aborting Windows IME composition / clearing composition string

Question

I'm having trouble aborting IME composition on Windows.

I'm handling WM_IME_STARTCOMPOSITION and positioning my candidate window, and WM_IME_COMPOSITION as I press a key to start composing as you'd expect. I'm then handling WM_IME_ENDCOMPOSITION at the end and normal use cases are fine.

However, my problem is when I change focus inside of the application. I don't receive WM_IME_ENDCOMPOSITION so I have to deal with this situation manually. What I am doing is this:

ImmNotifyIME( himc, NI_COMPOSITIONSTR, CPS_CANCEL, 0 );
ImmNotifyIME( himc, NI_CLOSECANDIDATE, 0, 0 );

The candidate list correctly disappears, but the composition string isn't cleared. If I then call ImmGetCompositionString with GCS_COMPSTR, it's still there. Therefore if I give focus back, receive WM_IME_STARTCOMPOSITION and the first WM_IME_COMPOSITION - I end up inheriting the previous composition string, which I don't want. I want to start afresh.

ImmSetCompositionString() looks also like it would work but I can't figure out how to get it to clear the string.

Does anyone have any suggestions? MSDN seems to suggest that the calls to ImmNotifyIME() would do the job, but I must be missing something.

Answer 1

You may clear composition with this:

ImmSetCompositionStringW(himc, SCS_SETSTR, L"", sizeof(wchar_t), L"", sizeof(wchar_t));

In addition, in my application, when input loses focus I release input context:

ImmReleaseContext(hwnd, himc);

And get it again when focus gained:

ImmGetContext(hwnd);