Markdown editor

MarkdownEditor is a stateful entity — a live-preview markdown editor in the style of Obsidian. Every line renders formatted (headings sized, emphasis styled, list markers drawn as bullets and checkboxes, fenced code highlighted, links clickable) while the cursor line — and any line the selection touches — reveals its markdown syntax for editing, with the markers dimmed. Text soft-wraps to the editor width, and list items keep a hanging indent across wrapped lines.

It shares its text model with Editor — the pure, unit-tested EditorModel — so cursor, selection, clipboard, and undo behave identically. The markdown understanding lives in three pure, unit-tested passes under guise::markdown: block (line classification), inline (emphasis, code, links), and layout (what each row shows, and how its bytes map back to the source).

#MarkdownEditor (entity)

Create it with cx.new and keep the Entity. It emits MarkdownEditorEvent::Change on every edit and MarkdownEditorEvent::LinkClick when a link is activated — ⌘click normally, plain click when read-only. Wikilink targets ([[Page]]) arrive as the page name; url links as the url.

use guise::markdown::{MarkdownEditor, MarkdownEditorEvent};

let editor = cx.new(|cx| {
    MarkdownEditor::new(cx)
        .value("# Notes\n\n- [ ] try **guise**")
        .placeholder("Start writing…")
});

cx.subscribe(&editor, |_this, _editor, event: &MarkdownEditorEvent, _cx| {
    match event {
        MarkdownEditorEvent::Change(text) => { /* persist the document */ }
        MarkdownEditorEvent::LinkClick(target) => { /* open the target */ }
    }
})
.detach();

Runtime API: text(), set_text(value, cx), focus_handle(), model() (read the underlying EditorModel), edit(cx, |model| …) (mutate it with change-event and scroll bookkeeping), toggle_task(line, cx), set_style, and MarkdownEditor::bind(&entity, &signal, cx) for two-way binding to a Signal<String> (see Reactive state).

#What renders

• Headings #–######, scaled and bold, with extra space above.
• Emphasis — **bold**, *italic* / _italic_, ***both***, ~~strikethrough~~, ==highlight==, and `inline code`.
• Links — [text](url), [[WikiLink]], [[Page|alias]]; underlined in the accent color with the target hidden until revealed.
• Lists — -/*/+ bullets, 1./1) numbers, and - [ ]/- [x] task checkboxes, nested by indentation with hanging indents. Checked tasks dim their text.
• Quotes — > per level, drawn as accent bars.
• Fenced code — ``` blocks on a tinted surface, with Rust / SQL / JSON highlighting from the fence's info string (the Editor Language tokenizers).
• Thematic breaks — --- / *** / ___ as a rule.
• YAML frontmatter and tables render as dimmed/plain monospace source.

#Editing behavior

• Live reveal — the cursor line (and every line a selection touches) shows its raw markdown with dimmed markers; leaving the line re-renders it. List markers stay rendered even on the cursor line; the caret parks at the content start.
• Enter continues lists and quotes (- , - [ ] , 4. , > ) and clears the marker instead when the item is empty. ⇧ isn't special — use Backspace at the content start to strip a marker.
• Tab / ⇧Tab indent and outdent list items from anywhere on the line.
• ⌘B / ⌘I toggle ** / * around the selection or the word at the caret; ⌘K wraps the selection as [selection]() with the caret in the parentheses.
• ⌘Enter toggles the checkbox on a task line; clicking the box does too.
• Arrows move by visual row through soft-wrapped text, with a sticky goal column. ⌘←/→ jump to line edges, ⌥←/→ by word, ⌘↑/↓ to the document edges — the same map as Editor, including select-all, copy/cut/paste, and undo/redo.

#Example

cargo run -p guise-ui --example markdown

opens a small document exercising everything above.