Crate day_piece_texteditor

Expand description

day-piece-texteditor: a styled-text editor bound two-way to a Signal<StyledText> (docs/texteditor.md).

let doc = Signal::new(StyledText::markdown("**Hello**, _world_.", Font::Body));
let sel = Signal::new(0..0);

column((
    // The toolbar is ordinary Day pieces; the piece ships no chrome of its own.
    button("B").action(move || doc.update(|d| {
        let on = !d.style_of(sel.get_untracked(), Font::Body).bold();
        d.apply(sel.get_untracked(), Font::Body, move |s| s.set_bold(on));
    })),
    text_editor(doc).selection(sel).min_lines(8),
))

It edits the same StyledText a label renders and the Markdown / HTML / RTF codecs read and write, in each platform’s own rich-text view: NSTextView, UITextView, GtkTextView, QTextEdit, an EditText over a SpannableStringBuilder, RichEditBox, the ArkTS RichEditor, and a contenteditable element. There is no composed tier and there must not be one: a hand-rolled editor loses IME composition, bidirectional cursor movement, the platform’s undo stack, dictation, and the accessibility tree, and loses them invisibly.

§Who owns the attributes

Day does. The native view owns the characters (typing, deletion, IME, undo, autocorrect) and reports them as Event::TextChanged; the piece diffs that against the text it last knew, reflows its runs over the edit (StyledText::reflow), and writes the signal. Attributes only ever travel Day → native.

That is why every arm turns the platform’s own formatting UI off (iOS’s allowsEditingTextAttributes, the macOS font panel) rather than reading it back: an editor whose attributes can change from two directions has to reconcile them, and reconciling an attributed string across eight toolkits is a much larger promise than this piece makes. Everything a toolbar does goes through the bound signal instead, in Rust, where it behaves identically on all nine targets and is testable on the headless one. docs/texteditor.md records the per-toolkit hook a future read-back would use.

Modules§

highlight: Syntax highlighting as runs (docs/texteditor.md §9): a tokenizer is a pure function from text to Vec<TextRun>, and TextEditor::highlight re-runs it on every edit and pushes the runs back as an attributes patch, so the caret and the undo stack stay where they are. Nothing here touches a toolkit; the same runs restyle all eight arms, and a test asserts them on the headless one.

Structs§

EditorProps: Full props (realize). Only doc, selection and editable change after build.
TextEditor: A styled-text editor bound two-way to a StyledText signal. Build with text_editor.

Enums§

EditorPatch

Constants§

HIGHLIGHT_LIMIT: The size past which a live highlighter leaves the text plain (512 KiB); see TextEditor::highlight_limit.
KEY_PREFIX: The prefix a claimed key rides on that same channel: "key Enter", "key Tab", the day key name an Event::Key would carry on a backend that can send one.
KIND
SEL_PREFIX: The prefix a selection report carries in its payload. The tag cannot cross a JNI / C-ABI / JS boundary (§8.2), so the payload has to be self-describing: "sel <start> <end>", in BYTE offsets, which every arm converts into from its own indexing.
TEXT_PREFIX: The prefix a text report carries on the same channel, for a backend whose piece bridge can only send Event::Custom (HarmonyOS’s ArkTS side is the one that has to): "txt <the text>", the whole document, exactly as Event::TextChanged carries it.

Traits§

TextEditorBuilder: Builder methods of TextEditor, reachable through a Decorated (docs/api-style.md “Typed builders and erasure”): generic modifiers and typed ones chain in any order.

Functions§

auto_indent: The indentation a new line takes after Enter typed at newline_at: the previous line’s leading whitespace, one level deeper when that line ends in an opening bracket. None when there is nothing to insert.
byte_of_char: A character offset back to a byte offset, clamped into the string.
byte_of_utf16: A UTF-16 offset back to a byte offset, clamped into the string.
char_range: A byte range as a character range (GTK’s TextIter, ArkUI’s spans).
closer_after: The closer to type after an opener typed at at, when the caret sits at the end of its line or before whitespace or another closer: { [ ( and the two quotes. None where a closer would land inside a word.
diff_edit: Recover a single contiguous edit from the old and new text: (offset, removed, inserted) in bytes.
flatten: A single-line editor’s text: every line break a space, byte for byte, so the offsets of an edit computed against the raw text still hold.
selection_payload: The selection payload every arm emits.
support: Whether the compiled backend edits styled text natively.
tab_indent: The spaces a Tab inserts at caret: to the next tab stop of width indent, counted in characters from the start of the caret’s line.
text_editor: text_editor(doc): the platform’s rich-text view over a StyledText signal.
text_editor_text: text_editor_text(text): the same editor over a plain String signal, for an app whose model holds text rather than a document (a request body, a file). The piece keeps a StyledText of its own: edits write the string, a string the app writes replaces the document’s text, and a TextEditor::highlight supplies whatever styling there is.
text_payload: The text payload for an arm that has only the custom channel; see TEXT_PREFIX.
utf16_range: A byte range as a UTF-16 range (Apple, Android, XAML).

Type Aliases§

Highlighter: What TextEditor::highlight takes: text in, runs over every byte of it out.