rework toolbar to use attachment pattern, simpler external control

src/lib/Toolbar.ts

@@ -1,5 +1,5 @@
 import { createAttachmentKey, type Attachment } from 'svelte/attachments';
-import { writable, type Writable } from 'svelte/store';
+import { get, writable, type Writable } from 'svelte/store';
 
 export type ToolbarToggleState = 'on' | 'off';
 
@@ -14,62 +14,98 @@ export type ToolbarToggleOptions = {
 const toggleValue = (current: ToolbarToggleState): ToolbarToggleState =>
 	current === 'on' ? 'off' : 'on';
 
-/** createGenericToggle creates a toggle. If a list of toggles is passed, the toggle is created as a group item */
-const createGenericToggle = (
-	toggles: Writable<ToolbarToggleState>[] | null,
-	opts: ToolbarToggleOptions = {}
-) => {
-	const toggleState = opts.state ?? writable<ToolbarToggleState>('off');
-	// If this is a group, add this toggle to it
-	if (toggles !== null) toggles.push(toggleState);
+/**
+ * A single toggleable toolbar item. Can coordinate with other toggles in a group.
+ */
+export class ToolbarToggle {
+	private _state: Writable<ToolbarToggleState>;
+	private _parent: ToolbarGroup | undefined;
 
-	return {
-		state: toggleState,
-		[createAttachmentKey()]: ((node) => {
+	constructor(opts: ToolbarToggleOptions = {}) {
+		this._state = opts.state ?? writable('off');
+	}
+
+	/**
+	 * Creates a new toggleable toolbar item with a parent group.
+	 *
+	 * @param parent The parent group to which this toggle belongs.
+	 * @param opts Options for the toggle.
+	 * @returns A new ToolbarToggle instance.
+	 */
+	static withParent(parent: ToolbarGroup, opts: ToolbarToggleOptions = {}) {
+		const toggle = new ToolbarToggle(opts);
+		toggle._parent = parent;
+		return toggle;
+	}
+
+	/**
+	 * Returns the store that manages the state of the toggle.
+	 */
+	get store() {
+		return this._state;
+	}
+
+	/**
+	 * Returns the current state of the toggle.
+	 */
+	get state() {
+		return get(this._state);
+	}
+
+	/**
+	 * Sets the state of the toggle.
+	 */
+	set state(value: ToolbarToggleState) {
+		this._state.set(value);
+	}
+
+	/**
+	 * Returns a Svelte 5 Attachment for the toggle.
+	 */
+	get attachment(): Attachment {
+		return (node) => {
 			const el = node as HTMLElement;
 			// Subscribe to store
-			const unsubscribe = toggleState.subscribe((state) => {
+			const unsubscribe = this._state.subscribe((state) => {
 				el.dataset.state = state;
 			});
 
+			// Add a listener for the click event
+			el.addEventListener('click', (e: MouseEvent) => {
+				const target = e.currentTarget as HTMLElement;
+				if (!target) return;
+
+				this._state.update(toggleValue);
+
+				// If this is a group, turn off all other toggles
+				if (this._parent) {
+					this._parent.disableAll(this);
+				}
+			});
+
 			return unsubscribe;
-		}) as Attachment,
-		onclick: (e: MouseEvent) => {
-			const target = e.currentTarget as HTMLElement;
-			if (!target) return;
+		};
+	}
 
-			toggleState.update(toggleValue);
-
-			// If this is a group, turn off all other toggles
-			if (toggles !== null) {
-				toggles.forEach((toggle) => {
-					if (toggle !== toggleState) {
-						toggle.update(() => 'off');
-					}
-				});
-			}
-		}
-	};
-};
+	/**
+	 * Returns props including the attachment for the toggle, allowing easy spreading
+	 * to an HTML element. Should NOT be used in addition to manually attaching the toggle.
+	 *
+	 * Can be advantageous as spreading seems to allow CSS tree-shaking to work properly.
+	 */
+	get props() {
+		return {
+			[createAttachmentKey()]: this.attachment
+		};
+	}
+}
 
