README

ArcOverlayMixin

This mixin is a port of iron-overlay-behavior that works with LitElement.

Use ArcOverlayMixin to implement an element that can be hidden or shown, and displays on top of other content. It includes an optional backdrop, and can be used to implement a variety of UI controls including dialogs and drop downs. Multiple overlays may be displayed at once.

See the demo source code for an example.

Usage

Installation

npm i @advanced-rest-client/arc-overlay-mixin

Example

import { LitElement } from 'lit-element';
import { ArcOverlayMixin } from '@advanced-rest-client/arc-overlay-mixin';

class ArcOverlayImpl extends ArcOverlayMixin(LitElement) {
  static get properties() {
    return {
      myProp: { type: String }
    };
  }
}

Closing and canceling

An overlay may be hidden by closing or canceling. The difference between close and cancel is user intent. Closing generally implies that the user acknowledged the content on the overlay. By default, it will cancel whenever the user taps outside it or presses the escape key. This behavior is configurable with the nocancelonesckey and the nocancelonoutsideclick properties. close() should be called explicitly by the implementer when the user interacts with a control in the overlay element. When the dialog is canceled, the overlay fires an 'iron-overlay-canceled' event. Call preventDefault on this event to prevent the overlay from closing.

Positioning

By default the element is sized and positioned to fit and centered inside the window. You can position and size it manually using CSS. See ArcFitMixin.

Backdrop

Set the withbackdrop attribute to display a backdrop behind the overlay. The backdrop is appended to <body> and is of type <iron-overlay-backdrop>. See its doc page for styling options. In addition, with-backdrop will wrap the focus within the content in the light DOM. Override the _focusableNodes getter to achieve a different behavior.

Limitations

The element is styled to appear on top of other content by setting its z-index property. You must ensure no element has a stacking context with a higher z-index than its parent stacking context. You should place this element as a child of <body> whenever possible.

Development

Testing

npm run test

Demo

npm start

Usage no npm install needed!