[dialer] pressing power button should silence incoming call

Proposed solution: When the phone is ringing and you don't want to answer it or decline the call, "say its in your pocket" pressing the down volume button on the side of the phone should mute the ringer.

Status changed to 'Confirmed' because the bug affects multiple users.

As agreed at the sprint in DC, pressing the power button when an incoming call is happening should cause the ringer and haptic feedback to stop immediately, effectively "dismissing" the call.

Marking this as critical because all phones have a way to silence the call without rejecting it (which causes it to go immediately to voice mail). Pretty basic feature that we should have.

We just need a signal we can listen for in telephony-service when the power button is pressed and then we can handle the rest.

just a remind we need to listen for both pressed and release (fast pressed and release), to avoid conflict with the long press used to turn off the phone.

a proper solution would require unity-system-compositor to "know" the telephony state to not blank screen & emit button press. (right now unity-system-compositor does not emit button press only screen on/off)

By pressing the down button the call is not "dismissed" but silenced. The caller will not know that action from the user. If a user dismisses a call, the other side always knows or receives some sort of feedback.

@olga - but would the call be dismissed on the second strike ?

e.g. incoming call
user presses power key once - silences ringtone/vibra off, but screen stays on with incoming call info/swipe to act available
user presses power key again (second time) - call is rejected, screen is turned off

@Kevin I think we considered the volume down button before the power button but if we can do it for the power button, fine by me. As for the use case you described, go ahead. I think this is an elegant solution.

Hey, how about turning the phone display down? I've been using that for many years and really miss it on Ubuntu.

QtGestures provides a recognition pattern for that gesture already, including making sure that it doesn't happen by accident etc. So only if the phone is sitting on a flat surface, display facing upwards, an incoming call comes in, you turn it around and it'll shut up.

Here's the gesture I'm talking about (search for "turnover"): https://bugs.launchpad.net/ubuntu-ux/+bug/1388070

> Hey, how about turning the phone display down? I've been using that for
> many years and really miss it on Ubuntu.

I think once we come up with a generic solution for "shutting things
up", adding that gesture should be relatively easy. But a power/volume
button press to start with is probably as useful.

Please refer to specifications in the following link, p 34.
https://docs.google.com/a/canonical.com/document/d/1BRy9-DEXr3A1D7PHkJaXmjbe7xbRmxKkzANXuu-F6lc/edit#

fix when we can as this is a very common use case and reported in testing

Status changed to 'Confirmed' because the bug affects multiple users.

This bug was fixed in the package telephony-service - 0.1+15.04.20150120.2-0ubuntu1

---------------
telephony-service (0.1+15.04.20150120.2-0ubuntu1) vivid; urgency=low

  [ CI Train Bot ]
  * Resync trunk

  [ Tiago Salem Herrmann ]
  * Invoke LiveCall view when answering incoming calls. (LP: #1410961)
  * Silence incoming calls when power button is pressed. (LP: #1376240)
 -- Ubuntu daily release <email address hidden> Tue, 20 Jan 2015 16:53:13 +0000

This bug was fixed in the package telephony-service - 0.1+15.04.20150121~rtm-0ubuntu1

---------------
telephony-service (0.1+15.04.20150121~rtm-0ubuntu1) 14.09; urgency=low

  [ Ubuntu daily release ]
  * New rebuild forced

  [ Gustavo Pichorim Boiko ]
  * Update pot file.
  * Silence incoming calls when power button is pressed. (LP: #1376240)
  * Check if the account exists before accessing the pointer. (LP:
    #1408029)
 -- Ubuntu daily release <email address hidden> Wed, 21 Jan 2015 22:04:24 +0000

I think this bug is only partially fixed. An incoming call is not silenced by tapping the power button, however the screen goes dark first and users don't know if the call continues "ringing". Switching the screen off gives the impression that the call was declined.

The desired solution is: press the power button and silence/mute call.
Second press: screen goes dark.

As per comment #10