monitor-config-manager: Use single filter function to build configs

Add a find_monitors function that allows to search for monitors that match
the MonitorMatchRule filter and use this to look for the primary monitor and
the other monitors that need to match the requested filter in order to be
configured.

Having just one function doing this kind of checks reduces the possibility
of unexpected results.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/522>

src/backends/meta-monitor-config-manager.c

@@ -542,19 +542,76 @@ meta_monitor_config_manager_get_stored (MetaMonitorConfigManager *config_manager
 typedef enum _MonitorMatchRule
 {
   MONITOR_MATCH_ALL = 0,
-  MONITOR_MATCH_EXTERNAL = (1 << 0)
+  MONITOR_MATCH_EXTERNAL = (1 << 0),
+  MONITOR_MATCH_BUILTIN = (1 << 1),
+  MONITOR_MATCH_VISIBLE = (1 << 2),
+  MONITOR_MATCH_WITH_SUGGESTED_POSITION = (1 << 3),
 } MonitorMatchRule;
 
+static gboolean
+monitor_matches_rule (MetaMonitor        *monitor,
+                      MetaMonitorManager *monitor_manager,
+                      MonitorMatchRule    match_rule)
+{
+  if (!monitor)
+    return FALSE;
+
+  if (match_rule & MONITOR_MATCH_BUILTIN)
+    {
+      if (!meta_monitor_is_laptop_panel (monitor))
+        return FALSE;
+    }
+  else if (match_rule & MONITOR_MATCH_EXTERNAL)
+    {
+      if (meta_monitor_is_laptop_panel (monitor))
+        return FALSE;
+    }
+
+  if (match_rule & MONITOR_MATCH_VISIBLE)
+    {
+      if (meta_monitor_is_laptop_panel (monitor) &&
+          is_lid_closed (monitor_manager))
+        return FALSE;
+    }
+
+  if (match_rule & MONITOR_MATCH_WITH_SUGGESTED_POSITION)
+    {
+      if (!meta_monitor_get_suggested_position (monitor, NULL, NULL))
+        return FALSE;
+    }
+
+  return TRUE;
+}
+
+static GList *
+find_monitors (MetaMonitorManager *monitor_manager,
+               MonitorMatchRule    match_rule)
+{
+  GList *result = NULL;
+  GList *monitors, *l;
+
+  monitors = meta_monitor_manager_get_monitors (monitor_manager);
+  for (l = g_list_last (monitors); l; l = l->prev)
+    {
+      MetaMonitor *monitor = l->data;
+
+      if (monitor_matches_rule (monitor, monitor_manager, match_rule))
+        result = g_list_prepend (result, monitor);
+    }
+
+  return result;
+}
+
 static MetaMonitor *
 find_monitor_with_highest_preferred_resolution (MetaMonitorManager *monitor_manager,
                                                 MonitorMatchRule    match_rule)
 {
-  GList *monitors;
+  g_autoptr (GList) monitors = NULL;
   GList *l;
   int largest_area = 0;
   MetaMonitor *largest_monitor = NULL;
 
-  monitors = meta_monitor_manager_get_monitors (monitor_manager);
+  monitors = find_monitors (monitor_manager, match_rule);
   for (l = monitors; l; l = l->next)
     {
       MetaMonitor *monitor = l->data;
@@ -562,12 +619,6 @@ find_monitor_with_highest_preferred_resolution (MetaMonitorManager *monitor_mana
       int width, height;
       int area;
 
-      if (match_rule & MONITOR_MATCH_EXTERNAL)
-        {
-          if (meta_monitor_is_laptop_panel (monitor))
-            continue;
-        }
-
       mode = meta_monitor_get_preferred_mode (monitor);
       meta_monitor_mode_get_resolution (mode, &width, &height);
       area = width * height;
@@ -593,38 +644,28 @@ find_monitor_with_highest_preferred_resolution (MetaMonitorManager *monitor_mana
  * alternatives, except if no other alternatives exist.
  */
 static MetaMonitor *
-find_primary_monitor (MetaMonitorManager *monitor_manager)
+find_primary_monitor (MetaMonitorManager *monitor_manager,
+                      MonitorMatchRule    match_rule)
 {
   MetaMonitor *monitor;
 
