add volume_change event

makefile

@@ -1,12 +1,12 @@
 CFLAGS   = -std=c99 -Wall -DNDEBUG -Ofast -ffast-math -fvisibility=hidden -fno-common
-LIBS     = -framework Carbon -framework Cocoa -F/System/Library/PrivateFrameworks -framework SkyLight
+LIBS     = -framework Carbon -framework Cocoa -framework CoreAudio -F/System/Library/PrivateFrameworks -framework SkyLight
 ODIR     = bin
 SRC      = src
 
 _OBJ = alias.o background.o bar_item.o custom_events.o event.o graph.o \
        image.o mouse.o shadow.o text.o message.o mouse.o bar.o window.o \
        bar_manager.o display.o event_loop.o group.o mach.o popup.o \
-       animation.o workspace.om
+       animation.o workspace.om volume.o
 OBJ  = $(patsubst %, $(ODIR)/%, $(_OBJ))
 
 .PHONY: all clean arm x86 profile leak universal

src/bar_item.c

@@ -2,6 +2,7 @@
 #include "bar_manager.h"
 #include "event_loop.h"
 #include "event.h"
+#include "volume.h"
 
 struct bar_item* bar_item_create() {
   struct bar_item* bar_item = malloc(sizeof(struct bar_item));
@@ -994,6 +995,11 @@ void bar_item_parse_subscribe_message(struct bar_item* bar_item, char* message,
   while (event.text && event.length > 0) {
     uint64_t event_flag = custom_events_get_flag_for_name(&g_bar_manager.custom_events,
                                                           event.text                   );
+
+    if (event_flag & UPDATE_VOLUME_CHANGE) {
+      begin_receiving_volume_events();
+    }
+
     bar_item->update_mask |= event_flag;
 
     if (!event_flag) {

src/bar_manager.c

@@ -733,6 +733,18 @@ void bar_manager_handle_mouse_exited(struct bar_manager* bar_manager, struct bar
   }
 }
 
+void bar_manager_handle_volume_change(struct bar_manager* bar_manager, float volume) {
+  struct env_vars env_vars;
+  env_vars_init(&env_vars);
+  char volume_str[16];
+  snprintf(volume_str, 16, "%.2f", volume);
+  env_vars_set(&env_vars, string_copy("INFO"), string_copy(volume_str));
+  bar_manager_custom_events_trigger(bar_manager,
+                                    COMMAND_SUBSCRIBE_VOLUME_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

@@ -101,6 +101,7 @@ void bar_manager_handle_space_change(struct bar_manager* bar_manager, bool force
 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_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

@@ -29,6 +29,7 @@ void custom_events_init(struct custom_events* custom_events) {
   custom_events_append(custom_events, string_copy(COMMAND_SUBSCRIBE_SYSTEM_WILL_SLEEP), NULL);
   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);
 }
 
 void custom_events_append(struct custom_events* custom_events, char* name, char* notification) {

src/custom_events.h

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

src/event.c

@@ -250,3 +250,9 @@ EVENT_CALLBACK(EVENT_HANDLER_MOUSE_EXITED) {
     CFRelease(context);
     return EVENT_SUCCESS;
 }
+
+EVENT_CALLBACK(EVENT_HANDLER_VOLUME_CHANGED) {
+  bar_manager_handle_volume_change(&g_bar_manager, *(float*)context);
+  free(context);
+  return EVENT_SUCCESS;
+}

src/event.h

@@ -29,6 +29,7 @@ EVENT_CALLBACK(EVENT_HANDLER_MACH_MESSAGE);
 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_DISTRIBUTED_NOTIFICATION);
 
 #define EVENT_QUEUED     0x0
@@ -59,6 +60,7 @@ enum event_type {
     MOUSE_UP,
     MOUSE_ENTERED,
     MOUSE_EXITED,
+    VOLUME_CHANGED,
     DISTRIBUTED_NOTIFICATION,
 
     EVENT_TYPE_COUNT
@@ -83,6 +85,7 @@ static const char *event_type_str[] = {
     [MOUSE_UP]                       = "mouse_up",
     [MOUSE_ENTERED]                  = "mouse_entered",
     [MOUSE_EXITED]                   = "mouse_exited",
+    [VOLUME_CHANGED]                 = "volume_changed",
     [DISTRIBUTED_NOTIFICATION]       = "distributed_notification",
 
