) {                        *scanLine++ = colormap[numIterations % ColormapSize];                        allBlack = false;                    } else {                        *scanLine++ = qRgb(0, 0, 0);                    }                }            }            if (allBlack && pass == 0) {                pass = 4;            } else {                if (!restart)                    emit renderedImage(image, scaleFactor);                ++pass;            }        }        mutex.lock();        if (!restart)            condition.wait(&mutex);        restart = false;        mutex.unlock();    }}uint RenderThread::rgbFromWaveLength(double wave){    double r = 0.0;    double g = 0.0;    double b = 0.0;    if (wave >= 380.0 && wave <= 440.0) {        r = -1.0 * (wave - 440.0) / (440.0 - 380.0);        b = 1.0;    } else if (wave >= 440.0 && wave <= 490.0) {        g = (wave - 440.0) / (490.0 - 440.0);        b = 1.0;    } else if (wave >= 490.0 && wave <= 510.0) {        g = 1.0;        b = -1.0 * (wave - 510.0) / (510.0 - 490.0);    } else if (wave >= 510.0 && wave <= 580.0) {        r = (wave - 510.0) / (580.0 - 510.0);        g = 1.0;    } else if (wave >= 580.0 && wave <= 645.0) {        r = 1.0;        g = -1.0 * (wave - 645.0) / (645.0 - 580.0);    } else if (wave >= 645.0 && wave <= 780.0) {        r = 1.0;    }    double s = 1.0;    if (wave > 700.0)        s = 0.3 + 0.7 * (780.0 - wave) / (780.0 - 700.0);    else if (wave <  420.0)        s = 0.3 + 0.7 * (wave - 380.0) / (420.0 - 380.0);    r = pow(r * s, 0.8);    g = pow(g * s, 0.8);    b = pow(b * s, 0.8);    return qRgb(int(r * 255), int(g * 255), int(b * 255));}