-  if (is_lid_closed (monitor_manager))
+  match_rule |= MONITOR_MATCH_VISIBLE;
-    {
-      monitor = meta_monitor_manager_get_primary_monitor (monitor_manager);
-      if (monitor && !meta_monitor_is_laptop_panel (monitor))
-        return monitor;
 
-      monitor =
+  monitor = meta_monitor_manager_get_primary_monitor (monitor_manager);
-        find_monitor_with_highest_preferred_resolution (monitor_manager,
+  if (monitor_matches_rule (monitor, monitor_manager, match_rule))
-                                                        MONITOR_MATCH_EXTERNAL);
+    return monitor;
-      if (monitor)
-        return monitor;
 
-      return find_monitor_with_highest_preferred_resolution (monitor_manager,
+  monitor = meta_monitor_manager_get_laptop_panel (monitor_manager);
-                                                             MONITOR_MATCH_ALL);
+  if (monitor_matches_rule (monitor, monitor_manager, match_rule))
-    }
+    return monitor;
-  else
-    {
-      monitor = meta_monitor_manager_get_primary_monitor (monitor_manager);
-      if (monitor)
-        return monitor;
 
-      monitor = meta_monitor_manager_get_laptop_panel (monitor_manager);
+  monitor = find_monitor_with_highest_preferred_resolution (monitor_manager,
-      if (monitor)
+                                                            match_rule);
-        return monitor;
+  if (monitor)
+    return monitor;
 
-      return find_monitor_with_highest_preferred_resolution (monitor_manager,
+  return find_monitor_with_highest_preferred_resolution (monitor_manager,
-                                                             MONITOR_MATCH_ALL);
+                                                         MONITOR_MATCH_ALL);
-    }
 }
 
 static MetaMonitorConfig *
@@ -744,20 +785,22 @@ MetaMonitorsConfig *
 meta_monitor_config_manager_create_linear (MetaMonitorConfigManager *config_manager)
 {
   MetaMonitorManager *monitor_manager = config_manager->monitor_manager;
+  g_autoptr (GList) monitors = NULL;
   GList *logical_monitor_configs;
   MetaMonitor *primary_monitor;
   MetaLogicalMonitorLayoutMode layout_mode;
   MetaLogicalMonitorConfig *primary_logical_monitor_config;
   int x;
-  GList *monitors;
   GList *l;
   MetaMonitorsConfig *monitors_config;
 
-  primary_monitor = find_primary_monitor (monitor_manager);
+  primary_monitor = find_primary_monitor (monitor_manager,
+                                          MONITOR_MATCH_VISIBLE);
   if (!primary_monitor)
     return NULL;
 
   layout_mode = meta_monitor_manager_get_default_layout_mode (monitor_manager);
+  monitors = find_monitors (monitor_manager, MONITOR_MATCH_VISIBLE);
 
   primary_logical_monitor_config =
     create_preferred_logical_monitor_config (monitor_manager,
@@ -770,7 +813,6 @@ meta_monitor_config_manager_create_linear (MetaMonitorConfigManager *config_mana
                                            primary_logical_monitor_config);
 
   x = primary_logical_monitor_config->layout.width;
-  monitors = meta_monitor_manager_get_monitors (monitor_manager);
   for (l = monitors; l; l = l->next)
     {
       MetaMonitor *monitor = l->data;
@@ -779,10 +821,6 @@ meta_monitor_config_manager_create_linear (MetaMonitorConfigManager *config_mana
       if (monitor == primary_monitor)
         continue;
 
