Ui

Nvim UI protocol ui

UI Events ui-protocol ui-events

UIs can be implemented as external client processes communicating with Nvim over the RPC API. The default UI model is a terminal-like grid with a single, monospace font. The UI can opt-in to have windows drawn on separate grids, and have some elements ("widgets") presented by the UI itself rather than by Nvim ("externalized").

ui-option
Call nvim_ui_attach() to tell Nvim that your program wants to draw the Nvim screen grid with a size of width × height cells. This is typically done by an embedder at startup (see ui-startup), but UIs can also connect to a running Nvim instance and invoke nvim_ui_attach(). The options parameter is a map with these (optional) keys:

ui-rgb

ui-override

ui-ext-options

Specifying an unknown option is an error; UIs can check the api-metadata ui_options key for supported options.

By default Nvim requires all connected UIs to support the same capabilities, thus the active capabilities are the intersection of those requested. UIs may specify ui-override to invert this behavior (useful for debugging). The "option_set" event announces which capabilities are active.

Nvim sends RPC notifications to all attached UIs, with method name "redraw" and a single argument: an array (batch) of screen "update events". Each update event is itself an array whose first element is the event name and remaining elements are event-parameter tuples. Thus multiple events of the same kind can be sent contiguously without repeating the event name.

Example of a typical "redraw" batch in a single RPC notification:

['notification', 'redraw',
  [
    ['grid_resize', [2, 77, 36]],
    ['grid_line',
      [2, 0, 0, [[' ' , 0, 77]], false],
      [2, 1, 0, [['~', 7], [' ', 7, 76]], false],
      [2, 9, 0, [['~', 7], [' ', 7, 76]], false],
      ...
      [2, 35, 0, [['~', 7], [' ', 7, 76]], false],
      [1, 36, 0, [['[', 9], ['N'], ['o'], [' '], ['N'], ['a'], ['m'], ['e'], [']']], false],
      [1, 36, 9, [[' ', 9, 50]], false],
      [1, 36, 59, [['0', 9], [','], ['0'], ['-' ], ['1'], [' ', 9, 10], ['A'], ['l', 9, 2]], false]
    ],
    ['msg_showmode', [[]]],
    ['win_pos', [2, 1000, 0, 0, 77, 36]],
    ['grid_cursor_goto', [2, 0, 0]],
    ['flush', []]
  ]
]

Events must be handled in-order. Nvim sends a "flush" event when it has completed a redraw of the entire screen (so all windows have a consistent view of buffer state, options, etc.). Multiple "redraw" batches may be sent before the entire screen has been redrawn, with "flush" following only the last batch. The user should only see the final state (when "flush" is sent), not any intermediate state while processing part of the batch array, nor after a batch not ending with "flush".

By default, Nvim sends ui-global and ui-grid-old events (for backwards compatibility); these suffice to implement a terminal-like interface. However the new ui-linegrid represents text more efficiently (especially highlighted text), and allows UI capabilities requiring multiple grids. New UIs should implement ui-linegrid instead of ui-grid-old.

Nvim optionally sends various screen elements "semantically" as structured events instead of raw grid-lines, as specified by ui-ext-options. The UI must present such elements itself, Nvim will not draw them on the grid.

Future versions of Nvim may add new update kinds and may append new parameters to existing update kinds. Clients must be prepared to ignore such extensions, for forward-compatibility. api-contract

UI startup ui-startup

UI embedders (clients that start Nvim with --embed and later call nvim_ui_attach()) must start Nvim without --headless:

nvim --embed

Nvim will pause before loading startup files and reading buffers, so the UI has a chance to invoke requests and do early initialization. Startup will continue as soon as the UI invokes nvim_ui_attach().

A simple UI only needs to do a single nvim_ui_attach() request and then prepare to handle any UI event. A more featureful UI, which might need additional configuration of the Nvim process, should use the following startup procedure:

1. Invoke nvim_get_api_info(), if needed to setup the client library and/or to get the list of supported UI extensions.

2. Do any configuration that should be happen before user config is loaded. Buffers and windows are not available at this point, but this could be used to set g: variables visible to init.vim

3. If the UI wants to do additional setup after user config is loaded, register a VimEnter autocmd:

nvim_command("autocmd VimEnter * call rpcrequest(1, 'vimenter')")

4. Now invoke nvim_ui_attach(). The UI must handle user input by now: sourcing init.vim and loading buffers might lead to blocking prompts.

