win32-api

FFI Definitions of Windows win32 api for node-ffi-napi

Initialization

npm run repo:init

Packages

Package	Version	Dependencies	DevDependencies
win32-api
win32-def

What can I do with this?

Calling win32 native functions come from user32.dll, kernel32.dll, comctl32.dll by Node.js via node-ffi-napi

Installing

npm install win32-api

Usage

Find window and set window title

// **Find calc's hWnd, need running a calculator program manually at first**

/**
 * exposed modules:
 * C, Comctl32 for Comctl32 from lib/comctl32/api
 * K, Kernel32 for kernel32 from lib/kernel32/api
 * U, User32 for user32 from lib/user32/api
 */
import { K, U } from 'win32-api'
import * as ref from 'ref-napi'

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'    // null-terminated string 字符串必须以\0即null结尾!

const lpszWindow = Buffer.from(title, 'ucs2')
const hWnd = user32.FindWindowExW(0, 0, null, lpszWindow)

if (typeof hWnd === 'number' && hWnd > 0
  || typeof hWnd === 'bigint' && hWnd > 0
  || typeof hWnd === 'string' && hWnd.length > 0
) {
  console.log('buf: ', hWnd)

  // Change title of the Calculator
  const res = user32.SetWindowTextW(hWnd, Buffer.from('Node-Calculator\0', 'ucs2'))

  if ( ! res) {
    console.log('SetWindowTextW failed')
  }
  else {
    console.log('window title changed')
  }
}

Ref

import { U } from 'win32-api'
import * as ref from 'ref-napi'

// 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

// use of types and windef:

import * as ref from 'ref-napi'
import { K, DTypes as W } from 'win32-api'


const knl32 = K.load()

const lpszClass = Buffer.from('guard64\0', 'ucs2')
const hInstanceBuffer = ref.alloc(W.HANDLE_PVOID)
const hInstanceAddr = ref.address(hInstanceBuffer)

knl32.GetModuleHandleExW(0, lpszClass, hInstanceAddr)
// <[email protected] 00 00 a4 60 ff 7f 00 00, type: { indirection: 2, name: 'uint64*' }>
console.log(hInstanceBuffer)
console.log(hInstanceBuffer.readInt32LE(0))     // -> 1621360640           (60A40000)
console.log(hInstanceBuffer.readBigUInt64LE())  // -> 140734814748672n (7FFF60A40000)

Struct

// struct usage with ref-struct
import * as Struct from 'ref-struct'
import { DModel as M, DStruct as DS } from 'win32-api'

// https://msdn.microsoft.com/en-us/library/windows/desktop/dd162805(v=vs.85).aspx
const point: M.POINT_Struct = new Struct(DS.POINT)()
point.x = 100
point.y = 200
console.log(point)

// struct usage with ref-struct-di
import * as ref from 'ref-napi'
import * as StructDi from 'ref-struct-di'
import { DModel as M, DStruct as DS } from 'win32-api'

const Struct = StructDi(ref)
const point: M.POINT_Struct = new Struct(DS.POINT)()
point.x = 100
point.y = 200
console.log(point)

StructExt

// struct usage with ref-struct
import * as Struct from 'ref-struct-napi'
import {
  DModel as M,
  DStructExt,
} from 'win32-api'


// https://docs.microsoft.com/zh-cn/windows/win32/api/wingdi/ns-wingdi-display_devicew 
const dd: M.DISPLAY_DEVICEW_Struct = new Struct(DStructExt.DISPLAY_DEVICEW)()
dd.cb = dd.ref().byteLength
console.log(dd)
/**
Detail in:
https://github.com/waitingsong/node-win32-api/blob/master/packages/win32-api/src/data-struct-ext/wingdi.h.ts
https://github.com/waitingsong/node-win32-api/blob/master/packages/win32-api/test/user32/60_EnumDisplayDevicesW.test.ts
*/

Async Find window and set window title

// **Find calc's hWnd, need running a calculator program manually at first**

import { U } from 'win32-api'
import * as ref from 'ref-napi'


const u32 = U.load(['FindWindowExW', 'SetWindowTextW'])
const lpszClass = Buffer.from('CalcFrame\0', 'ucs2')

u32.FindWindowExW.async(0, 0, lpszClass, null, (err, hWnd) => {
  if (err) {
    throw err
  }

  if (typeof hWnd === 'number' && hWnd > 0
    || typeof hWnd === 'bigint' && hWnd > 0
    || typeof hWnd === 'string' && hWnd.length > 0
  ) {
    const title = 'Node-Calculator'
    // Change title of the Calculator
    u32.SetWindowTextW.async(hWnd, Buffer.from(title + '\0', 'ucs2'), err2 => {
      if (err2) {
        throw err2
      }

      const buf = Buffer.alloc(title.length * 2)
      u32.GetWindowTextW.async(hWnd, buf, buf.byteLength, err3 => {
        if (err3) {
          throw err3
        }

        const str = buf.toString('ucs2').replace(/\0+$/, '')
        if (str !== title) {
          throw new Error(`title should be changed to ${title}, bug got ${str}`)
        }
      })
    })
  }
  else {
    throw new Error('FindWindowExW() failed')
  }
})

Demo

• create_window
• Demos
• Tests

Dependencies Troubleshooting

Compile successfully with

• Node.js v12, Python v3.7 and VS2017
• Node.js v10, Python v2.7 and VS2017

If installation of node-gyp fails: Check out node-gyp and windows-build-tools

Relevant

• Windows Api documentation
• Windows Data Types
• System Error Codes
• FFI doc
• ref doc
• ref-struct

License

MIT

Languages

• English
• 中文