compositor: Introduce tile picker API

Plugins might want to know when they should show
a tile picker UI and, since we control the tiling
state from the window manager side, we just need
to tell the compositor when they should do that.

This commit adds the necessary plumbing to let the
compositor and plugins know when a tile picker should
be shown.

src/compositor/compositor.c

@@ -1456,6 +1456,14 @@ meta_compositor_hide_tile_preview (MetaCompositor *compositor)
   meta_plugin_manager_hide_tile_preview (compositor->plugin_mgr);
 }
 
+void
+meta_compositor_show_tile_picker (MetaCompositor *compositor,
+                                  MetaWindow     *window,
+                                  int             tile_monitor_number)
+{
+  meta_plugin_manager_show_tile_picker (compositor->plugin_mgr, window, tile_monitor_number);
+}
+
 void
 meta_compositor_show_window_menu (MetaCompositor     *compositor,
                                   MetaWindow         *window,

src/compositor/meta-plugin-manager.c

@@ -404,3 +404,24 @@ meta_plugin_manager_create_inhibit_shortcuts_dialog (MetaPluginManager *plugin_m
 
   return meta_inhibit_shortcuts_dialog_default_new (window);
 }
+
+gboolean
+meta_plugin_manager_show_tile_picker (MetaPluginManager *plugin_mgr,
+                                      MetaWindow        *window,
+                                      int                tile_monitor_number)
+{
+  MetaPlugin *plugin = plugin_mgr->plugin;
+  MetaPluginClass *klass = META_PLUGIN_GET_CLASS (plugin);
+  MetaDisplay *display = plugin_mgr->compositor->display;
+
+  if (display->display_opening)
+    return FALSE;
+
+  if (klass->show_tile_picker)
+    {
+      klass->show_tile_picker (plugin, window, tile_monitor_number);
+      return TRUE;
+    }
+
+  return FALSE;
+}

src/compositor/meta-plugin-manager.h

@@ -98,4 +98,9 @@ MetaInhibitShortcutsDialog *
   meta_plugin_manager_create_inhibit_shortcuts_dialog (MetaPluginManager *plugin_mgr,
                                                        MetaWindow        *window);
 
+gboolean meta_plugin_manager_show_tile_picker (MetaPluginManager *plugin_mgr,
+                                               MetaWindow        *window,
+                                               int                tile_monitor_number);
+
+
 #endif

src/core/window.c

@@ -3153,6 +3153,12 @@ meta_window_tile (MetaWindow   *window,
   if (window->frame)
     meta_frame_queue_draw (window->frame);
 
+  /* If the window doesn't have a tile match after being tiled, ask the
+   * compositor to show the tile picker.
+   */
+  if (META_WINDOW_TILED_SIDE_BY_SIDE (window) && !window->tile_match)
+    meta_compositor_show_tile_picker (window->display->compositor, window, window->monitor->number);
+
 out:
   if (should_notify)
     g_object_notify_by_pspec (G_OBJECT (window), obj_props[PROP_TILE_MODE]);

src/meta/compositor.h

@@ -122,6 +122,10 @@ void meta_compositor_show_tile_preview (MetaCompositor *compositor,
                                         MetaRectangle  *tile_rect,
                                         int             tile_monitor_number);
 void meta_compositor_hide_tile_preview (MetaCompositor *compositor);
+void meta_compositor_show_tile_picker  (MetaCompositor *compositor,
+                                        MetaWindow     *window,
+                                        int             tile_monitor_number);
+
 void meta_compositor_show_window_menu (MetaCompositor     *compositor,
                                        MetaWindow         *window,
 				       MetaWindowMenuType  menu,

src/meta/meta-plugin.h

@@ -251,6 +251,14 @@ struct _MetaPluginClass
    */
   MetaInhibitShortcutsDialog * (* create_inhibit_shortcuts_dialog) (MetaPlugin *plugin,
                                                                     MetaWindow *window);
+
+  /**
+   * MetaPluginClass::show_tile_picker:
+   *
+   */
+  void * (* show_tile_picker) (MetaPlugin *plugin,
+                               MetaWindow *window,
+                               int         tile_monitor_number);
 };
 
 /**