5. If step 3 was used, Nvim will send a blocking "vimenter" request to the UI. Inside this request handler, the UI can safely do any initialization before entering normal mode, for example reading variables set by init.vim.

ui-startup-stdin
An UI can support the native read from stdin feature as invoked with command | nvim - for the builtin TUI. -- The embedding process can detect that its stdin is open to a file which not is a terminal, just like Nvim does. It then needs to forward this fd to Nvim. As fd=0 is already is used to send rpc data from the embedder to Nvim, it needs to use some other file descriptor, like fd=3 or higher.

Then, stdin_fd option should be passed to nvim_ui_attach and Nvim will implicitly read it as a buffer. This option can only be used when Nvim is launched with --embed option, as described above.

Global Events ui-global

The following UI events are always emitted, and describe global state of the editor.

Set the window title, and icon (minimized) window title, respectively. In windowing systems not distinguishing between the two, "set_icon" can be ignored.

cursor_style_enabled is a boolean indicating if the UI should set the cursor style. mode_info is a list of mode property maps. The current mode is given by the mode_idx field of the mode_change event.

Each mode property map may contain these keys:

cursor_shape: "block", "horizontal", "vertical" cell_percentage: Cell % occupied by the cursor. blinkwait, blinkon, blinkoff: See cursor-blinking. attr_id: Cursor attribute id (defined by hl_attr_define). When attr_id is 0, the background and foreground colors should be swapped. attr_id_lm: Cursor attribute id for when :lmap is on. short_name: Mode code name, see 'guicursor'. name: Mode descriptive name. mouse_shape: (To be implemented.)

Some keys are missing in some modes.

The following keys are deprecated:

hl_id: Use attr_id instead. id_lm: Use attr_id_lm instead.

UI-related option changed, where name is one of:

Triggered when the UI first connects to Nvim, and whenever an option is changed by the user or a plugin.

Options are not represented here if their effects are communicated in other UI events. For example, instead of forwarding the 'mouse' option value, the "mouse_on" and "mouse_off" UI events directly indicate if mouse support is active. Some options like 'ambiwidth' have already taken effect on the grid, where appropriate empty cells are added, however a UI might still use such options when rendering raw text sent from Nvim, like for ui-cmdline.

The current-directory of the embedded Nvim process changed to path.

Editor mode changed. The mode parameter is a string representing the current mode. mode_idx is an index into the array emitted in the mode_info_set event. UIs should change the cursor style according to the properties specified in the corresponding item. The set of modes reported will change in new versions of Nvim, for instance more submodes and temporary states might be represented as separate modes.

'mouse' was enabled/disabled in the current editor mode. Useful for a terminal UI, or embedding into an application where Nvim mouse would conflict with other usages of the mouse. Other UI:s may ignore this event.

Indicates to the UI that it must stop rendering the cursor. This event is misnamed and does not actually have anything to do with busyness.

:suspend command or CTRL-Z mapping is used. A terminal client (or another client where it makes sense) could suspend itself. Other clients can safely ignore it.

The menu mappings changed.

Notify the user with an audible or visual bell, respectively.

Nvim is done redrawing the screen. For an implementation that renders to an internal buffer, this is the time to display the redrawn parts to the user.

Grid Events (line-based) ui-linegrid

Activated by the ext_linegrid ui-option. Recommended for all new UIs. Deactivates ui-grid-old implicitly.

The biggest change compared to ui-grid-old is to use a single grid_line event to update the contents of a screen line (whereas the old protocol used a combination of cursor, highlight and text events)

Most of these events take a grid index as first parameter. Grid 1 is the global grid used by default for the entire editor screen state. The ext_linegrid capability by itself will never cause any additional grids to be created; to enable per-window grids, activate ui-multigrid.

Highlight attribute groups are predefined. UIs should maintain a table to map numerical highlight ids to the actual attributes.

