[RFC wayland-protocols V3] Add Primary Selection Protocol Version 1

Carlos Garnacho carlosg at gnome.org
Thu Feb 4 18:26:59 UTC 2016


Hi!,

Chiming in late...

On Thu, Jan 7, 2016 at 3:50 AM, Lyude <cpaul at redhat.com> wrote:
> Signed-off-by: Lyude <cpaul at redhat.com>
> ---
>
> Notes:
>                                 Changes since V2
>     * Bunch of grammatical/wording fixes from whot
>     * Addition of wp_primary_selection_offer::end_offers, for marking the end of a
>       list of mime type offers
>     * selection_offers are no longer sent before an input event, and are sent at the
>       first opportunity a client has to do a primary selection paste. This decision
>       comes from a discussion with Jasper, where a couple of clients (such as emacs)
>       were brought up that have their own bindings for primary selection pasting.
>       Eventually I will probably work on adding some sort of paste_hint event to
>       this so that the compositor can decide what keybinding triggers a primary
>       selection paste, I agree with Jasper that it would be best to solve the issue
>       of rebinding primary selection pastes after we have the basic protocol for
>       primary selection worked out.
>
>  Makefile.am                                        |   1 +
>  unstable/primary-selection/README                  |   4 +
>  .../primary-selection-unstable-v1.xml              | 176 +++++++++++++++++++++
>  3 files changed, 181 insertions(+)
>  create mode 100644 unstable/primary-selection/README
>  create mode 100644 unstable/primary-selection/primary-selection-unstable-v1.xml
>
> diff --git a/Makefile.am b/Makefile.am
> index 5926a41..582a49e 100644
> --- a/Makefile.am
> +++ b/Makefile.am
> @@ -5,6 +5,7 @@ unstable_protocols =                                                            \
>         unstable/text-input/text-input-unstable-v1.xml                          \
>         unstable/input-method/input-method-unstable-v1.xml                      \
>         unstable/xdg-shell/xdg-shell-unstable-v5.xml                            \
> +       unstable/primary-selection/primary-selection-unstable-v1.xml            \
>         $(NULL)
>
>  nobase_dist_pkgdata_DATA =                                                     \
> diff --git a/unstable/primary-selection/README b/unstable/primary-selection/README
> new file mode 100644
> index 0000000..2dfce3d
> --- /dev/null
> +++ b/unstable/primary-selection/README
> @@ -0,0 +1,4 @@
> +Primary selection protocol
> +
> +Maintainers:
> +Lyude <cpaul at redhat.com>
> diff --git a/unstable/primary-selection/primary-selection-unstable-v1.xml b/unstable/primary-selection/primary-selection-unstable-v1.xml
> new file mode 100644
> index 0000000..057ba38
> --- /dev/null
> +++ b/unstable/primary-selection/primary-selection-unstable-v1.xml
> @@ -0,0 +1,176 @@
> +<?xml version="1.0" encoding="UTF-8"?>
> +
> +<protocol name="primary_selection">
> +  <copyright>
> +    Copyright © 2015 Red Hat
> +
> +    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_primary_selection_device_manager_v1" version="1">
> +    <description summary="X primary selection emulation">
> +      Provides the ability to have a primary selection device to match that of
> +      the X server. This allows users to select bodies of text, and then paste
> +      them in another buffer without having to do the initial copy.
> +
> +      The primary selection device manager is also in charge of handling
> +      client's requests to indicate that text has been selected, along with
> +      handling clients access to selected text.
> +    </description>
> +
> +    <request name="create_primary_selection_source">
> +      <description summary="create a new primary selection source">
> +        Create a new primary selection source.
> +      </description>
> +      <arg name="id" type="new_id" interface="zwp_primary_selection_source_v1"/>
> +    </request>
> +
> +    <request name="get_primary_selection_device">
> +      <description summary="primary selection device manager">
> +        Singleton global object that manages the zwp_primary_selection_device_v1
> +        objects for each wl_seat.
> +      </description>
> +      <arg name="id" type="new_id" interface="zwp_primary_selection_device_v1"/>
> +      <arg name="seat" type="object" interface="wl_seat"/>
> +    </request>

The name of these two requests feel a bit redundant, they end up in:

zwp_primary_selection_device_manager_v1_create_primary_selection_source
zwp_primary_selection_device_manager_v1_get_primary_selection_device

"primary selection" is twice on both, and the functions are close to
the 80 chars limit :). I'd suggest "create_source" and "get_device",
the "primary selection" nature is already implicit in the protocol
name/prefix, and the returned types.

