Client: Support running with no screens

[ChangeLog][QPA plugin] The QPA plugin now supports running with no screens
attached. This is handled by adding a fake screen when the last screen is
disconnected, similarly to what the other QPA plugins do.

Fixes: QTBUG-79111
Change-Id: I4a0e023ae784217dd030f0c62f12487fdff4825c
Reviewed-by: Paul Olav Tvete <paul.tvete@qt.io>

1 files changed, 4 insertions, 0 deletions

diff --git a/src/client/qwaylanddisplay_p.h b/src/client/qwaylanddisplay_p.h
index 14bb77198..cd845b44e 100644
--- a/src/client/qwaylanddisplay_p.h
+++ b/src/client/qwaylanddisplay_p.h
@@ -76,6 +76,7 @@ QT_BEGIN_NAMESPACE
 class QAbstractEventDispatcher;
 class QSocketNotifier;
 class QPlatformScreen;
+class QPlatformPlaceholderScreen;
 
 namespace QtWayland {
     class qt_surface_extension;
@@ -124,6 +125,8 @@ public:
 #endif
 
     QList<QWaylandScreen *> screens() const { return mScreens; }
+    QPlatformPlaceholderScreen *placeholderScreen() const { return mPlaceholderScreen; }
+    void ensureScreen();
 
     QWaylandScreen *screenForOutput(struct wl_output *output) const;
     void handleScreenInitialized(QWaylandScreen *screen);
@@ -228,6 +231,7 @@ private:
     QScopedPointer<QWaylandShm> mShm;
     QList<QWaylandScreen *> mWaitingScreens;
     QList<QWaylandScreen *> mScreens;
+    QPlatformPlaceholderScreen *mPlaceholderScreen = nullptr;
     QList<QWaylandInputDevice *> mInputDevices;
     QList<Listener> mRegistryListeners;
     QWaylandIntegration *mWaylandIntegration = nullptr;