FFI Definitions of Windows win32 api for node-ffi
Calling win32 native functions come from user32.dll, kernel32.dll, comctl32.dll by Node.js
npm install --save win32-api// find calc's hWnd, need run a calculator program manually at first
/**
* expose module:
* C, Comctl32 for Comctl32 from lib/comctl32/api
* K, Kernel32 for kernel32 from lib/kernel32/api
* U, User32 for user32 from lib/user32/api
*/
const {K, U} = require('win32-api'); // or {Kernel32, User32}
const ref = require('ref');
const knl32 = K.load();
const user32 = U.load(); // load all apis defined in lib/{dll}/api from user32.dll
// const user32 = U.load(['FindWindowExW']); // load only one api defined in lib/{dll}/api from user32.dll
const title = 'Calculator\0'; // null-terminated string
// const title = '计算器\0'; // string in chinese
const lpszWindow = Buffer.from(title, 'ucs2');
const hWnd = user32.FindWindowExW(null, null, null, lpszWindow);
if (hWnd && ! hWnd.isNull()) {
// Caution: output hWnd will cuase exception in the following process, even next script!
// So do NOT do this in the production code!
// console.log('buf: ', hWnd); // avoid this
console.log('buf: ', ref.address(hWnd)); // this is ok
// Change title of the Calculator
const res = user32.SetWindowTextW(hWnd, Buffer.from('Node-Calculator\0', 'ucs2'));
if ( ! res) {
// See: [System Error Codes] below
const errcode = knl32.GetLastError();
const len = 255;
const buf = Buffer.alloc(len);
const p = 0x00001000 | 0x00000200; // FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_IGNORE_INSERTS
const langid = 0x0409; // 0x0409: US, 0x0000: Neutral locale language
const msglen = knl32.FormatMessageW(p, null, errcode, langid, buf, len, null);
if (msglen) {
console.log(ref.reinterpretUntilZeros(buf, 2).toString('ucs2'));
}
}
else {
console.log('window title changed');
}
}// use the types exposed by the module for TypeScript dev
import { U } from 'win32-api';
import * as ref from 'ref';
// so we can all agree that a buffer with the int value written
// to it could be represented as an "int *"
const buf = Buffer.alloc(4);
buf.writeInt32LE(12345, 0);
const hex = ref.hexAddress(buf);
console.log(typeof hex);
console.log(hex); // ← '7FA89D006FD8'
buf.type = ref.types.int; // @ts-ignore
// now we can dereference to get the "meaningful" value
console.log(ref.deref(buf)); // ← 12345// struct usage by ref-struct
import * as Struct from 'ref-struct';
import { DStruct as DS } from 'win32-api';
// https://msdn.microsoft.com/en-us/library/windows/desktop/dd162805(v=vs.85).aspx
const point = new Struct(DS.POINT)();
point.x = 100;
point.y = 200;
console.log(point);// usage of types and windef:
import { K, FModel as FM, DTypes as W } from 'win32-api';
import * as ref from 'ref';
const knl32 = K.load();
const buf = <FM.FFIBuffer> Buffer.alloc(4); // ← here the types
buf.writeInt32LE(12345, 0);
// const hInstance =<FM.FFIBuffer> Buffer.alloc(process.arch === 'x64' ? 8 : 4);
const hInstance = <FM.FFIBuffer> ref.alloc(W.HINSTANCE); // W.HINSTANCE is 'int64*' under x64, 'int32*' under ia32
knl32.GetModuleHandleExW(0, null, hInstance);- If installation of node-gyp fails: Check out node-gyp and windows-build-tools