0.程序 main() 函数执行流程图

QtCreator-程序入口流程图.png

1.Restarter restarter(argc, argv)

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int main(int argc, char **argv)
{
    Restarter restarter(argc, argv);
    ......
    return restarter.restartOrExit(app.exec());
}

程序重启器，用于某些配置修改后，需要重启程序才能够使配置生效。

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class Restarter
{
public:
    Restarter(int argc, char *argv[])
    {
        Q_UNUSED(argc)
        m_executable = QString::fromLocal8Bit(argv[0]);
        m_workingPath = QDir::currentPath();
    }

    void setArguments(const QStringList &args) { m_args = args; }

    QString executable() const { return m_executable; }
    QStringList arguments() const { return m_args; }
    QString workingPath() const { return m_workingPath; }

    int restartOrExit(int exitCode)
    {
        // 根据 "restart" 属性判断是需要重启程序
        return qApp->property("restart").toBool() ? restart(exitCode) : exitCode;
    }

    int restart(int exitCode)
    {
        // 启动进程
        QProcess::startDetached(m_executable, m_args, m_workingPath);
        return exitCode;
    }

private:
    QString m_executable;  // 可执行程序名称
    QStringList m_args;    // 可执行程序的命令参数
    QString m_workingPath; // 可执行程序所在的工作目录
};

2.SharedTools::QtSingleApplication app()

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    SharedTools::QtSingleApplication app((QLatin1String(Core::Constants::IDE_DISPLAY_NAME)),
                                         numberofArguments,
                                         options.appArguments.data());
......
#if QT_VERSION < QT_VERSION_CHECK(6, 0, 0)
    app.setAttribute(Qt::AA_UseHighDpiPixmaps);
    app.setAttribute(Qt::AA_DisableWindowContextHelpButton);
#endif
......
    QTranslator translator;
    QTranslator qtTranslator;
......
    app.installTranslator(&translator);
    app.installTranslator(&qtTranslator);
    app.setProperty("qtc_locale", locale);
......
    app.setDesktopFileName("org.qt-project.qtcreator.desktop");

    bool isBlock = foundAppOptions.contains(QLatin1String(BLOCK_OPTION));
    if (app.isRunning() && (pid != -1 || isBlock
                            || foundAppOptions.contains(QLatin1String(CLIENT_OPTION)))) {
        app.setBlock(isBlock);
        if (app.sendMessage(PluginManager::serializedArguments(), 5000 /*timeout*/, pid))
            return 0;

        // Message could not be send, maybe it was in the process of quitting
        if (app.isRunning(pid)) {
            // Nah app is still running, ask the user
            int button = askMsgSendFailed();
            while (button == QMessageBox::Retry) {
                if (app.sendMessage(PluginManager::serializedArguments(), 5000 /*timeout*/, pid))
                    return 0;
                if (!app.isRunning(pid)) // App quit while we were trying so start a new creator
                    button = QMessageBox::Yes;
                else
                    button = askMsgSendFailed();
            }
            if (button == QMessageBox::No)
                return -1;
        }
    }

    // Set up remote arguments.
    QObject::connect(&app, &SharedTools::QtSingleApplication::messageReceived,
                     &pluginManager, &PluginManager::remoteArguments);

    QObject::connect(&app, SIGNAL(fileOpenRequest(QString)), coreplugin->plugin(),
                     SLOT(fileOpenRequest(QString)));

    // shutdown plugin manager on the exit
    QObject::connect(&app, &QCoreApplication::aboutToQuit, &pluginManager, &PluginManager::shutdown);

    return restarter.restartOrExit(app.exec());

QtSingleApplication 提供了每个用户只能启动一次的应用程序的功能。
Qt 提供了解决方案组件项目 qtproject/qt-solutions https://github.com/qtproject/qt-solutions
Qt Creator 里的 QtSingleApplication 和 qt-solutions 有些不一样

qtproject/qt-solutions 提供的解决方案项目在另外的篇章展开分析：QtSingleApplication（TODO）

3.程序工作环境配置

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QCoreApplication::setApplicationName(Core::Constants::IDE_CASED_ID);
QCoreApplication::setApplicationVersion(QLatin1String(Core::Constants::IDE_VERSION_LONG));
QCoreApplication::setOrganizationName(QLatin1String(Core::Constants::IDE_SETTINGSVARIANT_STR));
QGuiApplication::setApplicationDisplayName(Core::Constants::IDE_DISPLAY_NAME);

auto cleanup = qScopeGuard([] { Utils::Singleton::deleteAll(); });

const QStringList pluginArguments = app.arguments();

/*Initialize global settings and resetup install settings with QApplication::applicationDirPath */
setupInstallSettings(options.installSettingsPath);
Utils::QtcSettings *settings = createUserSettings();
// static Utils::QtcSettings *createUserSettings()
// {
//     return new Utils::QtcSettings(QSettings::IniFormat,
//                                   QSettings::UserScope,
//                                   QLatin1String(Core::Constants::IDE_SETTINGSVARIANT_STR),
//                                   QLatin1String(Core::Constants::IDE_CASED_ID));
// }
Utils::QtcSettings *globalSettings
    = new Utils::QtcSettings(QSettings::IniFormat,
                             QSettings::SystemScope,
                             QLatin1String(Core::Constants::IDE_SETTINGSVARIANT_STR),
                             QLatin1String(Core::Constants::IDE_CASED_ID));
Utils::TerminalCommand::setSettings(settings);
loadFonts();
// void loadFonts()
// {
//     const QDir dir(resourcePath() + "/fonts/");

//     const QFileInfoList fonts = dir.entryInfoList(QStringList("*.ttf"), QDir::Files);
//     for (const QFileInfo &fileInfo : fonts)
//         QFontDatabase::addApplicationFont(fileInfo.absoluteFilePath());
// }

主要理解这两个代表什么就行了
QSettings::UserScope
QSettings::SystemScope

TODO：QSettings 需要另外的篇章介绍。

4.PluginManager pluginManager

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PluginManager pluginManager;
PluginManager::setPluginIID(QLatin1String("org.qt-project.Qt.QtCreatorPlugin"));
PluginManager::setGlobalSettings(globalSettings);
PluginManager::setSettings(settings);
...
// 读取所有路径下的插件属性信息
PluginManager::setPluginPaths(pluginPaths);
...
PluginManager::checkForProblematicPlugins();
// 加载插件
PluginManager::loadPlugins();