[mutter] remote-desktop: Check for screencast only when required

[Georges Basile Stavracas Neto <gbsneto src gnome org>]

commit b8524504f475c98591c6f04b7dfcab47d023ac8f
Author: Olivier Fourdan <ofourdan redhat com>
Date:   Mon Jun 29 15:01:55 2020 +0200

    remote-desktop: Check for screencast only when required
    
    The portal API requires a screencast session only for absolution motion
    with remote desktop, other methods including relative motion do not
    require a screencast session.
    
    There is no reason to be more strict than the API actually is, check for
    a screencast session only when required, like for absolute motion events
    and touch events.
    
    Tested with https://gitlab.gnome.org/snippets/1122
    
    Closes: https://gitlab.gnome.org/GNOME/mutter/-/issues/1307

 src/backends/meta-remote-desktop-session.c | 34 +++++++++++++++++++++++-------
 1 file changed, 26 insertions(+), 8 deletions(-)
---
diff --git a/src/backends/meta-remote-desktop-session.c b/src/backends/meta-remote-desktop-session.c
index a7f128dfa6..28191a1e08 100644
--- a/src/backends/meta-remote-desktop-session.c
+++ b/src/backends/meta-remote-desktop-session.c
@@ -273,14 +273,6 @@ meta_remote_desktop_session_check_can_notify (MetaRemoteDesktopSession *session,
       return FALSE;
     }
 
-  if (!session->screen_cast_session)
-    {
-      g_dbus_method_invocation_return_error (invocation, G_DBUS_ERROR,
-                                             G_DBUS_ERROR_FAILED,
-                                             "No screen cast active");
-      return FALSE;
-    }
-
   return TRUE;
 }
 
@@ -591,6 +583,15 @@ handle_notify_pointer_motion_absolute (MetaDBusRemoteDesktopSession *skeleton,
   if (!meta_remote_desktop_session_check_can_notify (session, invocation))
     return TRUE;
 
+
+  if (!session->screen_cast_session)
+    {
+      g_dbus_method_invocation_return_error (invocation, G_DBUS_ERROR,
+                                             G_DBUS_ERROR_FAILED,
+                                             "No screen cast active");
+      return TRUE;
+    }
+
   stream = meta_screen_cast_session_get_stream (session->screen_cast_session,
                                                 stream_path);
   if (!stream)
@@ -628,6 +629,14 @@ handle_notify_touch_down (MetaDBusRemoteDesktopSession *skeleton,
   if (!meta_remote_desktop_session_check_can_notify (session, invocation))
     return TRUE;
 
+  if (!session->screen_cast_session)
+    {
+      g_dbus_method_invocation_return_error (invocation, G_DBUS_ERROR,
+                                             G_DBUS_ERROR_FAILED,
+                                             "No screen cast active");
+      return TRUE;
+    }
+
   stream = meta_screen_cast_session_get_stream (session->screen_cast_session,
                                                 stream_path);
   if (!stream)
@@ -666,6 +675,15 @@ handle_notify_touch_motion (MetaDBusRemoteDesktopSession *skeleton,
   if (!meta_remote_desktop_session_check_can_notify (session, invocation))
     return TRUE;
 
+
+  if (!session->screen_cast_session)
+    {
+      g_dbus_method_invocation_return_error (invocation, G_DBUS_ERROR,
+                                             G_DBUS_ERROR_FAILED,
+                                             "No screen cast active");
+      return TRUE;
+    }
+
   stream = meta_screen_cast_session_get_stream (session->screen_cast_session,
                                                 stream_path);
   if (!stream)