MetaWayland: don't destroy the output list, emit the right events instead

Destroying the output list causes toolkits to believe that all
monitors were unplugged, which then causes assertions in code
that have outside knowledge of this not having happened (like
in code using GnomeRR DBus API).

src/wayland/meta-wayland-private.h

@@ -130,7 +130,7 @@ typedef struct
 
 struct _MetaWaylandCompositor
 {
-  GList *outputs;
+  GHashTable *outputs;
 
   struct wl_display *wayland_display;
   struct wl_event_loop *wayland_loop;

src/wayland/meta-wayland.c

@@ -630,16 +630,40 @@ meta_wayland_compositor_create_region (struct wl_client *wayland_client,
   region->region = cairo_region_create ();
 }
 
+typedef struct {
+  MetaOutput               *output;
+  struct wl_global         *global;
+  int                       x, y;
+  enum wl_output_transform  transform;
+
+  GList                    *resources;
+} MetaWaylandOutput;
+
+static void
+output_resource_destroy (struct wl_resource *res)
+{
+  MetaWaylandOutput *wayland_output;
+
+  wayland_output = wl_resource_get_user_data (res);
+  wayland_output->resources = g_list_remove (wayland_output->resources, res);
+}
+
 static void
 bind_output (struct wl_client *client,
              void *data,
              guint32 version,
              guint32 id)
 {
-  MetaOutput *output = data;
+  MetaWaylandOutput *wayland_output = data;
+  MetaOutput *output = wayland_output->output;
   struct wl_resource *resource;
+  guint mode_flags;
 
   resource = wl_resource_create (client, &wl_output_interface, version, id);
+  wayland_output->resources = g_list_prepend (wayland_output->resources, resource);
+
+  wl_resource_set_user_data (resource, wayland_output);
+  wl_resource_set_destructor (resource, output_resource_destroy);
 
   meta_verbose ("Binding output %p/%s (%u, %u, %u, %u) x %f\n",
 		output, output->name,
@@ -660,9 +684,13 @@ bind_output (struct wl_client *client,
 			  output->product,
 			  output->crtc->transform);
 
+  mode_flags = WL_OUTPUT_MODE_CURRENT;
+  if (output->crtc->current_mode == output->preferred_mode)
+    mode_flags |= WL_OUTPUT_MODE_PREFERRED;
+
   wl_resource_post_event (resource,
 			  WL_OUTPUT_MODE,
-			  WL_OUTPUT_MODE_PREFERRED | WL_OUTPUT_MODE_CURRENT,
+			  mode_flags,
 			  (int)output->crtc->rect.width,
 			  (int)output->crtc->rect.height,
 			  (int)output->crtc->current_mode->refresh_rate);
@@ -673,29 +701,111 @@ bind_output (struct wl_client *client,
 }
 
