monitor-config-manager: Verify that logical monitors are adjecent

Logical monitors in a configuration must be adjecent to each other,
meaning there will be at least one pixel long side touching some other
logical monitor.

The exception to this is when there is only one logical monitor, which
cannot be adjecent to any other.

https://bugzilla.gnome.org/show_bug.cgi?id=777732

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

@@ -893,6 +893,34 @@ meta_verify_logical_monitor_config (MetaLogicalMonitorConfig *logical_monitor_co
   return TRUE;
 }
 
+static gboolean
+has_adjecent_neighbour (MetaMonitorsConfig       *config,
+                        MetaLogicalMonitorConfig *logical_monitor_config)
+{
+  GList *l;
+
+  if (!config->logical_monitor_configs->next)
+    {
+      g_assert (config->logical_monitor_configs->data ==
+                logical_monitor_config);
+      return TRUE;
+    }
+
+  for (l = config->logical_monitor_configs; l; l = l->next)
+    {
+      MetaLogicalMonitorConfig *other_logical_monitor_config = l->data;
+
+      if (logical_monitor_config == other_logical_monitor_config)
+        continue;
+
+      if (meta_rectangle_is_adjecent_to (&logical_monitor_config->layout,
+                                         &other_logical_monitor_config->layout))
+        return TRUE;
+    }
+
+  return FALSE;
+}
+
 gboolean
 meta_verify_monitors_config (MetaMonitorsConfig *config,
                              GError            **error)
@@ -935,6 +963,13 @@ meta_verify_monitors_config (MetaMonitorsConfig *config,
           has_primary = TRUE;
         }
 
+      if (!has_adjecent_neighbour (config, logical_monitor_config))
+        {
+          g_set_error (error, G_IO_ERROR, G_IO_ERROR_FAILED,
+                       "Logical monitors not adjecent");
+          return FALSE;
+        }
+
       region = g_list_prepend (region, &logical_monitor_config->layout);
     }
 

src/core/boxes-private.h

@@ -215,4 +215,7 @@ GList* meta_rectangle_find_nonintersected_monitor_edges (
                                            const GList         *monitor_rects,
                                            const GSList        *all_struts);
 
+gboolean meta_rectangle_is_adjecent_to (MetaRectangle *rect,
+                                        MetaRectangle *other);
+
 #endif /* META_BOXES_PRIVATE_H */

src/core/boxes.c

@@ -2013,3 +2013,26 @@ meta_rectangle_find_nonintersected_monitor_edges (
 
   return ret;
 }
+
+gboolean
+meta_rectangle_is_adjecent_to (MetaRectangle *rect,
+                               MetaRectangle *other)
+{
+  int rect_x1 = rect->x;
+  int rect_y1 = rect->y;
+  int rect_x2 = rect->x + rect->width;
+  int rect_y2 = rect->y + rect->height;
+  int other_x1 = other->x;
+  int other_y1 = other->y;
+  int other_x2 = other->x + other->width;
+  int other_y2 = other->y + other->height;
+
+  if ((rect_x1 == other_x2 || rect_x2 == other_x1) &&
+      !(rect_y2 <= other_y1 || rect_y1 >= other_y2))
+    return TRUE;
+  else if ((rect_y1 == other_y2 || rect_y2 == other_y1) &&
+           !(rect_x2 <= other_x1 || rect_x1 >= other_x2))
+    return TRUE;
+  else
+    return FALSE;
+}

src/tests/unit-tests.c

@@ -26,6 +26,7 @@
 #include <meta/util.h>
 
 #include "compositor/meta-plugin-manager.h"
+#include "core/boxes-private.h"
 #include "core/main-private.h"
 #include "tests/meta-backend-test.h"
 #include "tests/monitor-unit-tests.h"
@@ -180,6 +181,36 @@ meta_test_util_later_schedule_from_later (void)
   g_assert_cmpint (data.state, ==, META_TEST_LATER_FINISHED);
 }
 
+static void
+meta_test_adjecent_to (void)
+{
+  MetaRectangle base = { .x = 10, .y = 10, .width = 10, .height = 10 };
+  MetaRectangle adjecent[] = {
+    { .x = 20, .y = 10, .width = 10, .height = 10 },
+    { .x = 0, .y = 10, .width = 10, .height = 10 },
+    { .x = 0, .y = 1, .width = 10, .height = 10 },
+    { .x = 20, .y = 19, .width = 10, .height = 10 },
+    { .x = 10, .y = 20, .width = 10, .height = 10 },
+    { .x = 10, .y = 0, .width = 10, .height = 10 },
+  };
+  MetaRectangle not_adjecent[] = {
+    { .x = 0, .y = 0, .width = 10, .height = 10 },
+    { .x = 20, .y = 20, .width = 10, .height = 10 },
+    { .x = 21, .y = 10, .width = 10, .height = 10 },
+    { .x = 10, .y = 21, .width = 10, .height = 10 },
+    { .x = 10, .y = 5, .width = 10, .height = 10 },
+    { .x = 11, .y = 10, .width = 10, .height = 10 },
+    { .x = 19, .y = 10, .width = 10, .height = 10 },
+  };
+  unsigned int i;
+
+  for (i = 0; i < G_N_ELEMENTS (adjecent); i++)
+    g_assert (meta_rectangle_is_adjecent_to (&base, &adjecent[i]));
+
+  for (i = 0; i < G_N_ELEMENTS (not_adjecent); i++)
+    g_assert (!meta_rectangle_is_adjecent_to (&base, &not_adjecent[i]));
+}
+
 static gboolean
 run_tests (gpointer data)
 {
@@ -202,6 +233,8 @@ init_tests (int argc, char **argv)
   g_test_add_func ("/util/meta-later/schedule-from-later",
                    meta_test_util_later_schedule_from_later);
 
+  g_test_add_func ("/core/boxes/adjecent-to", meta_test_adjecent_to);
+
   init_monitor_store_tests ();
   init_monitor_tests ();
 }