UI: Clock on Desktop (#2891)

* Clock on desktop
* Gui: gui_active_view_port_count
* Gui: move gui_active_view_port_count to private header, update docs
* Desktop: simplify desktop clock code
* Desktop: refactor clock
* Desktop: optimize clock code
* Desktop: 3rd cleanup round
* Desktop: 4th cleanup round, missing bits and pieces

Co-authored-by: hedger <hedger@users.noreply.github.com>
Co-authored-by: あく <alleteam@gmail.com>

applications/services/gui/gui.c

@@ -17,6 +17,26 @@ ViewPort* gui_view_port_find_enabled(ViewPortArray_t array) {
     return NULL;
 }
 
+size_t gui_active_view_port_count(Gui* gui, GuiLayer layer) {
+    furi_assert(gui);
+    furi_check(layer < GuiLayerMAX);
+    size_t ret = 0;
+
+    gui_lock(gui);
+    ViewPortArray_it_t it;
+    ViewPortArray_it_last(it, gui->layers[layer]);
+    while(!ViewPortArray_end_p(it)) {
+        ViewPort* view_port = *ViewPortArray_ref(it);
+        if(view_port_is_enabled(view_port)) {
+            ret++;
+        }
+        ViewPortArray_previous(it);
+    }
+    gui_unlock(gui);
+
+    return ret;
+}
+
 void gui_update(Gui* gui) {
     furi_assert(gui);
     if(!gui->direct_draw) furi_thread_flags_set(gui->thread_id, GUI_THREAD_FLAG_DRAW);

applications/services/gui/gui_i.h

@@ -75,6 +75,12 @@ struct Gui {
     ViewPort* ongoing_input_view_port;
 };
 
+/** Find enabled ViewPort in ViewPortArray
+ *
+ * @param[in]  array  The ViewPortArray instance
+ *
+ * @return     ViewPort instance or NULL
+ */
 ViewPort* gui_view_port_find_enabled(ViewPortArray_t array);
 
 /** Update GUI, request redraw
@@ -83,8 +89,30 @@ ViewPort* gui_view_port_find_enabled(ViewPortArray_t array);
  */
 void gui_update(Gui* gui);
 
+/** Input event callback
+ * 
+ * Used to receive input from input service or to inject new input events
+ *
+ * @param[in]  value  The value pointer (InputEvent*)
+ * @param      ctx    The context (Gui instance)
+ */
 void gui_input_events_callback(const void* value, void* ctx);
 
+/** Get count of view ports in layer
+ *
+ * @param      gui        The Gui instance
+ * @param[in]  layer      GuiLayer that we want to get count of view ports
+ */
+size_t gui_active_view_port_count(Gui* gui, GuiLayer layer);
+
+/** Lock GUI
+ *
+ * @param      gui   The Gui instance
+ */
 void gui_lock(Gui* gui);
 
+/** Unlock GUI
+ *
+ * @param      gui   The Gui instance
+ */
 void gui_unlock(Gui* gui);