win32-api/src/util/user32/GetWindowText.ts

FFI definitions of windows win32 api for node-ffi

import assert from 'node:assert'

import { ucsBufferToString } from 'win32-def'

import { load } from '##/lib/user32/index.js'
import type { LibUser32 } from '##/lib/user32/index.js'


const fnName: keyof LibUser32 = 'GetWindowTextW'
const fnAsyncName: keyof LibUser32 = 'GetWindowTextW_Async'
type FnType = LibUser32[typeof fnAsyncName]
// type RetType = ReturnType<FnType>
type ParamType = Parameters<FnType>

/**
 * Retrieves a handle to a window whose class name and window name match the specified strings.
 * The function searches child windows, beginning with the one following the specified child window.
 * This function does not perform a case-sensitive search.
 * @link https://learn.microsoft.com/en-us/windows/win32/api/winuser/nf-winuser-getwindowtextw
 *
 * 检索其类名和窗口名称与指定字符串匹配的窗口的句柄。 函数搜索子窗口，从指定子窗口后面的子窗口开始。 此函数不执行区分大小写的搜索。
 * @link https://learn.microsoft.com/zh-cn/windows/win32/api/winuser/nf-winuser-getwindowtextw
 */
export async function GetWindowText(
  hWnd: ParamType[0],
  nMaxCount: ParamType[2],
): Promise<string> {

  const lib = load([fnName])
  const fn = lib[fnAsyncName] as FnType
  assert(typeof fn === 'function', `Function "${fnAsyncName}" not found`)

  const buf = Buffer.alloc(nMaxCount * 2)
  const resLength = await fn(hWnd, buf, nMaxCount)
  const len2 = Math.min(resLength, nMaxCount - 1)

  const title = ucsBufferToString(buf, len2)
  return title || ''
}