我看過Stellarium代碼，不知道從哪里開始

Question

我在 GitHub 上查看了Stellarium （用於像現在這樣查看天空的軟件）代碼有一段時間了。 我想盡快寫一個這樣的程序，所以我開始學習C++。 我查看了代碼，想知道這些部分的作用。 然后我問自己一個問題：“Stellarium 代碼從哪里開始？” 我想知道 Stellarium 首先在代碼的哪一部分運行，或者 Stellarium 在代碼的哪一部分得到運行調用。

聚苯乙烯

我只是 C++ 的初學者。 我不完全理解它，所以如果我不知道一切並且如果我錯過了我的問題，請不要生我的氣。

Answer 1

Stellarium 在main.cpp文件中的“src”文件夾中“啟動”。

腳本：

/*
 * Stellarium
 * Copyright (C) 2002 Fabien Chereau
 * Copyright (C) 2012 Timothy Reaves
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Suite 500, Boston, MA  02110-1335, USA.
 */

#include "StelMainView.hpp"
#include "StelSplashScreen.hpp"
#include "StelTranslator.hpp"
#include "StelLogger.hpp"
#include "StelFileMgr.hpp"
#include "CLIProcessor.hpp"
#include "StelIniParser.hpp"
#include "StelUtils.hpp"
#ifndef DISABLE_SCRIPTING
#include "StelScriptOutput.hpp"
#endif

#include <QDebug>

#ifndef USE_QUICKVIEW
    #include <QApplication>
    #include <QMessageBox>
    #include <QStyleFactory>
#else
    #include <QGuiApplication>
#endif
#include <QCoreApplication>
#include <QDir>
#include <QFile>
#include <QFileInfo>
#include <QFontDatabase>
#include <QGuiApplication>
#include <QSettings>
#include <QString>
#include <QStringList>
#include <QTextStream>
#include <QTranslator>
#include <QNetworkDiskCache>
#include <QThread>

#include <clocale>

#ifdef Q_OS_WIN
    #include <Windows.h>
    //we use WIN32_LEAN_AND_MEAN so this needs to be included
    //to use timeBeginPeriod/timeEndPeriod
    #include <mmsystem.h>

    // Default to High Performance Mode on machines with hybrid graphics
    // Details: https://stackoverflow.com/questions/44174859/how-to-give-an-option-to-select-graphics-adapter-in-a-directx-11-application
    extern "C"
    {
    #ifdef _MSC_VER
        __declspec(dllexport) DWORD NvOptimusEnablement = 0x00000001;
        __declspec(dllexport) int AmdPowerXpressRequestHighPerformance = 0x00000001;
    #else
        __attribute__((dllexport)) DWORD NvOptimusEnablement = 0x00000001;
        __attribute__((dllexport)) int AmdPowerXpressRequestHighPerformance = 0x00000001;
    #endif
    }
#else
    extern "C"
    {
        int NvOptimusEnablement = 1;
        int AmdPowerXpressRequestHighPerformance = 1;
    }
#endif //Q_OS_WIN

//! @class CustomQTranslator
//! Provides custom i18n support.
class CustomQTranslator : public QTranslator
{
    using QTranslator::translate;
public:
    virtual bool isEmpty() const { return false; }

    //! Overrides QTranslator::translate().
    //! Calls StelTranslator::qtranslate().
    //! @param context Qt context string - IGNORED.
    //! @param sourceText the source message.
    //! @param comment optional parameter
    virtual QString translate(const char *context, const char *sourceText, const char *disambiguation = Q_NULLPTR, int n = -1) const
    {
        Q_UNUSED(context);
        Q_UNUSED(n);
        return StelTranslator::globalTranslator->qtranslate(sourceText, disambiguation);
    }
};


