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

[Jonas Ådahl <jadahl src gnome org>]

commit f267ca08f04749d26388b4b49e13c99bd94851b8
Author: Pascal Nowack <Pascal Nowack gmx de>
Date:   Wed Nov 24 08:55:11 2021 +0100

    settings: Add new screenshare mode setting for the RDP backend
    
    Implementing support for virtual monitors should be done without
    regressions.
    By default, gnome-remote-desktop currently mirrors the primary monitor.
    For now, this behaviour should be preserved.
    In order to be able to use virtual monitor in a remote desktop session,
    a switch is needed.
    
    So, 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.

 src/grd-enums.h                                    |  6 +++++
 src/grd-settings.c                                 | 29 ++++++++++++++++++++++
 src/grd-settings.h                                 |  2 ++
 ...org.gnome.desktop.remote-desktop.gschema.xml.in | 27 ++++++++++++++++++++
 4 files changed, 64 insertions(+)
---
diff --git a/src/grd-enums.h b/src/grd-enums.h
index ffab8212..e3ecc404 100644
--- a/src/grd-enums.h
+++ b/src/grd-enums.h
@@ -21,6 +21,12 @@
 #ifndef GRD_ENUMS_H
 #define GRD_ENUMS_H
 
+typedef enum
+{
+  GRD_RDP_SCREEN_SHARE_MODE_MIRROR_PRIMARY,
+  GRD_RDP_SCREEN_SHARE_MODE_EXTEND,
+} GrdRdpScreenShareMode;
+
 typedef enum
 {
   GRD_VNC_AUTH_METHOD_PROMPT,
diff --git a/src/grd-settings.c b/src/grd-settings.c
index 4560a375..6d0d157f 100644
--- a/src/grd-settings.c
+++ b/src/grd-settings.c
@@ -32,6 +32,7 @@
 
 enum
 {
+  RDP_SCREEN_SHARE_MODE_CHANGED,
   RDP_SERVER_CERT_CHANGED,
   RDP_SERVER_KEY_CHANGED,
   RDP_VIEW_ONLY_CHANGED,
@@ -50,6 +51,8 @@ struct _GrdSettings
 
   struct {
     GSettings *settings;
+
+    GrdRdpScreenShareMode screen_share_mode;
     char *server_cert;
     char *server_key;
     gboolean view_only;
@@ -121,6 +124,12 @@ grd_settings_override_vnc_port (GrdSettings *settings,
   settings->vnc.port = port;
 }
 
+GrdRdpScreenShareMode
+grd_settings_get_screen_share_mode (GrdSettings *settings)
+{
+  return settings->rdp.screen_share_mode;
+}
+
 char *
 grd_settings_get_rdp_server_cert (GrdSettings *settings)
 {
@@ -248,6 +257,13 @@ grd_settings_get_vnc_auth_method (GrdSettings *settings)
     return settings->vnc.auth_method;
 }
 
+static void
+update_screen_share_mode (GrdSettings *settings)
+{
+  settings->rdp.screen_share_mode =
+    g_settings_get_enum (settings->rdp.settings, "screen-share-mode");
+}
+
 static void
 update_rdp_tls_cert (GrdSettings *settings)
 {
@@ -290,6 +306,11 @@ on_rdp_settings_changed (GSettings   *rdp_settings,
                          const char  *key,
                          GrdSettings *settings)
 {
+  if (strcmp (key, "screen-share-mode") == 0)
+    {
+      update_screen_share_mode (settings);
+      g_signal_emit (settings, signals[RDP_SCREEN_SHARE_MODE_CHANGED], 0);
+    }
   if (strcmp (key, "tls-cert") == 0)
     {
       update_rdp_tls_cert (settings);
@@ -348,6 +369,7 @@ grd_settings_init (GrdSettings *settings)
   g_signal_connect (settings->vnc.settings, "changed",
                     G_CALLBACK (on_vnc_settings_changed), settings);
 
+  update_screen_share_mode (settings);
   update_rdp_tls_cert (settings);
   update_rdp_tls_key (settings);
   update_rdp_view_only (settings);
@@ -365,6 +387,13 @@ grd_settings_class_init (GrdSettingsClass *klass)
 
   object_class->finalize = grd_settings_finalize;
 
+  signals[RDP_SCREEN_SHARE_MODE_CHANGED] =
+    g_signal_new ("rdp-screen-share-mode-changed",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_LAST,
+                  0,
+                  NULL, NULL, NULL,
+                  G_TYPE_NONE, 0);
   signals[RDP_SERVER_CERT_CHANGED] =
     g_signal_new ("rdp-tls-cert-changed",
                   G_TYPE_FROM_CLASS (klass),
diff --git a/src/grd-settings.h b/src/grd-settings.h
index e12e47ed..528167fa 100644
--- a/src/grd-settings.h
+++ b/src/grd-settings.h
@@ -45,6 +45,8 @@ void grd_settings_override_rdp_port (GrdSettings *settings,
 void grd_settings_override_vnc_port (GrdSettings *settings,
                                      int          port);
 
+GrdRdpScreenShareMode grd_settings_get_screen_share_mode (GrdSettings *settings);
+
 char * grd_settings_get_rdp_server_cert (GrdSettings *settings);
 
 char * grd_settings_get_rdp_server_key (GrdSettings *settings);
diff --git a/src/org.gnome.desktop.remote-desktop.gschema.xml.in 
b/src/org.gnome.desktop.remote-desktop.gschema.xml.in
index 0779c8c6..e61e6bc5 100644
--- a/src/org.gnome.desktop.remote-desktop.gschema.xml.in
+++ b/src/org.gnome.desktop.remote-desktop.gschema.xml.in
@@ -2,6 +2,33 @@
   <schema id='org.gnome.desktop.remote-desktop' path='/org/gnome/desktop/remote-desktop/'>
   </schema>
   <schema id='org.gnome.desktop.remote-desktop.rdp' path='/org/gnome/desktop/remote-desktop/rdp/'>
+    <key name='screen-share-mode' enum='org.gnome.desktop.remote-desktop.GrdRdpScreenShareMode'>
+      <default>'mirror-primary'</default>
+      <summary>Screenshare mode of RDP connections</summary>
+      <description>
+        The screenshare mode specifies, whether the RDP backend mirrors the
+        primary screen, or whether a virtual monitor is created.
+
+        For the initial resolution of the virtual monitor, the RDP backend uses
+        either the client core data ([MS-RDPBCGR] 2.2.1.3.2) or the client
+        monitor data ([MS-RDPBCGR] 2.2.1.3.6), depending on what is available.
+
+        When using a remote desktop session with a virtual monitor, clients can
+        resize the resolution of the virtual monitor during a session with the
+        Display Control Channel Extension ([MS-RDPEDISP]).
+
+        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 resolution of this virtual monitor is derived from the
+                    monitor configuration, submitted by the remote desktop
+                    client.
+      </description>
+    </key>
     <key name='tls-cert' type='s'>
       <default>''</default>
       <summary>Path to the certificate file</summary>