Add uppermost, current layer status widget to oled

app/include/zmk/display/widgets/layer_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_layer_status {
+    sys_snode_t node;
+    lv_obj_t *obj;
+};
+
+int zmk_widget_layer_status_init(struct zmk_widget_layer_status *widget, lv_obj_t *parent);
+lv_obj_t *zmk_widget_layer_status_obj(struct zmk_widget_layer_status *widget);

app/src/display/Kconfig

@@ -8,6 +8,7 @@ menuconfig ZMK_DISPLAY
     select LVGL
 	select LVGL_THEMES
 	select LVGL_THEME_MONO
+    select LVGL_BUILD_IN_FONT_ROBOTO_12
 
 if ZMK_DISPLAY
 

app/src/display/status_screen.c

@@ -6,6 +6,7 @@
 
 #include <zmk/display/widgets/output_status.h>
 #include <zmk/display/widgets/battery_status.h>
+#include <zmk/display/widgets/layer_status.h>
 #include <zmk/display/status_screen.h>
 
 #include <logging/log.h>
@@ -19,6 +20,8 @@ static struct zmk_widget_battery_status battery_status_widget;
 static struct zmk_widget_output_status output_status_widget;
 #endif
 
+static struct zmk_widget_layer_status layer_status_widget;
+
 lv_obj_t *zmk_display_status_screen() {
     lv_obj_t *screen;
     lv_obj_t *zmk_version_label;
@@ -39,8 +42,12 @@ lv_obj_t *zmk_display_status_screen() {
                  0);
 #endif
 
+    zmk_widget_layer_status_init(&layer_status_widget, screen);
+    lv_obj_align(zmk_widget_layer_status_obj(&layer_status_widget), NULL, LV_ALIGN_IN_BOTTOM_LEFT, 0,
+                 0);
+
     lv_label_set_text(zmk_version_label, "ZMK v0.1.0");
-    lv_obj_align(zmk_version_label, NULL, LV_ALIGN_IN_BOTTOM_MID, 0, 0);
+    lv_obj_align(zmk_version_label, NULL, LV_ALIGN_IN_BOTTOM_RIGHT, 0, 0);
 
     return screen;
 }

app/src/display/widgets/CMakeLists.txt

@@ -3,3 +3,5 @@
 
 target_sources_ifdef(CONFIG_ZMK_WIDGET_BATTERY_STATUS app PRIVATE battery_status.c)
 target_sources_ifdef(CONFIG_ZMK_WIDGET_OUTPUT_STATUS app PRIVATE output_status.c)
+
+target_sources(app PRIVATE layer_status.c)

app/src/display/widgets/layer_status.c

@@ -0,0 +1,65 @@
+/*
+ * Copyright (c) 2020 The ZMK Contributors
+ *
+ * SPDX-License-Identifier: MIT
+ */
+
+#include <logging/log.h>
+LOG_MODULE_DECLARE(zmk, CONFIG_ZMK_LOG_LEVEL);
+
+#include <zmk/display/widgets/layer_status.h>
+#include <zmk/events/layer-state-changed.h>
+#include <zmk/event-manager.h>
+#include <zmk/endpoints.h>
+#include <zmk/keymap.h>
+
+static sys_slist_t widgets = SYS_SLIST_STATIC_INIT(&widgets);
+static lv_style_t label_style;
+
+void layer_status_init() {
+    if (label_style.text.font != NULL) {
+        return;
+    }
+
+    lv_style_copy(&label_style, &lv_style_plain);
+    label_style.text.color = LV_COLOR_BLACK;
+    label_style.text.font = &lv_font_roboto_12;
+    label_style.text.letter_space = 1;
+    label_style.text.line_space = 1;
+}
+
+void set_layer_symbol(lv_obj_t *label) {
+    int active_layer_index = zmk_keymap_highest_layer_active();
+    char text[6] = {};
+
+    LOG_DBG("Layer changed to %i", active_layer_index);
+    sprintf(text, LV_SYMBOL_KEYBOARD "%i ", active_layer_index);
+
+    lv_label_set_text(label, text);
+}
+
+int zmk_widget_layer_status_init(struct zmk_widget_layer_status *widget, lv_obj_t *parent) {
+    layer_status_init();
+    widget->obj = lv_label_create(parent, NULL);
+    lv_label_set_style(widget->obj, LV_LABEL_STYLE_MAIN, &label_style);
+
+    lv_obj_set_size(widget->obj, 40, 15);
+    set_layer_symbol(widget->obj);
+
+    sys_slist_append(&widgets, &widget->node);
+
+    return 0;
+}
+
+lv_obj_t *zmk_widget_layer_status_obj(struct zmk_widget_layer_status *widget) {
+    return widget->obj;
+}
+
+int layer_status_listener(const struct zmk_event_header *eh) {
+    struct zmk_widget_layer_status *widget;
+    SYS_SLIST_FOR_EACH_CONTAINER(&widgets, widget, node) { set_layer_symbol(widget->obj); }
+    return 0;
+}
+
+ZMK_LISTENER(widget_layer_status, layer_status_listener)
+ZMK_SUBSCRIPTION(widget_layer_status, layer_state_changed);