> +
> +    <request name="destroy" type="destructor">
> +      <description summary="destroy the primary selection device manager">
> +        Destroy the primary selection device manager.
> +      </description>
> +    </request>
> +  </interface>
> +
> +  <interface name="zwp_primary_selection_device_v1" version="1">
> +    <request name="set_selection">
> +      <description summary="set the primary selection">
> +        Set the current contents of the primary selection buffer. This clears
> +        anything which was previously held in the primary selection buffer.
> +      </description>
> +      <arg name="source" type="object" interface="zwp_primary_selection_source_v1"/>

wl_data_device.set_selection allows unsetting the current selection by
passing NULL. I think it'd be worth allowing this too for the same
reasons, clients might want to unset the selection (eg. gtk+ clears
the primary selection when the client is the owner of the primary
selection data and you unselect the text).

This arg might need allow-null="true" then.

> +    </request>
> +
> +    <event name="selection_offer">
> +      <description summary="introduce a new wp_primary_selection_offer">
> +        Similar to wl_data_device::data_offer, this event introduces a new
> +        wp_primary_selection_offer object that may be used to receive the
> +        current primary selection. Immediately folliwng this event, the new
> +        wp_primary_selection_offer object will send out
> +        wp_primary_selection_offer::offer events to describe the mime types it
> +        offers.
> +      </description>
> +      <arg name="offer" type="new_id" interface="zwp_primary_selection_offer_v1"/>
> +    </event>
> +
> +    <request name="destroy" type="destructor">
> +      <description summary="destroy the primary selection device">
> +        Destroy the primary selection device.
> +      </description>
> +    </request>
> +  </interface>
> +
> +  <interface name="zwp_primary_selection_offer_v1" version="1">
> +    <description summary="offer to transfer primary selection contents">
> +      A wp_primary_selection_offer represents an offer to transfer the contents
> +      of the primary selection clipboard to the client. Similar to
> +      wl_data_offer, the offer also describes the different mime types that the
> +      data can be converted to and provides the mechanisms for transferring the
> +      data directly to the client.
> +    </description>
> +
> +    <request name="receive">
> +      <description summary="request that the data is transferred">
> +        To transfer the contents of the primary selection clipboard, the client
> +        issues this request and indicates the mime type that it wants to
> +        receive. The transfer happens through the passed file descriptor
> +        (typically created with the pipe system call). The source client writes
> +        the data in the mime type representation requested and then closes the
> +        file descriptor.
> +
> +        The receiving client reads from the read end of the pipe until EOF and
> +        closes its end, at which point the transfer is complete.
> +      </description>
> +      <arg name="mime_type" type="string"/>
> +      <arg name="fd" type="fd"/>
> +    </request>
> +
> +    <request name="destroy" type="destructor">
> +      <description summary="destroy the primary selection offer">
> +        Destroy the primary selection offer.
> +      </description>
> +    </request>
> +
> +    <event name="offer">
> +      <description summary="advertise offered mime type">
> +        Sent immediately after creating the wp_primary_selection_offer object.
> +        One event per offered mime type.
> +      </description>
> +      <arg name="mime_type" type="string"/>
> +    </event>
> +
> +    <event name="end_offers">
> +      <description summary="mark the end of the list of available mime types">
> +        Sent after we've send offer events for all of the available mime types.
> +      </description>

Here I see a slight difference with wl_data_device and wl_data_offer
that would be great to even out, as it better allows clients to
abstract wl_data_* and zwp_primary_selection_* in common interfaces.

In zwp_primary_selection, you first receive a
zwp_primary_selection_device_v1.selection_offer, and then this event
in zwp_primary_selection_offer_v1, whereas in the wayland core
protocol both the "offer introduction" and the "offer being put to
use" events happen both on wl_data_device (.data_offer and .selection,
respectively).

This event can be maybe seen as belonging to the offer (it's state of
the offer, at least), but I admit I'm more sold on the final event
where you can start using the offer to be a device one.

Cheers
  Carlos


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