add brightness_change event using private DisplayServices framework

makefile

@@ -1,5 +1,5 @@
 CFLAGS   = -std=c99 -Wall -DNDEBUG -Ofast -ffast-math -fvisibility=hidden -fno-common
-LIBS     = -framework Carbon -framework Cocoa -framework CoreAudio -F/System/Library/PrivateFrameworks -framework SkyLight
+LIBS     = -framework Carbon -framework Cocoa -framework CoreAudio -F/System/Library/PrivateFrameworks -framework SkyLight -framework DisplayServices
 ODIR     = bin
 SRC      = src
 

src/bar_item.c

@@ -1000,6 +1000,10 @@ void bar_item_parse_subscribe_message(struct bar_item* bar_item, char* message,
       begin_receiving_volume_events();
     }
 
+    if (event_flag & UPDATE_BRIGHTNESS_CHANGE) {
+      begin_receiving_brightness_events();
+    }
+
     bar_item->update_mask |= event_flag;
 
     if (!event_flag) {
@@ -1007,6 +1011,5 @@ void bar_item_parse_subscribe_message(struct bar_item* bar_item, char* message,
     }
 
     event = get_token(&message);
-
   }
 }

src/bar_manager.c

@@ -745,6 +745,18 @@ void bar_manager_handle_volume_change(struct bar_manager* bar_manager, float vol
   env_vars_destroy(&env_vars);
 }
 
+void bar_manager_handle_brightness_change(struct bar_manager* bar_manager, float brightness) {
+  struct env_vars env_vars;
+  env_vars_init(&env_vars);
+  char brightness_str[16];
+  snprintf(brightness_str, 16, "%d", (int)(brightness*100. + 0.5));
+  env_vars_set(&env_vars, string_copy("INFO"), string_copy(brightness_str));
+  bar_manager_custom_events_trigger(bar_manager,
+                                    COMMAND_SUBSCRIBE_BRIGHTNESS_CHANGE,
+                                    &env_vars                           );
+  env_vars_destroy(&env_vars);
+}
+
 void bar_manager_handle_front_app_switch(struct bar_manager* bar_manager, char* info) {
   struct env_vars env_vars;
   env_vars_init(&env_vars);

src/bar_manager.h

@@ -102,6 +102,7 @@ void bar_manager_handle_display_change(struct bar_manager* bar_manager);
 void bar_manager_handle_system_woke(struct bar_manager* bar_manager);
 void bar_manager_handle_system_will_sleep(struct bar_manager* bar_manager);
 void bar_manager_handle_volume_change(struct bar_manager* bar_manager, float volume);
+void bar_manager_handle_brightness_change(struct bar_manager* bar_manager, float brightness);
 void bar_manager_custom_events_trigger(struct bar_manager* bar_manager, char* name, struct env_vars* env_vars);
 
 void bar_manager_destroy(struct bar_manager* bar_manager);

src/custom_events.c

@@ -30,6 +30,7 @@ void custom_events_init(struct custom_events* custom_events) {
   custom_events_append(custom_events, string_copy(COMMAND_SUBSCRIBE_MOUSE_ENTERED_GLOBAL), NULL);
   custom_events_append(custom_events, string_copy(COMMAND_SUBSCRIBE_MOUSE_EXITED_GLOBAL), NULL);
   custom_events_append(custom_events, string_copy(COMMAND_SUBSCRIBE_VOLUME_CHANGE), NULL);
+  custom_events_append(custom_events, string_copy(COMMAND_SUBSCRIBE_BRIGHTNESS_CHANGE), NULL);
 }
 
 void custom_events_append(struct custom_events* custom_events, char* name, char* notification) {

src/custom_events.h

@@ -12,6 +12,7 @@
 #define UPDATE_ENTERED_GLOBAL     1ULL << 8
 #define UPDATE_EXITED_GLOBAL      1ULL << 9
 #define UPDATE_VOLUME_CHANGE      1ULL << 10
+#define UPDATE_BRIGHTNESS_CHANGE  1ULL << 11
 
 extern void* g_workspace_context;
 extern void workspace_create_custom_observer(void** context, char* name);

src/display.c

@@ -3,8 +3,26 @@
 extern int workspace_display_notch_height(uint32_t did);
 extern struct event_loop g_event_loop;
 extern int g_connection;
+extern bool g_brightness_events;
 
