node-ffi - callback extraction of EnumWindows

Question

Requirement is to get all windows open in current desktop. I am trying to invoke EnumWindows from node-ffi which gives handler length as 0.

node reference link: node

Answer 1

I do not take credit for any of this code, it is merely the other answer on here, fix and then converted to regular Javascript instead of Coffee Script

var ref = require('ref');
var ffi = require('ffi');

var voidPtr = ref.refType(ref.types.void);
var stringPtr = ref.refType(ref.types.CString);

var user32 = ffi.Library('user32.dll', {
    EnumWindows: ['bool', [voidPtr, 'int32']],
    GetWindowTextA : ['long', ['long', stringPtr, 'long']]
});

windowProc = ffi.Callback('bool', ['long', 'int32'], function(hwnd, lParam) {
  var buf, name, ret;
  buf = new Buffer(255);
  ret = user32.GetWindowTextA(hwnd, buf, 255);
  name = ref.readCString(buf, 0);
  console.log(name);
  return true;
});

user32.EnumWindows(windowProc, 0);

Answer 2

You seem to be treating 'hwnd' as a pointer, think you can simply use a int or long. This worked for me (coffeescript) :

ref = require 'ref'
ffi = require 'ffi

voidPtr = ref.refType(ref.types.void)
stringPtr = ref.refType(ref.types.CString)

bindings =
    EnumWindows: ['bool', [voidPtr, 'int32']]
    GetWindowTextA : ['long', ['long', stringPtr, 'long']]

user32 = ffi.Library('user32.dll', bindings)

windowProc = ffi.Callback 'bool', ['long', 'int32'], (hwnd, lParam) ->
    buf = new Buffer 255
    ret = libm.GetWindowTextA hwnd, buf, 255
    name = ref.readCString(buf, 0)
    console.log name
    true

user32.EnumWindows windowProc, 0