Re: [Qemu-devel] [PATCH] Monitor: Convert do_sendkey() to QObject, QError

Luiz Capitulino
2010-07-22T13:50:05Z

On Thu, 22 Jul 2010 14:45:35 +0100
"Daniel P. Berrange" <berrange@redhat.com> wrote:

> On Thu, Jul 22, 2010 at 10:28:39AM -0300, Luiz Capitulino wrote:
> > On Wed, 21 Jul 2010 20:06:56 +0100
> > "Daniel P. Berrange" <berrange@redhat.com> wrote:
> >
> > > On Wed, Jul 21, 2010 at 03:44:14PM -0300, Luiz Capitulino wrote:
> > > > Another related issue is that, this probably should an async handler. But
> > > > as we don't have the proper infrastructure yet, I'm ok with having this in
> > > > its current form.
> > > >
> > > > > +- "hold_time": duration in milliseconds to hold the keys down (json-int, optional, default=100)
> > >
> > > Having 'hold-time' which applies to the full list of keys is limiting
> > > the flexibility of apps. eg, it means you can only do
> > >
> > > down ctrl
> > > down alt
> > > down f1
> > > wait 100ms
> > > up ctrl
> > > up alt
> > > up f1
> > >
> > > Again I can see why the impl works this way currently, because it is
> > > clearly a nicer option for humans. For a machine protocol though it
> > > seems sub-optimal. What if app needed more flexibility over ordering
> > > of press+release events eg to release in a different order
> > >
> > > down ctrl
> > > down alt
> > > down f1
> > > wait 100ms
> > > up f1
> > > up ctrl
> > > up alt
> > >
> > > Should we just follow VNC and explicitly have a up/down flag in
> > > the protocol & let press & release events be sent separately.
> > >
> > > { "execute": "sendkey", "arguments": { "keycode": 0x31, "down": true } }
> > >
> > > We could allow multiple keycodes in one message
> > >
> > > { "execute": "sendkey", "arguments": { "keycodes": [ 0x31, 0x32 ], "down": true } }
> > >
> > > but its not really adding critical functionality that can't be got by
> > > sending a sequence of sendkey commands in a row.
> >
> > Hm, looks good to me, but then the hold time would be the time period
> > between the down/up commands. This won't be reliable in case the client
> > wants to exactly wait 100ms, as we can have network latency, for example.
> >
> > Isn't this a problem? I believe VNC doesn't have this feature, right?
>
> Correct, VNC just sends each individual press / release event as a separate
> message, so you can have network delay effects there too.
>
> If we needed to support precise delays safe from network delay for some
> simulation needs, then you'd probably need a more complex structure
> where you can provide a whole sequence of operations. And why stop at
> keys, including mouse movement & buttons to.
>
> { "execute": "sendinput", "arguments": {
> "sequence" : [
> { "event": "keypress", "keycode": 0x31 },
> { "event": "keypress", "keycode": 0x75 },
> { "event": "wait", "delay": 100 },
> { "event": "mousepress", "button": 1 },
> { "event": "mousemove", "xdelta": 1, "ydelta": 1 },
> { "event": "keyrelease", "keycode": 0x31 },
> { "event": "wait", "delay": 100 },
> { "event": "keyrelease", "keycode": 0x75 },
> { "event": "mousepos", "x": 102, "y": 102 },
> ]
> } }
>
> This is getting kind of advanced now. Whether we need this vs the simpler
> sendkey, mouse_move, etc command comes down to whether we need ability to
> set precise delays between events. We could stick with the individual
> simple commands & add a advanced one alter

Yeah, agreed and I think the current design (ie. hold_time) is simpler.