Files
webawesome/src/components/dropdown/dropdown.ts
2022-08-17 11:37:37 -04:00

452 lines
14 KiB
TypeScript

import { html } from 'lit';
import { customElement, property, query } from 'lit/decorators.js';
import { classMap } from 'lit/directives/class-map.js';
import { animateTo, stopAnimations } from '../../internal/animate';
import { emit, waitForEvent } from '../../internal/event';
import { scrollIntoView } from '../../internal/scroll';
import ShoelaceElement from '../../internal/shoelace-element';
import { getTabbableBoundary } from '../../internal/tabbable';
import { watch } from '../../internal/watch';
import { getAnimation, setDefaultAnimation } from '../../utilities/animation-registry';
import { LocalizeController } from '../../utilities/localize';
import '../popup/popup';
import styles from './dropdown.styles';
import type SlButton from '../button/button';
import type SlIconButton from '../icon-button/icon-button';
import type SlMenuItem from '../menu-item/menu-item';
import type SlMenu from '../menu/menu';
import type SlPopup from '../popup/popup';
import type { CSSResultGroup } from 'lit';
/**
* @since 2.0
* @status stable
*
* @dependency sl-popup
*
* @slot - The dropdown's content.
* @slot trigger - The dropdown's trigger, usually a `<sl-button>` element.
*
* @event sl-show - Emitted when the dropdown opens.
* @event sl-after-show - Emitted after the dropdown opens and all animations are complete.
* @event sl-hide - Emitted when the dropdown closes.
* @event sl-after-hide - Emitted after the dropdown closes and all animations are complete.
*
* @csspart base - The component's internal wrapper.
* @csspart trigger - The container that wraps the trigger.
* @csspart panel - The panel that gets shown when the dropdown is open.
*
* @animation dropdown.show - The animation to use when showing the dropdown.
* @animation dropdown.hide - The animation to use when hiding the dropdown.
*/
@customElement('sl-dropdown')
export default class SlDropdown extends ShoelaceElement {
static styles: CSSResultGroup = styles;
@query('.dropdown') popup: SlPopup;
@query('.dropdown__trigger') trigger: HTMLElement;
@query('.dropdown__panel') panel: HTMLElement;
private readonly localize = new LocalizeController(this);
/** Indicates whether or not the dropdown is open. You can use this in lieu of the show/hide methods. */
@property({ type: Boolean, reflect: true }) open = false;
/**
* The preferred placement of the dropdown panel. Note that the actual placement may vary as needed to keep the panel
* inside of the viewport.
*/
@property({ reflect: true }) placement:
| 'top'
| 'top-start'
| 'top-end'
| 'bottom'
| 'bottom-start'
| 'bottom-end'
| 'right'
| 'right-start'
| 'right-end'
| 'left'
| 'left-start'
| 'left-end' = 'bottom-start';
/** Disables the dropdown so the panel will not open. */
@property({ type: Boolean, reflect: true }) disabled = false;
/**
* By default, the dropdown is closed when an item is selected. This attribute will keep it open instead. Useful for
* controls that allow multiple selections.
*/
@property({ attribute: 'stay-open-on-select', type: Boolean, reflect: true }) stayOpenOnSelect = false;
/** The dropdown will close when the user interacts outside of this element (e.g. clicking). */
@property({ attribute: false }) containingElement?: HTMLElement;
/** The distance in pixels from which to offset the panel away from its trigger. */
@property({ type: Number }) distance = 0;
/** The distance in pixels from which to offset the panel along its trigger. */
@property({ type: Number }) skidding = 0;
/**
* Enable this option to prevent the panel from being clipped when the component is placed inside a container with
* `overflow: auto|scroll`.
