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Re: [Qemu-devel] [PATCH] vnc: add additional key up event before repeate
From: |
Anthony Liguori |
Subject: |
Re: [Qemu-devel] [PATCH] vnc: add additional key up event before repeated key down |
Date: |
Tue, 9 Sep 2014 20:47:56 -0700 |
On Tue, Sep 9, 2014 at 8:31 PM, Chun Yan Liu <address@hidden> wrote:
>
>
>>>> On 9/10/2014 at 02:23 AM, in message <address@hidden>,
> Markus Armbruster <address@hidden> wrote:
>> "Chun Yan Liu" <address@hidden> writes:
>>
>>>>>> On 9/6/2014 at 05:23 AM, in message
>> > <address@hidden>, Stefano
>> > Stabellini <address@hidden> wrote:
>> >> On Fri, 5 Sep 2014, Chunyan Liu wrote:
>> >> > Using xen tools 'xl vncviewer' with tigervnc (default on SLE-12),
>> >> > found that: the display of the guest is unexpected while keep
>> >> > pressing a key. We expect the same character multiple times, but
>> >> > it prints only one time. This happens on a PV guest in text mode.
>> >> >
>> >> > After debugging, found that tigervnc sends repeated key down events
>> >> > in this case, to differentiate from user pressing the same key many
>> >> > times. Vnc server only prints the character when it finally receives
>> >> > key up event.
>> >>
>> >> Is this actually how a vnc client should behave?
>> >> How do the vnc client and server from realvnc behave in this regard
>> >> (they are the reference implementation)?
>> >
>> > VNC protocol doesn't specify how to handle key repetition. Tightvnc
>> > sends key-down&key-up repeatedly, but some example like RealVNC for
>> > Windows does the same thing - it sends only repeated key-down.
>> >
>> > Generally the VNC keyboard handling gives lot of space for interpretation
>> > and so the implementations differ.
>>
>> If implementations differ, and QEMU already behaves like some of them,
>> then why change it?
>
> To change qemu side because we could not expect each VNC client behaves
> the same when holding key down, some sending key-down, key-up, key-down,
> key-up; but some sending key-down, key-down, key-down .... Without change,
> client only sending key-down, key-up, key-down,key-up ... can get correct
> display.
The VNC keyboard handling is pretty straight forward. The keys sent
are symbolic and correspond to input events (as interpreted by an
application). Whether you get repeat events depends on a lot of
client side configuration.
>> What exactly gets fixed and what gets broken by the
>> proposed change?
>
> Holding the key down, only one character is printed, but repeated characters
> are expected. Happens on some vnc client. Either vnc client or vnc server
> should change some to match.
You should fix TigerVNC. It's broken if it isn't sending repeat events.
Regards,
Anthony Liguori
>>
>> [...]
>>
>>
>
>
>
- [Qemu-devel] [PATCH] vnc: add additional key up event before repeated key down, Chunyan Liu, 2014/09/04
- Re: [Qemu-devel] [PATCH] vnc: add additional key up event before repeated key down, Stefano Stabellini, 2014/09/05
- Re: [Qemu-devel] [PATCH] vnc: add additional key up event before repeated key down, Chun Yan Liu, 2014/09/08
- Re: [Qemu-devel] [PATCH] vnc: add additional key up event before repeated key down, Markus Armbruster, 2014/09/09
- Re: [Qemu-devel] [PATCH] vnc: add additional key up event before repeated key down, Chun Yan Liu, 2014/09/09
- Re: [Qemu-devel] [PATCH] vnc: add additional key up event before repeated key down,
Anthony Liguori <=
- Re: [Qemu-devel] [PATCH] vnc: add additional key up event before repeated key down, Chun Yan Liu, 2014/09/10
- Re: [Qemu-devel] [PATCH] vnc: add additional key up event before repeated key down, Markus Armbruster, 2014/09/17
- Re: [Qemu-devel] [PATCH] vnc: add additional key up event before repeated key down, Peter Maydell, 2014/09/17
- Re: [Qemu-devel] [PATCH] vnc: add additional key up event before repeated key down, Markus Armbruster, 2014/09/17
- Re: [Qemu-devel] [PATCH] vnc: add additional key up event before repeated key down, Gerd Hoffmann, 2014/09/17
- Re: [Qemu-devel] [PATCH] vnc: add additional key up event before repeated key down, Peter Maydell, 2014/09/17
- [Qemu-devel] 答复: [PATCH] vnc: add additional key up event before repeated key down, Li, Guang, 2014/09/18