Spectacle源码及分析3 —— Main.cpp解析2

接前一篇文章《Spectacle源码及分析2 —— Main.cpp解析1》：

Spectacle源码及分析2 —— Main.cpp解析1_蓝天居士的博客-CSDN博客

继续深入分析Main.cpp。

（7）代码片段：

SpectacleCore lCore;

 SpectacleCore类的定义在src/SpectacleCore.h中，源码如下：

class SpectacleCore : public QObject
{
    Q_OBJECT
 
public:
    enum class StartMode {
        Gui = 0,
        DBus = 1,
        Background = 2,
    };
 
    explicit SpectacleCore(QObject *parent = nullptr);
    ~SpectacleCore() override = default;
    void init();
 
    QString filename() const;
    void setFilename(const QString &filename);
 
    void populateCommandLineParser(QCommandLineParser *lCmdLineParser);
    void initGuiNoScreenshot();
 
Q_SIGNALS:
 
    void errorMessage(const QString &errString);
    void allDone();
    void grabFailed();
 
public Q_SLOTS:
 
    void takeNewScreenshot(Spectacle::CaptureMode theCaptureMode, int theTimeout, bool theIncludePointer, bool theIncludeDecorations);
    void showErrorMessage(const QString &theErrString);
    void screenshotUpdated(const QPixmap &thePixmap);
    void screenshotsUpdated(const QVector &imgs);
    void screenshotCanceled();
    void screenshotFailed();
    void doStartDragAndDrop();
    void doNotify(const QUrl &theSavedAt);
    void doCopyPath(const QUrl &savedAt);
 
    void onActivateRequested(QStringList arguments, const QString & /*workingDirectory */);
 
private:
    void ensureGuiInitiad();
    void initGui(int theDelay, bool theIncludePointer, bool theIncludeDecorations);
    Platform::GrabMode toPlatformGrabMode(Spectacle::CaptureMode theCaptureMode);
    void setUpShortcuts();
 
    StartMode mStartMode;
    bool mNotify;
    QString mFileNameString;
    QUrl mFileNameUrl;
    PlatformPtr mPlatform;
    MainWindowPtr mMainWindow = nullptr;
    EditorPtr mQuickEditor;
    bool mIsGuiInited = false;
    bool mCopyImageToClipboard;
    bool mCopyLocationToClipboard;
    bool mSaveToOutput;
    bool mEditExisting;
    bool mExistingLoaded;
 
    KWayland::Client::PlasmaShell *mWaylandPlasmashell = nullptr;
};

（8）代码片段：

QCommandLineParser lCmdLineParser;
 
aboutData.setupCommandLine(&lCmdLineParser);
lCore.populateCommandLineParser(&lCmdLineParser);

设置命令行解析器。

（9）代码片段：

// first parsing for help-about
lCmdLineParser.process(app.arguments());
aboutData.processCommandLine(&lCmdLineParser);

首先解析“’帮助”中的“关于”项。对应的图形界面如下图所示：

（10）代码片段：

QGuiApplication::setFallbackSessionManagementEnabled(false);

QGuiApplication::setFallbackSessionManagementEnabled的介绍如下（引自https://doc.qt.io/qt-5/qguiapplication.html#setFallbackSessionManagementEnabled）

void QGuiApplication::setFallbackSessionManagementEnabled(bool enabled)

Sets whether QGuiApplication will use fallback session management to enabled.

This function was introduced in Qt 5.6.

（11）代码片段：

auto disableSessionManagement = [](QSessionManager &sm) {
    sm.setRestartHint(QSessionManager::RestartNever);
};

QSessionManager::setRestartHint的介绍如下（引自QSessionManager — Qt for Python）

PySide2.QtGui.QSessionManager.setRestartHint(arg__1)¶

Parameters:

arg__1 – RestartHint

Sets the application’s restart hint to hint . On application startup, the hint is set to RestartIfRunning .

Note

These flags are only hints, a session manager may or may not respect them.

We recommend setting the restart hint in saveStateRequest() because most session managers perform a checkpoint shortly after an application’s startup.

（12）代码片段：

QObject::connect(&app, &QGuiApplication::commitDataRequest, disableSessionManagement);
QObject::connect(&app, &QGuiApplication::saveStateRequest, disableSessionManagement);

以下内容引自：QObject::connect 的几种连接方式_也许云知道的博客-CSDN博客_qobject::connect

QObject::connect 的几种连接方式

一、使用 SIGNAL、SLOT

[static] QMetaObject::Connection QObject::connect(const QObject *sender, const char *signal, const QObject *receiver, const char *method, Qt::ConnectionType type = Qt::AutoConnection)

For example

QLabel *label = new QLabel;
QScrollBar *scrollBar = new QScrollBar;
QObject::connect(scrollBar, SIGNAL(valueChanged(int)),label,  SLOT(setNum(int)));

二、使用 PointerToMemberFunction

[static] QMetaObject::Connection QObject::connect(const QObject *sender, PointerToMemberFunction signal, const QObject *receiver, PointerToMemberFunction method, Qt::ConnectionType type = Qt::AutoConnection)

For example

QLabel *label = new QLabel;
QLineEdit *lineEdit = new QLineEdit;
QObject::connect(lineEdit, &QLineEdit::textChanged,label,  &QLabel::setText);

这种方式有个问题，就是当你的槽函数有两个重载时，它会连接哪个呢？所以需要指定

// 假设类的槽函数有连个重载，分别为 void Example::func()  、void Example::func(int) 
// 我们需要连接 void Example::func(int) ,则
connect(this, somesignal, example, static_cast<void (Example:: *)(int)>(&Example::func));

三、使用 lambda

[static] QMetaObject::Connection QObject::connect(const QObject *sender, PointerToMemberFunction signal, Functor functor)

For example

void someFunction();
QPushButton *button = new QPushButton;
QObject::connect(button, &QPushButton::clicked, someFunction);

 Lambda expressions can also be used:

QByteArray page = ...;
QTcpSocket *socket = new QTcpSocket;
socket->connectToHost("qt-project.org", 80);
QObject::connect(socket, &QTcpSocket::connected, [=] () {socket->write("GET " + page + "\r\n");});