 /**
  * A group of toggles in a toolbar. Makes each toggle exclusive of the others, disabling all other
  * toggles when any given toggle is enabled.
  */
 export class ToolbarGroup {
-	private _name: string;
-	private _toggles: Writable<ToolbarToggleState>[] = [];
-
-	constructor(name: string) {
-		this._name = name;
-	}
-
-	/**
-	 * The name of the toolbar group.
-	 */
-	get name() {
-		return this._name;
-	}
+	private _toggles: ToolbarToggle[] = [];
 
 	/**
 	 * Creates a new toolbar toogle item in the group.
@@ -77,7 +113,35 @@ export class ToolbarGroup {
 	 * @returns object containing state and properties
 	 */
 	toggle(opts: ToolbarToggleOptions = {}) {
-		return createGenericToggle(this._toggles, opts);
+		const toggle = ToolbarToggle.withParent(this, opts);
+		this._toggles.push(toggle);
+		return toggle;
+	}
+
+	/**
+	 * Disables all toggles in the group except the one specified.
+	 * @param except - The toggle to exclude from disabling.
+	 */
+	disableAll(except?: ToolbarToggle) {
+		this._toggles.forEach((t) => {
+			if (t !== except) {
+				t.state = 'off';
+			}
+		});
+	}
+
+	/**
+	 * Enables the specified toggle and disables all other toggles in the group.
+	 * @param toggle - The toggle to enable.
+	 */
+	enable(toggle: ToolbarToggle) {
+		this._toggles.forEach((t) => {
+			if (t == toggle) {
+				t.state = 'on';
+			} else {
+				t.state = 'off';
+			}
+		});
 	}
 }
 
@@ -91,14 +155,10 @@ export class Toolbar {
 
 	/**
 	 * Creates a new toolbar group.
-	 * @param name The name of the group.
 	 * @returns The newly created toolbar group.
 	 */
-	group(name: string) {
-		if (this._groups.some((g) => g.name === name)) {
-			throw new Error(`Toolbar group "${name}" already exists.`);
-		}
-		const g = new ToolbarGroup(name);
+	group() {
+		const g = new ToolbarGroup();
 		this._groups.push(g);
 		return g;
 	}
@@ -109,6 +169,6 @@ export class Toolbar {
 	 * @returns object containing state and properties
 	 */
 	toggle(opts: ToolbarToggleOptions = {}) {
-		return createGenericToggle(null, opts);
+		return new ToolbarToggle(opts);
 	}
 }

src/routes/+page.svelte

@@ -32,8 +32,9 @@
 	let dialogOpen = $state(false);
 
 	const toolbar = new Toolbar();
-	const fontGroup = toolbar.group('font');
-	const { state: boldState, ...boldProps } = fontGroup.toggle();
+	const fontGroup = toolbar.group();
+	const boldToggle = fontGroup.toggle();
+	const boldStore = boldToggle.store;
 </script>
 
 <title>sui</title>
@@ -219,7 +220,7 @@
 	<p class="title">Toolbar</p>
 
 	<div class="my-2">
-		<p>Bold is enabled: {$boldState}</p>
+		<p>Bold is enabled: {$boldStore}</p>
 	</div>
 
 	<div
@@ -236,20 +237,30 @@
 		</div>
 		<div class="bg-sui-text/50 w-[1px] self-stretch"></div>
 		<div class="flex items-center gap-1">
-			<button class="item" title="Toggle Bold" aria-label="bold" {...boldProps}>
+			<button class="item" title="Toggle Bold" aria-label="bold" {@attach boldToggle.attachment}>
 				<TextB size="1.25em" />
 			</button>
-			<button class="item" title="Toggle Italic" aria-label="italic" {...fontGroup.toggle()}>
+			<button
+				class="item"
+				title="Toggle Italic"
+				aria-label="italic"
+				{@attach fontGroup.toggle().attachment}
+			>
 				<TextItalic size="1.25em" />
 			</button>
-			<button class="item" title="Toggle Underline" aria-label="underline" {...fontGroup.toggle()}>
+			<button
+				class="item"
+				title="Toggle Underline"
+				aria-label="underline"
+				{@attach fontGroup.toggle().attachment}
+			>
 				<TextUnderline size="1.25em" />
 			</button>
 			<button
 				class="item"
 				title="Toggle Strikethrough"
 				aria-label="strikethrough"
-				{...fontGroup.toggle()}
+				{...fontGroup.toggle().props}
 			>
 				<TextStrikethrough size="1.25em" />
 			</button>