-      if (meta_monitor_is_laptop_panel (monitor) &&
-          is_lid_closed (monitor_manager))
-        continue;
-
       logical_monitor_config =
         create_preferred_logical_monitor_config (monitor_manager,
                                                  monitor,
@@ -815,7 +853,7 @@ meta_monitor_config_manager_create_fallback (MetaMonitorConfigManager *config_ma
   MetaLogicalMonitorLayoutMode layout_mode;
   MetaLogicalMonitorConfig *primary_logical_monitor_config;
 
-  primary_monitor = find_primary_monitor (monitor_manager);
+  primary_monitor = find_primary_monitor (monitor_manager, MONITOR_MATCH_ALL);
   if (!primary_monitor)
     return NULL;
 
@@ -842,21 +880,24 @@ meta_monitor_config_manager_create_suggested (MetaMonitorConfigManager *config_m
 {
   MetaMonitorManager *monitor_manager = config_manager->monitor_manager;
   MetaLogicalMonitorConfig *primary_logical_monitor_config = NULL;
+  g_autoptr (GList) monitors = NULL;
   MetaMonitor *primary_monitor;
   MetaLogicalMonitorLayoutMode layout_mode;
   GList *logical_monitor_configs;
   GList *region;
-  int x, y;
-  GList *monitors;
   GList *l;
+  int x, y;
 
-  primary_monitor = find_primary_monitor (monitor_manager);
+  primary_monitor = find_primary_monitor (monitor_manager,
+                                          MONITOR_MATCH_WITH_SUGGESTED_POSITION);
   if (!primary_monitor)
     return NULL;
 
   if (!meta_monitor_get_suggested_position (primary_monitor, &x, &y))
     return NULL;
 
+  monitors = find_monitors (monitor_manager,
+                            MONITOR_MATCH_WITH_SUGGESTED_POSITION);
   layout_mode = meta_monitor_manager_get_default_layout_mode (monitor_manager);
 
   primary_logical_monitor_config =
@@ -870,7 +911,6 @@ meta_monitor_config_manager_create_suggested (MetaMonitorConfigManager *config_m
                                            primary_logical_monitor_config);
   region = g_list_prepend (NULL, &primary_logical_monitor_config->layout);
 
-  monitors = meta_monitor_manager_get_monitors (monitor_manager);
   for (l = monitors; l; l = l->next)
     {
       MetaMonitor *monitor = l->data;
@@ -879,8 +919,7 @@ meta_monitor_config_manager_create_suggested (MetaMonitorConfigManager *config_m
       if (monitor == primary_monitor)
         continue;
 
-      if (!meta_monitor_get_suggested_position (monitor, &x, &y))
+      meta_monitor_get_suggested_position (monitor, &x, &y);
-        continue;
 
       logical_monitor_config =
         create_preferred_logical_monitor_config (monitor_manager,
@@ -1211,24 +1250,21 @@ static MetaMonitorsConfig *
 create_for_switch_config_external (MetaMonitorConfigManager *config_manager)
 {
   MetaMonitorManager *monitor_manager = config_manager->monitor_manager;
+  g_autoptr (GList) monitors = NULL;
   GList *logical_monitor_configs = NULL;
   int x = 0;
   MetaLogicalMonitorLayoutMode layout_mode;
-  GList *monitors;
   GList *l;
   MetaMonitorsConfig *monitors_config;
 
+  monitors = find_monitors (monitor_manager, MONITOR_MATCH_EXTERNAL);
   layout_mode = meta_monitor_manager_get_default_layout_mode (monitor_manager);
 
-  monitors = meta_monitor_manager_get_monitors (monitor_manager);
   for (l = monitors; l; l = l->next)
     {
       MetaMonitor *monitor = l->data;
       MetaLogicalMonitorConfig *logical_monitor_config;
 
-      if (meta_monitor_is_laptop_panel (monitor))
-        continue;
-
       logical_monitor_config =
         create_preferred_logical_monitor_config (monitor_manager,
                                                  monitor,