//! Copies the default configuration file.
//! This function copies the default_cfg.ini file to config.ini (or other
//! name specified on the command line located in the user data directory.
void copyDefaultConfigFile(const QString& newPath)
{
    QString defaultConfigFilePath = StelFileMgr::findFile("data/default_cfg.ini");
    if (defaultConfigFilePath.isEmpty())
        qFatal("ERROR copyDefaultConfigFile failed to locate data/default_cfg.ini. Please check your installation.");
    QFile::copy(defaultConfigFilePath, newPath);
    if (!StelFileMgr::exists(newPath))
    {
        qFatal("ERROR copyDefaultConfigFile failed to copy file %s  to %s. You could try to copy it by hand.",
            qPrintable(defaultConfigFilePath), qPrintable(newPath));
    }
    QFile::setPermissions(newPath, QFile::permissions(newPath) | QFileDevice::WriteOwner);
}

//! Removes all items from the cache.
void clearCache()
{
    QNetworkDiskCache* cacheMgr = new QNetworkDiskCache();
    cacheMgr->setCacheDirectory(StelFileMgr::getCacheDir());
    cacheMgr->clear(); // Removes all items from the cache.
}

// Main stellarium procedure
int main(int argc, char **argv)
{
    Q_INIT_RESOURCE(mainRes);
    Q_INIT_RESOURCE(guiRes);

#ifdef Q_OS_WIN
    // Fix for the speeding system clock bug on systems that use ACPI
    // See http://support.microsoft.com/kb/821893
    UINT timerGrain = 1;
    if (timeBeginPeriod(timerGrain) == TIMERR_NOCANDO)
    {
        // If this is too fine a grain, try the lowest value used by a timer
        timerGrain = 5;
        if (timeBeginPeriod(timerGrain) == TIMERR_NOCANDO)
            timerGrain = 0;
    }
#endif

    // Seed the PRNG
    qsrand(QDateTime::currentMSecsSinceEpoch());

    QCoreApplication::setApplicationName("stellarium");
    QCoreApplication::setApplicationVersion(StelUtils::getApplicationVersion());
    QCoreApplication::setOrganizationDomain("stellarium.org");
    QCoreApplication::setOrganizationName("stellarium");

    // Support high DPI pixmaps and fonts
    QCoreApplication::setAttribute(Qt::AA_UseHighDpiPixmaps, true);
    #if (QT_VERSION>=QT_VERSION_CHECK(5, 6, 0))
    QCoreApplication::setAttribute(Qt::AA_EnableHighDpiScaling, true);
    #endif

    #if defined(Q_OS_MAC)
    QFileInfo appInfo(QString::fromUtf8(argv[0]));
    QDir appDir(appInfo.absolutePath());
    appDir.cdUp();
    QCoreApplication::addLibraryPath(appDir.absoluteFilePath("PlugIns"));
    #elif defined(Q_OS_WIN)
    QFileInfo appInfo(QString::fromUtf8(argv[0]));
    QCoreApplication::addLibraryPath(appInfo.absolutePath());
    #endif  

    QGuiApplication::setDesktopSettingsAware(false);

#ifndef USE_QUICKVIEW
    QApplication::setStyle(QStyleFactory::create("Fusion"));
    // The QApplication MUST be created before the StelFileMgr is initialized.
    QApplication app(argc, argv);
#else
    QGuiApplication::setDesktopSettingsAware(false);
    QGuiApplication app(argc, argv);
#endif

    // QApplication sets current locale, but
    // we need scanf()/printf() and friends to always work in the C locale,
    // otherwise configuration/INI file parsing will be erroneous.
    setlocale(LC_NUMERIC, "C");

    // Solution for bug: https://bugs.launchpad.net/stellarium/+bug/1498616
    qputenv("QT_HARFBUZZ", "old");

    // Init the file manager
    StelFileMgr::init();

    SplashScreen::present();

    // Log command line arguments.
    QString argStr;
    QStringList argList;
    for (int i=0; i<argc; ++i)
    {
        argList << argv[i];
        argStr += QString("%1 ").arg(argv[i]);
    }
    // add contents of STEL_OPTS environment variable.
    QString envStelOpts(qgetenv("STEL_OPTS").constData());
    if (envStelOpts.length()>0)
    {
        argList+= envStelOpts.split(" ");
        argStr += " " + envStelOpts;
    }
    //save the modified arg list as an app property for later use
    qApp->setProperty("stelCommandLine", argList);