Resize a grid. If grid wasn't seen by the client before, a new grid is being created with this size.

The first three arguments set the default foreground, background and special colors respectively. cterm_fg and cterm_bg specifies the default color codes to use in a 256-color terminal.

The RGB values will always be valid colors, by default. If no colors have been set, they will default to black and white, depending on 'background'. By setting the ext_termcolors option, instead -1 will be used for unset colors. This is mostly useful for a TUI implementation, where using the terminal builtin ("ANSI") defaults are expected.

Note: Unlike the corresponding ui-grid-old events, the screen is not always cleared after sending this event. The UI must repaint the screen with changed background color itself.

ui-event-hl_attr_define
Add a highlight with id to the highlight table, with the attributes specified by the rgb_attr and cterm_attr dicts, with the following (all optional) keys.

foreground: foreground color. background: background color. special: color to use for various underlines, when present. reverse: reverse video. Foreground and background colors are switched. italic: italic text. bold: bold text. strikethrough: struckthrough text. underline: underlined text. The line has special color. undercurl: undercurled text. The curl has special color. underdouble: double underlined text. The lines have special color. underdotted: underdotted text. The dots have special color. underdashed: underdashed text. The dashes have special color. altfont: alternative font. blend: blend level (0-100). Could be used by UIs to support blending floating windows to the background or to signal a transparent cursor. url: URL associated with this highlight. UIs should present the region as a clickable hyperlink.

For absent color keys the default color should be used. Don't store the default value in the table, rather a sentinel value, so that a changed default color will take effect. All boolean keys default to false, and will only be sent when they are true.

Highlights are always transmitted both for both the RGB format and as terminal 256-color codes, as the rgb_attr and cterm_attr parameters respectively. The ui-rgb option has no effect anymore. Most external UIs will only need to store and use the rgb_attr attributes.

id 0 will always be used for the default highlight with colors defined by default_colors_set and no styles applied.

Note: Nvim may reuse id values if its internal highlight table is full. In that case Nvim will always issue redraws of screen cells that are affected by redefined ids, so UIs do not need to keep track of this themselves.

info is an empty array by default, and will be used by the ui-hlstate extension explained below.

The built-in highlight group name was set to use the attributes hl_id defined by a previous hl_attr_define call. This event is not needed to render the grids which use attribute ids directly, but is useful for a UI who want to render its own elements with consistent highlighting. For instance a UI using ui-popupmenu events, might use the hl-Pmenu family of builtin highlights.

ui-event-grid_line
Redraw a continuous part of a row on a grid, starting at the column col_start. cells is an array of arrays each with 1 to 3 items: [text(, hl_id, repeat)] . text is the UTF-8 text that should be put in a cell, with the highlight hl_id defined by a previous hl_attr_define call. If hl_id is not present the most recently seen hl_id in the same call should be used (it is always sent for the first cell in the event). If repeat is present, the cell should be repeated repeat times (including the first time), otherwise just once.

The right cell of a double-width char will be represented as the empty string. Double-width chars never use repeat.

If the array of cell changes doesn't reach to the end of the line, the rest should remain unchanged. A whitespace char, repeated enough to cover the remaining line, will be sent when the rest of the line should be cleared.

wrap is a boolean indicating that this line wraps to the next row. When redrawing a line which wraps to the next row, Nvim will emit a grid_line event covering the last column of the line with wrap set to true, followed immediately by a grid_line event starting at the first column of the next row.

Clear a grid.

grid will not be used anymore and the UI can free any data associated with it.

Makes grid the current grid and row, col the cursor position on this grid. This event will be sent at most once in a redraw batch and indicates the visible cursor position.

Scroll a region of grid. This is semantically unrelated to editor scrolling, rather this is an optimized way to say "copy these screen cells".

The following diagrams show what happens per scroll direction. "===" represents the SR (scroll region) boundaries. "---" represents the moved rectangles. Note that dst and src share a common region.

If rows is bigger than 0, move a rectangle in the SR up, this can happen while scrolling down.

