0e69349f6f
The example refines the image by running a number of passes with increasing number of iterations, which is not really visible to the user. Set an informational text string on the generated image which provides this information along with the elapsed time. The idea is to do the same to the corresponding Qt for Python example to have some sort of speed comparison for number crunching. Add a command line option for the number of passes. Make the window a bit larger to accommodate the information. Change-Id: I2afc1009ab53b580123d82a6aa645d9ffaa63ea2 Reviewed-by: Paul Wicking <paul.wicking@qt.io>
246 lines
7.8 KiB
C++
246 lines
7.8 KiB
C++
/****************************************************************************
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**
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** Copyright (C) 2021 The Qt Company Ltd.
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** Contact: https://www.qt.io/licensing/
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**
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** This file is part of the examples of the Qt Toolkit.
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**
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** $QT_BEGIN_LICENSE:BSD$
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** Commercial License Usage
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** Licensees holding valid commercial Qt licenses may use this file in
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** accordance with the commercial license agreement provided with the
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** Software or, alternatively, in accordance with the terms contained in
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** a written agreement between you and The Qt Company. For licensing terms
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** and conditions see https://www.qt.io/terms-conditions. For further
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** information use the contact form at https://www.qt.io/contact-us.
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**
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** BSD License Usage
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** Alternatively, you may use this file under the terms of the BSD license
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** as follows:
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**
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** "Redistribution and use in source and binary forms, with or without
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** modification, are permitted provided that the following conditions are
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** met:
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** * Redistributions of source code must retain the above copyright
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** notice, this list of conditions and the following disclaimer.
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** * Redistributions in binary form must reproduce the above copyright
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** notice, this list of conditions and the following disclaimer in
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** the documentation and/or other materials provided with the
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** distribution.
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** * Neither the name of The Qt Company Ltd nor the names of its
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** contributors may be used to endorse or promote products derived
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** from this software without specific prior written permission.
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**
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**
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** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
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**
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** $QT_END_LICENSE$
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**
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****************************************************************************/
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#include "renderthread.h"
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#include <QImage>
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#include <QElapsedTimer>
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#include <QTextStream>
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#include <cmath>
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int RenderThread::numPasses = 8;
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//! [0]
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RenderThread::RenderThread(QObject *parent)
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: QThread(parent)
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{
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for (int i = 0; i < ColormapSize; ++i)
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colormap[i] = rgbFromWaveLength(380.0 + (i * 400.0 / ColormapSize));
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}
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//! [0]
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//! [1]
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RenderThread::~RenderThread()
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{
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mutex.lock();
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abort = true;
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condition.wakeOne();
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mutex.unlock();
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wait();
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}
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//! [1]
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//! [2]
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void RenderThread::render(double centerX, double centerY, double scaleFactor,
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QSize resultSize, double devicePixelRatio)
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{
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QMutexLocker locker(&mutex);
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this->centerX = centerX;
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this->centerY = centerY;
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this->scaleFactor = scaleFactor;
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this->devicePixelRatio = devicePixelRatio;
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this->resultSize = resultSize;
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if (!isRunning()) {
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start(LowPriority);
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} else {
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restart = true;
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condition.wakeOne();
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}
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}
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//! [2]
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//! [3]
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void RenderThread::run()
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{
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QElapsedTimer timer;
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forever {
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mutex.lock();
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const double devicePixelRatio = this->devicePixelRatio;
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const QSize resultSize = this->resultSize * devicePixelRatio;
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const double requestedScaleFactor = this->scaleFactor;
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const double scaleFactor = requestedScaleFactor / devicePixelRatio;
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const double centerX = this->centerX;
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const double centerY = this->centerY;
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mutex.unlock();
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//! [3]
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//! [4]
