ImmGetContext returns error 0 when calling across processes

Question

ImmGetContext returns error 0 when calling across processes

Yucheng Song 41

Hi, I'm trying to use ImmGetContext to get the IME context of another process's window, but getting error "himc = 0". The documentation doesn't mention any process boundary restrictions.

Code:

import time

import win32api
import win32gui
import ctypes
from ctypes import windll, byref, c_uint, c_wchar


def switch_to_english():
    # 获取输入法上下文
    imm32 = ctypes.windll.imm32
    # 获取前台窗口句柄
    hwnd1 = win32gui.GetForegroundWindow()
    hwnd = ctypes.windll.imm32.ImmGetDefaultIMEWnd(hwnd1)
    if not hwnd:
        print("无法获取活动窗口")
        return False
    # 尝试获取当前具有键盘输入焦点的窗口句柄
    focus_hwnd = win32gui.GetFocus()

    # 优先尝试对 focus_hwnd 调用 ImmGetContext
    if focus_hwnd:
        print("1")
        himc = imm32.ImmGetContext(focus_hwnd)
    else:
        print("2")
        himc = imm32.ImmGetContext(hwnd)

    if not himc:
        print("无法获取 IME 上下文")
        return False
    from ctypes import wintypes

    HWND = wintypes.HWND
    BOOL = wintypes.BOOL
    DWORD = wintypes.DWORD

    if himc:
        # 设置为英文模式
        conversion = DWORD(0)
        sentence = DWORD(0)
        imm32.ImmGetConversionStatus(himc, byref(conversion), byref(sentence))
        # conversion.value &= ~0x0001
        imm32.ImmSetConversionStatus(himc, conversion.value, sentence.value)
        imm32.ImmSetOpenStatus(himc, BOOL(0))
    # time.sleep(2)


if __name__ == '__main__':
    switch_to_english()

Output:

2
Failed to get IME context

Process finished with exit code 0

Environment:

Windows Version: Windows 10 22H2
Python Version: Python 3.13.0
Running with administrator privileges

Questions:

Is ImmGetContext designed to work across process boundaries?
If yes, what additional permissions or settings are needed?
If not, what's the recommended way to control IME status of windows from other processes?

I've checked the documentation at https://learn.microsoft.com/en-us/windows/win32/api/imm/nf-imm-immgetcontext but found no explicit mention of process boundary restrictions.

Jeanine Zhang-MSFT 11,356 Reputation points Microsoft External Staff

2024-12-09T01:54:56.87+00:00

According to your code, it is python. And it is out of our support scope. If you could reproduce the issue in the win32 app, we could provide better help.

Yucheng Song 41

Hi, here is a C++ code,

#include <iostream>

#include <windows.h>
#include <imm.h>
#include <stdio.h>

#pragma comment(lib, "imm32.lib")

int main() {
    // 找到目标窗口（这里以记事本为例）
    HWND targetWindow = FindWindow(L"Notepad", NULL);
    if (!targetWindow) {
        printf("Cannot find target window\n");
        return 1;
    }

    // 尝试获取IME上下文
    HIMC himc = ImmGetContext(targetWindow);
    if (!himc) {
        printf("ImmGetContext failed, error: %d\n", GetLastError());
        return 1;
    }

    // 尝试获取转换状态
    DWORD dwConversion, dwSentence;
    if (!ImmGetConversionStatus(himc, &dwConversion, &dwSentence)) {
        printf("ImmGetConversionStatus failed\n");
        ImmReleaseContext(targetWindow, himc);
        return 1;
    }

    // 释放上下文
    ImmReleaseContext(targetWindow, himc);

    return 0;
}

Deleted

This comment has been deleted due to a violation of our Code of Conduct. The comment was manually reported or identified through automated detection before action was taken. Please refer to our Code of Conduct for more information.

