Add support for volatile buttons to widget-boolean.c

Will be used by Gen 1 support.

src/alsa-sim.c

@@ -133,7 +133,7 @@ static void alsa_parse_comment_node(
       if (err < 0)
         fatal_alsa_error("snd_config_get_string error", err);
       if (strstr(access, "write"))
-        elem->writable = 1;
+        elem->is_writable = 1;
     } else if (strcmp(key, "type") == 0) {
       if (type != SND_CONFIG_TYPE_STRING) {
         printf("type type not string\n");

src/alsa.c

@@ -262,7 +262,7 @@ void alsa_set_elem_value(struct alsa_elem *elem, long value) {
 // return whether the element can be modified (is writable)
 int alsa_get_elem_writable(struct alsa_elem *elem) {
   if (elem->card->num == SIMULATED_CARD_NUM)
-    return elem->writable;
+    return elem->is_writable;
 
   snd_ctl_elem_info_t *elem_info;
 
@@ -273,6 +273,21 @@ int alsa_get_elem_writable(struct alsa_elem *elem) {
   return snd_ctl_elem_info_is_writable(elem_info);
 }
 
+// return whether the element is volatile (can change without
+// notification)
+int alsa_get_elem_volatile(struct alsa_elem *elem) {
+  if (elem->card->num == SIMULATED_CARD_NUM)
+    return elem->is_volatile;
+
+  snd_ctl_elem_info_t *elem_info;
+
+  snd_ctl_elem_info_alloca(&elem_info);
+  snd_ctl_elem_info_set_numid(elem_info, elem->numid);
+  snd_ctl_elem_info(elem->card->handle, elem_info);
+
+  return snd_ctl_elem_info_is_volatile(elem_info);
+}
+
 // get the number of values this element has
 // (most are just 1; the levels element is the exception)
 int alsa_get_elem_count(struct alsa_elem *elem) {

src/alsa.h

@@ -141,7 +141,8 @@ struct alsa_elem {
   GList *callbacks;
 
   // for simulated elements, the current state
-  int  writable;
+  int  is_writable;
+  int  is_volatile;
   long value;
 
   // for simulated enumerated elements, the items
@@ -219,6 +220,7 @@ long alsa_get_elem_value(struct alsa_elem *elem);
 int *alsa_get_elem_int_values(struct alsa_elem *elem);
 void alsa_set_elem_value(struct alsa_elem *elem, long value);
 int alsa_get_elem_writable(struct alsa_elem *elem);
+int alsa_get_elem_volatile(struct alsa_elem *elem);
 int alsa_get_elem_count(struct alsa_elem *elem);
 int alsa_get_item_count(struct alsa_elem *elem);
 char *alsa_get_item_name(struct alsa_elem *elem, int i);

src/widget-boolean.c

@@ -6,6 +6,7 @@
 struct boolean {
   struct alsa_elem *elem;
   GtkWidget        *button;
+  guint             source;
   const char       *text[2];
 };
 
@@ -42,7 +43,16 @@ static void toggle_button_updated(
   toggle_button_set_text(data->button, data->text[value]);
 }
 
+static gboolean update_toggle_button(struct boolean *data) {
+  toggle_button_updated(data->elem, data);
+
+  return G_SOURCE_CONTINUE;
+}
+
 static void on_destroy(struct boolean *data) {
+  if (data->source)
+    g_source_remove(data->source);
+
   g_free(data);
 }
 
@@ -82,6 +92,11 @@ GtkWidget *make_boolean_alsa_elem(
 
   toggle_button_updated(elem, data);
 
+  // periodically update volatile controls
+  if (alsa_get_elem_volatile(elem))
+    data->source =
+      g_timeout_add_seconds(1, (GSourceFunc)update_toggle_button, data);
+
   g_object_weak_ref(G_OBJECT(data->button), (GWeakNotify)on_destroy, data);
 
   return data->button;