Question

我正在尝试创建一个窗口，然后获取所创建窗口的hwnd。

目前，我调用subprocess.run("run.exe")来创建窗口，然后继续调用wg.GetForegroundWindow()来获取前景窗口的hwnd，它应该是新创建的窗口。但是，这不能很好地工作，因为程序必须在它被检测为前景之前完成打开，并且用户可以在平均时间内改变焦点。

是否有更一致的方法来获取hwnd？

编辑：以下评论帮助我现在正在做的事情：

def create_window():
    user32 = ctypes.windll.user32
    ole32 = ctypes.windll.ole32

    EVENT_OBJECT_CREATE = 0x8000
    def callback(hWinEventHook, event, hwnd, idObject, idChild, dwEventThread, dwmsEventTime):
        if is_real_window(hwnd):
            print(get_text(hwnd), "HOOKED")
            user32.UnhookWinEvent(hWinEventHook)
            return hwnd

    WinEventProcType = ctypes.WINFUNCTYPE(
        None, 
        ctypes.wintypes.HANDLE,
        ctypes.wintypes.DWORD,
        ctypes.wintypes.HWND,
        ctypes.wintypes.LONG,
        ctypes.wintypes.LONG,
        ctypes.wintypes.DWORD,
        ctypes.wintypes.DWORD
    )

    WinEventProc = WinEventProcType(callback)

    user32.SetWinEventHook.restype = ctypes.wintypes.HANDLE
    hook = user32.SetWinEventHook(
        EVENT_OBJECT_CREATE,
        EVENT_OBJECT_CREATE,
        0,
        WinEventProc,
        0,
        0,
        0
    )
    if hook == 0:
        print('SetWinEventHook failed')
        sys.exit(1)

    msg = ctypes.wintypes.MSG()

    x = subprocess.Popen("C:\\cygwin64\\bin\\mintty.exe")

    m = user32.GetMessageW(ctypes.byref(msg), 0, 0, 0)

然而，这面临两个问题。第一个，虽然我可以在回调函数中访问hwnd，但似乎没有办法让create_window返回这个值。其次，即使在调用UnhookWinEvent之后，GetMessage窗口仍继续运行。

我可以做些什么来解决这些问题？

Answer 1

分配在回调中收到的hwnd与范围有关。回调函数是异步调用的，因此不可能返回值。相反，您可以将值分配给另一个作用域中的变量，例如到全局变量：
```
def callback((hWinEventHook, event, hwnd, ...):
    global HWND
    HWND = hwnd
    ....
```
尽管GetMessage可以永远运行，但实际上它正在等待消息发送。发布到它的消息队列。正如Microsoft Docs for the GetMessage function中所述：

从调用线程的消息队列中检索消息。该功能分派传入的已发送消息，直到发布的消息可供检索为止。

在调用GetMessage之前，请记住存储线程ID，例如在全局变量中：
```
def create_window(..):
    global THREAD_ID
    THREAD_ID = win32api.GetCurrentThreadId()

    ...
    m = user32.GetMessageW(ctypes.byref(msg), 0, 0, 0)
```
因此，任何发布到安装该挂钩的线程的消息都会使 GetMessage停止“运行”并返回一个值：
```
def callback(...):
    ...
    win32gui.PostThreadMessage(THREAD_ID, win32con.WM_QUIT, 0, 0)
    # also valid:
    # win32gui.PostThreadMessage(THREAD_ID, win32con.WM_MOVE, 0, 0)  
```

要进行摘钩，首先需要GetMessage循环退出。自然调用UnhookWinEvent的位置在GetMessage之后，因此当后面退出，将完成下一步的摘机：

def create_window(hWinEventHook, event, hwnd, ...):
    ...
    m = user32.GetMessage(ctypes.byref(msg), 0, 0, 0)
    user32.UnhookWinEvent( hWinEventHook )
    return HWND

要轻松地将回调中收到的hwnd与可执行文件进行匹配，有一个有用的getProcessFileaname函数，它返回完整路径到可执行文件（由于要点的作者） keturn/trackwindow.py）

"""
Much credit to Eric Blade for this:
https://mail.python.org/pipermail/python-win32/2009-July/009381.html
and David Heffernan:
http://stackoverflow.com/a/15898768/9585
"""
import win32con
import ctypes
import ctypes.wintypes

user32 = ctypes.windll.user32
kernel32 = ctypes.windll.kernel32


# limited information would be sufficient, but our platform doesn't have it.
processFlag = getattr(win32con, 'PROCESS_QUERY_LIMITED_INFORMATION',
                      win32con.PROCESS_QUERY_INFORMATION)

threadFlag = getattr(win32con, 'THREAD_QUERY_LIMITED_INFORMATION',
                     win32con.THREAD_QUERY_INFORMATION)


def getProcessID(dwEventThread, hwnd):
    # It's possible to have a window we can get a PID out of when the thread
    # isn't accessible, but it's also possible to get called with no window,
    # so we have two approaches.

    hThread = kernel32.OpenThread(threadFlag, 0, dwEventThread)

    if hThread:
        try:
            processID = kernel32.GetProcessIdOfThread(hThread)
            if not processID:
                print("Couldn't get process for thread %s: %s" %
                         (hThread, ctypes.WinError()))
        finally:
            kernel32.CloseHandle(hThread)
    else:
        errors = ["No thread handle for %s: %s" %
                  (dwEventThread, ctypes.WinError(),)]

        if hwnd:
            processID = ctypes.wintypes.DWORD()
            threadID = user32.GetWindowThreadProcessId(
                hwnd, ctypes.byref(processID))
            if threadID != dwEventThread:
                print("Window thread != event thread? %s != %s" %
                         (threadID, dwEventThread))
            if processID:
                processID = processID.value
            else:
                errors.append(
                    "GetWindowThreadProcessID(%s) didn't work either: %s" % (
                    hwnd, ctypes.WinError()))
                processID = None
        else:
            processID = None

        if not processID:
            for err in errors:
                print(err)

    return processID


def getProcessFilename(processID):
    hProcess = kernel32.OpenProcess(processFlag, 0, processID)
    if not hProcess:
        print("OpenProcess(%s) failed: %s" % (processID, ctypes.WinError()))
        return None

    try:
        filenameBufferSize = ctypes.wintypes.DWORD(4096)
        filename = ctypes.create_unicode_buffer(filenameBufferSize.value)
        kernel32.QueryFullProcessImageNameW(hProcess, 0, ctypes.byref(filename),
                                            ctypes.byref(filenameBufferSize))

        return filename.value
    finally:
        kernel32.CloseHandle(hProcess)

获取创建窗口的hwnd处理程序

1 个答案: