@schukai/monster/source/components/layout/panel.mjs

Monster is a simple library for creating fast, robust and lightweight websites.

/**
 * Copyright © schukai GmbH and all contributing authors, {{copyRightYear}}. All rights reserved.
 * Node module: @schukai/monster
 *
 * This source code is licensed under the GNU Affero General Public License version 3 (AGPLv3).
 * The full text of the license can be found at: https://www.gnu.org/licenses/agpl-3.0.en.html
 *
 * For those who do not wish to adhere to the AGPLv3, a commercial license is available.
 * Acquiring a commercial license allows you to use this software without complying with the AGPLv3 terms.
 * For more information about purchasing a commercial license, please contact schukai GmbH.
 *
 * SPDX-License-Identifier: AGPL-3.0
 */

import {
	assembleMethodSymbol,
	CustomElement,
	registerCustomElement,
} from "../../dom/customelement.mjs";
import { DeadMansSwitch } from "../../util/deadmansswitch.mjs";

import { PanelStyleSheet } from "./stylesheet/panel.mjs";
import { instanceSymbol } from "../../constants.mjs";

export { Panel };

/**
 * @private
 * @type {symbol}
 */
const PanelElementSymbol = Symbol("PanelElement");

/**
 * local symbol
 * @private
 * @type {symbol}
 */
const resizeObserverSymbol = Symbol("resizeObserver");

/**
 * @private
 * @type {symbol}
 */
const timerCallbackSymbol = Symbol("timerCallback");

/**
 * A Panel is a container that can hold other elements and is used to display content in a structured way.
 *
 * @fragments /fragments/components/layout/panel/
 *
 * @example /examples/components/layout/panel-simple
 *
 * @since 3.54.0
 * @copyright schukai GmbH
 * @summary The Panel component is used to display a panel, isn't that cool?
 */
class Panel extends CustomElement {
	/**
	 * This method is called by the `instanceof` operator.
	 * @return {symbol}
	 */
	static get [instanceSymbol]() {
		return Symbol.for("@schukai/monster/components/layout/panel");
	}

	/**
	 * To set the options via the HTML tag, the attribute `data-monster-options` must be used.
	 * @see {@link https://monsterjs.org/en/doc/#configurate-a-monster-control}
	 *
	 * The individual configuration values can be found in the table.
	 *
	 * @property {Object} templates Template definitions
	 * @property {string} templates.main Main template
	 * @property {string} heightAdjustment Height adjustment
	 */
	get defaults() {
		return Object.assign({}, super.defaults, {
			templates: {
				main: getTemplate(),
			},
			heightAdjustment: 4,
		});
	}

	/**
	 *
	 * @return {Panel}
	 */
	[assembleMethodSymbol]() {
		super[assembleMethodSymbol]();

		initControlReferences.call(this);
		initEventHandler.call(this);

		calcHeight.call(this);
	}

	/**
	 * This method is called by the dom and should not be called directly.
	 *
	 * @return {void}
	 */
	connectedCallback() {
		super.connectedCallback();
		attachResizeObserver.call(this);

		// disable scrolling in parent node
		if (this.parentNode && this.parentNode instanceof HTMLElement) {
			this.parentNode.style.overflow = "hidden";
		}
	}

	/**
	 * This method is called by the dom and should not be called directly.
	 *
	 * @return {void}
	 */
	disconnectedCallback() {
		super.disconnectedCallback();
		disconnectResizeObserver.call(this);
	}

	/**
	 * @return {string}
	 */
	static getTag() {
		return "monster-panel";
	}

	/**
	 * @return {CSSStyleSheet[]}
	 */
	static getCSSStyleSheet() {
		return [PanelStyleSheet];
	}
}

/**
 * @private
 */
function calcHeight() {
	this.style.boxSizing = "border-box";

	const height = calculateMaximumHeight.call(this, this);
	if (height < 0) {
		return;
	}

	this.style.height = `${height}px`;
}

/**
 * Calculate the maximum height of an element based on the window's inner height
 * @param element
 * @return {*}
 */
function calculateMaximumHeight(element) {
	let totalBottomBorder = 0;
	let totalBottomPadding = 0;
	let totalBottomMargin = 0;
	let totalOutlineHeight = 0;
	let totalBoxShadowHeight = 0;
	let currentElement = element;

	// Get the distance from the top of the element to the top of the viewport
	const distanceFromTop = element.getBoundingClientRect().top;

	// Loop through the elements up to the body to sum up the bottom borders, padding, and margin
	while (currentElement && currentElement !== document.body) {
		const style = window.getComputedStyle(currentElement);

		// Box sizing
		const boxSizing = style.boxSizing;

		// Borders, padding, and margin
		const borderBottomWidth = parseFloat(style.borderBottomWidth);
		const paddingBottom = parseFloat(style.paddingBottom);
		const marginBottom = parseFloat(style.marginBottom);

		// Outline and box-shadow
		const outlineHeight = parseFloat(style.outlineWidth);
		// This is a simplification; box-shadow is more complex to parse
		const boxShadowVertical = parseFloat(style.boxShadow.split(" ")[3] || 0);

		// Accumulate values
		totalBottomBorder += isNaN(borderBottomWidth) ? 0 : borderBottomWidth;
		totalBottomPadding +=
			isNaN(paddingBottom) || boxSizing === "border-box" ? 0 : paddingBottom;
		totalBottomMargin += isNaN(marginBottom) ? 0 : marginBottom;
		totalOutlineHeight += isNaN(outlineHeight) ? 0 : outlineHeight;
		totalBoxShadowHeight += isNaN(boxShadowVertical) ? 0 : boxShadowVertical;

		currentElement = currentElement.parentNode || currentElement.host;
	}

	// Calculate the maximum height by subtracting the distance, borders, padding, margin, outline, and box-shadow from the window's inner height
	const maximumHeight =
		window.innerHeight -
		distanceFromTop -
		totalBottomBorder -
		totalBottomPadding -
		totalBottomMargin -
		totalOutlineHeight -
		totalBoxShadowHeight;
	return maximumHeight + this.getOption("heightAdjustment");
}

/**
 * @private
 */
function attachResizeObserver() {
	// against flickering
	this[resizeObserverSymbol] = new ResizeObserver(() => {
		if (this[timerCallbackSymbol] instanceof DeadMansSwitch) {
			try {
				this[timerCallbackSymbol].touch();
				return;
			} catch (e) {
				delete this[timerCallbackSymbol];
			}
		}

		this[timerCallbackSymbol] = new DeadMansSwitch(200, () => {
			calcHeight.call(this);
		});
	});

	this[resizeObserverSymbol].observe(this.ownerDocument.body);
	this[resizeObserverSymbol].observe(document.scrollingElement);
}

function disconnectResizeObserver() {
	if (this[resizeObserverSymbol] instanceof ResizeObserver) {
		this[resizeObserverSymbol].disconnect();
	}
}

/**
 * @private
 * @return {Panel}
 * @throws {Error} no shadow-root is defined
 */
function initControlReferences() {
	if (!this.shadowRoot) {
		throw new Error("no shadow-root is defined");
	}

	this[PanelElementSymbol] = this.shadowRoot.querySelector(
		"[data-monster-role=control]",
	);
}

/**
 * @private
 */
function initEventHandler() {
	return this;
}

/**
 * @private
 * @return {string}
 */
function getTemplate() {
	// language=HTML
	return `
        <div data-monster-role="control" part="control">
            <slot></slot>
        </div>`;
}

registerCustomElement(Panel);