+-------------------------+
| (clipped above SR)      |            ^
|=========================| dst_top    |
| dst (still in SR)       |            |
+-------------------------+ src_top    |
| src (moved up) and dst  |            |
|-------------------------| dst_bot    |
| src (invalid)           |            |
+=========================+ src_bot

If rows is less than zero, move a rectangle in the SR down, this can happen while scrolling up.

+=========================+ src_top
| src (invalid)           |            |
|------------------------ | dst_top    |
| src (moved down) and dst|            |
+-------------------------+ src_bot    |
| dst (still in SR)       |            |
|=========================| dst_bot    |
| (clipped below SR)      |            v
+-------------------------+

cols is always zero in this version of Nvim, and reserved for future use.

Note when updating code from ui-grid-old events: ranges are end-exclusive, which is consistent with API conventions, but different from set_scroll_region which was end-inclusive.

The scrolled-in area will be filled using ui-event-grid_line directly after the scroll event. The UI thus doesn't need to clear this area as part of handling the scroll event.

Grid Events (cell-based) ui-grid-old

This is the legacy representation of the screen grid, emitted if ui-linegrid is not active. New UIs should implement ui-linegrid instead.

The grid is resized to width and height cells.

Clear the grid.

Clear from the cursor position to the end of the current line.

Move the cursor to position (row, col). Currently, the same cursor is used to define the position for text insertion and the visible cursor. However, only the last cursor position, after processing the entire array in the "redraw" event, is intended to be a visible cursor position.

Set the default foreground, background and special colors respectively.

ui-event-highlight_set
Set the attributes that the next text put on the grid will have. attrs is a dict with the keys below. Any absent key is reset to its default value. Color defaults are set by the update_fg etc updates. All boolean keys default to false.

foreground: foreground color. background: background color. special: color to use for various underlines, when present. reverse: reverse video. Foreground and background colors are switched. italic: italic text. bold: bold text. strikethrough: struckthrough text. underline: underlined text. The line has special color. undercurl: undercurled text. The curl has special color. underdouble: double underlined text. The lines have special color. underdotted: underdotted text. The dots have special color. underdashed: underdashed text. The dashes have special color.

The (utf-8 encoded) string text is put at the cursor position (and the cursor is advanced), with the highlights as set by the last highlight_set update.

Define the scroll region used by scroll below.

Note: ranges are end-inclusive, which is inconsistent with API conventions.

Scroll the text in the scroll region. The diagrams below illustrate what will happen, depending on the scroll direction. "=" is used to represent the SR(scroll region) boundaries and "-" the moved rectangles. Note that dst and src share a common region.

If count is bigger than 0, move a rectangle in the SR up, this can happen while scrolling down.

+-------------------------+
| (clipped above SR)      |            ^
|=========================| dst_top    |
| dst (still in SR)       |            |
+-------------------------+ src_top    |
| src (moved up) and dst  |            |
|-------------------------| dst_bot    |
| src (cleared)           |            |
+=========================+ src_bot

If count is less than zero, move a rectangle in the SR down, this can happen while scrolling up.

+=========================+ src_top
| src (cleared)           |            |
|------------------------ | dst_top    |
| src (moved down) and dst|            |
+-------------------------+ src_bot    |
| dst (still in SR)       |            |
|=========================| dst_bot    |
| (clipped below SR)      |            v
+-------------------------+

Detailed highlight state Extension ui-hlstate

Activated by the ext_hlstate ui-option. Activates ui-linegrid implicitly.

By default Nvim will only describe grid cells using the final calculated highlight attributes, as described by the dict keys in ui-event-highlight_set. The ext_hlstate extension allows to the UI to also receive a semantic description of the highlights active in a cell. In this mode highlights will be predefined in a table, see ui-event-hl_attr_define and ui-event-grid_line. The info parameter in hl_attr_define will contain a semantic description of the highlights. As highlight groups can be combined, this will be an array of items, with the item with highest priority last. Each item is a dictionary with the following possible keys:

kind: always present. One of the following values: "ui": Builtin UI highlight. highlight-groups "syntax": Highlight applied to a buffer by a syntax declaration or other runtime/plugin functionality such as nvim_buf_add_highlight() "terminal": highlight from a process running in a terminal-emulator. Contains no further semantic information. ui_name: Highlight name from highlight-groups. Only for "ui" kind. hi_name: Name of the final :highlight group where the used attributes are defined. id: Unique numeric id representing this item.

