[PATCH wayland-protocols v3] Add screensaver idle inhibitor protocol
Yong Bakos
junk at humanoriented.com
Mon Jun 6 15:08:00 UTC 2016
On Jun 6, 2016, at 7:18 AM, Pekka Paalanen <ppaalanen at gmail.com> wrote:
>
> On Fri, 3 Jun 2016 10:39:24 -0500
> Yong Bakos <junk at humanoriented.com> wrote:
>
>> Hi,
>>
>> On Jun 3, 2016, at 4:04 AM, Pekka Paalanen <ppaalanen at gmail.com> wrote:
>>>
>>> On Fri, 3 Jun 2016 09:26:24 +0800
>>> Jonas Ådahl <jadahl at gmail.com> wrote:
>>>
>>>> On Thu, Jun 02, 2016 at 02:24:20PM -0700, Bryce Harrington wrote:
>>>>> This interface allows disabling of screensaver/screenblanking on a
>>>>> per-surface basis. As long as the surface remains visible and
>>>>> non-occluded it blocks the screensaver, etc. from activating on the
>>>>> output(s) that the surface is visible on.
>>>>>
>>>>> To uninhibit, simply destroy the inhibitor object.
>>>>>
>>>>> Signed-off-by: Bryce Harrington <bryce at bryceharrington.org>
>>>>> ---
>>>>>
>>>>> v2:
>>>>> + Rename protocol to idle-inhibit
>>>>> v3:
>>>>> + Added a destructor for the idle manager
>>>>> + Changed sub-surface behavior to inherit idle from parent surface
>>>>> + Various wording changes suggested by pq
>>>>>
>>>
>>> Hi,
>>>
>>> you posted the last one marked as v3, so this would have been v4.
>>>
>>>> Hi,
>>>>
>>>> I think this looks sane, I only have a couple of questions that might
>>>> need clarification.
>>>>
>>>>>
>>>>> Makefile.am | 1 +
>>>>> unstable/idle-inhibit/README | 4 ++
>>>>> unstable/idle-inhibit/idle-inhibit-unstable-v1.xml | 84 ++++++++++++++++++++++
>>>>> 3 files changed, 89 insertions(+)
>>>>> create mode 100644 unstable/idle-inhibit/README
>>>>> create mode 100644 unstable/idle-inhibit/idle-inhibit-unstable-v1.xml
>>>>>
>>>>> diff --git a/Makefile.am b/Makefile.am
>>>>> index 71d2632..de691db 100644
>>>>> --- a/Makefile.am
>>>>> +++ b/Makefile.am
>>>>> @@ -8,6 +8,7 @@ unstable_protocols = \
>>>>> unstable/relative-pointer/relative-pointer-unstable-v1.xml \
>>>>> unstable/pointer-constraints/pointer-constraints-unstable-v1.xml \
>>>>> unstable/tablet/tablet-unstable-v1.xml \
>>>>> + unstable/idle-inhibit/idle-inhibit-unstable-v1.xml \
>>>>> $(NULL)
>>>>>
>>>>> stable_protocols = \
>>>>> diff --git a/unstable/idle-inhibit/README b/unstable/idle-inhibit/README
>>>>> new file mode 100644
>>>>> index 0000000..396e871
>>>>> --- /dev/null
>>>>> +++ b/unstable/idle-inhibit/README
>>>>> @@ -0,0 +1,4 @@
>>>>> +Screensaver inhibition protocol
>>>>> +
>>>>> +Maintainers:
>>>>> +Bryce Harrington <bryce at osg.samsung.com>
>>>>> diff --git a/unstable/idle-inhibit/idle-inhibit-unstable-v1.xml b/unstable/idle-inhibit/idle-inhibit-unstable-v1.xml
>>>>> new file mode 100644
>>>>> index 0000000..af3a911
>>>>> --- /dev/null
>>>>> +++ b/unstable/idle-inhibit/idle-inhibit-unstable-v1.xml
>>>>> @@ -0,0 +1,84 @@
>>>>> +<?xml version="1.0" encoding="UTF-8"?>
>>>>> +<protocol name="idle_inhibit_unstable_v1">
>>>>> +
>>>>> + <copyright>
>>>>> + Copyright © 2015 Samsung Electronics Co., Ltd
>>>>> +
>>>>> + Permission is hereby granted, free of charge, to any person obtaining a
>>>>> + copy of this software and associated documentation files (the "Software"),
>>>>> + to deal in the Software without restriction, including without limitation
>>>>> + the rights to use, copy, modify, merge, publish, distribute, sublicense,
>>>>> + and/or sell copies of the Software, and to permit persons to whom the
>>>>> + Software is furnished to do so, subject to the following conditions:
>>>>> +
>>>>> + The above copyright notice and this permission notice (including the next
>>>>> + paragraph) shall be included in all copies or substantial portions of the
>>>>> + Software.
