Protocol text_input_unstable_v3 — Protocol for composing text

This protocol allows compositors to act as input methods and to send text to applications. A text input object is used to manage state of what are typically text entry fields in the application.

This document adheres to the RFC 2119 when using words like "must", "should", "may", etc.

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.

License
    Copyright © 2012, 2013 Intel Corporation
    Copyright © 2015, 2016 Jan Arne Petersen
    Copyright © 2017, 2018 Red Hat, Inc.
    Copyright © 2018       Purism SPC

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Interface zwp_text_input_v3 — 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 preedit_string and commit_string events.

Text is valid UTF-8 encoded, indices and lengths are in bytes. Indices must not point to middle bytes inside a code point: they must either point to the first byte of a code point or to the end of the buffer. Lengths must be measured between two valid indices.

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 commit 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.

Request zwp_text_input_v3.destroy — Destroy the wp_text_input

Destroy the wp_text_input object. Also disables all surfaces enabled through this wp_text_input object.

Request zwp_text_input_v3.enable — Request text input to be enabled

Requests text input on the surface previously obtained from the enter event.

This request must be issued every time the active text input changes to a new one, including within the current surface. Use zwp_text_input_v3.disable when there is no longer any input focus on the current surface.

Clients must not enable more than one text input on the single seat and should disable the current text input before enabling the new one. At most one instance of text input may be in enabled state per instance, Requests to enable the another text input when some text input is active must be ignored by compositor.

This request resets all state associated with previous enable, disable, set_surrounding_text, set_text_change_cause, 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 must follow if the text input supports the necessary functionality.

State set with this request is double-buffered. It will get applied on the next zwp_text_input_v3.commit request, and stay valid until the next committed enable or disable request.

The changes must be applied by the compositor after issuing a zwp_text_input_v3.commit request.

Request zwp_text_input_v3.disable — Disable text input on a surface

Explicitly disable text input on the current surface (typically when there is no focus on any text entry inside the surface).

State set with this request is double-buffered. It will get applied on the next zwp_text_input_v3.commit request.

Request zwp_text_input_v3.set_surrounding_text — sets the surrounding text

Sets the surrounding plain text around the input, excluding the preedit text.

The client should notify the compositor of any changes in any of the values carried with this request, including changes caused by handling incoming text-input events as well as changes caused by other mechanisms like keyboard typing.

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.

Text is UTF-8 encoded, and should include the cursor position, the complete selection and additional characters before and after them. There is a maximum length of wayland messages, so text can not be longer than 4000 bytes.

Cursor is the byte offset of the cursor within text buffer.

Anchor is the byte offset of the selection anchor within text buffer. If there is no selected text, anchor is the same as cursor.

If any preedit text is present, it is replaced with a cursor for the purpose of this event.

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 committed 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.

  • text string: None
  • cursor int: None
  • anchor int: None

Request zwp_text_input_v3.set_text_change_cause — indicates the cause of surrounding text change

Tells the compositor why the text surrounding the cursor changed.

Whenever the client detects an external change in text, cursor, or anchor posision, it must issue this request to the compositor. This request is intended to give the input method a chance to update the preedit text in an appropriate way, e.g. by removing it when the user starts typing with a keyboard.

cause describes the source of the change.

The value set with this request is double-buffered. It must be applied and reset to initial at the next zwp_text_input_v3.commit request.

The initial value of cause is input_method.

  • cause uint: None

Request zwp_text_input_v3.set_content_type — 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 next zwp_text_input_v3.commit request. Subsequent attempts to update them may have no effect. The values remain valid until the next committed enable or disable request.

The initial value for hint is none, and the initial value for purpose is normal.

  • hint uint: None
  • purpose uint: None

Request zwp_text_input_v3.set_cursor_rectangle — 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 committed 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.

  • x int: None
  • y int: None
  • width int: None
  • height int: None

Request zwp_text_input_v3.commit — commit state

Atomically applies state changes recently sent to the compositor.

The commit request establishes and updates the state of the client, and must be issued after any changes to apply them.

Text input state (enabled status, content purpose, content hint, surrounding text and change cause, cursor rectangle) is conceptually double-buffered within the context of a text input, i.e. between a committed enable request and the following committed 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.

Requests are applied in the order of arrival.

Neither current nor pending state are modified unless noted otherwise.

The compositor must count the number of commit requests coming from each zwp_text_input_v3 object and use the count as the serial in done events.

Event zwp_text_input_v3.enter — enter event

Notification that this seat's text-input focus is on a certain surface.

If client has created multiple text input objects, compositor must send this event to all of them.

When the seat has the keyboard capability the text-input focus follows the keyboard focus. This event sets the current surface for the text-input object.

Event zwp_text_input_v3.leave — 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 clears the current surface. It is sent before the enter notification for the new focus. After leave event, compositor must ignore requests from any text input instances until next enter event.

When the seat has the keyboard capability the text-input focus follows the keyboard focus.

Event zwp_text_input_v3.preedit_string — pre-edit

Notify when a new composing text (pre-edit) should be set at the current cursor position. Any previously set composing text must be removed. Any previously existing selected text must be removed.

The argument text contains the pre-edit string buffer.

The parameters cursor_begin and cursor_end are counted in bytes relative to the beginning of the submitted text buffer. Cursor should be hidden when both are equal to -1.

They could be represented by the client as a line if both values are the same, or as a text highlight otherwise.

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, and cursor_begin, cursor_end and cursor_hidden are all 0.

  • text string: None
  • cursor_begin int: None
  • cursor_end int: None

Event zwp_text_input_v3.commit_string — 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.

  • text string: None

Event zwp_text_input_v3.delete_surrounding_text — delete surrounding text

Notify when the text around the current cursor position should be deleted.

Before_length and after_length are the number of bytes before and after the current cursor index (excluding the selection) to delete.

If a preedit text is present, in effect before_length is counted from the beginning of it, and after_length from its end (see done event sequence).

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.

  • before_length uint: length of text before current cursor position
  • after_length uint: length of text after current cursor position

Event zwp_text_input_v3.done — apply changes

Instruct the application to apply changes to state requested by the preedit_string, commit_string and delete_surrounding_text 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 must 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. Calculate surrounding text to send. 5. Insert new preedit text in cursor position. 6. Place cursor inside preedit text.

The serial number reflects the last state of the zwp_text_input_v3 object known to the compositor. The value of the serial argument must be equal to the number of commit requests already issued on that object. When the client receives a done event with a serial different than the number of past commit requests, it must proceed as normal, except it should not change the current state of the zwp_text_input_v3 object.

  • serial uint: None

Enum zwp_text_input_v3.change_cause — text change reason

Reason for the change of surrounding text or cursor posision.

  • input_method: input method caused the change
  • other: something else than the input method caused the change

Enum zwp_text_input_v3.content_hint — content hint

Content hint is a bitmask to allow to modify the behavior of the text input.

Enum zwp_text_input_v3.content_purpose — 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.

Interface zwp_text_input_manager_v3 — text input manager

A factory for text-input objects. This object is a global singleton.

Request zwp_text_input_manager_v3.destroy — Destroy the wp_text_input_manager

Destroy the wp_text_input_manager object.

Request zwp_text_input_manager_v3.get_text_input — create a new text input object

Creates a new text-input object for a given seat.