init Files

libraries/lvgl/examples/others/observer/lv_example_observer_2.c

@@ -0,0 +1,136 @@
+#include "../../lv_examples.h"
+#if LV_USE_OBSERVER && LV_USE_SLIDER && LV_USE_LABEL && LV_BUILD_EXAMPLES
+
+/*This the only interface between the UI and the application*/
+static lv_subject_t engine_subject;
+
+static void app_init(void);
+static void ui_init(void);
+
+/**
+ * Simple PIN login screen to start an engine.
+ * The only interface between the UI and the application is a single "subject".
+ */
+void lv_example_observer_2(void)
+{
+    lv_subject_init_int(&engine_subject, 0);
+    app_init();
+    ui_init();
+}
+
+/*--------------------------------------------------
+ * APPLICATION
+ *
+ * This part contains a demo application logic.
+ * It doesn't know anything about the internals of the UI
+ * and uses any the `engine_subject` as an interface.
+ * -------------------------------------------------*/
+static void engine_state_observer_cb(lv_observer_t * observer, lv_subject_t * subject)
+{
+    LV_UNUSED(observer);
+
+    int32_t v = lv_subject_get_int(subject);
+    LV_UNUSED(v);
+    /*In a real application set/clear a pin here*/
+    LV_LOG_USER("Engine state: %" LV_PRId32, v);
+}
+
+static void app_init(void)
+{
+    lv_subject_add_observer(&engine_subject, engine_state_observer_cb, NULL);
+}
+
+/*--------------------------------------------------
+ * USER INTERFACE
+ *
+ * This part contains only UI related code and data.
+ * In a project it would a separate file and the
+ * application couldn't see its internals
+ * -------------------------------------------------*/
+
+typedef enum {
+    LOGGED_OUT,
+    LOGGED_IN,
+    AUTH_FAILED,
+} auth_state_t;
+
+static lv_subject_t auth_state_subject;
+
+static void textarea_event_cb(lv_event_t * e)
+{
+    lv_obj_t * ta = lv_event_get_target(e);
+    if(lv_strcmp(lv_textarea_get_text(ta), "hello") == 0) {
+        lv_subject_set_int(&auth_state_subject, LOGGED_IN);
+    }
+    else {
+        lv_subject_set_int(&auth_state_subject, AUTH_FAILED);
+    }
+}
+
+static void info_label_observer_cb(lv_observer_t * observer, lv_subject_t * subject)
+{
+    lv_obj_t * label = lv_observer_get_target(observer);
+    switch(lv_subject_get_int(subject)) {
+        case LOGGED_IN:
+            lv_label_set_text(label, "Login successful");
+            break;
+        case LOGGED_OUT:
+            lv_label_set_text(label, "Logged out");
+            break;
+        case AUTH_FAILED:
+            lv_label_set_text(label, "Login failed");
+            break;
+    }
+}
+
+static void log_out_click_event_cb(lv_event_t * e)
+{
+    LV_UNUSED(e);
+    lv_subject_set_int(&auth_state_subject, LOGGED_OUT);
+}
+
+static void ui_init(void)
+{
+    lv_subject_init_int(&auth_state_subject, LOGGED_OUT);
+
+    /*Create a slider in the center of the display*/
+    lv_obj_t * ta = lv_textarea_create(lv_screen_active());
+    lv_obj_set_pos(ta, 10, 10);
+    lv_obj_set_width(ta, 200);
+    lv_textarea_set_one_line(ta, true);
+    lv_textarea_set_password_mode(ta, true);
+    lv_textarea_set_placeholder_text(ta, "The password is: hello");
+    lv_obj_add_event_cb(ta, textarea_event_cb, LV_EVENT_READY, NULL);
+    lv_obj_bind_state_if_eq(ta, &auth_state_subject, LV_STATE_DISABLED, LOGGED_IN);
+
+    lv_obj_t * kb = lv_keyboard_create(lv_screen_active());
+    lv_keyboard_set_textarea(kb, ta);
+
+    lv_obj_t * btn;
+    lv_obj_t * label;
+
+    /*Create a log out button which will be active only when logged in*/
+    btn = lv_button_create(lv_screen_active());
+    lv_obj_set_pos(btn, 220, 10);
+    lv_obj_add_event_cb(btn, log_out_click_event_cb, LV_EVENT_CLICKED, NULL);
+    lv_obj_bind_state_if_not_eq(btn, &auth_state_subject, LV_STATE_DISABLED, LOGGED_IN);
+
+    label = lv_label_create(btn);
+    lv_label_set_text(label, "LOG OUT");
+
+    /*Create a label to show info*/
+    label = lv_label_create(lv_screen_active());
+    lv_obj_set_pos(label, 10, 60);
+    lv_subject_add_observer_obj(&auth_state_subject, info_label_observer_cb, label, NULL);
+
+    /*Create button which will be active only when logged in*/
+    btn = lv_button_create(lv_screen_active());
+    lv_obj_set_pos(btn, 10, 80);
+    lv_obj_add_flag(btn, LV_OBJ_FLAG_CHECKABLE);
+    lv_obj_bind_state_if_not_eq(btn, &auth_state_subject, LV_STATE_DISABLED, LOGGED_IN);
+    lv_button_bind_checked(btn, &engine_subject);
+    label = lv_label_create(btn);
+    lv_label_set_text(label, "START ENGINE");
+}
+
+#endif