[PATCH weston-ivi-shell v2 02/15] ivi application protocol:

Fri Mar 7 08:39:44 PST 2014

On Mar 7, 2014 7:56 AM, "Nobuhiko Tanibata" <
NOBUHIKO_TANIBATA at xddp.denso.co.jp> wrote:
>
> Add interface ivi_application, which creates ivi_surface objects tied
> to a given wl_surface with a given id. The given id can be used in a
> shell to identify which application is assigned to a wl_surface and
> layout the surface wherever the shell wants. ivi_surface objects can
> be used to receive status of wl_surface in the scenegraph of the
> compositor.
>
> Signed-off-by: Nobuhiko Tanibata <NOBUHIKO_TANIBATA at xddp.denso.co.jp>
> ---
>
> Changes for v2:
>    - Rename "error" to "warning" because meaning of "error" in wayland is
fatal.
>
>  protocol/ivi-application.xml | 88
++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 88 insertions(+)
>  create mode 100755 protocol/ivi-application.xml
>
> diff --git a/protocol/ivi-application.xml b/protocol/ivi-application.xml
> new file mode 100755
> index 0000000..8659ec6
> --- /dev/null
> +++ b/protocol/ivi-application.xml
> @@ -0,0 +1,88 @@
> +<?xml version="1.0" encoding="UTF-8"?>
> +<protocol name="ivi_application">
> +
> +    <copyright>
> +    Copyright (C) 2013 DENSO CORPORATION
> +    Copyright (c) 2013 BMW Car IT GmbH
> +
> +    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 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="ivi_surface" version="1">
> +        <description summary="application interface to surface in ivi
compositor"/>
> +
> +        <request name="destroy" type="destructor">
> +            <description summary="destroy ivi_surface"/>
> +        </request>
> +
> +        <event name="visibility">
> +            <description summary="visibility of surface in ivi
compositor has changed">
> +                The new visibility state is provided in argument
visibility.
> +                If visibility is 0, the surface has become invisible.
> +                If visibility is not 0, the surface has become visible.
> +            </description>
> +            <arg name="visibility" type="int"/>
> +        </event>
> +
> +    </interface>
> +
> +    <interface name="ivi_application" version="1">
> +        <description summary="interface for ivi applications to use ivi
compositor features"/>
> +
> +        <request name="surface_create">
> +            <description summary="create surface in ivi compositor">
> +                surface_create will create a new surface with surface_id
in ivi compositor,
> +                if it does not yet exists. If the surface with
surface_id already exists in
> +                ivi compositor, the application content provided in
argument surface will
> +                be used as surface content. If an other ivi application
already registered
> +                content for surface with surface_id, an warning event
will indicate the problem.
> +            </description>
> +            <arg name="id_surface" type="uint"/>
> +            <arg name="surface" type="object" interface="wl_surface"/>
> +            <arg name="id" type="new_id" interface="ivi_surface"/>
> +        </request>
> +
> +        <enum name="warning_code">
> +            <description summary="possible warning codes returned by ivi
compositor">
> +                These warning codes define all possible warning codes
returned by ivi compositor
> +                on server-side warnings.
> +            </description>
> +            <entry name="invalid_wl_surface" value="1"
summary="wl_surface is invalid"/>
> +            <entry name="surface_id_in_use" value="2"
summary="surface_id is in use and can not be shared"/>
> +        </enum>

I have a couple more thoughts about these errors/warnings.  For one, I
think some of these should be errors.  For instance, there is no way that
the given wl_surface will be invalid unless the client has destroyed it.
Honestly, I'm not even sure if it's possible, given how libwayland is
written, to get a truely invalid wl_surface.  From what you've written in
previous e-mails, I can't quite tell but it sounds like you want to prevent
a client from attaaching multiple ivi_surface objects (and IVI ID's) to the
same surface.  If this is the case then doing so should probably also be a
fatal error because that means the client was written wrong.

With regards to what happens if a client tries to use an ID that's already
in use, I'm not 100% sure what to do there.  You know IVI systems better
than I do.  Is this something that happens with some degree of regularity?
Or is this something that only happens if the there is a mistake in the
client code?  I'll leave that up to you.

That said, if there is an issue, you need to explicitly say what happens to
the newly created ivi_surface object.  The Wayland protocol has no concept
of returning NULL.  Whenever a request or event is fired which has a new_id
parameter, both client and server-side objects always get created.  If
surface_create can throw a non-fatal error, we need to decide what happens
to the new ivi_surface object.  One way to do this would be to have the
error/warning event on the ivi_surface itself instead of on
ivi_application.  Then the client would know that if it recieves the
error/warning, that it needs to destroy the corresponding ivi_surface.
Otherwise, like you note below, they have to roundtrip after every call to
ivi_application.surface_create.

Thanks,
--Jason Ekstrand

> +
> +        <event name="warning">
> +            <description summary="server-side warning detected">
> +                The ivi compositor encountered warning while processing
a request by this
> +                application. The warning is defined by argument
warning_code and optional
> +                warning_text.
> +                If the application requires to associate this warning
event to a request,
> +                it can
> +                    1. send request
> +                    2. force display roundtrip
> +                    3. check, if warning event was received
> +                 but this restricts the application to have only one
open request at a time.
> +            </description>
> +            <arg name="warning_code" type="int"/>
> +            <arg name="warning_text" type="string" allow-null="true"/>
> +        </event>
> +
> +    </interface>
> +
> +</protocol>
> --
> 1.8.3.1
>
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