DileOverlayMixin

Mixin to create overlay elements. It has the functionality to position custom elements in various ways, and open or close the elements with a smooth animation.

Requirements

This mixin need two elements in the web component to make its work:

• Overlay layer, to show / hide some content
• Trigger element, to click and toggle the overlay state

Both elements should be in the shadow DOM of the custom element and need to have this ids:

• #overlay for the overlay layer content
• #trigger for the element to asign the close / hide functions

Also is necessary to asign some styles to the overlay element:

#overlay {
  display: none;
  position: absolute;
  opacity: 0;
}

Usually you may also prefer to asign some additional styles, to make a transition between hide / show states:

#overlay {
  display: none;
  position: absolute;
  opacity: 0;
  transition: ease 0.5s;
  transition-property: transform, opacity;
  transform: translateY(-10px);
}

To create the smooth animation there is also necessary to create a "opened" CSS class, to asing styles to the open state of the overlay layer.

#overlay.opened {
  opacity: 1;
  transform: translateY(0);
}

Of course, you can customize your own styles to create your preferred animations.

Installation

npm install @dile/dile-overlay-mixin

Usage

Use the mixin

import { LitElement, html, css } from 'lit';
import { DileOverlayMixin } from '@dile/dile-overlay-mixin';

class NewComponent  extends DileOverlayMixin(LitElement) {

}

Properties

The mixin offers several properties to customize the the way it shows the overlay.

• horizontalAlign: String property to set the horizontal position of the menu. Valid values are "under_left", "under_right", "left", "right" or "center". Default to "under_left".
• verticalAlign: String property to set the vertical position of the menu. Valid values are "bottom", "center" or "top". Default to "bottom".
• moveTop: Number of pixels to modify the default vertical position of the overlay. Accepts positive (move down) an negative (move up) values. Default 0.
• moveLeft: Number of pixels to modify the default horizontal position of the overlay. Accepts positive (move right) an negative (move left) values. Default 0.

Overlay state

This mixin also includes a "state" property called "_overlayClass". In order to have the opened/closed state in the overlay layer you should assign the property into the class attribute.

<div id="overlay" class="${this._overlayClass}">
  I am the overlay layer
</div>

Methods

• open(): Use it to open the menu overlay box
• close(): Use it to close the menu overlay box
• toggle(): Toggles the menu-overlay box

Important note: the trigger does not opens the menu by itself. You must call the open() or toggle() method to open the menu when you need. The trigger by default is used only for positioning the menu overlay.

For example, you can use the the toogle() method as a click handler on the trigger.

<span id="trigger" @click=${this.toggle}>This is the trigger</span>

Custom events

• overlay-opened: dispatched when the overlay opens.
• overlay-closed: dispatched when the overlay closes.

Implementations of DileOverlayMixin

There are some components that implements DileOverlayMixin.

• dile-persistent-toast
• dile-menu-overlay