Create a fallback shellSurface in wl_shell::get_shell_surface

This makes QWaylandShellPrivate::shell_get_shell_surface behave
similarly to QWaylandCompositorPrivate::compositor_create_surface.

First, a signal is emitted letting a compositor implementation create
its own subclass of QWaylandShellSurface if desired. If it's not
created, a plain QWaylandShellSurface is created instead.

It also makes the API more consistent, as the creation of shell surfaces
now mimick the creation of surfaces and xdg surfaces.

qwindow-compositor has been updated to take advantage of the new API

Change-Id: I7c7262dd253dc37843e8e471a4ead5f6e87b0ced
Reviewed-by: Giulio Camuffo <giulio.camuffo@kdab.com>

4 files changed, 28 insertions, 16 deletions

diff --git a/examples/wayland/qwindow-compositor/windowcompositor.cpp b/examples/wayland/qwindow-compositor/windowcompositor.cpp
index a8504b517..5b3b69059 100644
--- a/examples/wayland/qwindow-compositor/windowcompositor.cpp
+++ b/examples/wayland/qwindow-compositor/windowcompositor.cpp
@@ -111,8 +111,8 @@ WindowCompositor::WindowCompositor(QWindow *window)
     , m_wlShell(new QWaylandWlShell(this))
     , m_xdgShell(new QWaylandXdgShell(this))
 {
-    connect(m_wlShell, &QWaylandWlShell::createShellSurface, this, &WindowCompositor::onCreateWlShellSurface);
-    connect(m_xdgShell, &QWaylandXdgShell::createXdgSurface, this, &WindowCompositor::onCreateXdgSurface);
+    connect(m_wlShell, &QWaylandWlShell::shellSurfaceCreated, this, &WindowCompositor::onWlShellSurfaceCreated);
+    connect(m_xdgShell, &QWaylandXdgShell::xdgSurfaceCreated, this, &WindowCompositor::onXdgSurfaceCreated);
     connect(m_xdgShell, &QWaylandXdgShell::createXdgPopup, this, &WindowCompositor::onCreateXdgPopup);
 }
 
@@ -189,29 +189,27 @@ WindowCompositorView * WindowCompositor::findView(const QWaylandSurface *s) cons
     return Q_NULLPTR;
 }
 
-void WindowCompositor::onCreateWlShellSurface(QWaylandSurface *s, const QWaylandResource &res)
+void WindowCompositor::onWlShellSurfaceCreated(QWaylandWlShellSurface *wlShellSurface)
 {
-    QWaylandSurface *surface = s;
-
-    QWaylandWlShellSurface *wlShellSurface = new QWaylandWlShellSurface(m_wlShell, surface, res);
     connect(wlShellSurface, &QWaylandWlShellSurface::startMove, this, &WindowCompositor::onStartMove);
     connect(wlShellSurface, &QWaylandWlShellSurface::startResize, this, &WindowCompositor::onWlStartResize);
     connect(wlShellSurface, &QWaylandWlShellSurface::setTransient, this, &WindowCompositor::onSetTransient);
     connect(wlShellSurface, &QWaylandWlShellSurface::setPopup, this, &WindowCompositor::onSetPopup);
-    WindowCompositorView *view = findView(s);
+
+    WindowCompositorView *view = findView(wlShellSurface->surface());
     Q_ASSERT(view);
     view->m_wlShellSurface = wlShellSurface;
 }
 
-void WindowCompositor::onCreateXdgSurface(QWaylandSurface *surface, const QWaylandResource &res)
+void WindowCompositor::onXdgSurfaceCreated(QWaylandXdgSurface *xdgSurface)
 {
-    QWaylandXdgSurface *xdgSurface = new QWaylandXdgSurface(m_xdgShell, surface, res);
     connect(xdgSurface, &QWaylandXdgSurface::startMove, this, &WindowCompositor::onStartMove);
     connect(xdgSurface, &QWaylandXdgSurface::startResize, this, &WindowCompositor::onXdgStartResize);
 
-    WindowCompositorView *view = findView(surface);
+    WindowCompositorView *view = findView(xdgSurface->surface());
     Q_ASSERT(view);
     view->m_xdgSurface = xdgSurface;
+
     connect(xdgSurface, &QWaylandXdgSurface::setMaximized, view, &WindowCompositorView::onXdgSetMaximized);
     connect(xdgSurface, &QWaylandXdgSurface::setFullscreen, view, &WindowCompositorView::onXdgSetFullscreen);
     connect(xdgSurface, &QWaylandXdgSurface::unsetMaximized, view, &WindowCompositorView::onXdgUnsetMaximized);
diff --git a/examples/wayland/qwindow-compositor/windowcompositor.h b/examples/wayland/qwindow-compositor/windowcompositor.h
index 63068d1ae..c8b796ee9 100644
--- a/examples/wayland/qwindow-compositor/windowcompositor.h
+++ b/examples/wayland/qwindow-compositor/windowcompositor.h
@@ -127,8 +127,8 @@ private slots:
     void triggerRender();
 
