[PATCHv4 wayland-protocols] text-input: Add v3 of the text-input protocol

Dorota Czaplejewicz dorota.czaplejewicz at puri.sm
Thu May 3 15:41:21 UTC 2018

From: Carlos Garnacho <carlosg at gnome.org>

This new protocol description is a simplification over v2.

- All pre-edit text styling is gone.
- Pre-edit cursor can span characters.
- No events regarding input panel (OSK) state nor covered rectangle.
  Compositors are still free to handle situations where the keyboard
  focus rectangle is covered by the input panel.
- No set_preferred_language request for clients.
- There is no event to send keysyms. Compositors can use wl_keyboard
  interface instead.
- All state is double-buffered, with specified state.
- Use Unicode codepoints to measure strings.

Signed-off-by: Dorota Czaplejewicz <dorota.czaplejewicz at puri.sm>
Signed-off-by: Carlos Garnacho <carlosg at gnome.org>
This is the next update coming from Purism to perfect the text input protocol.

The following changes added on top of PATCHv3:

- Fixed whitespaces.
- Removed enable flags - the same information can be gathered from the first requests after enter.
- Changed offsets inside UTF-8 strings to use Unicode character counts in order to remove the possibility of communicating invalid state.
- Specified the exact lifetime of double-buffered state, and initial values.
- Made changes requested by the IM double-buffered.

Some questions remain open. One is: how to specify how much text to capture in set_surrounding_text, and how often to update?

A possible change that I decided against for now is to replace enable/disable events by create/destroy of a new object, which would make more state lifetimes encoded in the protocol.

After reading a blog post on fcitx [0], I got the impression that letting the compositor know some persistent ID of a text edit instance could be useful, however I'm not sure what the use cases are.

As always, I'm happy to hear feedback.

Dorota Czaplejewicz

[0] https://www.csslayer.info/wordpress/fcitx-dev/gaps-between-wayland-and-fcitx-or-all-input-methods/

 Makefile.am                                    |   1 +
 unstable/text-input/text-input-unstable-v3.xml | 362 +++++++++++++++++++++++++
 2 files changed, 363 insertions(+)
 create mode 100644 unstable/text-input/text-input-unstable-v3.xml