    // Parse for first set of CLI arguments - stuff we want to process before other
    // output, such as --help and --version
    CLIProcessor::parseCLIArgsPreConfig(argList);

    #ifdef Q_OS_WIN
    if (qApp->property("onetime_angle_mode").isValid())
    {
        app.setAttribute(Qt::AA_UseOpenGLES, true);
    }
    if (qApp->property("onetime_mesa_mode").isValid())
    {
        app.setAttribute(Qt::AA_UseSoftwareOpenGL, true);
    }
    #endif

    // Start logging.
    StelLogger::init(StelFileMgr::getUserDir()+"/log.txt");
    StelLogger::writeLog(argStr);

    // OK we start the full program.
    // Print the console splash and get on with loading the program
    QString versionLine = QString("This is %1 - %2").arg(StelUtils::getApplicationName()).arg(STELLARIUM_URL);
    QString copyrightLine = QString("Copyright (C) %1 Fabien Chereau et al.").arg(COPYRIGHT_YEARS);
    int maxLength = qMax(versionLine.size(), copyrightLine.size());
    qDebug() << qPrintable(QString(" %1").arg(QString().fill('-', maxLength+2)));
    qDebug() << qPrintable(QString("[ %1 ]").arg(versionLine.leftJustified(maxLength, ' ')));
    qDebug() << qPrintable(QString("[ %1 ]").arg(copyrightLine.leftJustified(maxLength, ' ')));
    qDebug() << qPrintable(QString(" %1").arg(QString().fill('-', maxLength+2)));
    qDebug() << "Writing log file to:" << QDir::toNativeSeparators(StelLogger::getLogFileName());
    qDebug() << "File search paths:";
    int n=0;
    for (const auto& i : StelFileMgr::getSearchPaths())
    {
        qDebug() << " " << n << ". " << QDir::toNativeSeparators(i);
        ++n;
    }

    // Now manage the loading of the proper config file
    QString configName;
    try
    {
        configName = CLIProcessor::argsGetOptionWithArg(argList, "-c", "--config-file", "config.ini").toString();
    }
    catch (std::runtime_error& e)
    {
        qWarning() << "WARNING: while looking for --config-file option: " << e.what() << ". Using \"config.ini\"";
        configName = "config.ini";
    }

    QString configFileFullPath = StelFileMgr::findFile(configName, StelFileMgr::Flags(StelFileMgr::Writable|StelFileMgr::File));
    if (configFileFullPath.isEmpty())
    {
        configFileFullPath = StelFileMgr::findFile(configName, StelFileMgr::New);
        if (configFileFullPath.isEmpty())
            qFatal("Could not create configuration file %s.", qPrintable(configName));
    }

    QSettings* confSettings = Q_NULLPTR;
    if (StelFileMgr::exists(configFileFullPath))
    {
        confSettings = new QSettings(configFileFullPath, StelIniFormat, Q_NULLPTR);
        // Implement "restore default settings" feature.
        bool restoreDefaultConfigFile = false;
        if (CLIProcessor::argsGetOption(argList, "", "--restore-defaults"))
            restoreDefaultConfigFile=true;
        else
            restoreDefaultConfigFile = confSettings->value("main/restore_defaults", false).toBool();

        if (!restoreDefaultConfigFile)
        {
            QString version = confSettings->value("main/version", "0.0.0").toString();
            if (version!=QString(PACKAGE_VERSION))
            {
                QTextStream istr(&version);
                char tmp;
                int v1=0;
                int v2=0;
                istr >> v1 >> tmp >> v2;
                // Config versions less than 0.6.0 are not supported, otherwise we will try to use it
                if (v1==0 && v2<6)
                {
                    // The config file is too old to try an importation
                    qDebug() << "The current config file is from a version too old for parameters to be imported ("
                             << (version.isEmpty() ? "<0.6.0" : version) << ").\n"
                             << "It will be replaced by the default config file.";
                    restoreDefaultConfigFile = true;
                }
                else
                {
                    qDebug() << "Attempting to use an existing older config file.";
                    confSettings->setValue("main/version", QString(PACKAGE_VERSION)); // Upgrade version of config.ini
                    clearCache();
                    qDebug() << "Clear cache and update config.ini...";
                }
            }
        }

        if (restoreDefaultConfigFile)
        {
            if (confSettings)
                delete confSettings;

