Centralise window filtering around a new SceneWindowFilter class

This way WaylandServer can implement its own filter with its own set of
rules without having Scene be too involved in it.

src/scene.cpp

@@ -138,6 +138,7 @@ QRect SceneDelegate::viewport() const
 
 Scene::Scene(QObject *parent)
     : QObject(parent)
+    , m_filter(this)
 {
 }
 
@@ -611,12 +612,10 @@ void Scene::createStackingOrder()
         if (!win->readyForPainting()) {
             windows.removeAll(win);
         }
-        if (waylandServer() && waylandServer()->isScreenLocked()) {
+        if (!m_filter.filterAcceptsWindow(win)) {
-            if (!win->isLockScreen() && !win->isInputMethod()) {
             windows.removeAll(win);
         }
     }
-    }
 
     // TODO: cache the stacking_order in case it has not changed
     for (Toplevel *c : std::as_const(windows)) {
@@ -654,7 +653,7 @@ void Scene::finalPaintWindow(EffectWindowImpl *w, int mask, const QRegion &regio
 // will be eventually called from drawWindow()
 void Scene::finalDrawWindow(EffectWindowImpl *w, int mask, const QRegion &region, WindowPaintData &data)
 {
-    if (waylandServer() && waylandServer()->isScreenLocked() && !w->window()->isLockScreen() && !w->window()->isInputMethod()) {
+    if (!m_filter.filterAcceptsWindow(w->window())) {
         return;
     }
     w->sceneWindow()->performPaint(mask, region, data);
@@ -871,4 +870,20 @@ Scene::EffectFrame::~EffectFrame()
 {
 }
 
+//****************************************
+// ScreenLockerFilter
+//****************************************
+
+ScreenLockerFilter::ScreenLockerFilter(Scene *s)
+{
+    QObject::connect(waylandServer(), &WaylandServer::lockStateChanged, s, &Scene::addRepaintFull);
+}
+
+ScreenLockerFilter::~ScreenLockerFilter() = default;
+
+bool ScreenLockerFilter::filterAcceptsWindow(KWin::Toplevel *w) const
+{
+    return !waylandServer()->isScreenLocked() || (w->isLockScreen() || w->isInputMethod());
+}
+
 } // namespace

src/scene.h

@@ -15,6 +15,8 @@
 #include "toplevel.h"
 #include "utils/common.h"
 
+#include <optional>
+
 #include <QElapsedTimer>
 #include <QMatrix4x4>
 
@@ -44,6 +46,15 @@ class SurfacePixmapX11;
 class SurfaceTexture;
 class WindowItem;
 
+class ScreenLockerFilter
+{
+public:
+    ScreenLockerFilter(Scene *scene);
+    ~ScreenLockerFilter();
+
+    bool filterAcceptsWindow(KWin::Toplevel *w) const;
+};
+
 class SceneDelegate : public RenderLayerDelegate
 {
     Q_OBJECT
@@ -264,6 +275,7 @@ protected:
 
     // windows in their stacking order
     QVector<Window *> stacking_order;
+    ScreenLockerFilter m_filter;
 
 private:
     std::chrono::milliseconds m_expectedPresentTimestamp = std::chrono::milliseconds::zero();

src/scenes/opengl/scene_opengl.cpp

@@ -313,7 +313,7 @@ Scene::Window *SceneOpenGL::createWindow(Toplevel *t)
 
 void SceneOpenGL::finalDrawWindow(EffectWindowImpl *w, int mask, const QRegion &region, WindowPaintData &data)
 {
-    if (waylandServer() && waylandServer()->isScreenLocked() && !w->window()->isLockScreen() && !w->window()->isInputMethod()) {
+    if (!m_filter.filterAcceptsWindow(w->window())) {
         return;
     }
     performPaintWindow(w, mask, region, data);

src/wayland_server.cpp

@@ -600,6 +600,7 @@ void WaylandServer::initScreenLocker()
             connect(seat, &KWaylandServer::SeatInterface::timestampChanged,
                     screenLockerApp, &ScreenLocker::KSldApp::userActivity);
         }
+        Q_EMIT lockStateChanged();
     });
 
     connect(ScreenLocker::KSldApp::self(), &ScreenLocker::KSldApp::unlocked, this, [this, screenLockerApp]() {
@@ -615,7 +616,7 @@ void WaylandServer::initScreenLocker()
                        screenLockerApp, &ScreenLocker::KSldApp::userActivity);
         }
         ScreenLocker::KSldApp::self()->setWaylandFd(-1);
-        Compositor::self()->scene()->addRepaintFull();
+        Q_EMIT lockStateChanged();
     });
 
     ScreenLocker::KSldApp::self()->initialize();

src/wayland_server.h

@@ -239,6 +239,7 @@ Q_SIGNALS:
     void shellClientRemoved(KWin::AbstractClient *);
     void initialized();
     void foreignTransientChanged(KWaylandServer::SurfaceInterface *child);
+    void lockStateChanged();
 
 private:
     int createScreenLockerConnection();