 
+float g_last_brightness = 0;
+static void brightness_handler(void* notification_center, uint32_t did, void* name, const void* sender, CFDictionaryRef info) {
+  float* brightness = malloc(sizeof(float));
+  memset(brightness, 0, sizeof(float));
+  DisplayServicesGetBrightness(did, brightness);
+  if (g_last_brightness < *brightness - 1e-2 || g_last_brightness > *brightness + 1e-2) {
+    g_last_brightness = *brightness;
+    struct event *event = event_create(&g_event_loop,
+                                       BRIGHTNESS_CHANGED,
+                                       (void *) brightness);
+
+    event_loop_post(&g_event_loop, event);
+  } else {
+    free(brightness);
+  }
+}
+
 static DISPLAY_EVENT_HANDLER(display_handler) {
     if (flags & kCGDisplayAddFlag) {
         struct event *event = event_create(&g_event_loop,
@@ -12,12 +30,16 @@ static DISPLAY_EVENT_HANDLER(display_handler) {
                                            (void *)(intptr_t) did);
 
         event_loop_post(&g_event_loop, event);
+        if (g_brightness_events && DisplayServicesCanChangeBrightness(did))
+          DisplayServicesRegisterForBrightnessChangeNotifications(did, did, (void*)brightness_handler);
     } else if (flags & kCGDisplayRemoveFlag) {
         struct event *event = event_create(&g_event_loop,
                                            DISPLAY_REMOVED,
                                            (void *)(intptr_t) did);
 
         event_loop_post(&g_event_loop, event);
+        if (g_brightness_events && DisplayServicesCanChangeBrightness(did))
+          DisplayServicesUnregisterForBrightnessChangeNotifications(did, did);
     } else if (flags & kCGDisplayMovedFlag) {
         struct event *event = event_create(&g_event_loop,
                                            DISPLAY_MOVED,
@@ -211,4 +233,16 @@ bool display_end() {
             == kCGErrorSuccess;
 }
 
+void begin_receiving_brightness_events() {
+  if (g_brightness_events) return;
+  g_brightness_events = true;
+  uint32_t count;
+  uint32_t* result = display_active_display_list(&count);
+  for (int i = 0; i < count; i++) {
+    uint32_t did = *(result + i);
+    if (DisplayServicesCanChangeBrightness(did)) {
+      DisplayServicesRegisterForBrightnessChangeNotifications(did, did, (void*)brightness_handler);
+    }
+  }
+}
 

src/display.h

@@ -6,6 +6,11 @@
 #define DISPLAY_EVENT_HANDLER(name) void name(uint32_t did, CGDisplayChangeSummaryFlags flags, void *context)
 typedef DISPLAY_EVENT_HANDLER(display_callback);
 
+extern CGError DisplayServicesRegisterForBrightnessChangeNotifications(uint32_t did, uint32_t passthrough, void* callback);
+extern CGError DisplayServicesUnregisterForBrightnessChangeNotifications(uint32_t did, uint32_t passthrough);
+extern CGError DisplayServicesGetBrightness(uint32_t did, float* brightness);
+extern CGError DisplayServicesCanChangeBrightness(uint32_t did);
+
 extern CFUUIDRef CGDisplayCreateUUIDFromDisplayID(uint32_t did);
 extern CFArrayRef SLSCopyManagedDisplays(int cid);
 extern uint64_t SLSManagedDisplayGetCurrentSpace(int cid, CFStringRef uuid);
@@ -31,3 +36,5 @@ CGRect display_bounds(uint32_t did);
 uint64_t display_space_id(uint32_t did);
 uint64_t *display_space_list(uint32_t did, int *count);
 int display_arrangement(uint32_t did);
+
+void begin_receiving_brightness_events();