>>>>> +
>>>>> + THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
>>>>> + IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
>>>>> + FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
>>>>> + THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
>>>>> + LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
>>>>> + FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
>>>>> + DEALINGS IN THE SOFTWARE.
>>>>> + </copyright>
>>>>> +
>>>>> + <interface name="zwp_idle_inhibit_manager_v1" version="1">
>>>>> + <description summary="control behavior when display idles">
>>>>> + This interface permits inhibiting the idle behavior such as screen
>>>>> + blanking, locking, and screensaving. The client binds the idle manager
>>>>> + globally, then creates idle-inhibitor objects for each surface.
>>>>
>>>> + for each surface that should inhibit the idle behavior. ?
>>>
>>> Yeah, makes sense.
>>>
>>>>> +
>>>>> + Warning! The protocol described in this file is experimental and
>>>>> + backward incompatible changes may be made. Backward compatible changes
>>>>> + may be added together with the corresponding interface version bump.
>>>>> + Backward incompatible changes are done by bumping the version number in
>>>>> + the protocol and interface names and resetting the interface version.
>>>>> + Once the protocol is to be declared stable, the 'z' prefix and the
>>>>> + version number in the protocol and interface names are removed and the
>>>>> + interface version number is reset.
>>>>> + </description>
>>>>> +
>>
>> Shouldn't there be a "create" request so clients can obtain the manager object?
>
> Hi,
>
> that request is wl_registry.bind, as for all globals.
>
>>>>> + <request name="destroy" type="destructor">
>>>>> + <description summary="destroy the idle inhibitor object">
>>
>> destroy the idle inhibit manager
>>
>>
>>>>> + This destroys the inhibit manager.
>>>
>>> Good addition. Should probably say how destroying the manager affects
>>> the inhibitors created from it (no effect at all)?
>>
>> Agreed w/ pq. But, is the inhibit manager a /singleton/ global?
>
> Yes.
>
>>>>> + </description>
>>>>> + </request>
>>>>> +
>>>>> + <request name="create_inhibitor">
>>>>> + <description summary="create a new inhibitor object">
>>>>> + Create a new inhibitor object associated with the given surface.
>>>>> + </description>
>>>>> + <arg name="id" type="new_id" interface="zwp_idle_inhibitor_v1"/>
>>>>> + <arg name="surface" type="object" interface="wl_surface"
>>>>> + summary="the surface that inhibits the idle behavior"/>
>>>>> + </request>
>>
>> Does it make sense to associate inhibitors to surfaces, rather than clients?
>> See below.
>
> Yes, they must be associated to surfaces.
>
>>>>> +
>>>>> + </interface>
>>>>> +
>>>>> + <interface name="zwp_idle_inhibitor_v1" version="1">
>>>>> + <description summary="context object for inhibiting idle behavior">
>>>>> + An idle inhibitor prevents the output that the associated surface is
>>>>> + visible on from being blanked, dimmed, locked, set to power save, or
>>>>> + otherwise obscured due to lack of user interaction. Any active
>>>>> + screensaver processes are also temporarily blocked from displaying.
>>>>> +
>>>>> + If the surface is destroyed, unmapped, becomes occluded or otherwise
>>>>> + loses visibility, the screen behavior is restored to normal; if the
>>>>> + surface subsequently regains visibility the inhibitor takes effect once
>>>>> + again.
>>
>> I don't believe this is a good choice. Imagine the case of a surface-less
>> 'inhibitor daemon.'
>
> An ordinary client must not be able to do that.
>
>> There may be no visible surface (is my thinking out
>> of scope here?). Imagine another case, that of a "caffeine" widget. This
>> widget's surface would be hidden when another app is fullscreen.
>
> If you cannot see the widget anyway, it must not be able to affect
> screen saving. Therefore by definition, surfaceless clients must not be
> able to inhibit.
>
>> Furthermore, I don't believe that inhibition should be coupled to outputs.
>> See below.
>
> It should work per-output. If there is important info on just one
> output, why should the other outputs also stay on for no good reason?
Just because I'm looking at info on one monitor doesn't mean I want my other
monitors to go to sleep. I can imagine this being specified via a shell's
screensaver/power savings config panel, with a checkbox enabling "idle per screen" or "idle
all screens in unison." So I think this is a moot point. However, I
don't believe that just because a surface is occluded, that it's ability
to inhibit idling should be suppressed.
