feat(slock): implement ext_session_lock_v1 backend

note: did not run lints or fully test yet

src/wayland/session_lock/session_lock.hpp

@@ -0,0 +1,92 @@
+#pragma once
+
+#include <qobject.h>
+#include <qtclasshelpermacros.h>
+#include <qtmetamacros.h>
+#include <qwindow.h>
+
+class QSWaylandSessionLock;
+class QSWaylandSessionLockSurface;
+class QSWaylandSessionLockIntegration;
+
+class SessionLockManager: public QObject {
+	Q_OBJECT;
+
+public:
+	SessionLockManager(QObject* parent = nullptr): QObject(parent) {}
+	Q_DISABLE_COPY_MOVE(SessionLockManager);
+
+	// Returns true if a lock was acquired.
+	// If true is returned the caller must watch the global screen list and create/destroy
+	// windows with an attached LockWindowExtension to match it.
+	bool lock();
+
+	// Returns true if the session was locked and is now unlocked.
+	bool unlock();
+
+	[[nodiscard]] bool isLocked() const;
+
+	static bool sessionLocked();
+
+signals:
+	// This signal is sent once the compositor considers the session to be fully locked.
+	// This corrosponds to the ext_session_lock_v1::locked event.
+	void locked();
+
+	// This signal is sent once the compositor considers the session to be unlocked.
+	// This corrosponds to the ext_session_lock_v1::finished event.
+	//
+	// The session lock will end in one of three cases.
+	// 1. unlock() is called.
+	// 2. The SessionLockManager is destroyed.
+	// 3. The compositor forcibly unlocks the session.
+	//
+	// After receiving this event the caller should destroy all of its lock surfaces.
+	void unlocked();
+
+private slots:
+	//void onUnlocked();
+
+private:
+	QSWaylandSessionLock* mLock = nullptr;
+
+	friend class LockWindowExtension;
+};
+
+class LockWindowExtension: public QObject {
+	Q_OBJECT;
+
+public:
+	LockWindowExtension(QObject* parent = nullptr): QObject(parent) {}
+	~LockWindowExtension() override;
+
+	// Attach this lock extension to the given window.
+	// The extension is reparented to the window and replaces any existing lock extension.
+	// Returns false if the window cannot be used.
+	bool attach(QWindow* window, SessionLockManager* manager);
+
+	// This must be called in place of QWindow::setVisible. Calling QWindow::setVisible will result in a crash.
+	// To make a window invisible, destroy it as it cannot be recovered.
+	void setVisible();
+
+	[[nodiscard]] bool isLocked() const;
+
+	static LockWindowExtension* get(QWindow* window);
+
+signals:
+	// This signal is sent once the compositor considers the session to be fully locked.
+	// See SessionLockManager::locked for details.
+	void locked();
+
+	// After receiving this signal the window is no longer in use by the compositor
+	// and should be destroyed. See SessionLockManager::unlocked for details.
+	void unlocked();
+
+private:
+	QSWaylandSessionLockSurface* surface = nullptr;
+	QSWaylandSessionLock* lock = nullptr;
+	bool immediatelyVisible = false;
+
+	friend class QSWaylandSessionLockSurface;
+	friend class QSWaylandSessionLockIntegration;
+};