xwayland: Handle the case of windows being realized before redirection

If Xwayland gets to realize a window meant for composition before the
compositor redirected windows (i.e. redirect mode is not RedirectDrawManual
yet), the window would stay "invisible" as we wouldn't create a
wl_surface/wl_shell_surface for it at any later point.

This scenario may happen if the wayland compositor sets up a X11 socket
upfront, but waits to raise Xwayland until there are X11 clients. In this
case the first data on the socket is the client's, the compositor can hardly
beat that in order to redirect subwindows before the client realizes a
Window.

In order to jump across this hurdle, allow the late creation of a matching
(shell) surface for the WindowPtr on SetWindowPixmapProc, so it is ensured
to be created after the compositor set up redirection.

Signed-off-by: Carlos Garnacho <carlosg@gnome.org>
Reviewed-by: Michel Dänzer <mdaenzer@redhat.com>
Reviewed-by: Olivier Fourdan <ofourdan@redhat.com>
(cherry picked from commit 78cc8b6f9613fc71f6ecc7e8848d54364a250634)

2 files changed, 26 insertions, 0 deletions

diff --git a/hw/xwayland/xwayland.c b/hw/xwayland/xwayland.c
index 9a4b52fa9..baa08d87b 100644
--- a/hw/xwayland/xwayland.c
+++ b/hw/xwayland/xwayland.c
@@ -700,6 +700,26 @@ xwl_save_screen(ScreenPtr pScreen, int on)
 }
 
 static void
+xwl_set_window_pixmap(WindowPtr window,
+                      PixmapPtr pixmap)
+{
+    ScreenPtr screen = window->drawable.pScreen;
+    struct xwl_screen *xwl_screen;
+
+    xwl_screen = xwl_screen_get(screen);
+
+    screen->SetWindowPixmap = xwl_screen->SetWindowPixmap;
+    (*screen->SetWindowPixmap) (window, pixmap);
+    xwl_screen->SetWindowPixmap = screen->SetWindowPixmap;
+    screen->SetWindowPixmap = xwl_set_window_pixmap;
+
+    if (!RegionNotEmpty(&window->winSize))
+        return;
+
+    ensure_surface_for_window(window);
+}
+
+static void
 frame_callback(void *data,
                struct wl_callback *callback,
                uint32_t time)
@@ -1185,6 +1205,11 @@ xwl_screen_init(ScreenPtr pScreen, int argc, char **argv)
     xwl_screen->CloseScreen = pScreen->CloseScreen;
     pScreen->CloseScreen = xwl_close_screen;
 
+    if (xwl_screen->rootless) {
+        xwl_screen->SetWindowPixmap = pScreen->SetWindowPixmap;
+        pScreen->SetWindowPixmap = xwl_set_window_pixmap;
+    }
+
     pScreen->CursorWarpedTo = xwl_cursor_warped_to;
     pScreen->CursorConfinedTo = xwl_cursor_confined_to;
 
diff --git a/hw/xwayland/xwayland.h b/hw/xwayland/xwayland.h
index dfa3b37c3..0854df456 100644
--- a/hw/xwayland/xwayland.h
+++ b/hw/xwayland/xwayland.h
@@ -133,6 +133,7 @@ struct xwl_screen {
     UnrealizeWindowProcPtr UnrealizeWindow;
     DestroyWindowProcPtr DestroyWindow;
     XYToWindowProcPtr XYToWindow;
+    SetWindowPixmapProcPtr SetWindowPixmap;
 
     struct xorg_list output_list;
     struct xorg_list seat_list;