@diddledan/proportional-height-box/proportional-height-box.js

Web component to resize child element to proportional height based on the width similar to fitvids

var __decorate = (this && this.__decorate) || function (decorators, target, key, desc) {
    var c = arguments.length, r = c < 3 ? target : desc === null ? desc = Object.getOwnPropertyDescriptor(target, key) : desc, d;
    if (typeof Reflect === "object" && typeof Reflect.decorate === "function") r = Reflect.decorate(decorators, target, key, desc);
    else for (var i = decorators.length - 1; i >= 0; i--) if (d = decorators[i]) r = (c < 3 ? d(r) : c > 3 ? d(target, key, r) : d(target, key)) || r;
    return c > 3 && r && Object.defineProperty(target, key, r), r;
};
import { LitElement, html, css, property } from 'lit-element';
/**
 * proportional-height-box
 *
 * A block-level element that resizes proportionally, based on code from fitvids.js (http://fitvidsjs.com/)
 *
 * The `width` and `height` parameters specify a proportional ratio, **not the exact size**.
 *
 * @demo demo/index.html
 */
class ProportionalHeightBox extends LitElement {
    constructor() {
        super(...arguments);
        /* The width proportion of the desired aspect ratio */
        this.width = 4;
        /* The height proportion of the desired aspect ratio */
        this.height = 3;
    }
    render() {
        return html `
    <div id="proportional" style="${this.computeStyle(this.width, this.height)}">
      <slot></slot>
    </div>
    `;
    }
    /**
      * Computes the CSS styling
      * @param {number} width The width portion of the aspect ratio
      * @param {number} height The height portion of the aspect ratio
      */
    computeStyle(width, height) {
        var ratio = (height / width) * 100;
        return `padding-top: ${ratio}%`;
    }
}
ProportionalHeightBox.styles = [
    css `
    :host {
      display: block;
      width: 100%;
    }
    #proportional {
      position: relative;
      display: block;
      height: 0;
    }
    #proportional > ::slotted(*) {
      position: absolute;
      display: block;
      width: 100%;
      height: 100%;
      top: 0;
    }
    `
];
__decorate([
    property({ type: Number })
], ProportionalHeightBox.prototype, "width", void 0);
__decorate([
    property({ type: Number })
], ProportionalHeightBox.prototype, "height", void 0);
customElements.define('proportional-height-box', ProportionalHeightBox);