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int halfWidth = resultSize.width() / 2;
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//! [4] //! [5]
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int halfHeight = resultSize.height() / 2;
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QImage image(resultSize, QImage::Format_RGB32);
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image.setDevicePixelRatio(devicePixelRatio);
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int pass = 0;
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while (pass < numPasses) {
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const int MaxIterations = (1 << (2 * pass + 6)) + 32;
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const int Limit = 4;
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bool allBlack = true;
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timer.restart();
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for (int y = -halfHeight; y < halfHeight; ++y) {
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if (restart)
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break;
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if (abort)
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return;
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auto scanLine =
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reinterpret_cast<uint *>(image.scanLine(y + halfHeight));
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const double ay = centerY + (y * scaleFactor);
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for (int x = -halfWidth; x < halfWidth; ++x) {
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const double ax = centerX + (x * scaleFactor);
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double a1 = ax;
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double b1 = ay;
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int numIterations = 0;
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do {
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++numIterations;
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const double a2 = (a1 * a1) - (b1 * b1) + ax;
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const double b2 = (2 * a1 * b1) + ay;
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if ((a2 * a2) + (b2 * b2) > Limit)
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break;
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++numIterations;
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a1 = (a2 * a2) - (b2 * b2) + ax;
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b1 = (2 * a2 * b2) + ay;
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if ((a1 * a1) + (b1 * b1) > Limit)
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break;
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} while (numIterations < MaxIterations);
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if (numIterations < MaxIterations) {
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*scanLine++ = colormap[numIterations % ColormapSize];
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allBlack = false;
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} else {
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*scanLine++ = qRgb(0, 0, 0);
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}
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}
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}
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if (allBlack && pass == 0) {
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pass = 4;
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} else {
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if (!restart) {
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QString message;
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QTextStream str(&message);
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str << " Pass " << (pass + 1) << '/' << numPasses
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<< ", max iterations: " << MaxIterations << ", time: ";
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const auto elapsed = timer.elapsed();
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if (elapsed > 2000)
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str << (elapsed / 1000) << 's';
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else
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str << elapsed << "ms";
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image.setText(infoKey(), message);
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emit renderedImage(image, requestedScaleFactor);
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}
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//! [5] //! [6]
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++pass;
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}
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//! [6] //! [7]
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}
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//! [7]
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//! [8]
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mutex.lock();
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//! [8] //! [9]
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if (!restart)
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condition.wait(&mutex);
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restart = false;
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mutex.unlock();
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}
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}
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//! [9]
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//! [10]
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uint RenderThread::rgbFromWaveLength(double wave)
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{
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double r = 0;
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double g = 0;
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double b = 0;
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if (wave >= 380.0 && wave <= 440.0) {
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r = -1.0 * (wave - 440.0) / (440.0 - 380.0);
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b = 1.0;
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} else if (wave >= 440.0 && wave <= 490.0) {
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g = (wave - 440.0) / (490.0 - 440.0);
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b = 1.0;
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} else if (wave >= 490.0 && wave <= 510.0) {
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g = 1.0;
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b = -1.0 * (wave - 510.0) / (510.0 - 490.0);
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} else if (wave >= 510.0 && wave <= 580.0) {
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r = (wave - 510.0) / (580.0 - 510.0);
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g = 1.0;
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} else if (wave >= 580.0 && wave <= 645.0) {
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r = 1.0;
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g = -1.0 * (wave - 645.0) / (645.0 - 580.0);
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} else if (wave >= 645.0 && wave <= 780.0) {
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r = 1.0;
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}
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double s = 1.0;
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if (wave > 700.0)
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s = 0.3 + 0.7 * (780.0 - wave) / (780.0 - 700.0);
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else if (wave < 420.0)
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s = 0.3 + 0.7 * (wave - 380.0) / (420.0 - 380.0);
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r = std::pow(r * s, 0.8);
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g = std::pow(g * s, 0.8);
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b = std::pow(b * s, 0.8);
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return qRgb(int(r * 255), int(g * 255), int(b * 255));
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}
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//! [10]
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