Qt之Gui的事件转换

QGuiApplication的实现类QGuiApplicationPrivate方法processWindowSystemEvent处理window系统事件

static void processWindowSystemEvent(QWindowSystemInterfacePrivate::WindowSystemEvent *e);

在QWindowSystemInterface的处理事件方法中会调用上面的processWindowSystemEvent方法

flushWindowSystemEvents发送消息
QT_DEFINE_QPA_EVENT_HANDLER
定义为

#define QT_DEFINE_QPA_EVENT_HANDLER(ReturnType, HandlerName, ...) \template Q_GUI_EXPORT ReturnType QWindowSystemInterface::HandlerName<QWindowSystemInterface::DefaultDelivery>(__VA_ARGS__); \template Q_GUI_EXPORT ReturnType QWindowSystemInterface::HandlerName<QWindowSystemInterface::SynchronousDelivery>(__VA_ARGS__); \template Q_GUI_EXPORT ReturnType QWindowSystemInterface::HandlerName<QWindowSystemInterface::AsynchronousDelivery>(__VA_ARGS__); \template<typename Delivery> ReturnType QWindowSystemInterface::HandlerName(__VA_ARGS__)

QGuiApplication初始化时会加载QGeneralPlugin

键盘对应 QEvdevKeyboardPlugin，创建QEvdevKeyboardManager

QEvdevMouseManager::QEvdevMouseManager(const QString &key, const QString &specification, QObject *parent): QObject(parent), m_x(0), m_y(0), m_xoffset(0), m_yoffset(0)
{Q_UNUSED(key);QString spec = QString::fromLocal8Bit(qgetenv("QT_QPA_EVDEV_MOUSE_PARAMETERS"));if (spec.isEmpty())spec = specification;auto parsed = QEvdevUtil::parseSpecification(spec);m_spec = std::move(parsed.spec);for (const QStringRef &arg : qAsConst(parsed.args)) {if (arg.startsWith(QLatin1String("xoffset="))) {m_xoffset = arg.mid(8).toInt();} else if (arg.startsWith(QLatin1String("yoffset="))) {m_yoffset = arg.mid(8).toInt();}}// add all mice for devices specified in the argument listfor (const QString &device : qAsConst(parsed.devices))addMouse(device);if (parsed.devices.isEmpty()) {qCDebug(qLcEvdevMouse, "evdevmouse: Using device discovery");if (auto deviceDiscovery = QDeviceDiscovery::create(QDeviceDiscovery::Device_Mouse | QDeviceDiscovery::Device_Touchpad, this)) {// scan and add already connected keyboardsconst QStringList devices = deviceDiscovery->scanConnectedDevices();for (const QString &device : devices)addMouse(device);connect(deviceDiscovery, &QDeviceDiscovery::deviceDetected,this, &QEvdevMouseManager::addMouse);connect(deviceDiscovery, &QDeviceDiscovery::deviceRemoved,this, &QEvdevMouseManager::removeMouse);}}QInputDeviceManager *manager = QGuiApplicationPrivate::inputDeviceManager();connect(manager, &QInputDeviceManager::cursorPositionChangeRequested, [this](const QPoint &pos) {m_x = pos.x();m_y = pos.y();clampPosition();});
}

addMouse会创建QEvdevMouseHandler打开设备，并且根据文件描述符创建QSocketNotifier注册到事件分发器中
将QEvdevMouseHandler的鼠标信号与QEvdevMouseManager对应的槽函数建立联系，信号触发时，对应的槽函数会调用，执行QWindowSystemInterface的事件处理函数，将事件转化为QEvent

鼠标对应 QEvdevMousePlugin

QPA

qt的平台抽象，window实现代码在plugins/platforms/window下
判断window的事件函数为

QtWindows::WindowEventType windowEventType(UINT message, WPARAM wParam, LPARAM lParam);

QWindowsContext的windowsProc处理事件，其实现类为QWindowsContextPrivate

struct QWindowsContextPrivate {QWindowsContextPrivate();unsigned m_systemInfo = 0;QSet<QString> m_registeredWindowClassNames;HandleBaseWindowHash m_windows;HDC m_displayContext = nullptr;int m_defaultDPI = 96;QWindowsKeyMapper m_keyMapper;QWindowsMouseHandler m_mouseHandler;QWindowsPointerHandler m_pointerHandler;QWindowsMimeConverter m_mimeConverter;QWindowsScreenManager m_screenManager;QSharedPointer<QWindowCreationContext> m_creationContext;
#if QT_CONFIG(tabletevent)QScopedPointer<QWindowsTabletSupport> m_tabletSupport;
#endifconst HRESULT m_oleInitializeResult;QWindow *m_lastActiveWindow = nullptr;bool m_asyncExpose = false;HPOWERNOTIFY m_powerNotification = nullptr;HWND m_powerDummyWindow = nullptr;
};