Add onDidChangeKeyboardLayout on Mac

.gitignore

@@ -1,2 +1,3 @@
 /build/
+/node_modules/
 npm-debug.log

index.js

@@ -32,6 +32,14 @@ NativeBinding.prototype.getCurrentKeyboardLayout = function() {
     return null;
   }
 };
+NativeBinding.prototype.onDidChangeKeyboardLayout = function(callback) {
+  try {
+    this._init();
+    this._keymapping.onDidChangeKeyboardLayout(callback);
+  } catch(err) {
+    console.error(err);
+  }
+}
 
 var binding = new NativeBinding();
 
@@ -41,3 +49,6 @@ exports.getCurrentKeyboardLayout = function() {
 exports.getKeyMap = function() {
   return binding.getKeyMap();
 };
+exports.onDidChangeKeyboardLayout = function(callback) {
+  return binding.onDidChangeKeyboardLayout(callback);
+}

src/keyboard_mac.mm

@@ -167,4 +167,44 @@ void _GetCurrentKeyboardLayout(const v8::FunctionCallbackInfo<v8::Value>& args)
   args.GetReturnValue().Set(result);
 }
 
+static v8::Persistent<v8::Function, v8::CopyablePersistentTraits<v8::Function>> _cb;
+
+uv_loop_t *loop = uv_default_loop();
+uv_async_t async;
+
+void notificationCallback(CFNotificationCenterRef center, void *observer, CFStringRef name, const void *object, CFDictionaryRef userInfo) {
+  uv_async_send(&async);
+}
+
+static void asyncSendHandler(uv_async_t *handle) {
+  auto isolate = Isolate::GetCurrent();
+  v8::HandleScope scope(isolate);
+  auto context = isolate->GetCurrentContext();
+  auto global = context->Global();
+
+  const int argc = 0;
+  v8::Handle<v8::Value> argv[argc];
+
+  auto fn = Local<v8::Function>::New(isolate, _cb);
+  fn->Call(global, argc, argv);
+}
+
+void _OnDidChangeKeyboardLayout(const v8::FunctionCallbackInfo<v8::Value>& args) {
+
+  uv_async_init(loop, &async, (uv_async_cb)asyncSendHandler);
+
+  auto isolate = Isolate::GetCurrent();
+  v8::Handle<v8::Function> arg0 = v8::Handle<v8::Function>::Cast(args[0]);
+  v8::Persistent<v8::Function> cb(isolate, arg0);
+  _cb = cb;
+
+  CFNotificationCenterRef center = CFNotificationCenterGetDistributedCenter();
+
+  // add an observer
+  CFNotificationCenterAddObserver(center, NULL, notificationCallback,
+    kTISNotifySelectedKeyboardInputSourceChanged, NULL,
+    CFNotificationSuspensionBehaviorDeliverImmediately
+  );
+}
+
 } // namespace vscode_keyboard

src/keyboard_win.cc

@@ -351,4 +351,8 @@ void _GetCurrentKeyboardLayout(const v8::FunctionCallbackInfo<v8::Value>& args)
   args.GetReturnValue().Set(result);
 }
 
+void _OnDidChangeKeyboardLayout(const v8::FunctionCallbackInfo<v8::Value>& args) {
+
+}
+
 }  // namespace vscode_keyboard

src/keyboard_x.cc

@@ -232,4 +232,8 @@ void _GetCurrentKeyboardLayout(const v8::FunctionCallbackInfo<v8::Value>& args)
   XCloseDisplay(display);
 }
 
+void _OnDidChangeKeyboardLayout(const v8::FunctionCallbackInfo<v8::Value>& args) {
+  
+}
+
 } // namespace vscode_keyboard

src/keymapping.cc

@@ -21,6 +21,7 @@ using v8::Value;
 void init(Local<Object> exports) {
   NODE_SET_METHOD(exports, "getKeyMap", _GetKeyMap);
   NODE_SET_METHOD(exports, "getCurrentKeyboardLayout", _GetCurrentKeyboardLayout);
+  NODE_SET_METHOD(exports, "onDidChangeKeyboardLayout", _OnDidChangeKeyboardLayout);
 }
 
 NODE_MODULE(addon, init)

src/keymapping.h

@@ -7,6 +7,7 @@
 #define KEYMAPPING_H_
 
 #include <node.h>
+#include <uv.h>
 #include <string>
 #include <vector>
 #include "../deps/chromium/keyboard_codes.h"
@@ -34,6 +35,7 @@ typedef struct {
 
 void _GetKeyMap(const v8::FunctionCallbackInfo<v8::Value>& args);
 void _GetCurrentKeyboardLayout(const v8::FunctionCallbackInfo<v8::Value>& args);
+void _OnDidChangeKeyboardLayout(const v8::FunctionCallbackInfo<v8::Value>& args);
 
 }  // namespace vscode_keyboard