Multi-line text editor — text

An editable text area with a cursor, selection, undo/redo, search and scrolling. Text is stored as a vector of lines and edited by logical (row, grapheme) positions, so emoji, accents and CJK text are never split, and only the visible lines are formatted when drawing.

Usage

text_area(
  value = "",
  placeholder = "",
  id = NULL,
  classes = NULL,
  style = NULL,
  disabled = FALSE,
  line_numbers = FALSE,
  wrap = TRUE,
  read_only = FALSE,
  language = NULL,
  tab_size = 4L,
  tab_behavior = "focus",
  auto_indent = FALSE,
  validate = NULL,
  max_history = 200L,
  highlighter = NULL
)

Arguments

value: Initial text.
placeholder: Text shown while the area is empty.
id: Optional identifier.
classes: Optional classes.
style: A style().
disabled: Disabled areas cannot be focused or edited.
line_numbers: Show line numbers?
wrap: Wrap long lines? If FALSE the view scrolls horizontally.
read_only: Block editing?
language: Optional language label supplied to the highlighter.
tab_size: Spaces per tab stop.
tab_behavior: "focus" (Tab moves focus) or "indent".
auto_indent: Keep the indentation on Enter?
validate: Optional function(value) returning NULL/TRUE when valid or a message.
max_history: Maximum number of undo steps.
highlighter: Optional viewport-first syntax highlighter; see r_highlighter().

Value

A TextArea widget. Useful members: $value, $set_text(), $insert(), $selection, $cursor_row, $cursor_column, $goto_line(), $cursor_position(), $undo(), $redo(), $find(), $replace(), $replace_all(), $find_next(), $find_previous(), $match_count.

Details

Keys: arrows, Home/End, Ctrl+Home/End, Ctrl+Left/Right (words), PageUp/PageDown, Shift+ to select, Ctrl+A select all, Enter, Backspace, Delete, Ctrl+Backspace / Ctrl+Delete (words), Ctrl+U / Ctrl+K (to line start / end), Ctrl+C / Ctrl+X / Ctrl+V (copy, cut, paste with the app clipboard; copy also reaches the system clipboard via OSC 52 when the terminal supports it), Ctrl+Z undo, Ctrl+Y redo, Ctrl+F find (Enter / Down next, Up previous, Ctrl+R regex, Alt+C case, Esc close), F3 / Shift+F3 next / previous match. Tab moves focus unless tab_behavior = "indent". The mouse places the cursor, drags select and the wheel scrolls. A bracketed paste is one undo step.

Messages (event$data): "textarea.changed" (version, lines, valid; read the text with $value), "textarea.selection_changed" (empty, start_row, start_column, end_row, end_column) and "textarea.valid" / "textarea.invalid" (error).

Editing groups: typing is merged into undo steps per word, paste, delete-selection and line operations are single steps. The history is bounded (max_history steps and about 2 million characters). Tabs in text are expanded to spaces. This widget is experimental.

Examples

ed <- text_area("Hello\nworld", id = "editor", line_numbers = TRUE)
ed$insert("!")
ed$value
#> [1] "!Hello\nworld"
ed$find("wor")
ed$selection
#> [1] "wor"