[PATCHv4 wayland-protocols] text-input: Add v3 of the text-input protocol
Dorota Czaplejewicz
dorota.czaplejewicz at puri.sm
Thu May 3 19:22:46 UTC 2018
On Thu, 3 May 2018 20:47:27 +0200
Silvan Jegen <s.jegen at gmail.com> wrote:
> Hi Dorota
>
> Some comments and typo fixes below.
>
> On Thu, May 03, 2018 at 05:41:21PM +0200, Dorota Czaplejewicz wrote:
> > 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.
> >
> > Cheers,
> > 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.
> > +
> > + THE COPYRIGHT HOLDERS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS
> > + SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND
> > + FITNESS, IN NO EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY
> > + SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
> > + WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN
> > + AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION,
> > + ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF
> > + THIS SOFTWARE.
> > + </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.
>
> That way we make sure we don't put the cursor/anchor between bytes that
> belong to the same UTF-8 encoded Unicode code point which is nice. It
> also means that the client has to parse all the UTF-8 encoded strings
> into Unicode code points up to the desired cursor/anchor position
> on each "preedit_string" event. For each "delete_surrounding_text" event
> the client has to parse the UTF-8 sequences before and after the cursor
> position up to the requested Unicode code point.
>
> I feel like we are processing the UTF-8 string already in the
> input-method. So I am not sure that we should parse it again on the
> client side. Parsing it again would also mean that the client would need
> to know about UTF-8 which would be nice to avoid.
>
> Thoughts?
The client needs to know about Unicode, but not necessarily about UTF-8. Specifying code points is actually an advantage here, because byte offsets are inherently expressed relative to UTF-8. By counting with code points, client's internal representation can be UTF-16 or maybe even something else.
There's no avoiding the parsing either. What the application cares about is that the cursor falls between glyphs. The application cannot know that in all cases. Unicode allows the same sequence to be displayed in multiple ways (fallback):
https://unicode.org/emoji/charts/emoji-zwj-sequences.html
One could make an argument that byte offsets should never be close to ZWJ characters, but I think this decision is better left to the application, which knows what exactly it is presenting to the user.
>
>
> > +
> > + 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.
>
> s/enabl/enable/
>
>
> > + 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
>
> Maybe "plays a special role" sounds more natural than "performs a special
> role"?
>
>
> > + 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.
>
> s/highligt/highlight/
>
>
> > +
> > + 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
>
> s/delete_surrounding_string/delete_surrounding_text/
>
> Thanks for all the work!
>
Thanks for reviewing, and for reminding me of the importance of spellcheck :)
I'll take this opportunity to point out that I made the algorithm to apply changes dependent on the cursor, while I let the cursor be removed altogether elsewhere. That will be fixed in the next revision.
Cheers,
Dorota
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/pgp-signature
Size: 833 bytes
Desc: OpenPGP digital signature
URL: <https://lists.freedesktop.org/archives/wayland-devel/attachments/20180503/a523bc62/attachment.sig>
More information about the wayland-devel
mailing list