            QString backupFile(configFileFullPath.left(configFileFullPath.length()-3) + QString("old"));
            if (QFileInfo(backupFile).exists())
                QFile(backupFile).remove();

            QFile(configFileFullPath).rename(backupFile);
            copyDefaultConfigFile(configFileFullPath);
            confSettings = new QSettings(configFileFullPath, StelIniFormat);
            qWarning() << "Resetting defaults config file. Previous config file was backed up in " << QDir::toNativeSeparators(backupFile);
            clearCache();
        }
    }
    else
    {
        qDebug() << "Config file " << QDir::toNativeSeparators(configFileFullPath) << " does not exist. Copying the default file.";
        copyDefaultConfigFile(configFileFullPath);
        confSettings = new QSettings(configFileFullPath, StelIniFormat);
    }

    Q_ASSERT(confSettings);
    qDebug() << "Config file is: " << QDir::toNativeSeparators(configFileFullPath);

    #ifndef DISABLE_SCRIPTING
    QString outputFile = StelFileMgr::getUserDir()+"/output.txt";
    if (confSettings->value("main/use_separate_output_file", false).toBool())
        outputFile = StelFileMgr::getUserDir()+"/output-"+QDateTime::currentDateTime().toString("yyyyMMdd-HHmmss")+".txt";
    StelScriptOutput::init(outputFile);
    #endif

    // Override config file values from CLI.
    CLIProcessor::parseCLIArgsPostConfig(argList, confSettings);

    // Add the DejaVu font that we use everywhere in the program
    const QString& fName = StelFileMgr::findFile("data/DejaVuSans.ttf");
    if (!fName.isEmpty())
        QFontDatabase::addApplicationFont(fName);

    QString fileFont = confSettings->value("gui/base_font_file", "").toString();
    if (!fileFont.isEmpty())
    {
        const QString& afName = StelFileMgr::findFile(QString("data/%1").arg(fileFont));
        if (!afName.isEmpty() && !afName.contains("file not found"))
            QFontDatabase::addApplicationFont(afName);
        else
            qWarning() << "ERROR while loading custom font " << QDir::toNativeSeparators(fileFont);
    }

    // Set the default application font and font size.
    // Note that style sheet will possibly override this setting.
#ifdef Q_OS_WIN
    // Let's try avoid ugly font rendering on Windows.
    // Details: https://sourceforge.net/p/stellarium/discussion/278769/thread/810a1e5c/
    QString baseFont = confSettings->value("gui/base_font_name", "Verdana").toString();
    QFont tmpFont(baseFont);
    tmpFont.setStyleHint(QFont::AnyStyle, QFont::OpenGLCompatible);
#else
    QString baseFont = confSettings->value("gui/base_font_name", "DejaVu Sans").toString();
    QFont tmpFont(baseFont);
#endif
    tmpFont.setPixelSize(confSettings->value("gui/gui_font_size", 13).toInt());
    QGuiApplication::setFont(tmpFont);

    // Initialize translator feature
    StelTranslator::init(StelFileMgr::getInstallationDir() + "/data/iso639-1.utf8");

    // Use our custom translator for Qt translations as well
    CustomQTranslator trans;
    app.installTranslator(&trans);

    StelMainView mainWin(confSettings);
    mainWin.show();
    SplashScreen::finish(&mainWin);
    app.exec();
    mainWin.deinit();

    delete confSettings;
    StelLogger::deinit();

    #ifdef Q_OS_WIN
    if(timerGrain)
        timeEndPeriod(timerGrain);
    #endif //Q_OS_WIN

    return 0;
}

感謝所有的努力。

聚苯乙烯

我知道這個問題很不清楚，但我不能做得更好。