python - 在python中使用SendMessage在前台窗口中设置文本

Question

我们有一个旧的遗留数据库，需要来自另一个系统的输入。将数据输入数据库表单的SendInput方法缓慢且不可靠，设置剪贴板然后^v也不可靠(我不知道为什么，但数据库接口(interface)很旧，2000年代初)。经过大量摆弄后，我发现使用 SendMessage 设置文本然后发送 VK_RETURN 速度很快(比 SendInput/keybd_event 快得多)并且对我们的数据库可靠。现在这段纯 C 代码可以工作:

    HWND fghwnd = GetForegroundWindow();
    DWORD threadId = GetWindowThreadProcessId(fghwnd, NULL);
    DWORD myId = GetCurrentThreadId();
    if (AttachThreadInput(myId, threadId, true)) {
        HWND ctrl = GetFocus();
        SendMessage(ctrl, WM_SETTEXT, 0, (LPARAM) sendbuf); // TESTING
        PostMessage(ctrl, WM_KEYDOWN, VK_RETURN, 0);
        PostMessage(ctrl, WM_KEYUP, VK_RETURN, 0);
        AttachThreadInput(myId, threadId, false);
    } else {
        printf("\nError: AttachThreadInput failure!\n");
    }

但是 python 中的这个却没有:

    foregroundHwnd = win32gui.GetForegroundWindow()
    foregroundThreadID = win32process.GetWindowThreadProcessId(foregroundHwnd)[0]
    ourThreadID = win32api.GetCurrentThreadId()
    if foregroundThreadID != ourThreadID:
        win32process.AttachThreadInput(foregroundThreadID, ourThreadID, True)
        focus_whd = win32gui.GetFocus()
        win32gui.SendMessage(focus_whd, win32con.WM_SETTEXT, None, "test text")
        win32gui.PostMessage(focus_whd, win32con.WM_KEYDOWN, win32con.VK_RETURN, None)
        win32gui.PostMessage(focus_whd, win32con.WM_KEYUP, win32con.VK_RETURN, None)
        win32process.AttachThreadInput(foregroundThreadID, ourThreadID, False)

问题是，我们的大部分新逻辑都是用 python 编写的。我把 C 代码变成了一个小的 python 模块，它可以工作，但结果现在我依赖于微软庞大的编译器，并且对模块构建进行了大量的摆弄。我想要一个仅使用 python 的解决方案。

有什么想法为什么这个Python代码不起作用吗？这些系统调用看起来相同...

Answer 1

是的，AttachThreadInput 失败。根据这里的评论https://toster.ru/q/79336 win32process.GetWindowThreadProcessId 返回错误值，必须使用 ctypes。此代码有效:

"""
Fast "paste" implemented via calls to Windows internals, sends parameter
string and RETURN after that

Usage:

from paste import paste
paste("test")

"""

import time
import random
import string
from ctypes import windll
import ctypes
import win32con

def random_string(string_length=10):
    """Generate a random string of fixed length """
    letters = string.ascii_lowercase
    return ''.join(random.choice(letters) for i in range(string_length))

ERROR_INVALID_PARAMETER = 87

def paste(text_to_paste):
    """Fast "paste" using WM_SETTEXT method + Enter key"""
    current_hwnd = windll.user32.GetForegroundWindow()
    current_thread_id = windll.kernel32.GetCurrentThreadId()
    thread_process_id = windll.user32.GetWindowThreadProcessId(current_hwnd, None)
    if thread_process_id != current_thread_id:
        res = windll.user32.AttachThreadInput(thread_process_id, current_thread_id, True)
        # ERROR_INVALID_PARAMETER means that the two threads are already attached.
        if res == 0 and ctypes.GetLastError() != ERROR_INVALID_PARAMETER:
            print("WARN: could not attach thread input to thread {0} ({1})"
                .format(thread_process_id, ctypes.GetLastError()))
            return
        focus_whd = windll.user32.GetFocus()
        windll.user32.SendMessageW(focus_whd, win32con.WM_SETTEXT, None, text_to_paste)
        windll.user32.PostMessageW(focus_whd, win32con.WM_KEYDOWN, win32con.VK_RETURN, None)
        windll.user32.PostMessageW(focus_whd, win32con.WM_KEYUP, win32con.VK_RETURN, None)
        res = windll.user32.AttachThreadInput(thread_process_id, current_thread_id, True)


if __name__ == '__main__':
    time.sleep(5) # time to switch to the target
    # paste random 150 char string
    paste(random_string(150))