diff --git a/Makefile.am b/Makefile.am
index 4b9a901..86d7ca9 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -3,6 +3,7 @@ unstable_protocols =								\
 	unstable/fullscreen-shell/fullscreen-shell-unstable-v1.xml		\
 	unstable/linux-dmabuf/linux-dmabuf-unstable-v1.xml			\
 	unstable/text-input/text-input-unstable-v1.xml				\
+	unstable/text-input/text-input-unstable-v3.xml				\
 	unstable/input-method/input-method-unstable-v1.xml			\
 	unstable/xdg-shell/xdg-shell-unstable-v5.xml				\
 	unstable/xdg-shell/xdg-shell-unstable-v6.xml				\
diff --git a/unstable/text-input/text-input-unstable-v3.xml b/unstable/text-input/text-input-unstable-v3.xml
new file mode 100644
index 0000000..ed5204f
--- /dev/null
+++ b/unstable/text-input/text-input-unstable-v3.xml
@@ -0,0 +1,362 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<protocol name="text_input_unstable_v3">
+  <copyright>
+    Copyright © 2012, 2013 Intel Corporation
+    Copyright © 2015, 2016 Jan Arne Petersen
+    Copyright © 2017, 2018 Red Hat, Inc.
+    Copyright © 2018 Purism SPC
+    Permission to use, copy, modify, distribute, and sell this
+    software and its documentation for any purpose is hereby granted
+    without fee, provided that the above copyright notice appear in
+    all copies and that both that copyright notice and this permission
+    notice appear in supporting documentation, and that the name of
+    the copyright holders not be used in advertising or publicity
+    pertaining to distribution of the software without specific,
+    written prior permission.  The copyright holders make no
+    representations about the suitability of this software for any
+    purpose.  It is provided "as is" without express or implied
+    warranty.
+  </copyright>
+  <interface name="zwp_text_input_v3" version="1">
+    <description summary="text input">
+      The zwp_text_input_v3 interface represents text input and input methods
+      associated with a seat. It provides enter/leave events to follow the
+      text input focus for a seat.
+      Requests are used to enable/disable the text-input object and set
+      state information like surrounding and selected text or the content type.
+      The information about the entered text is sent to the text-input object
+      via the pre-edit and commit_string events.
+      Text is valid UTF-8 encoded, indices and lengths are in code points. If a
+      grapheme is made up of multiple code points, an index pointing to any of
+      them should be interpreted as pointing to the first one.
+      Focus moving throughout surfaces will result in the emission of
+      zwp_text_input_v3.enter and zwp_text_input_v3.leave events. The focused
+      surface must perform zwp_text_input_v3.enable and
+      zwp_text_input_v3.disable requests as the keyboard focus moves across
+      editable and non-editable elements of the UI. Those two requests are not
+      expected to be paired with each other, the compositor must be able to
+      handle consecutive series of the same request.
+      State is sent by the state requests (set_surrounding_text,
+      set_content_type and set_cursor_rectangle) and a commit request.
+      After an enter event or disable request all state information is
+      invalidated and needs to be resent by the client.
+      This protocol defines requests and events necessary for regular clients
+      to communicate with an input method. The zwp_input_method protocol
+      defines the interfaces necessary to implement standalone input methods.
+      If a compositor implements both interfaces, it will be the arbiter of the
+      communication between both.
+      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>
+    <request name="destroy" type="destructor">
+      <description summary="Destroy the wp_text_input">
+       Destroy the wp_text_input object. Also disables all surfaces enabled
+       through this wp_text_input object.
+      </description>
+    </request>
+    <request name="enable">
+      <description summary="Request text input to be enabled">
+        Requests text input. This request should be issued every time the
+        active text input changes, including within one surface.
+        This request resets all state associated with previous enable,
+        set_surrounding_text, set_content_type, and set_cursor_rectangle
+        requests, as well as the state associated with preedit_string,
+        commit_string, and delete_surrounding_text events.
+        The set_surrounding_text, set_content_type and set_cursor_rectangle
+        requests should follow if the text input supports the necessary
+        functionality.
+        The changes must be applied by the compositor after issuing a
+        zwp_text_input_v3.commit request.
+      </description>
+    </request>
+    <request name="disable">
+      <description summary="Disable text input on a surface">
+        Explicitly disable text input in a surface (typically when there is no
+        focus on any text entry inside the surface).
+      </description>
+    </request>
+    <request name="set_surrounding_text">
+      <description summary="sets the surrounding text">
+        Sets the surrounding plain text around the input position.
+        Text is UTF-8 encoded. Cursor is the Unicode code point offset within
+        the surrounding text.
+        Anchor is the Unicode code point offset of the selection anchor within
+        the surrounding text. If there is no selected text, anchor is the same
+        as cursor.
+        If the client is unaware of the text around the cursor, it should not
