[gnome-remote-desktop] settings: Add new screenshare mode setting for the VNC backend

[Jonas Ådahl <jadahl src gnome org>]

commit a7d80c4466026667f928cb77e1fb79f82b5386a1
Author: Vasilis Liaskovitis <vliaskovitis suse com>
Date:   Thu Jul 14 20:27:04 2022 +0200

    settings: Add new screenshare mode setting for the VNC backend
    
    By default, gnome-remote-desktop currently mirrors the primary monitor.
    Similarly to RDP, add a new gsetting, which allows choosing between
    remote desktop sessions, where the primary monitor is recorded and
    remote desktop sessions, which create and use a virtual monitor.
    The latter also allows the usage of gnome-remote-desktop, when no
    physical monitors are attached.
    
    Based on RDP virtual monitor commits by Pascal Nowack <Pascal Nowack gmx de>
    https://gitlab.gnome.org/GNOME/gnome-remote-desktop/-/merge_requests/69

 src/grd-enums.h                                    |  6 +++++
 src/grd-settings.c                                 | 28 ++++++++++++++++++++++
 src/grd-settings.h                                 |  2 ++
 ...org.gnome.desktop.remote-desktop.gschema.xml.in | 26 ++++++++++++++++++++
 4 files changed, 62 insertions(+)
---
diff --git a/src/grd-enums.h b/src/grd-enums.h
index e3ecc404..44b181d6 100644
--- a/src/grd-enums.h
+++ b/src/grd-enums.h
@@ -33,4 +33,10 @@ typedef enum
   GRD_VNC_AUTH_METHOD_PASSWORD
 } GrdVncAuthMethod;
 
+typedef enum
+{
+  GRD_VNC_SCREEN_SHARE_MODE_MIRROR_PRIMARY,
+  GRD_VNC_SCREEN_SHARE_MODE_EXTEND,
+} GrdVncScreenShareMode;
+
 #endif /* GRD_ENUMS_H */
diff --git a/src/grd-settings.c b/src/grd-settings.c
index dad5d570..f8f34021 100644
--- a/src/grd-settings.c
+++ b/src/grd-settings.c
@@ -43,6 +43,7 @@ enum
   VNC_VIEW_ONLY_CHANGED,
   VNC_AUTH_METHOD_CHANGED,
   VNC_ENCRYPTION_CHANGED,
+  VNC_SCREEN_SHARE_MODE_CHANGED,
 
   N_SIGNALS
 };
@@ -69,6 +70,7 @@ struct _GrdSettings
     gboolean view_only;
     GrdVncAuthMethod auth_method;
     int port;
+    GrdVncScreenShareMode screen_share_mode;
   } vnc;
 };
 
@@ -106,6 +108,12 @@ grd_settings_get_screen_share_mode (GrdSettings *settings)
   return settings->rdp.screen_share_mode;
 }
 
+GrdVncScreenShareMode
+grd_settings_get_vnc_screen_share_mode (GrdSettings *settings)
+{
+  return settings->vnc.screen_share_mode;
+}
+
 char *
 grd_settings_get_rdp_server_cert (GrdSettings *settings)
 {
@@ -266,6 +274,13 @@ update_screen_share_mode (GrdSettings *settings)
     g_settings_get_enum (settings->rdp.settings, "screen-share-mode");
 }
 
+static void
+update_vnc_screen_share_mode (GrdSettings *settings)
+{
+  settings->vnc.screen_share_mode =
+    g_settings_get_enum (settings->vnc.settings, "screen-share-mode");
+}
+
 static void
 update_rdp_enabled (GrdSettings *settings)
 {
@@ -359,6 +374,11 @@ on_vnc_settings_changed (GSettings   *vnc_settings,
       update_vnc_enabled (settings);
       g_signal_emit (settings, signals[VNC_ENABLED_CHANGED], 0);
     }
+  else if (strcmp (key, "screen-share-mode") == 0)
+    {
+      update_vnc_screen_share_mode (settings);
+      g_signal_emit (settings, signals[VNC_SCREEN_SHARE_MODE_CHANGED], 0);
+    }
   else if (strcmp (key, "view-only") == 0)
     {
       update_vnc_view_only (settings);
@@ -403,6 +423,7 @@ grd_settings_init (GrdSettings *settings)
   update_vnc_enabled (settings);
   update_vnc_view_only (settings);
   update_vnc_auth_method (settings);
+  update_vnc_screen_share_mode (settings);
 
   settings->rdp.port = GRD_RDP_SERVER_PORT;
   settings->vnc.port = GRD_VNC_SERVER_PORT;
@@ -471,4 +492,11 @@ grd_settings_class_init (GrdSettingsClass *klass)
                   0,
                   NULL, NULL, NULL,
                   G_TYPE_NONE, 0);
+  signals[VNC_SCREEN_SHARE_MODE_CHANGED] =
+    g_signal_new ("vnc-screen-share-mode-changed",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_LAST,
+                  0,
+                  NULL, NULL, NULL,
+                  G_TYPE_NONE, 0);
 }
diff --git a/src/grd-settings.h b/src/grd-settings.h
index 449894ae..a73e72de 100644
--- a/src/grd-settings.h
+++ b/src/grd-settings.h
@@ -65,4 +65,6 @@ gboolean grd_settings_get_vnc_view_only (GrdSettings *settings);
 
 GrdVncAuthMethod grd_settings_get_vnc_auth_method (GrdSettings *settings);
 
+GrdVncScreenShareMode grd_settings_get_vnc_screen_share_mode (GrdSettings *settings);
+
 #endif /* GRD_SETTINGS_H */
diff --git a/src/org.gnome.desktop.remote-desktop.gschema.xml.in 
b/src/org.gnome.desktop.remote-desktop.gschema.xml.in
index 6ea48754..b67d2491 100644
--- a/src/org.gnome.desktop.remote-desktop.gschema.xml.in
+++ b/src/org.gnome.desktop.remote-desktop.gschema.xml.in
@@ -90,5 +90,31 @@
          * password - by requiring the remote client to provide a known password
       </description>
     </key>
+    <key name='screen-share-mode' enum='org.gnome.desktop.remote-desktop.GrdVncScreenShareMode'>
+      <default>'mirror-primary'</default>
+      <summary>Screenshare mode of VNC connections</summary>
+      <description>
+        The screenshare mode specifies, whether the VNC backend mirrors the
+        primary screen, or whether a virtual monitor is created.
+
+        For the initial resolution of the virtual monitor, the VNC backend
+        uses a default size of 1920x1080 pixels.
+
+        When using a remote desktop session with a virtual monitor, clients can
+        resize the resolution of the virtual monitor during a session with the
+        setDesktopSize PDU.
+
+        Allowed screenshare modes include:
+
+         * mirror-primary - Record the primary monitor of the current user
+                            session.
+
+         * extend - Create a new virtual monitor and use it for the remote
+                    desktop session. The initial monitor resolution of this
+                    virtual monitor is set to 1920x1080 pixels. Clients can
+                    override the initial resolution with subsequent monitor
+                    configuration updates.
+      </description>
+    </key>
   </schema>
 </schemalist>