Note: "ui" items will have both ui_name and hi_name present. These can differ, because the builtin group was linked to another group :hi-link , or because 'winhighlight' was used. UI items will be transmitted, even if the highlight group is cleared, so ui_name can always be used to reliably identify screen elements, even if no attributes have been applied.

Multigrid Events ui-multigrid

Activated by the ext_multigrid ui-option. Activates ui-linegrid implicitly.

See ui-linegrid for grid events. See nvim_ui_try_resize_grid() to request changing the grid size. See nvim_input_mouse() for sending mouse events to Nvim.

The multigrid extension gives UIs more control over how windows are displayed:

By default, the grid size is handled by Nvim and set to the outer grid size (i.e. the size of the window frame in Nvim) whenever the split is created. Once a UI sets a grid size, Nvim does not handle the size for that grid and the UI must change the grid size whenever the outer size is changed. To delegate grid-size handling back to Nvim, request the size (0, 0).

A window can be hidden and redisplayed without its grid being deallocated. This can happen multiple times for the same window, for instance when switching tabs.

Set the position and size of the grid in Nvim (i.e. the outer grid size). If the window was previously hidden, it should now be shown again.

Display or reconfigure floating window win. The window should be displayed above another grid anchor_grid at the specified position anchor_row and anchor_col. For the meaning of anchor and more details of positioning, see nvim_open_win(). mouse_enabled is true if the window can receive mouse events.

Display or reconfigure external window win. The window should be displayed as a separate top-level window in the desktop environment, or something similar.

Stop displaying the window. The window can be shown again later.

Close the window.

Display messages on grid. The grid will be displayed at row on the default grid (grid=1), covering the full column width. scrolled indicates whether the message area has been scrolled to cover other grids. It can be useful to draw a separator then msgsep. The Builtin TUI draws a full line filled with sep_char ('fillchars' msgsep field) and hl-MsgSeparator highlight.

When ui-messages is active, no message grid is used, and this event will not be sent.

Indicates the range of buffer text displayed in the window, as well as the cursor position in the buffer. All positions are zero-based. botline is set to one more than the line count of the buffer, if there are filler lines past the end. scroll_delta contains how much the top line of a window moved since win_viewport was last emitted. It is intended to be used to implement smooth scrolling. For this purpose it only counts "virtual" or "displayed" lines, so folds only count as one line. When scrolling more than a full screen it is an approximate value.

All updates, such as grid_line, in a batch affects the new viewport, despite the fact that win_viewport is received after the updates. Applications implementing, for example, smooth scrolling should take this into account and keep the grid separated from what's displayed on the screen and copy it to the viewport destination once win_viewport is received.

Indicates the margins of a window grid which are _not_ part of the viewport as indicated by the win_viewport event. This happens e.g. in the presence of 'winbar' and floating window borders.

Updates the position of an extmark which is currently visible in a window. Only emitted if the mark has the ui_watched attribute.

Popupmenu Events ui-popupmenu

Activated by the ext_popupmenu ui-option.

This UI extension delegates presentation of the popupmenu-completion and command-line 'wildmenu'.

Show popupmenu-completion. items is an array of completion items to show; each item is an array of the form [word, kind, menu, info] as defined at complete-items, except that word is replaced by abbr if present. selected is the initially-selected item, a zero-based index into the array of items (-1 if no item is selected). row and col give the anchor position, where the first character of the completed word will be. When ui-multigrid is used, grid is the grid for the anchor position. When ext_cmdline is active, grid is set to -1 to indicate the popupmenu should be anchored to the external cmdline. Then col will be a byte position in the cmdline text.

Select an item in the current popupmenu. selected is a zero-based index into the array of items from the last popupmenu_show event, or -1 if no item is selected.

Hide the popupmenu.

Tabline Events ui-tabline

Activated by the ext_tabline ui-option.

