117 lines
4.9 KiB
JavaScript
117 lines
4.9 KiB
JavaScript
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import { noChange } from '../lit-html.js';
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import { directive, Directive, PartType } from '../directive.js';
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/**
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* @license
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* Copyright 2018 Google LLC
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* SPDX-License-Identifier: BSD-3-Clause
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*/
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const important = 'important';
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// The leading space is important
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const importantFlag = ' !' + important;
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// How many characters to remove from a value, as a negative number
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const flagTrim = 0 - importantFlag.length;
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class StyleMapDirective extends Directive {
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constructor(partInfo) {
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var _a;
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super(partInfo);
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if (partInfo.type !== PartType.ATTRIBUTE ||
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partInfo.name !== 'style' ||
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((_a = partInfo.strings) === null || _a === void 0 ? void 0 : _a.length) > 2) {
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throw new Error('The `styleMap` directive must be used in the `style` attribute ' +
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'and must be the only part in the attribute.');
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}
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}
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render(styleInfo) {
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return Object.keys(styleInfo).reduce((style, prop) => {
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const value = styleInfo[prop];
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if (value == null) {
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return style;
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}
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// Convert property names from camel-case to dash-case, i.e.:
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// `backgroundColor` -> `background-color`
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// Vendor-prefixed names need an extra `-` appended to front:
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// `webkitAppearance` -> `-webkit-appearance`
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// Exception is any property name containing a dash, including
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// custom properties; we assume these are already dash-cased i.e.:
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// `--my-button-color` --> `--my-button-color`
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prop = prop.includes('-')
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? prop
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: prop
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.replace(/(?:^(webkit|moz|ms|o)|)(?=[A-Z])/g, '-$&')
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.toLowerCase();
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return style + `${prop}:${value};`;
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}, '');
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}
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update(part, [styleInfo]) {
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const { style } = part.element;
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if (this._previousStyleProperties === undefined) {
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this._previousStyleProperties = new Set();
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for (const name in styleInfo) {
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this._previousStyleProperties.add(name);
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}
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return this.render(styleInfo);
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}
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// Remove old properties that no longer exist in styleInfo
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// We use forEach() instead of for-of so that re don't require down-level
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// iteration.
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this._previousStyleProperties.forEach((name) => {
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// If the name isn't in styleInfo or it's null/undefined
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if (styleInfo[name] == null) {
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this._previousStyleProperties.delete(name);
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if (name.includes('-')) {
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style.removeProperty(name);
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}
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else {
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// Note reset using empty string (vs null) as IE11 does not always
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// reset via null (https://developer.mozilla.org/en-US/docs/Web/API/ElementCSSInlineStyle/style#setting_styles)
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// eslint-disable-next-line @typescript-eslint/no-explicit-any
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style[name] = '';
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}
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}
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});
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// Add or update properties
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for (const name in styleInfo) {
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const value = styleInfo[name];
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if (value != null) {
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this._previousStyleProperties.add(name);
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const isImportant = typeof value === 'string' && value.endsWith(importantFlag);
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if (name.includes('-') || isImportant) {
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style.setProperty(name, isImportant
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? value.slice(0, flagTrim)
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: value, isImportant ? important : '');
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}
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else {
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// eslint-disable-next-line @typescript-eslint/no-explicit-any
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style[name] = value;
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}
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}
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}
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return noChange;
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}
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}
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/**
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* A directive that applies CSS properties to an element.
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*
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* `styleMap` can only be used in the `style` attribute and must be the only
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* expression in the attribute. It takes the property names in the
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* {@link StyleInfo styleInfo} object and adds the properties to the inline
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* style of the element.
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*
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* Property names with dashes (`-`) are assumed to be valid CSS
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* property names and set on the element's style object using `setProperty()`.
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* Names without dashes are assumed to be camelCased JavaScript property names
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* and set on the element's style object using property assignment, allowing the
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* style object to translate JavaScript-style names to CSS property names.
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*
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* For example `styleMap({backgroundColor: 'red', 'border-top': '5px', '--size':
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* '0'})` sets the `background-color`, `border-top` and `--size` properties.
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*
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* @param styleInfo
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* @see {@link https://lit.dev/docs/templates/directives/#stylemap styleMap code samples on Lit.dev}
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*/
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const styleMap = directive(StyleMapDirective);
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export { styleMap };
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//# sourceMappingURL=style-map.js.map
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