xrandr: Handle hotplug_mode_update for VM guest resizingHEADmaster

When an output has the hotplug_mode_update property (e.g. SPICE/QXL
virtual displays), auto-configure to the new preferred mode on hotplug
events instead of applying stored configuration from monitors.xml.

This allows VM guest resolutions to follow host window resizes, which
stopped working when spice-vdagent switched from reconfiguring displays
directly to sending hotplug events expecting the DE to handle them.

Fixes #78

1 files changed, 34 insertions, 0 deletions

diff --git a/plugins/xrandr/msd-xrandr-manager.c b/plugins/xrandr/msd-xrandr-manager.c
index 78e538f..4402fd9 100644
--- a/plugins/xrandr/msd-xrandr-manager.c
+++ b/plugins/xrandr/msd-xrandr-manager.c
@@ -1572,6 +1572,22 @@ apply_color_profiles (void)
         }
 }
 
+static gboolean
+has_hotplug_mode_update (MateRRScreen *screen)
+{
+        MateRROutput **outputs;
+        int i;
+
+        outputs = mate_rr_screen_list_outputs (screen);
+
+        for (i = 0; outputs[i] != NULL; i++) {
+                if (mate_rr_output_get_hotplug_mode_update (outputs[i]))
+                        return TRUE;
+        }
+
+        return FALSE;
+}
+
 static void
 on_randr_event (MateRRScreen *screen, gpointer data)
 {
@@ -1600,6 +1616,24 @@ on_randr_event (MateRRScreen *screen, gpointer data)
                  */
                 show_timestamps_dialog (manager, "ignoring since change > config");
                 log_msg ("  Ignoring event since change >= config\n");
+        } else if (has_hotplug_mode_update (screen)) {
+                /* An output has the hotplug_mode_update property, which
+                 * means that the driver is requesting that the desktop
+                 * environment apply a new preferred mode on hotplug events
+                 * to handle dynamic guest resizing (e.g. SPICE/QXL in VMs).
+                 *
+                 * In this case, always auto-configure to use the new
+                 * preferred mode rather than applying stored configurations.
+                 */
+
+                show_timestamps_dialog (manager, "hotplug_mode_update detected, auto-configuring");
+
+                if (config_timestamp != priv->last_config_timestamp) {
+                        priv->last_config_timestamp = config_timestamp;
+                        auto_configure_outputs (manager, config_timestamp);
+                        log_msg ("  Automatically configured outputs for hotplug_mode_update\n");
+                } else
+                        log_msg ("  Ignored hotplug_mode_update event as timestamps are the same\n");
         } else {
                 /* Here, config_timestamp > change_timestamp.  This means that
                  * the screen got reconfigured because of hotplug/unplug; the X