Yucheng Song 41

Hi, here is a C++ code,

#include <iostream>

#include <windows.h>
#include <imm.h>
#include <stdio.h>

#pragma comment(lib, "imm32.lib")

int main() {
    // 找到目标窗口（这里以记事本为例）
    HWND targetWindow = FindWindow(L"Notepad", NULL);
    if (!targetWindow) {
        printf("Cannot find target window\n");
        return 1;
    }

    // 尝试获取IME上下文
    HIMC himc = ImmGetContext(targetWindow);
    if (!himc) {
        printf("ImmGetContext failed, error: %d\n", GetLastError());
        return 1;
    }

    // 尝试获取转换状态
    DWORD dwConversion, dwSentence;
    if (!ImmGetConversionStatus(himc, &dwConversion, &dwSentence)) {
        printf("ImmGetConversionStatus failed\n");
        ImmReleaseContext(targetWindow, himc);
        return 1;
    }

    // 释放上下文
    ImmReleaseContext(targetWindow, himc);

    return 0;
}

Yucheng Song 41 Reputation points

2024-12-09T14:55:33.9733333+00:00

Hi, the C++ code is as below.

1 answer

Your answer

Jeanine Zhang-MSFT 11,356 Reputation points Microsoft External Staff

2024-12-09T01:54:56.87+00:00

According to your code, it is python. And it is out of our support scope. If you could reproduce the issue in the win32 app, we could provide better help.
Yucheng Song 41 Reputation points

2024-12-09T14:53:07.0933333+00:00

Hi, here is a C++ code,

#include <iostream> #include <windows.h> #include <imm.h> #include <stdio.h> #pragma comment(lib, "imm32.lib") int main() { // 找到目标窗口（这里以记事本为例） HWND targetWindow = FindWindow(L"Notepad", NULL); if (!targetWindow) { printf("Cannot find target window\n"); return 1; } // 尝试获取IME上下文 HIMC himc = ImmGetContext(targetWindow); if (!himc) { printf("ImmGetContext failed, error: %d\n", GetLastError()); return 1; } // 尝试获取转换状态 DWORD dwConversion, dwSentence; if (!ImmGetConversionStatus(himc, &dwConversion, &dwSentence)) { printf("ImmGetConversionStatus failed\n"); ImmReleaseContext(targetWindow, himc); return 1; } // 释放上下文 ImmReleaseContext(targetWindow, himc); return 0; }
Deleted

This comment has been deleted due to a violation of our Code of Conduct. The comment was manually reported or identified through automated detection before action was taken. Please refer to our Code of Conduct for more information.
Yucheng Song 41 Reputation points

2024-12-09T14:54:29.0933333+00:00

Hi, here is a C++ code,

#include <iostream> #include <windows.h> #include <imm.h> #include <stdio.h> #pragma comment(lib, "imm32.lib") int main() { // 找到目标窗口（这里以记事本为例） HWND targetWindow = FindWindow(L"Notepad", NULL); if (!targetWindow) { printf("Cannot find target window\n"); return 1; } // 尝试获取IME上下文 HIMC himc = ImmGetContext(targetWindow); if (!himc) { printf("ImmGetContext failed, error: %d\n", GetLastError()); return 1; } // 尝试获取转换状态 DWORD dwConversion, dwSentence; if (!ImmGetConversionStatus(himc, &dwConversion, &dwSentence)) { printf("ImmGetConversionStatus failed\n"); ImmReleaseContext(targetWindow, himc); return 1; } // 释放上下文 ImmReleaseContext(targetWindow, himc); return 0; }
Yucheng Song 41 Reputation points

2024-12-09T14:55:33.9733333+00:00

Hi, the C++ code is as below.

Answer 1

ImmGetContext is not designed to work across process boundaries. The documentation indicates that a thread should not access the input context created by another thread, which implies that the function is intended for use within the same process. Therefore, when you attempt to call ImmGetContext on a window from another process, it will fail, resulting in a handle of 0.

To control the IME status of windows from other processes, you would need to use inter-process communication (IPC) methods to send messages or commands to the target process, which can then handle the IME context appropriately within its own execution context.

References:

Share via

ImmGetContext returns error 0 when calling across processes

1 answer

Your answer