Re: [PATCH v3 0/5] MR944: win32u: Make desktop resize logic asynchronous.

[Zhiyi Zhang (＠zhiyi)]

On Thu Sep 29 10:36:42 2022 +0000, Rémi Bernon wrote:
> Hmm, I think that's the same logic as how it is currently done:
> `X11DRV_resize_desktop` is already sending a message to the desktop
> window if it's not called from the desktop thread, so its actual logic
> is only executed from the desktop thread:
> https://gitlab.winehq.org/wine/wine/-/blob/master/dlls/winex11.drv/desktop.c...
>     if (NtUserGetWindowThread( hwnd, NULL ) != GetCurrentThreadId())
>     {
>         send_message( hwnd, WM_X11DRV_RESIZE_DESKTOP, 0, 0 );
>     }
>     else
>     {
>         /* ... */
>         ungrab_clipping_window();
>     }
>
> From that thread, `ungrab_clipping_window` indeed skips the
> `XUngrabPointer`, but sends a `WM_X11DRV_CLIP_CURSOR_NOTIFY` message to
> the desktop window (so the thread itself):
> https://gitlab.winehq.org/wine/wine/-/blob/master/dlls/winex11.drv/mouse.c#L...
> void ungrab_clipping_window(void)
> {
>     /* ... */
>     if (clipping_cursor) XUngrabPointer( display, CurrentTime );
>     clipping_cursor = FALSE;
>     send_notify_message( NtUserGetDesktopWindow(),
> WM_X11DRV_CLIP_CURSOR_NOTIFY, 0, 0 );
> }
>
> Which is later use to reset some desktop clip_hwnd variable, and
> forwarded to the previously clipping window:
> https://gitlab.winehq.org/wine/wine/-/blob/master/dlls/winex11.drv/mouse.c#L...
>     if (hwnd == NtUserGetDesktopWindow())  /* change the clip window
> stored in the desktop process */
>     {
>         static HWND clip_hwnd;
>         HWND prev = clip_hwnd;
>         clip_hwnd = new_clip_hwnd;
>         if (prev) send_notify_message( prev,
> WM_X11DRV_CLIP_CURSOR_NOTIFY, (WPARAM)prev, 0 );
>     }
>
> This then translates, in the currently clipping thread, to the cursor
> being ungrabbed and the clipping window being destroyed:
> https://gitlab.winehq.org/wine/wine/-/blob/master/dlls/winex11.drv/mouse.c#L...
>     else if (hwnd == data->clip_hwnd)  /* this is a notification that
> clipping has been reset */
>     {
>         disable_xinput2();
>         NtUserDestroyWindow( hwnd );
>     }
>
> **Then however**, I think you're right that the changes can break
> clipping, but I think it's because of
> https://gitlab.winehq.org/wine/wine/-/merge_requests/944/diffs?commit_id=1cf...
> instead:
> Moving that part to `X11DRV_resize_desktop` makes it likely never match
> the condition, because the desktop is unlikely to be the foreground
> process. Instead I think it can simply send the
> `WM_X11DRV_CLIP_CURSOR_REQUEST` to the foreground window without even
> checking the thread id / pid.
>     /* forward clip_fullscreen_window request to the foreground window */
>     if ((foreground = NtUserGetForegroundWindow()) &&
>         (tid = NtUserGetWindowThread( foreground, &pid )) && pid == GetCurrentProcessId())
>     {
>         if (tid == GetCurrentThreadId()) clip_fullscreen_window(
> foreground, TRUE );
>         else send_notify_message( foreground,
> WM_X11DRV_CLIP_CURSOR_REQUEST, TRUE, TRUE );
>     }
>
> That should still asynchronously restore clipping from the foreground
> process if fullscreen clipping is enabled, and always after the reset
> logic described above.

Yeah, that sounds about right.