Add the ability to capture event and release later

app/include/zmk/event-manager.h

@@ -17,8 +17,12 @@ struct zmk_event_type
 
 struct zmk_event_header {
     const struct zmk_event_type* event;
+    u8_t last_listener_index;
 };
 
+#define ZMK_EV_EVENT_HANDLED 1
+#define ZMK_EV_EVENT_CAPTURED 2
+
 typedef int (*zmk_listener_callback_t)(const struct zmk_event_header *eh);
 struct zmk_listener
 {
@@ -33,7 +37,7 @@ struct zmk_event_subscription {
 #define ZMK_EVENT_DECLARE(event_type) \
     struct event_type* new_##event_type(); \
     bool is_##event_type(const struct zmk_event_header *eh); \
-    const struct event_type* cast_##event_type(const struct zmk_event_header *eh); \
+    struct event_type* cast_##event_type(const struct zmk_event_header *eh); \
     extern const struct zmk_event_type zmk_event_##event_type;
 
 #define ZMK_EVENT_IMPL(event_type) \
@@ -49,8 +53,8 @@ struct zmk_event_subscription {
     bool is_##event_type(const struct zmk_event_header *eh) { \
         return eh->event == &zmk_event_##event_type; \
     }; \
-    const struct event_type* cast_##event_type(const struct zmk_event_header *eh) {\
+    struct event_type* cast_##event_type(const struct zmk_event_header *eh) {\
-        return (const struct event_type*)eh; \
+        return (struct event_type*)eh; \
     };
     
 
@@ -68,4 +72,8 @@ struct zmk_event_subscription {
 #define ZMK_EVENT_RAISE(ev) \
     zmk_event_manager_raise((struct zmk_event_header *)ev);
 
+#define ZMK_EVENT_RELEASE(ev) \
+    zmk_event_manager_release((struct zmk_event_header *)ev);
+
 int zmk_event_manager_raise(struct zmk_event_header *event);
+int zmk_event_manager_release(struct zmk_event_header *event);

app/src/event_manager.c

@@ -17,16 +17,30 @@ extern struct zmk_event_type* __event_type_end[];
 extern struct zmk_event_subscription __event_subscriptions_start[];
 extern struct zmk_event_subscription __event_subscriptions_end[];
 
-int zmk_event_manager_raise(struct zmk_event_header *event)
+
+int zmk_event_manager_handle_from(struct zmk_event_header *event, u8_t start_index)
 {
-    int ret;
+    int ret = 0;
-    struct zmk_event_subscription *ev_sub;
+    u8_t len = __event_subscriptions_end - __event_subscriptions_start;
-    for (ev_sub = __event_subscriptions_start; ev_sub != __event_subscriptions_end; ev_sub++) {
+    for (int i = start_index + 1; i < len; i++) {
+        struct zmk_event_subscription *ev_sub = __event_subscriptions_start + i;
         if (ev_sub->event_type == event->event) {
             ret = ev_sub->listener->callback(event);
-            if (ret) {
+            if (ret < 0) {
                 LOG_DBG("Listener returned an error: %d", ret);
                 goto release;
+            } else if (ret > 0) {
+                switch (ret) {
+                    case ZMK_EV_EVENT_HANDLED:
+                        LOG_DBG("Listener handled the event");
+                        ret = 0;
+                        goto release;
+                    case ZMK_EV_EVENT_CAPTURED:
+                        LOG_DBG("Listener captured the event");
+                        event->last_listener_index = i;
+                        // Listeners are expected to free events they capture
+                        return 0;
+                }
             }
         }
     }
@@ -35,3 +49,13 @@ release:
     k_free(event);
     return ret;
 }
+
+int zmk_event_manager_raise(struct zmk_event_header *event)
+{
+    return zmk_event_manager_handle_from(event, 0);
+}
+
+int zmk_event_manager_release(struct zmk_event_header *event)
+{
+    return zmk_event_manager_handle_from(event, event->last_listener_index + 1);
+}