1 #include "../../lv_examples.h"
2 #if LV_USE_OBSERVER && LV_USE_SLIDER && LV_USE_LABEL && LV_BUILD_EXAMPLES
3
4 /*This the only interface between the UI and the application*/
5 static lv_subject_t engine_subject;
6
7 static void app_init(void);
8 static void ui_init(void);
9
10 /**
11 * Simple PIN login screen to start an engine.
12 * The only interface between the UI and the application is a single "subject".
13 */
lv_example_observer_2(void)14 void lv_example_observer_2(void)
15 {
16 lv_subject_init_int(&engine_subject, 0);
17 app_init();
18 ui_init();
19 }
20
21 /*--------------------------------------------------
22 * APPLICATION
23 *
24 * This part contains a demo application logic.
25 * It doesn't know anything about the internals of the UI
26 * and uses any the `engine_subject` as an interface.
27 * -------------------------------------------------*/
engine_state_observer_cb(lv_observer_t * observer,lv_subject_t * subject)28 static void engine_state_observer_cb(lv_observer_t * observer, lv_subject_t * subject)
29 {
30 LV_UNUSED(observer);
31
32 int32_t v = lv_subject_get_int(subject);
33 LV_UNUSED(v);
34 /*In a real application set/clear a pin here*/
35 LV_LOG_USER("Engine state: %" LV_PRId32, v);
36 }
37
app_init(void)38 static void app_init(void)
39 {
40 lv_subject_add_observer(&engine_subject, engine_state_observer_cb, NULL);
41 }
42
43 /*--------------------------------------------------
44 * USER INTERFACE
45 *
46 * This part contains only UI related code and data.
47 * In a project it would a separate file and the
48 * application couldn't see its internals
49 * -------------------------------------------------*/
50
51 typedef enum {
52 LOGGED_OUT,
53 LOGGED_IN,
54 AUTH_FAILED,
55 } auth_state_t;
56
57 static lv_subject_t auth_state_subject;
58
textarea_event_cb(lv_event_t * e)59 static void textarea_event_cb(lv_event_t * e)
60 {
61 lv_obj_t * ta = lv_event_get_target(e);
62 if(lv_strcmp(lv_textarea_get_text(ta), "hello") == 0) {
63 lv_subject_set_int(&auth_state_subject, LOGGED_IN);
64 }
65 else {
66 lv_subject_set_int(&auth_state_subject, AUTH_FAILED);
67 }
68 }
69
info_label_observer_cb(lv_observer_t * observer,lv_subject_t * subject)70 static void info_label_observer_cb(lv_observer_t * observer, lv_subject_t * subject)
71 {
72 lv_obj_t * label = lv_observer_get_target(observer);
73 switch(lv_subject_get_int(subject)) {
74 case LOGGED_IN:
75 lv_label_set_text(label, "Login successful");
76 break;
77 case LOGGED_OUT:
78 lv_label_set_text(label, "Logged out");
79 break;
80 case AUTH_FAILED:
81 lv_label_set_text(label, "Login failed");
82 break;
83 }
84 }
85
log_out_click_event_cb(lv_event_t * e)86 static void log_out_click_event_cb(lv_event_t * e)
87 {
88 LV_UNUSED(e);
89 lv_subject_set_int(&auth_state_subject, LOGGED_OUT);
90 }
91
ui_init(void)92 static void ui_init(void)
93 {
94 lv_subject_init_int(&auth_state_subject, LOGGED_OUT);
95
96 /*Create a slider in the center of the display*/
97 lv_obj_t * ta = lv_textarea_create(lv_screen_active());
98 lv_obj_set_pos(ta, 10, 10);
99 lv_obj_set_width(ta, 200);
100 lv_textarea_set_one_line(ta, true);
101 lv_textarea_set_password_mode(ta, true);
102 lv_textarea_set_placeholder_text(ta, "The password is: hello");
103 lv_obj_add_event_cb(ta, textarea_event_cb, LV_EVENT_READY, NULL);
104 lv_obj_bind_state_if_eq(ta, &auth_state_subject, LV_STATE_DISABLED, LOGGED_IN);
105
106 lv_obj_t * kb = lv_keyboard_create(lv_screen_active());
107 lv_keyboard_set_textarea(kb, ta);
108
109 lv_obj_t * btn;
110 lv_obj_t * label;
111
112 /*Create a log out button which will be active only when logged in*/
113 btn = lv_button_create(lv_screen_active());
114 lv_obj_set_pos(btn, 220, 10);
115 lv_obj_add_event_cb(btn, log_out_click_event_cb, LV_EVENT_CLICKED, NULL);
116 lv_obj_bind_state_if_not_eq(btn, &auth_state_subject, LV_STATE_DISABLED, LOGGED_IN);
117
118 label = lv_label_create(btn);
119 lv_label_set_text(label, "LOG OUT");
120
121 /*Create a label to show info*/
122 label = lv_label_create(lv_screen_active());
123 lv_obj_set_pos(label, 10, 60);
124 lv_subject_add_observer_obj(&auth_state_subject, info_label_observer_cb, label, NULL);
125
126 /*Create button which will be active only when logged in*/
127 btn = lv_button_create(lv_screen_active());
128 lv_obj_set_pos(btn, 10, 80);
129 lv_obj_add_flag(btn, LV_OBJ_FLAG_CHECKABLE);
130 lv_obj_bind_state_if_not_eq(btn, &auth_state_subject, LV_STATE_DISABLED, LOGGED_IN);
131 lv_button_bind_checked(btn, &engine_subject);
132 label = lv_label_create(btn);
133 lv_label_set_text(label, "START ENGINE");
134 }
135
136 #endif
137