*/
@property({ type: Boolean }) hoist = false;
connectedCallback() {
super.connectedCallback();
this.handleMenuItemActivate = this.handleMenuItemActivate.bind(this);
this.handlePanelSelect = this.handlePanelSelect.bind(this);
this.handleDocumentKeyDown = this.handleDocumentKeyDown.bind(this);
this.handleDocumentMouseDown = this.handleDocumentMouseDown.bind(this);
if (!this.containingElement) {
this.containingElement = this;
}
}
firstUpdated() {
this.panel.hidden = !this.open;
// If the dropdown is visible on init, update its position
if (this.open) {
this.addOpenListeners();
this.popup.active = true;
}
}
disconnectedCallback() {
super.disconnectedCallback();
this.removeOpenListeners();
this.hide();
}
focusOnTrigger() {
const slot = this.trigger.querySelector('slot')!;
const trigger = slot.assignedElements({ flatten: true })[0] as HTMLElement | undefined;
if (typeof trigger?.focus === 'function') {
trigger.focus();
}
}
getMenu() {
const slot = this.panel.querySelector('slot')!;
return slot.assignedElements({ flatten: true }).find(el => el.tagName.toLowerCase() === 'sl-menu') as
| SlMenu
| undefined;
}
handleDocumentKeyDown(event: KeyboardEvent) {
// Close when escape is pressed
if (event.key === 'Escape') {
this.hide();
this.focusOnTrigger();
return;
}
// Handle tabbing
if (event.key === 'Tab') {
// Tabbing within an open menu should close the dropdown and refocus the trigger
if (this.open && document.activeElement?.tagName.toLowerCase() === 'sl-menu-item') {
event.preventDefault();
this.hide();
this.focusOnTrigger();
return;
}
// Tabbing outside of the containing element closes the panel
//
// If the dropdown is used within a shadow DOM, we need to obtain the activeElement within that shadowRoot,
// otherwise `document.activeElement` will only return the name of the parent shadow DOM element.
setTimeout(() => {
const activeElement =
this.containingElement?.getRootNode() instanceof ShadowRoot
? document.activeElement?.shadowRoot?.activeElement
: document.activeElement;
if (
!this.containingElement ||
activeElement?.closest(this.containingElement.tagName.toLowerCase()) !== this.containingElement
) {
this.hide();
}
});
}
}
handleDocumentMouseDown(event: MouseEvent) {
// Close when clicking outside of the containing element
const path = event.composedPath();
if (this.containingElement && !path.includes(this.containingElement)) {
this.hide();
}
}
handleMenuItemActivate(event: CustomEvent) {
const item = event.target as SlMenuItem;
scrollIntoView(item, this.panel);
}
handlePanelSelect(event: CustomEvent) {
const target = event.target as HTMLElement;
// Hide the dropdown when a menu item is selected
if (!this.stayOpenOnSelect && target.tagName.toLowerCase() === 'sl-menu') {
this.hide();
this.focusOnTrigger();
}
}
handleTriggerClick() {
if (this.open) {
this.hide();
} else {
this.show();
}
}
handleTriggerKeyDown(event: KeyboardEvent) {
// Close when escape or tab is pressed
if (event.key === 'Escape') {
this.focusOnTrigger();
this.hide();
return;
}
// When spacebar/enter is pressed, show the panel but don't focus on the menu. This let's the user press the same
// key again to hide the menu in case they don't want to make a selection.
if ([' ', 'Enter'].includes(event.key)) {
event.preventDefault();
this.handleTriggerClick();
return;
}
const menu = this.getMenu();
if (menu) {
const menuItems = menu.defaultSlot.assignedElements({ flatten: true }) as SlMenuItem[];
const firstMenuItem = menuItems[0];
const lastMenuItem = menuItems[menuItems.length - 1];
// When up/down is pressed, we make the assumption that the user is familiar with the menu and plans to make a
// selection. Rather than toggle the panel, we focus on the menu (if one exists) and activate the first item for
// faster navigation.
if (['ArrowDown', 'ArrowUp', 'Home', 'End'].includes(event.key)) {
event.preventDefault();
// Show the menu if it's not already open
if (!this.open) {
this.show();
}
if (menuItems.length > 0) {
// Focus on the first/last menu item after showing
requestAnimationFrame(() => {
if (event.key === 'ArrowDown' || event.key === 'Home') {
menu.setCurrentItem(firstMenuItem);
firstMenuItem.focus();
}
if (event.key === 'ArrowUp' || event.key === 'End') {
menu.setCurrentItem(lastMenuItem);
lastMenuItem.focus();
}
});
}
}
// Other keys bring focus to the menu and initiate type-to-select behavior
const ignoredKeys = ['Tab', 'Shift', 'Meta', 'Ctrl', 'Alt'];
if (this.open && !ignoredKeys.includes(event.key)) {
menu.typeToSelect(event);
}
}
}
handleTriggerKeyUp(event: KeyboardEvent) {
// Prevent space from triggering a click event in Firefox
if (event.key === ' ') {
event.preventDefault();
}
}
handleTriggerSlotChange() {
this.updateAccessibleTrigger();
}
//
// Slotted triggers can be arbitrary content, but we need to link them to the dropdown panel with `aria-haspopup` and
// `aria-expanded`. These must be applied to the "accessible trigger" (the tabbable portion of the trigger element
// that gets slotted in) so screen readers will understand them. The accessible trigger could be the slotted element,
// a child of the slotted element, or an element in the slotted element's shadow root.