     [EVENT_TYPE_COUNT]               = "event_type_count"
@@ -99,6 +102,7 @@ static event_callback *event_handler[] = {
     [MOUSE_UP]                       = EVENT_HANDLER_MOUSE_UP,
     [MOUSE_ENTERED]                  = EVENT_HANDLER_MOUSE_ENTERED,
     [MOUSE_EXITED]                   = EVENT_HANDLER_MOUSE_EXITED,
+    [VOLUME_CHANGED]                 = EVENT_HANDLER_VOLUME_CHANGED,
     [DISTRIBUTED_NOTIFICATION]       = EVENT_HANDLER_DISTRIBUTED_NOTIFICATION,
 
     [MENU_BAR_HIDDEN_CHANGED]        = EVENT_HANDLER_MENU_BAR_HIDDEN_CHANGED,

src/misc/defines.h

@@ -93,6 +93,7 @@
 #define COMMAND_SUBSCRIBE_DISPLAY_CHANGE                    "display_change"
 #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_MOUSE_ENTERED                     "mouse.entered"
 #define COMMAND_SUBSCRIBE_MOUSE_EXITED                      "mouse.exited"
 #define COMMAND_SUBSCRIBE_MOUSE_CLICKED                     "mouse.clicked"

src/sketchybar.m

@@ -4,6 +4,7 @@
 #include "mach.h"
 #include "mouse.h"
 #include "message.h"
+#include "volume.h"
 
 #define LCFILE_PATH_FMT         "/tmp/sketchybar_%s.lock"
 
@@ -32,6 +33,7 @@ void *g_workspace_context;
 char g_config_file[4096];
 char g_lock_file[MAXLEN];
 bool g_verbose;
+bool g_volume_events;
 
 static int client_send_message(int argc, char **argv) {
     if (argc <= 1) {
@@ -148,6 +150,7 @@ static inline void init_misc_settings(void) {
     CGSetLocalEventsSuppressionInterval(0.0f);
     CGEnableEventStateCombining(false);
     g_connection = SLSMainConnectionID();
+    g_volume_events = false;
 }
 #pragma clang diagnostic pop
 

src/volume.c

@@ -0,0 +1,69 @@
+#include "volume.h"
+#include "event.h"
+
+extern bool g_volume_events;
+
+static AudioObjectPropertyAddress kVolumePropertyAddress = {
+                                            kAudioDevicePropertyVolumeScalar,
+                                            kAudioObjectPropertyScopeOutput,
+                                            kAudioObjectPropertyElementMain  };
+
+static AudioObjectPropertyAddress kMutePropertyAddress = {
+                                            kAudioDevicePropertyMute,
+                                            kAudioObjectPropertyScopeOutput,
+                                            kAudioObjectPropertyElementMain  };
+
+float g_last_volume = 0.f;
+static OSStatus handler(AudioObjectID id, uint32_t address_count, const AudioObjectPropertyAddress* addresses, void* context) {
+  float* volume = malloc(sizeof(float));
+  memset(volume, 0, sizeof(float));
+
+  uint32_t muted = 0;
+  uint32_t size = sizeof(uint32_t);
+
+  AudioObjectGetPropertyData(id,
+                             &kMutePropertyAddress,
+                             0,
+                             NULL,
+                             &size,
+                             &muted                );
+
+  size = sizeof(float);
+  AudioObjectGetPropertyData(id,
+                             &kVolumePropertyAddress,
+                             0,
+                             NULL,
+                             &size,
+                             volume                 );
+
+  if (muted) *volume = 0.f;
+  if (*volume > g_last_volume + 1e-2 || *volume < g_last_volume - 1e-2) {
+    g_last_volume = *volume;
+    struct event *event = event_create(&g_event_loop,
+                                       VOLUME_CHANGED,
+                                       (void *) volume);
+
+    event_loop_post(&g_event_loop, event);
+  }
+  return KERN_SUCCESS;
+}
+
+void begin_receiving_volume_events() {
+  if (g_volume_events) return;
+  AudioObjectPropertyAddress output_addr = {
+                                   kAudioHardwarePropertyDefaultOutputDevice,
+                                   kAudioObjectPropertyScopeGlobal,
+                                   kAudioObjectPropertyElementMain           };
+
+  AudioObjectID id = 0;
+  uint32_t size = sizeof(AudioObjectID);
+  AudioObjectGetPropertyData(kAudioObjectSystemObject,
+                             &output_addr,
+                             0,
+                             NULL,
+                             &size,
+                             &id                      );
+
+  AudioObjectAddPropertyListener(id, &kMutePropertyAddress, &handler, NULL);
+  AudioObjectAddPropertyListener(id, &kVolumePropertyAddress, &handler, NULL);
+}

src/volume.h

@@ -0,0 +1,5 @@
+#include "Carbon/Carbon.h"
+#include "CoreAudio/CoreAudio.h"
+#include <CoreAudio/AudioHardware.h>
+
+void begin_receiving_volume_events();