+        issue this request, to signify lack of support to the compositor.
+        There is a maximum length of wayland messages so text can not be
+        longer than 4000 bytes.
+        Values set with this request are double-buffered. They will get applied
+        on the next zwp_text_input_v3.commit request, and stay valid until the
+        next enable or disable request.
+        The initial state for affected fields is empty, meaning that the text
+        input does not support sending surrounding text. If the empty values
+        get applied, subsequent attempts to change them may have no effect.
+      </description>
+      <arg name="text" type="string"/>
+      <arg name="cursor" type="int"/>
+      <arg name="anchor" type="int"/>
+    </request>
+    <enum name="content_hint" bitfield="true">
+      <description summary="content hint">
+       Content hint is a bitmask to allow to modify the behavior of the text
+       input.
+      </description>
+      <entry name="none" value="0x0" summary="no special behavior"/>
+      <entry name="completion" value="0x1" summary="suggest word completions"/>
+      <entry name="spellcheck" value="0x2" summary="suggest word corrections"/>
+      <entry name="auto_capitalization" value="0x4" summary="switch to uppercase letters at the start of a sentence"/>
+      <entry name="lowercase" value="0x8" summary="prefer lowercase letters"/>
+      <entry name="uppercase" value="0x10" summary="prefer uppercase letters"/>
+      <entry name="titlecase" value="0x20" summary="prefer casing for titles and headings (can be language dependent)"/>
+      <entry name="hidden_text" value="0x40" summary="characters should be hidden"/>
+      <entry name="sensitive_data" value="0x80" summary="typed text should not be stored"/>
+      <entry name="latin" value="0x100" summary="just Latin characters should be entered"/>
+      <entry name="multiline" value="0x200" summary="the text input is multiline"/>
+    </enum>
+    <enum name="content_purpose">
+      <description summary="content purpose">
+       The content purpose allows to specify the primary purpose of a text
+       input.
+       This allows an input method to show special purpose input panels with
+       extra characters or to disallow some characters.
+      </description>
+      <entry name="normal" value="0" summary="default input, allowing all characters"/>
+      <entry name="alpha" value="1" summary="allow only alphabetic characters"/>
+      <entry name="digits" value="2" summary="allow only digits"/>
+      <entry name="number" value="3" summary="input a number (including decimal separator and sign)"/>
+      <entry name="phone" value="4" summary="input a phone number"/>
+      <entry name="url" value="5" summary="input an URL"/>
+      <entry name="email" value="6" summary="input an email address"/>
+      <entry name="name" value="7" summary="input a name of a person"/>
+      <entry name="password" value="8" summary="input a password (combine with sensitive_data hint)"/>
+      <entry name="pin" value="9" summary="input is a numeric password (combine with sensitive_data hint)"/>
+      <entry name="date" value="10" summary="input a date"/>
+      <entry name="time" value="11" summary="input a time"/>
+      <entry name="datetime" value="12" summary="input a date and time"/>
+      <entry name="terminal" value="13" summary="input for a terminal"/>
+    </enum>
+    <request name="set_content_type">
+      <description summary="set content purpose and hint">
+        Sets the content purpose and content hint. While the purpose is the
+        basic purpose of an input field, the hint flags allow to modify some
+        of the behavior.
+        Values set with this request are double-buffered. They will get applied
+        on the first zwp_text_input_v3.commit request after an enabl request.
+        Subsequent attempts to update them may have no effect. The values
+        remain valid until the next enable or disable request.
+        The initial value for hint is none, and the initial value for purpose
+        is normal.
+      </description>
+      <arg name="hint" type="uint" enum="content_hint"/>
+      <arg name="purpose" type="uint" enum="content_purpose"/>
+    </request>
+    <request name="set_cursor_rectangle">
+      <description summary="set cursor position">
+        Marks an area around the cursor as a x, y, width, height rectangle in surface
+        local coordinates.
+        Allows the compositor to put a window with word suggestions near the
+        cursor, without obstructing the text being input.
+        If the client is unaware of the position of edited text, it should not
+        issue this request, to signify lack of support to the compositor.
+        Values set with this request are double-buffered. They will get applied
+        on the next zwp_text_input_v3.commit request, and stay valid until the
+        next enable or disable request.
+        The initial values describing a cursor rectangle are empty. That means
+        the text input does not support describing the cursor area. If the
+        empty values get applied, subsequent attempts to change them may have
+        no effect.
+      </description>
+      <arg name="x" type="int"/>
+      <arg name="y" type="int"/>
+      <arg name="width" type="int"/>
+      <arg name="height" type="int"/>
+    </request>
+    <request name="commit">
+      <description summary="commit state">
+        Text input state (content purpose, content hint, surrounding text,
+        cursor rectangle) is conceptually double-buffered within the context
+        of a text input, i.e. between an enable request and the following
