[TSF-Application] How to use Text Service Framework on Multithreaded Apartment thread

Windmill_City 201

Trying to Activate the UI-Thread which is in Multithreaded Apartment, but it seems the call to ITfThreadMgr->Activate has no effect.

RLWA32 40,651 Reputation points

2021-01-15T11:43:10.357+00:00

For debugging purposes I suggest you change from an assignment to ATL's CComQIPtr (which doesn't return an HRESULT upon failure) to a conventional call to QueryInterface to provide some more diagnostic information. Alternatively, you could step through the ATL internals to determine the HRESULT of the failed QueryInterface call.
Windmill_City 201 Reputation points

2021-01-15T12:02:49.73+00:00

It says No_Interface, but in STA Thread, it returns right item
RLWA32 40,651 Reputation points

2021-01-15T12:08:24.123+00:00

Maybe you need to obtain the interface pointer in an STA thread and marshal it to you MTA thread.
Windmill_City 201 Reputation points

2021-01-16T11:02:22.507+00:00

ITfThreadMgr's SetFocus function is thread relevant, if I CoCreate it on a STA Thread, it just SetFocus the STA Thread, but not my UI Thread(MTA)
If I CoCreate it on UI Thread(MTA), it just cant QueryInterface for ITfUIElementMgr(E_NOINTERFACE)
RLWA32 40,651 Reputation points

2021-01-16T12:03:34.213+00:00

Maybe I just don't understand TSF, but ordinarily a UI Thread is STA, not MTA. So I'm a bit confused here.
Windmill_City 201 Reputation points

2021-01-16T12:34:21.73+00:00

My Main-Thread is MTA, and I created a window on it
So the UI Thread is MTA
Igor Tandetnik 1,106 Reputation points

2021-01-16T13:43:59.813+00:00

Running UI on MTA thread is unwise. Windows have thread affinity, doing anything to a window from a thread other than the one that created it would either fail, or block until the "right" thread gets around to pumping messages.

QueryInterface returning E_NOINTERFACE (when you know the component does in fact implement the interface in question) usually means the interface is not marshalable, and you are querying for it in a "wrong" apartment (an apartment that doesn't match the component's model), which requires marshaling the interface.

I'm not familiar with ITfThreadMgr et al. But since it has methods that take HWND as parameter, my guess is that it's not marshalable, uses STA model, and is meant to be used from a UI thread that joins STA and pumps window messages.
RLWA32 40,651 Reputation points

2021-01-16T16:42:32.203+00:00

@Windmill_City Some more background about user interface work and the MTA - User interface code + multi-threaded apartment = death
Windmill_City 201 Reputation points

2021-01-17T04:40:27.007+00:00

thanks a lot, give up the MTA should be the right choice

Accepted answer

Windmill_City 201 Reputation points

2021-01-16T10:52:39.887+00:00

Since the instance of ITfThreadMgr created by CoCreateInstance only for Apartment Thread, you should use TF_CreateThreadMgr to create a threadMgr that can be used in both Apartment Thread and MultiThreaded Thread.
https://learn.microsoft.com/en-us/windows/win32/api/msctf/nf-msctf-tf_createthreadmgr
Please sign in to rate this answer.

0 comments No comments
Sign in to comment

[TSF-Application] How to use Text Service Framework on Multithreaded Apartment thread

0 additional answers