Re: [PATCH 1/3] ui/sdl2: reenable the SDL2 Windows keyboard hook procedure

[Stefan Weil via <qemu-devel@nongnu.org>]

Am 09.09.24 um 09:26 schrieb Marc-André Lureau:

> Hi
>
> On Mon, Sep 9, 2024 at 10:22 AM Volker Rümelin <vr_qemu@t-online.de> wrote:
>> Windows only:
>>
>> The libSDL2 Windows message loop needs the libSDL2 Windows low
>> level keyboard hook procedure to grab the left and right Windows
>> keys correctly. Reenable the SDL2 Windows keyboard hook procedure.
>>
>> Because the QEMU Windows keyboard hook procedure is still needed
>> to filter out the special left Control key event for every Alt Gr
>> key event, it's important to install the two keyboard hook
>> procedures in the following order. First the SDL2 procedure, then
>> the QEMU procedure.
>>
>> Resolves: https://gitlab.com/qemu-project/qemu/-/issues/2139
>> Resolves: https://gitlab.com/qemu-project/qemu/-/issues/2323
>> Tested-by: Howard Spoelstra <hsp.cat7@gmail.com>
>> Signed-off-by: Volker Rümelin <vr_qemu@t-online.de>
>> ---
>>   ui/sdl2.c           | 53 ++++++++++++++++++++++++++++++---------------
>>   ui/win32-kbd-hook.c |  3 +++
>>   2 files changed, 38 insertions(+), 18 deletions(-)
>>
>> diff --git a/ui/sdl2.c b/ui/sdl2.c
>> index 98ed974371..ac37c173a1 100644
>> --- a/ui/sdl2.c
>> +++ b/ui/sdl2.c
[...]
>> @@ -877,6 +883,17 @@ static void sdl2_display_init(DisplayState *ds, DisplayOptions *o)
>>       SDL_EnableScreenSaver();
>>       memset(&info, 0, sizeof(info));
>>       SDL_VERSION(&info.version);
>> +    /*
>> +     * Since version 2.16.0 under Windows, SDL2 has its own low level
>> +     * keyboard hook procedure to grab the keyboard. The remaining task of
>> +     * QEMU's low level keyboard hook procedure is to filter out the special
>> +     * left Control up/down key event for every Alt Gr key event on keyboards
>> +     * with an international layout.
>> +     */
>> +    SDL_GetVersion(&ver);
>> +    if (ver.major == 2 && ver.minor < 16) {
>> +        win32_kbd_grab = true;
>> +    }
>>
> Note: there is no 2.16 release. They jumped from 2.0.22 to 2.24 (see
> https://github.com/libsdl-org/SDL/releases/tag/release-2.24.0)
>
> The windows hook was indeed added in 2.0.16, released on Aug 10, 2021.
>
> Given the distribution nature of the Windows binaries, I think we
> could simply depend on a much recent version without worrying about
> compatibility with < 2.0.16. This would help reduce the potential
> combinations of versions and bugs reports.

[...]

I agree. My builds for Windows typically use the very latest versions, 
for example mingw-w64-i686-SDL2-2.30.7-1-any for the next build. So 
depending on a recent SDL version would be fine for me.

Stefan W.