refactor: extract avatar-group logic into reusable mixin

packages/avatar-group/package.json

@@ -36,6 +36,7 @@
     "polymer"
   ],
   "dependencies": {
+    "@open-wc/dedupe-mixin": "^1.3.0",
     "@polymer/polymer": "^3.0.0",
     "@vaadin/a11y-base": "24.6.0-alpha8",
     "@vaadin/avatar": "24.6.0-alpha8",

packages/avatar-group/src/vaadin-avatar-group-mixin.d.ts

@@ -0,0 +1,99 @@
+/**
+ * @license
+ * Copyright (c) 2020 - 2024 Vaadin Ltd.
+ * This program is available under Apache License Version 2.0, available at https://vaadin.com/license/
+ */
+import type { Constructor } from '@open-wc/dedupe-mixin';
+import type { AvatarI18n } from '@vaadin/avatar/src/vaadin-avatar.js';
+import type { OverlayClassMixinClass } from '@vaadin/component-base/src/overlay-class-mixin.js';
+import type { ResizeMixinClass } from '@vaadin/component-base/src/resize-mixin.js';
+
+export interface AvatarGroupI18n extends AvatarI18n {
+  activeUsers: {
+    one: string;
+    many: string;
+  };
+  joined: string;
+  left: string;
+}
+
+export interface AvatarGroupItem {
+  name?: string;
+  abbr?: string;
+  img?: string;
+  colorIndex?: number;
+  className?: string;
+}
+
+/**
+ * A mixin providing common avatar functionality.
+ */
+export declare function AvatarGroupMixin<T extends Constructor<HTMLElement>>(
+  base: T,
+): Constructor<AvatarGroupMixinClass> & Constructor<OverlayClassMixinClass> & Constructor<ResizeMixinClass> & T;
+
+export declare class AvatarGroupMixinClass {
+  /**
+   * An array containing the items which will be stamped as avatars.
+   *
+   * The items objects allow to configure [`name`](#/elements/vaadin-avatar#property-name),
+   * [`abbr`](#/elements/vaadin-avatar#property-abbr), [`img`](#/elements/vaadin-avatar#property-img)
+   * and [`colorIndex`](#/elements/vaadin-avatar#property-colorIndex) properties on the
+   * stamped avatars, and set `className` to provide CSS class names.
+   *
+   * #### Example
+   *
+   * ```js
+   * group.items = [
+   *   {
+   *     name: 'User name',
+   *     img: 'url-to-image.png',
+   *     className: 'even'
+   *   },
+   *   {
+   *     abbr: 'JD',
+   *     colorIndex: 1,
+   *     className: 'odd'
+   *   },
+   * ];
+   * ```
+   */
+  items: AvatarGroupItem[] | undefined;
+
+  /**
+   * The maximum number of avatars to display. By default, all the avatars are displayed.
+   * When _maxItemsVisible_ is set, the overflowing avatars are grouped into one avatar with
+   * a dropdown. Setting 0 or 1 has no effect so there are always at least two avatars visible.
+   * @attr {number} max-items-visible
+   */
+  maxItemsVisible: number | null | undefined;
+
+  /**
+   * The object used to localize this component.
+   * To change the default localization, replace the entire
+   * _i18n_ object or just the property you want to modify.
+   *
+   * The object has the following JSON structure and default values:
+   * ```
+   * {
+   *   // Translation of the anonymous user avatar tooltip.
+   *   anonymous: 'anonymous',
+   *   // Translation of the avatar group accessible label.
+   *   // {count} is replaced with the actual count of users.
+   *   activeUsers: {
+   *     one: 'Currently one active user',
+   *     many: 'Currently {count} active users'
+   *   },
+   *   // Screen reader announcement when user joins group.
+   *   // {user} is replaced with the name or abbreviation.
+   *   // When neither is set, "anonymous" is used instead.
+   *   joined: '{user} joined',
+   *   // Screen reader announcement when user leaves group.
+   *   // {user} is replaced with the name or abbreviation.
+   *   // When neither is set, "anonymous" is used instead.
+   *   left: '{user} left'
+   * }
+   * ```
+   */
+  i18n: AvatarGroupI18n;
+}