unstable: add primary-selection protocol

This primary selection is similar in spirit to the eponimous
in X11, allowing a quick "select text + middle click" shortcut
to copying and pasting.

It's otherwise very similar to its Wayland counterpart, and
explicitly made consistent with it.

Signed-off-by: Simon Ser <contact@emersion.fr>
Reviewed-by: Jonas Ådahl <jadahl@gmail.com>
Reviewed-by: Carlos Garnacho <carlosg@gnome.org>

Makefile.am

@@ -22,6 +22,7 @@ unstable_protocols =								\
 	unstable/input-timestamps/input-timestamps-unstable-v1.xml	\
 	unstable/xdg-decoration/xdg-decoration-unstable-v1.xml	\
 	unstable/linux-explicit-synchronization/linux-explicit-synchronization-unstable-v1.xml \
+	unstable/primary-selection/primary-selection-unstable-v1.xml		\
 	$(NULL)
 
 stable_protocols =								\

unstable/primary-selection/README

@@ -0,0 +1,4 @@
+Primary selection protocol
+
+Maintainers:
+Simon Ser <contact@emersion.fr>

unstable/primary-selection/primary-selection-unstable-v1.xml

@@ -0,0 +1,225 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<protocol name="wp_primary_selection_unstable_v1">
+  <copyright>
+    Copyright © 2015, 2016 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>
+
+  <description summary="Primary selection protocol">
+    This protocol provides the ability to have a primary selection device to
+    match that of the X server. This primary selection is a shortcut to the
+    common clipboard selection, where text just needs to be selected in order
+    to allow copying it elsewhere. The de facto way to perform this action
+    is the middle mouse button, although it is not limited to this one.
+
+    Clients wishing to honor primary selection should create a primary
+    selection source and set it as the selection through
+    wp_primary_selection_device.set_selection whenever the text selection
+    changes. In order to minimize calls in pointer-driven text selection,
+    it should happen only once after the operation finished. Similarly,
+    a NULL source should be set when text is unselected.
+
+    wp_primary_selection_offer objects are first announced through the
+    wp_primary_selection_device.data_offer event. Immediately after this event,
+    the primary data offer will emit wp_primary_selection_offer.offer events
+    to let know of the mime types being offered.
+
+    When the primary selection changes, the client with the keyboard focus
+    will receive wp_primary_selection_device.selection events. Only the client
+    with the keyboard focus will receive such events with a non-NULL
+    wp_primary_selection_offer. Across keyboard focus changes, previously
+    focused clients will receive wp_primary_selection_device.events with a
+    NULL wp_primary_selection_offer.
+
+    In order to request the primary selection data, the client must pass
+    a recent serial pertaining to the press event that is triggering the
+    operation, if the compositor deems the serial valid and recent, the
+    wp_primary_selection_source.send event will happen in the other end
+    to let the transfer begin. The client owning the primary selection
+    should write the requested data, and close the file descriptor
+    immediately.
+
+    If the primary selection owner client disappeared during the transfer,
+    the client reading the data will receive a
+    wp_primary_selection_device.selection event with a NULL
+    wp_primary_selection_offer, the client should take this as a hint
+    to finish the reads related to the no longer existing offer.
+
+    The primary selection owner should be checking for errors during
+    writes, merely cancelling the ongoing transfer if any happened.
+  </description>
+
+  <interface name="zwp_primary_selection_device_manager_v1" version="1">
+    <description summary="X primary selection emulation">
+      The primary selection device manager is a singleton global object that
+      provides access to the primary selection. It allows to create
+      wp_primary_selection_source objects, as well as retrieving the per-seat
+      wp_primary_selection_device objects.
+    </description>
+
+    <request name="create_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_device">
+      <description summary="create a new primary selection device">
+        Create a new data device for a given seat.
+      </description>
+      <arg name="id" type="new_id" interface="zwp_primary_selection_device_v1"/>
+      <arg name="seat" type="object" interface="wl_seat"/>
+    </request>
+
+    <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">
+        Replaces the current selection. The previous owner of the primary
+        selection will receive a wp_primary_selection_source.cancelled event.
+
+        To unset the selection, set the source to NULL.
+      </description>
+      <arg name="source" type="object" interface="zwp_primary_selection_source_v1" allow-null="true"/>
+      <arg name="serial" type="uint" summary="serial of the event that triggered this request"/>
+    </request>
+
+    <event name="data_offer">
+      <description summary="introduce a new wp_primary_selection_offer">
+        Introduces a new wp_primary_selection_offer object that may be used
+        to receive the current primary selection. Immediately following this
+        event, the new wp_primary_selection_offer object will send
+        wp_primary_selection_offer.offer events to describe the offered mime
+        types.
+      </description>
+      <arg name="offer" type="new_id" interface="zwp_primary_selection_offer_v1"/>
+    </event>
+
+    <event name="selection">
+      <description summary="advertise a new primary selection">
+        The wp_primary_selection_device.selection event is sent to notify the
+        client of a new primary selection. This event is sent after the
+        wp_primary_selection.data_offer event introducing this object, and after
+        the offer has announced its mimetypes through
+        wp_primary_selection_offer.offer.
+
+        The data_offer is valid until a new offer or NULL is received
+        or until the client loses keyboard focus. The client must destroy the
+        previous selection data_offer, if any, upon receiving this event.
+      </description>
+      <arg name="id" type="object" interface="zwp_primary_selection_offer_v1" allow-null="true"/>
+    </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 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 announcing the
+        wp_primary_selection_offer through
+        wp_primary_selection_device.data_offer. One event is sent per offered
+        mime type.
+      </description>
+      <arg name="mime_type" type="string"/>
+    </event>
+  </interface>
+
+  <interface name="zwp_primary_selection_source_v1" version="1">
+    <description summary="offer to replace the contents of the primary selection">
+      The source side of a wp_primary_selection_offer, it provides a way to
+      describe the offered data and respond to requests to transfer the
+      requested contents of the primary selection clipboard.
+    </description>
+
+    <request name="offer">
+      <description summary="add an offered mime type">
+        This request adds a mime type to the set of mime types advertised to
+        targets. Can be called several times to offer multiple types.
+      </description>
+      <arg name="mime_type" type="string"/>
+    </request>
+
+    <request name="destroy" type="destructor">
+      <description summary="destroy the primary selection source">
+        Destroy the primary selection source.
+      </description>
+    </request>
+
+    <event name="send">
+      <description summary="send the primary selection contents">
+        Request for the current primary selection contents from the client.
+        Send the specified mime type over the passed file descriptor, then
+        close it.
+      </description>
+      <arg name="mime_type" type="string"/>
+      <arg name="fd" type="fd"/>
+    </event>
+
+    <event name="cancelled">
+      <description summary="request for primary selection contents was canceled">
+        This primary selection source is no longer valid. The client should
+        clean up and destroy this primary selection source.
+      </description>
+    </event>
+  </interface>
+</protocol>