 static void
-meta_wayland_compositor_create_outputs (MetaWaylandCompositor *compositor,
+wayland_output_destroy_notify (gpointer data)
+{
+  MetaWaylandOutput *wayland_output = data;
+  GList *resources;
+
+  /* Make sure the destructors don't mess with the list */
+  resources = wayland_output->resources;
+  wayland_output->resources = NULL;
+
+  wl_global_destroy (wayland_output->global);
+  g_list_free (resources);
+
+  g_slice_free (MetaWaylandOutput, wayland_output);
+}
+
+static void
+wayland_output_update_for_output (MetaWaylandOutput *wayland_output,
+				  MetaOutput        *output)
+{
+  GList *iter;
+  guint mode_flags;
+
+  mode_flags = WL_OUTPUT_MODE_CURRENT;
+  if (output->crtc->current_mode == output->preferred_mode)
+    mode_flags |= WL_OUTPUT_MODE_PREFERRED;
+
+  for (iter = wayland_output->resources; iter; iter = iter->next)
+    {
+      struct wl_resource *resource = iter->data;
+
+      if (wayland_output->x != output->crtc->rect.x ||
+	  wayland_output->y != output->crtc->rect.y ||
+	  wayland_output->transform != output->crtc->transform)
+	{
+	    wl_resource_post_event (resource,
+				    WL_OUTPUT_GEOMETRY,
+				    (int)output->crtc->rect.x,
+				    (int)output->crtc->rect.y,
+				    output->width_mm,
+				    output->height_mm,
+				    output->subpixel_order,
+				    output->vendor,
+				    output->product,
+				    output->crtc->transform);
+	}
+
+      wl_resource_post_event (resource,
+			      WL_OUTPUT_MODE,
+			      mode_flags,
+			      (int)output->crtc->rect.width,
+			      (int)output->crtc->rect.height,
+			      (int)output->crtc->current_mode->refresh_rate);
+    }
+
+  /* It's very important that we change the output pointer here, as
+     the old structure is about to be freed by MetaMonitorManager */
+  wayland_output->output = output;
+  wayland_output->x = output->crtc->rect.x;
+  wayland_output->y = output->crtc->rect.y;
+  wayland_output->transform = output->crtc->transform;
+}
+
+static GHashTable *
+meta_wayland_compositor_update_outputs (MetaWaylandCompositor *compositor,
 					MetaMonitorManager    *monitors)
 {
   MetaOutput *outputs;
   unsigned int i, n_outputs;
+  GHashTable *new_table;
 
   outputs = meta_monitor_manager_get_outputs (monitors, &n_outputs);
+  new_table = g_hash_table_new_full (NULL, NULL, NULL, wayland_output_destroy_notify);
 
   for (i = 0; i < n_outputs; i++)
     {
       MetaOutput *output = &outputs[i];
-      struct wl_global *global;
+      MetaWaylandOutput *wayland_output;
 
       /* wayland does not expose disabled outputs */
       if (output->crtc == NULL)
+	{
+	  g_hash_table_remove (compositor->outputs, GSIZE_TO_POINTER (output->output_id));
 	  continue;
-
-      global = wl_global_create (compositor->wayland_display,
-				 &wl_output_interface, 2,
-				 output, bind_output);
-      compositor->outputs = g_list_prepend (compositor->outputs, global);
 	}
 
+      wayland_output = g_hash_table_lookup (compositor->outputs, GSIZE_TO_POINTER (output->output_id));
+
+      if (wayland_output)
+	{
+	  g_hash_table_steal (compositor->outputs, GSIZE_TO_POINTER (output->output_id));
+	}
+      else
+	{
+	  wayland_output = g_slice_new0 (MetaWaylandOutput);
+	  wayland_output->global = wl_global_create (compositor->wayland_display,
+						     &wl_output_interface, 2,
+						     wayland_output, bind_output);
+	}
+
+      wayland_output_update_for_output (wayland_output, output);
+      g_hash_table_insert (new_table, GSIZE_TO_POINTER (output->output_id), wayland_output);
+    }
+
+  g_hash_table_destroy (compositor->outputs);
+  return new_table;
 }
 
 const static struct wl_compositor_interface meta_wayland_compositor_interface = {
@@ -1438,9 +1548,7 @@ static void
 on_monitors_changed (MetaMonitorManager    *monitors,
 		     MetaWaylandCompositor *compositor)
 {
-  g_list_free_full (compositor->outputs, (GDestroyNotify) wl_global_destroy);
+  compositor->outputs = meta_wayland_compositor_update_outputs (compositor, monitors);
-  compositor->outputs = NULL;
-  meta_wayland_compositor_create_outputs (compositor, monitors);
 }
 
 void
@@ -1553,7 +1661,9 @@ meta_wayland_init (void)
   monitors = meta_monitor_manager_get ();
   g_signal_connect (monitors, "monitors-changed",
 		    G_CALLBACK (on_monitors_changed), compositor);
-  meta_wayland_compositor_create_outputs (compositor, monitors);
+
+  compositor->outputs = g_hash_table_new_full (NULL, NULL, NULL, wayland_output_destroy_notify);
+  compositor->outputs = meta_wayland_compositor_update_outputs (compositor, monitors);
 
   compositor->stage = meta_wayland_stage_new ();