feat(display): Initial widget/status screen work.

* Battery and output status widgets
* Built in status screen combining them.
* Ability to define a custom status screen factory
  function.

app/include/zmk/ble.h

@@ -14,7 +14,9 @@ int zmk_ble_prof_next();
 int zmk_ble_prof_prev();
 int zmk_ble_prof_select(u8_t index);
 
+int zmk_ble_active_profile_index();
 bt_addr_le_t *zmk_ble_active_profile_addr();
+bool zmk_ble_active_profile_is_open();
 bool zmk_ble_active_profile_is_connected();
 char *zmk_ble_active_profile_name();
 

app/include/zmk/display/status_screen.h

@@ -0,0 +1,11 @@
+/*
+ * Copyright (c) 2020 Peter Johanson <peter@peterjohanson.com>
+ *
+ * SPDX-License-Identifier: MIT
+ */
+
+#pragma once
+
+#include <lvgl.h>
+
+lv_obj_t *zmk_display_status_screen();

app/include/zmk/display/widgets/battery_status.h

@@ -0,0 +1,18 @@
+/*
+ * Copyright (c) 2020 The ZMK Contributors
+ *
+ * SPDX-License-Identifier: MIT
+ */
+
+#pragma once
+
+#include <lvgl.h>
+#include <kernel.h>
+
+struct zmk_widget_battery_status {
+    sys_snode_t node;
+    lv_obj_t *obj;
+};
+
+int zmk_widget_battery_status_init(struct zmk_widget_battery_status *widget, lv_obj_t *parent);
+lv_obj_t *zmk_widget_battery_status_obj(struct zmk_widget_battery_status *widget);

app/include/zmk/display/widgets/output_status.h

@@ -0,0 +1,18 @@
+/*
+ * Copyright (c) 2020 The ZMK Contributors
+ *
+ * SPDX-License-Identifier: MIT
+ */
+
+#pragma once
+
+#include <lvgl.h>
+#include <kernel.h>
+
+struct zmk_widget_output_status {
+    sys_snode_t node;
+    lv_obj_t *obj;
+};
+
+int zmk_widget_output_status_init(struct zmk_widget_output_status *widget, lv_obj_t *parent);
+lv_obj_t *zmk_widget_output_status_obj(struct zmk_widget_output_status *widget);

app/include/zmk/endpoints.h

@@ -16,5 +16,6 @@ enum zmk_endpoint {
 
 int zmk_endpoints_select(enum zmk_endpoint endpoint);
 int zmk_endpoints_toggle();
+enum zmk_endpoint zmk_endpoints_selected();
 
 int zmk_endpoints_send_report(u8_t usage_report);