//
// For example, the accessible trigger of an <sl-button> is a <button> located inside its shadow root.
//
// To determine this, we assume the first tabbable element in the trigger slot is the "accessible trigger."
//
updateAccessibleTrigger() {
const slot = this.trigger.querySelector('slot')!;
const assignedElements = slot.assignedElements({ flatten: true }) as HTMLElement[];
const accessibleTrigger = assignedElements.find(el => getTabbableBoundary(el).start);
let target: HTMLElement;
if (accessibleTrigger) {
switch (accessibleTrigger.tagName.toLowerCase()) {
// Shoelace buttons have to update the internal button so it's announced correctly by screen readers
case 'sl-button':
case 'sl-icon-button':
target = (accessibleTrigger as SlButton | SlIconButton).button;
break;
default:
target = accessibleTrigger;
}
target.setAttribute('aria-haspopup', 'true');
target.setAttribute('aria-expanded', this.open ? 'true' : 'false');
}
}
/** Shows the dropdown panel. */
async show() {
if (this.open) {
return undefined;
}
this.open = true;
return waitForEvent(this, 'sl-after-show');
}
/** Hides the dropdown panel */
async hide() {
if (!this.open) {
return undefined;
}
this.open = false;
return waitForEvent(this, 'sl-after-hide');
}
/**
* Instructs the dropdown menu to reposition. Useful when the position or size of the trigger changes when the menu
* is activated.
*/
reposition() {
this.popup.reposition();
}
addOpenListeners() {
this.panel.addEventListener('sl-activate', this.handleMenuItemActivate);
this.panel.addEventListener('sl-select', this.handlePanelSelect);
document.addEventListener('keydown', this.handleDocumentKeyDown);
document.addEventListener('mousedown', this.handleDocumentMouseDown);
}
removeOpenListeners() {
this.panel.removeEventListener('sl-activate', this.handleMenuItemActivate);
this.panel.removeEventListener('sl-select', this.handlePanelSelect);
document.removeEventListener('keydown', this.handleDocumentKeyDown);
document.removeEventListener('mousedown', this.handleDocumentMouseDown);
}
@watch('open', { waitUntilFirstUpdate: true })
async handleOpenChange() {
if (this.disabled) {
this.open = false;
return;
}
this.updateAccessibleTrigger();
if (this.open) {
// Show
emit(this, 'sl-show');
this.addOpenListeners();
await stopAnimations(this);
this.panel.hidden = false;
this.popup.active = true;
const { keyframes, options } = getAnimation(this, 'dropdown.show', { dir: this.localize.dir() });
await animateTo(this.popup.popup, keyframes, options);
emit(this, 'sl-after-show');
} else {
// Hide
emit(this, 'sl-hide');
this.removeOpenListeners();
await stopAnimations(this);
const { keyframes, options } = getAnimation(this, 'dropdown.hide', { dir: this.localize.dir() });
await animateTo(this.popup.popup, keyframes, options);
this.panel.hidden = true;
this.popup.active = false;
emit(this, 'sl-after-hide');
}
}
render() {
return html`
<sl-popup
part="base"
id="dropdown"
placement=${this.placement}
distance=${this.distance}
skidding=${this.skidding}
strategy=${this.hoist ? 'fixed' : 'absolute'}
flip
shift
auto-size
auto-size-padding="10"
class=${classMap({
dropdown: true,
'dropdown--open': this.open
})}
>
<span
slot="anchor"
part="trigger"
class="dropdown__trigger"
@click=${this.handleTriggerClick}
@keydown=${this.handleTriggerKeyDown}
@keyup=${this.handleTriggerKeyUp}
>
<slot name="trigger" @slotchange=${this.handleTriggerSlotChange}></slot>
</span>
<div
part="panel"
class="dropdown__panel"
aria-hidden=${this.open ? 'false' : 'true'}
aria-labelledby="dropdown"
>
<slot></slot>
</div>
</sl-popup>
`;
}
}
setDefaultAnimation('dropdown.show', {
keyframes: [
{ opacity: 0, transform: 'scale(0.9)' },
{ opacity: 1, transform: 'scale(1)' }
],
options: { duration: 100, easing: 'ease' }
});
setDefaultAnimation('dropdown.hide', {
keyframes: [
{ opacity: 1, transform: 'scale(1)' },
{ opacity: 0, transform: 'scale(0.9)' }
],
options: { duration: 100, easing: 'ease' }
});
declare global {
interface HTMLElementTagNameMap {
'sl-dropdown': SlDropdown;
}
}