+        enable or disable request.
+        Protocol requests modify the pending state, as opposed to the current
+        state in use by the input method. A commit request atomically applies
+        all pending state, replacing the current state. After commit, the new
+        pending state is as documented for each related request.
+        The enable request performs a special role by indicating that the state
+        should be reset and updated with new values on the nearest commit.
+        The current or pending state are not modified unless noted otherwise.
+      </description>
+    </request>
+    <event name="enter">
+      <description summary="enter event">
+       Notification that this seat's text-input focus is on a certain surface.
+       When the seat has the keyboard capability the text-input focus follows
+       the keyboard focus.
+      </description>
+      <arg name="surface" type="object" interface="wl_surface"/>
+    </event>
+    <event name="leave">
+      <description summary="leave event">
+       Notification that this seat's text-input focus is no longer on
+       a certain surface. The client should reset any preedit string previously
+       set.
+       The leave notification is sent before the enter notification
+       for the new focus.
+       When the seat has the keyboard capability the text-input focus follows
+       the keyboard focus.
+      </description>
+      <arg name="surface" type="object" interface="wl_surface"/>
+    </event>
+    <event name="preedit_string">
+      <description summary="pre-edit">
+        Notify when a new composing text (pre-edit) should be set around the
+        current cursor position. Any previously set composing text should
+        be removed.
+        Values set with this event are double-buffered. They must be applied on
+        the next zwp_text_input_v3.done event, and stay valid until the
+        next enable or disable request.
+        The parameters cursor_begin and cursor_end are counted in Unicode
+        code points relative to the beginning of the submitted string. Cursor
+        should be hidden when both are equal to -1.
+        They could be represented by the cient as a line if both values are the
+        same, or as a text highligt otherwise.
+        The initial value of text is an empty string, and cursor_begin and
+        cursor_end are both 0.
+      </description>
+      <arg name="text" type="string" allow-null="true"/>
+      <arg name="cursor_begin" type="int"/>
+      <arg name="cursor_end" type="int"/>
+    </event>
+    <event name="commit_string">
+      <description summary="text commit">
+        Notify when text should be inserted into the editor widget. The text to
+        commit could be either just a single character after a key press or the
+        result of some composing (pre-edit).
+        Values set with this event are double-buffered. They must be applied
+        and reset to initial on the next zwp_text_input_v3.done event.
+        The initial value of text is an empty string.
+      </description>
+      <arg name="text" type="string" allow-null="true"/>
+    </event>
+    <event name="delete_surrounding_text">
+      <description summary="delete surrounding text">
+        Notify when the text around the current cursor position should be
+        deleted. Before_length and after_length are the number of Unicode
+        code points before and after the current cursor position (excluding the
+        selection) to delete.
+        Values set with this event are double-buffered. They must be applied
+        and reset to initial on the next zwp_text_input_v3.done event.
+        The initial values of both before_length and after_length are 0.
+      </description>
+      <arg name="before_length" type="uint" summary="length of text before current cursor position"/>
+      <arg name="after_length" type="uint" summary="length of text after current cursor position"/>
+    </event>
+    <event name="done">
+      <description summary="apply changes">
+        Instruct the application to apply changes to state requested by the
+        preedit_string, commit_string and delete_surrounding_string events. The
+        state relating to these events is double-buffered, and each one
+        modifies the pending state. This event replaces the current state with
+        the pending state.
+        The application should proceed by evaluating the changes in the
+        following order:
+        1. Replace existing preedit string with the cursor.
+        2. Delete requested surrounding text.
+        3. Insert commit string with the cursor at its end.
+        4. Insert new preedit text in cursor position.
+        5. Place cursor inside preedit text.
+      </description>
+    </event>
+  </interface>
+  <interface name="zwp_text_input_manager_v3" version="1">
+    <description summary="text input manager">
+      A factory for text-input objects. This object is a global singleton.
+    </description>
+    <request name="destroy" type="destructor">
+      <description summary="Destroy the wp_text_input_manager">
+       Destroy the wp_text_input_manager object.
+      </description>
+    </request>
+    <request name="get_text_input">
+      <description summary="create a new text input object">
+       Creates a new text-input object for a given seat.
+      </description>
+      <arg name="id" type="new_id" interface="zwp_text_input_v3"/>
+      <arg name="seat" type="object" interface="wl_seat"/>
+    </request>
+  </interface>

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