Tabline was updated. UIs should present this data in a custom tabline widget. Note: options curbuf + buffers were added in API7. curtab: Current Tabpage tabs: List of Dicts [{ "tab": Tabpage, "name": String }, ...] curbuf: Current buffer handle. buffers: List of Dicts [{ "buffer": buffer handle, "name": String}, ...]

Cmdline Events ui-cmdline

Activated by the ext_cmdline ui-option.

This UI extension delegates presentation of the cmdline (except 'wildmenu'). For command-line 'wildmenu' UI events, activate ui-popupmenu.

content: List of [attrs, string] [[{}, "t"], [attrs, "est"], ...]

Triggered when the cmdline is displayed or changed. The content is the full content that should be displayed in the cmdline, and the pos is the position of the cursor that in the cmdline. The content is divided into chunks with different highlight attributes represented as a dict (see ui-event-highlight_set).

firstc and prompt are text, that if non-empty should be displayed in front of the command line. firstc always indicates built-in command lines such as : (ex command) and / ? (search), while prompt is an input() prompt. indent tells how many spaces the content should be indented.

The Nvim command line can be invoked recursively, for instance by typing <c-r>= at the command line prompt. The level field is used to distinguish different command lines active at the same time. The first invoked command line has level 1, the next recursively-invoked prompt has level 2. A command line invoked from the cmdline-window has a higher level than the edited command line.

Change the cursor position in the cmdline.

Display a special char in the cmdline at the cursor position. This is typically used to indicate a pending state, e.g. after c_CTRL-V. If shift is true the text after the cursor should be shifted, otherwise it should overwrite the char at the cursor.

Should be hidden at next cmdline_show.

Hide the cmdline.

Show a block of context to the current command line. For example if the user defines a :function interactively:

:function Foo()
:  echo "foo"
:

lines is a list of lines of highlighted chunks, in the same form as the "cmdline_show" contents parameter.

Append a line at the end of the currently shown block.

Hide the block.

Message/Dialog Events ui-messages

Activated by the ext_messages ui-option. Activates ui-linegrid and ui-cmdline implicitly.

This UI extension delegates presentation of messages and dialogs. Messages that would otherwise render in the message/cmdline screen space, are emitted as UI events.

Nvim will not allocate screen space for the cmdline or messages. 'cmdheight' will be set to zero, but can be changed and used for the replacing cmdline or message window. Cmdline state is emitted as ui-cmdline events, which the UI must handle.

Display a message to the user.

kind Name indicating the message kind: "" (empty) Unknown (consider a feature-request: bugs) "confirm" confirm() or :confirm dialog "confirm_sub" :substitute confirm dialog :s_c "emsg" Error (errors, internal error, :throw, …) "echo" :echo message "echomsg" :echomsg message "echoerr" :echoerr message "lua_error" Error in :lua code "rpc_error" Error response from rpcrequest() "return_prompt" press-enter prompt after a multiple messages "quickfix" Quickfix navigation message "search_count" Search count message ("S" flag of 'shortmess') "wmsg" Warning ("search hit BOTTOM", W10, …) New kinds may be added in the future; clients should treat unknown kinds as the empty kind.

content Array of [attr_id, text_chunk, hl_id] tuples, building up the message text of chunks of different highlights. No extra spacing should be added between chunks, the text_chunk by itself contains any necessary whitespace. Messages can contain line breaks "\n".

replace_last Decides how multiple messages should be displayed: false: Display the message together with all previous messages that are still visible. true: Replace the message in the most-recent msg_show call, but any other visible message should still remain.

Clear all messages currently displayed by "msg_show". (Messages sent by other "msg_" events below will not be affected).

Shows 'showmode' and recording messages. content has the same format as in "msg_show". This event is sent with empty content to hide the last message.

Shows 'showcmd' messages. content has the same format as in "msg_show". This event is sent with empty content to hide the last message.

Used to display 'ruler' when there is no space for the ruler in a statusline. content has the same format as in "msg_show". This event is sent with empty content to hide the last message.

Sent when :messages command is invoked. History is sent as a list of entries, where each entry is a [kind, content] tuple.

Clear the :messages history.