feat: add an own lock screen with the bubble and your wallpaper

src/agent/sessionlock.h

@@ -0,0 +1,85 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+//
+// face-unlock's own lock screen, for whoever wants it on a compositor whose
+// lock screen is a program of its own (ext-session-lock: Hyprland, Niri,
+// Sway and others): `face-unlock lock`.
+//
+// Any other lock screen there covers the bubble, and only opens itself (it
+// gets the face through PAM, see src/lib/pam.sh). This one is the lock
+// screen, so the bubble shows on it and a face opens it straight away. The
+// picture behind it is the user's choice (LockWallpaper).
+//
+// Qt knows no ext-session-lock, so each screen's window gets the lock surface
+// role through Qt's shell integration, the way LayerShellQt gives windows the
+// layer-shell role. If this program goes away while locked, the compositor
+// keeps the session locked: that is the protocol's promise.
+
+#pragma once
+
+#include <QHash>
+#include <QObject>
+#include <QPointer>
+#include <QUrl>
+
+class BubbleController;
+class LockScreenController;
+class UserConfig;
+class QQmlEngine;
+class QQuickView;
+class QScreen;
+class LockIntegration;
+class Lock;
+
+class SessionLock : public QObject
+{
+    Q_OBJECT
+public:
+    SessionLock(QQmlEngine *engine, BubbleController *bubble, LockScreenController *screen, UserConfig *config, QObject *parent = nullptr);
+    ~SessionLock() override;
+
+    // Whether the compositor offers ext-session-lock.
+    static bool available();
+
+    // From the lock request until the lock is gone again.
+    bool isLocked() const
+    {
+        return m_lock != nullptr;
+    }
+    // The compositor has confirmed the lock: nothing unlocked is on screen.
+    bool isConfirmed() const
+    {
+        return m_confirmed;
+    }
+
+    // A file that says the screen is locked, so that an agent started again
+    // after a crash locks again (see main.cpp).
+    static QString markerPath();
+
+public Q_SLOTS:
+    void lock();
+    void unlock();
+
+Q_SIGNALS:
+    void lockedChanged(bool locked);
+    void confirmed();
+
+private:
+    friend class Lock;
+    void onLocked();
+    void onFinished();
+    void addScreen(QScreen *screen);
+    void removeScreen(QScreen *screen);
+    void release();
+
+    QQmlEngine *m_engine;
+    BubbleController *m_bubble;
+    LockScreenController *m_screen;
+    UserConfig *m_config;
+    LockIntegration *m_integration = nullptr;
+    Lock *m_lock = nullptr;
+    bool m_confirmed = false;
+    bool m_unlockWanted = false;
+    QHash<QScreen *, QPointer<QQuickView>> m_views;
+    // The pictures behind it, by output (see Wallpaper).
+    QHash<QString, QUrl> m_pictures;
+};