src/event.c

@@ -256,3 +256,9 @@ EVENT_CALLBACK(EVENT_HANDLER_VOLUME_CHANGED) {
   free(context);
   return EVENT_SUCCESS;
 }
+
+EVENT_CALLBACK(EVENT_HANDLER_BRIGHTNESS_CHANGED) {
+  bar_manager_handle_brightness_change(&g_bar_manager, *(float*)context);
+  free(context);
+  return EVENT_SUCCESS;
+}

src/event.h

@@ -30,6 +30,7 @@ EVENT_CALLBACK(EVENT_HANDLER_MOUSE_UP);
 EVENT_CALLBACK(EVENT_HANDLER_MOUSE_ENTERED);
 EVENT_CALLBACK(EVENT_HANDLER_MOUSE_EXITED);
 EVENT_CALLBACK(EVENT_HANDLER_VOLUME_CHANGED);
+EVENT_CALLBACK(EVENT_HANDLER_BRIGHTNESS_CHANGED);
 EVENT_CALLBACK(EVENT_HANDLER_DISTRIBUTED_NOTIFICATION);
 
 #define EVENT_QUEUED     0x0
@@ -61,6 +62,7 @@ enum event_type {
     MOUSE_ENTERED,
     MOUSE_EXITED,
     VOLUME_CHANGED,
+    BRIGHTNESS_CHANGED,
     DISTRIBUTED_NOTIFICATION,
 
     EVENT_TYPE_COUNT
@@ -86,6 +88,7 @@ static const char *event_type_str[] = {
     [MOUSE_ENTERED]                  = "mouse_entered",
     [MOUSE_EXITED]                   = "mouse_exited",
     [VOLUME_CHANGED]                 = "volume_changed",
+    [BRIGHTNESS_CHANGED]             = "brightness_changed",
     [DISTRIBUTED_NOTIFICATION]       = "distributed_notification",
 
     [EVENT_TYPE_COUNT]               = "event_type_count"
@@ -103,6 +106,7 @@ static event_callback *event_handler[] = {
     [MOUSE_ENTERED]                  = EVENT_HANDLER_MOUSE_ENTERED,
     [MOUSE_EXITED]                   = EVENT_HANDLER_MOUSE_EXITED,
     [VOLUME_CHANGED]                 = EVENT_HANDLER_VOLUME_CHANGED,
+    [BRIGHTNESS_CHANGED]             = EVENT_HANDLER_BRIGHTNESS_CHANGED,
     [DISTRIBUTED_NOTIFICATION]       = EVENT_HANDLER_DISTRIBUTED_NOTIFICATION,
 
     [MENU_BAR_HIDDEN_CHANGED]        = EVENT_HANDLER_MENU_BAR_HIDDEN_CHANGED,

src/misc/defines.h

@@ -94,6 +94,7 @@
 #define COMMAND_SUBSCRIBE_SYSTEM_WOKE                       "system_woke"
 #define COMMAND_SUBSCRIBE_SYSTEM_WILL_SLEEP                 "system_will_sleep"
 #define COMMAND_SUBSCRIBE_VOLUME_CHANGE                     "volume_change"
+#define COMMAND_SUBSCRIBE_BRIGHTNESS_CHANGE                 "brightness_change"
 #define COMMAND_SUBSCRIBE_MOUSE_ENTERED                     "mouse.entered"
 #define COMMAND_SUBSCRIBE_MOUSE_EXITED                      "mouse.exited"
 #define COMMAND_SUBSCRIBE_MOUSE_CLICKED                     "mouse.clicked"

src/sketchybar.m

@@ -34,6 +34,7 @@ char g_config_file[4096];
 char g_lock_file[MAXLEN];
 bool g_verbose;
 bool g_volume_events;
+bool g_brightness_events;
 
 static int client_send_message(int argc, char **argv) {
     if (argc <= 1) {
@@ -151,6 +152,7 @@ static inline void init_misc_settings(void) {
     CGEnableEventStateCombining(false);
     g_connection = SLSMainConnectionID();
     g_volume_events = false;
+    g_brightness_events = false;
 }
 #pragma clang diagnostic pop