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#include <QtGui>

#include <math.h>

#include "renderthread.h"

//! [0]

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));

}

//! [0]

//! [1]

RenderThread::~RenderThread()

{

    mutex.lock();

    abort = true;

    condition.wakeOne();

    mutex.unlock();

    wait();

}

//! [1]

//! [2]

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();

    }

}

//! [2]

//! [3]

void RenderThread::run()

{

    forever {

        mutex.lock();

        QSize resultSize = this->resultSize;

        double scaleFactor = this->scaleFactor;

        double centerX = this->centerX;

        double centerY = this->centerY;

        mutex.unlock();

//! [3]

//! [4]

        int halfWidth = resultSize.width() / 2;

//! [4] //! [5]

        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);

//! [5] //! [6]

                ++pass;

            }

//! [6] //! [7]

        }

//! [7]

//! [8]

        mutex.lock();

//! [8] //! [9]

        if (!restart)

            condition.wait(&mutex);

        restart = false;

        mutex.unlock();

    }

}

//! [9]

//! [10]

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));

}

//! [10]