     void onSurfaceCreated(QWaylandSurface *surface);
-    void onCreateWlShellSurface(QWaylandSurface *s, const QWaylandResource &resource);
-    void onCreateXdgSurface(QWaylandSurface *surface, const QWaylandResource &resource);
+    void onWlShellSurfaceCreated(QWaylandWlShellSurface *wlShellSurface);
+    void onXdgSurfaceCreated(QWaylandXdgSurface *xdgSurface);
     void onCreateXdgPopup(QWaylandSurface *surface, QWaylandSurface *parent, QWaylandInputDevice *inputDevice,
                           const QPoint &position, const QWaylandResource &resource);
     void onSetTransient(QWaylandSurface *parentSurface, const QPoint &relativeToParent, QWaylandWlShellSurface::FocusPolicy focusPolicy);
diff --git a/src/compositor/extensions/qwaylandwlshell.cpp b/src/compositor/extensions/qwaylandwlshell.cpp
index c6d13b392..817a01b9e 100644
--- a/src/compositor/extensions/qwaylandwlshell.cpp
+++ b/src/compositor/extensions/qwaylandwlshell.cpp
@@ -61,8 +61,9 @@ void QWaylandWlShellPrivate::shell_get_shell_surface(Resource *resource, uint32_
     Q_Q(QWaylandWlShell);
     QWaylandSurface *surface = QWaylandSurface::fromResource(surface_res);
 
-    wl_resource *res = wl_resource_create(resource->client(), &wl_shell_surface_interface,
-                                          wl_resource_get_version(resource->handle), id);
+    QWaylandResource shellSurfaceResource(wl_resource_create(resource->client(), &wl_shell_surface_interface,
+                                                             wl_resource_get_version(resource->handle), id));
+
     // XXX FIXME
     // The role concept was formalized in wayland 1.7, so that release adds one error
     // code for each interface that implements a role, and we are supposed to pass here
@@ -71,8 +72,19 @@ void QWaylandWlShellPrivate::shell_get_shell_surface(Resource *resource, uint32_
     // However we're still using wayland 1.4, which doesn't have interface specific role
     // errors, so the best we can do is to use wl_display's object_id error.
     wl_resource *displayRes = wl_client_get_object(resource->client(), 1);
-    if (surface->setRole(QWaylandWlShellSurface::role(), displayRes, WL_DISPLAY_ERROR_INVALID_OBJECT))
-        emit q->createShellSurface(surface, QWaylandResource(res));
+    if (!surface->setRole(QWaylandWlShellSurface::role(), displayRes, WL_DISPLAY_ERROR_INVALID_OBJECT))
+        return;
+
+    emit q->createShellSurface(surface, shellSurfaceResource);
+
+    QWaylandWlShellSurface *shellSurface = QWaylandWlShellSurface::fromResource(shellSurfaceResource.resource());
+    if (!shellSurface) {
+        // A QWaylandShellSurface was not created in response to the createShellSurface signal
+        // we create one as fallback here instead.
+        shellSurface = new QWaylandWlShellSurface(q, surface, shellSurfaceResource);
+    }
+
+    emit q->shellSurfaceCreated(shellSurface);
 }
 
 QWaylandWlShellSurfacePrivate::QWaylandWlShellSurfacePrivate()
diff --git a/src/compositor/extensions/qwaylandwlshell.h b/src/compositor/extensions/qwaylandwlshell.h
index 2420f4cd0..12905549e 100644
--- a/src/compositor/extensions/qwaylandwlshell.h
+++ b/src/compositor/extensions/qwaylandwlshell.h
@@ -51,6 +51,7 @@ class QWaylandClient;
 class QWaylandInputDevice;
 class QWaylandOutput;
 class QWaylandSurfaceRole;
+class QWaylandWlShellSurface;
 
 class Q_WAYLAND_COMPOSITOR_EXPORT QWaylandWlShell : public QWaylandExtensionTemplate<QWaylandWlShell>
 {
@@ -67,6 +68,7 @@ public:
 
 Q_SIGNALS:
     void createShellSurface(QWaylandSurface *surface, const QWaylandResource &resource);
+    void shellSurfaceCreated(QWaylandWlShellSurface *shellSurface);
 };
 
 class Q_WAYLAND_COMPOSITOR_EXPORT QWaylandWlShellSurface : public QWaylandExtensionTemplate<QWaylandWlShellSurface>