Re: [Qemu-devel] [PATCH v2] ui/input: fix event emitting of repeated combined keys

[Eric Blake]

On 09/26/2014 04:53 AM, Amos Kong wrote:
> On Fri, Sep 26, 2014 at 12:36:50PM +0200, Gerd Hoffmann wrote:
>> On Fr, 2014-09-26 at 18:23 +0800, Amos Kong wrote:
>>> Currently we emit press events of combined keys first, then emit
>>> release events by reverse order. But it doesn't match with physical
>>> keyboard if the keys contain continued & repeated keys.
>>>
>>> For example, (qemu) sendkey a-b-b
>>
>> Hmm, somehow I don't feel like building too much magic into this.
>> If you want send Ctrl-somekey twice just use two sendkey commands ...
> 
> 
> Before this patch, If 'sendkey r-o-o-t', only 'rot' can be inputted.

sendkey with multiple keys is designed for shift modifiers, NOT for
repeated keys.  'sendkey r-o-o-t' makes no sense; it is the equivalent
of mashing down the 'r', 'o', and 't' keys at once.  To send four
separate key events, you need to do 'sendkey r; sendkey o; sendkey o;
sendkey t'.  (Or libvirt should learn some syntactic sugar so you could
do 'sendkey r -- o -- o -- t' and sequence it automatically).

I don't think this patch is worth the effort.

> 
> People want to panic windows by sending Ctrl-Scrool-Scrool

s/Scrool/Scroll/

> http://msdn.microsoft.com/en-us/library/windows/hardware/ff545499(v=vs.85).aspx
> But current events order doesn't work.
> 
> In physical keyboard. We can prese Ctrl first, then press & release
> Scroll twice, then release Ctrl. It's very common behavior.
> 

Hmm.  This almost argues that we need a way to send a press without a
release, or a release without a press, rather than trying to make
'sendkey Ctrl-Scroll-Scroll' emulate double scroll pushes all while ctrl
is still held down.  But this example is MUCH more realistic than
'r-o-o-t', so maybe there is merit to your patch after all.

> So this fix just reference the physical implement, if you want to
> input same key twice, you have to release it before second pressing.
> (here we ignore the auto-repeat feature)
> 


-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org

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