>>>>> +
>>>>> + Note that in the case of a compound window (a surface with
>>>>> + sub-surfaces), the inhibitor effects should be inherited from the top
>>>>> + level surface.
>>>>
>>>> Does this mean that if we have a subsurface with an inhibitor object,
>>>> and for example an xdg_surface without one, the subsurface would still
>>>> not inhibit the idle behavior, as it'd inherit the behavior?
>>>>
>>>> If it should work like this, maybe we should make it an error to create
>>>> an idle inhibitor on a subsurface. If it should inhibit, I think it
>>>> needs to be clarified.
>>>
>>> Right, I was thinking something like: Sub-surfaces that do not have an
>>> inhibitor associated inherit the inhibition behaviour from their
>>> parent. This applies recursively.
>>>
>>> To clarify what I mean, lets consider an artificial case like this:
>>>
>>> wl_surface A is a top-level, only on output 1.
>>> wl_surface B is a sub-surface to A, only on output 2.
>>> wl_surface C is a sub-surface to B, only on output 3.
>>>
>>> wl_surface B has an inhibitor associated. All surfaces are completely
>>> visible etc. on their own outputs.
>>>
>>> Output 1 will go to powersave: no surface is inhibiting it.
>>>
>>> Output 2 does not go to powersave: B inhibitor is in effect.
>>>
>>> Output 3 does not go to powersave: C inherits B's inhibitor behaviour.
>>
>> I don't believe that inhibition should /only/ be coupled to outputs.
>> In the case of a "caffeine" widget or daemon, the use case is to
>> prevent /all/ outputs from idling, regardless of what output the widget's
>> surface resides upon.
>
> That is explicitly not what we want to enable.
>
> What is this "caffeine" you talk about? I've never heard of it. Maybe I
> never had to fight against screen saving.
Here's a screenshot of the Gnome-flavored implementation of the widget:
http://tinyurl.com/caffeine-widget-2
OSX and others have something similar. This program visually resides in the
menubar/taskbar of the shell. It has two states, on and off. On (caffeinated)
overrides the configured screensaver/sleep idle timeout, preventing /all/
monitors from idling. In the off (un-caffeinated) state, the system behaves
according to configuration.
Use case: I've configured my system to screensave at 5 minutes and put the
monitors to sleep at 10 minutes. But sometimes, I want to override this
without going in and changing my config, only to have to change it back
later. I run the caffeine widget, turn it on, and all my monitors remain on
despite me not interacting with my machine. This behavior remains valid
even if I am running a program fullscreen, which occludes the visibility
of the widget.
It sounds like, from what Bryce had wrote in a separate reply, such a
widget would use a different API and not this idle inhibitor protocol. I
might be misunderstanding his point.
>
>>> This raises a corner-case: If surface B becomes completely occluded so
>>> that the compositor considers it is no longer inhibiting, what happens
>>> with output 3? Should it powersave or not?
>>>
>>> That is a strange use case but still possible. I'm not sure what should
>>> happen. Should it behave like C had its own inhibitor, or should the
>>> inheritance take also the effectiveness of the inhibitor on B?
>>>
>>> I suppose you could pick either way.
>>>
>>>>> + </description>
>>>>> +
>>>>> + <request name="destroy" type="destructor">
>>>>> + <description summary="destroy the idle inhibitor object">
>>>>> + This removes the inhibitor effect from the associated wl_surface.
>>>>> + </description>
>>>>> + </request>
>>>>> +
>>>>> + </interface>
>>>>> +</protocol>
>>>>> --
>>>
>>> Ok, this looks quite good, just a couple clarifications would be nice.
>>>
>>> If you agree with my "inherited from parent" idea instead of from
>>> top-level, you get:
>>> Acked-by: Pekka Paalanen <pekka.paalanen at collabora.co.uk>
>>>
>>>
>>> Thanks,
>>> pq
>>
>> Forgive me if I didn't quite grok prior conversations about this protocol.
>
> It seems like your mindset is tuned to fighting against bad
> screensaving policies in a compositor, while Bryce's goal with the
> extension is to allow implementing proper and good screensaving policies
> *in the first place*, so that no fighting is needed.
>
> We want the compositor to behave correctly, not offer tools to override
> the compositor behaviour. Bugs should be fixed at their source, not
> worked around at every other place.
I hear you. Not fighting, per se, but rather 'temporarily override'.
I'm just stating that an application should be able to inhibit idling:
a) On all outputs
b) Whether it is visible or not
Per the use case I described above. Whether it uses this inhibitor protocol
or some other API is fine. But if such a use case /should/ use the inhibitor
protocol, then the per-output constraint and visibility constraint in the
protocol would make this functionality 'impossible'.
yong
> Thanks,
> pq
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