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view.js 26 KB

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  1. /**
  2. * @license Copyright (c) 2003-2020, CKSource - Frederico Knabben. All rights reserved.
  3. * For licensing, see LICENSE.md or https://ckeditor.com/legal/ckeditor-oss-license
  4. */
  5. /**
  6. * @module engine/view/view
  7. */
  8. import Document from './document';
  9. import DowncastWriter from './downcastwriter';
  10. import Renderer from './renderer';
  11. import DomConverter from './domconverter';
  12. import Position from './position';
  13. import Range from './range';
  14. import Selection from './selection';
  15. import MutationObserver from './observer/mutationobserver';
  16. import KeyObserver from './observer/keyobserver';
  17. import FakeSelectionObserver from './observer/fakeselectionobserver';
  18. import SelectionObserver from './observer/selectionobserver';
  19. import FocusObserver from './observer/focusobserver';
  20. import CompositionObserver from './observer/compositionobserver';
  21. import InputObserver from './observer/inputobserver';
  22. import ObservableMixin from '@ckeditor/ckeditor5-utils/src/observablemixin';
  23. import mix from '@ckeditor/ckeditor5-utils/src/mix';
  24. import { scrollViewportToShowTarget } from '@ckeditor/ckeditor5-utils/src/dom/scroll';
  25. import { injectUiElementHandling } from './uielement';
  26. import { injectQuirksHandling } from './filler';
  27. import CKEditorError from '@ckeditor/ckeditor5-utils/src/ckeditorerror';
  28. import env from '@ckeditor/ckeditor5-utils/src/env';
  29. /**
  30. * Editor's view controller class. Its main responsibility is DOM - View management for editing purposes, to provide
  31. * abstraction over the DOM structure and events and hide all browsers quirks.
  32. *
  33. * View controller renders view document to DOM whenever view structure changes. To determine when view can be rendered,
  34. * all changes need to be done using the {@link module:engine/view/view~View#change} method, using
  35. * {@link module:engine/view/downcastwriter~DowncastWriter}:
  36. *
  37. * view.change( writer => {
  38. * writer.insert( position, writer.createText( 'foo' ) );
  39. * } );
  40. *
  41. * View controller also register {@link module:engine/view/observer/observer~Observer observers} which observes changes
  42. * on DOM and fire events on the {@link module:engine/view/document~Document Document}.
  43. * Note that the following observers are added by the class constructor and are always available:
  44. *
  45. * * {@link module:engine/view/observer/mutationobserver~MutationObserver},
  46. * * {@link module:engine/view/observer/selectionobserver~SelectionObserver},
  47. * * {@link module:engine/view/observer/focusobserver~FocusObserver},
  48. * * {@link module:engine/view/observer/keyobserver~KeyObserver},
  49. * * {@link module:engine/view/observer/fakeselectionobserver~FakeSelectionObserver}.
  50. * * {@link module:engine/view/observer/compositionobserver~CompositionObserver}.
  51. *
  52. * This class also {@link module:engine/view/view~View#attachDomRoot binds the DOM and the view elements}.
  53. *
  54. * If you do not need full a DOM - view management, and only want to transform a tree of view elements to a tree of DOM
  55. * elements you do not need this controller. You can use the {@link module:engine/view/domconverter~DomConverter DomConverter} instead.
  56. *
  57. * @mixes module:utils/observablemixin~ObservableMixin
  58. */
  59. export default class View {
  60. /**
  61. * @param {module:engine/view/stylesmap~StylesProcessor} stylesProcessor The styles processor instance..
  62. */
  63. constructor( stylesProcessor ) {
  64. /**
  65. * Instance of the {@link module:engine/view/document~Document} associated with this view controller.
  66. *
  67. * @readonly
  68. * @type {module:engine/view/document~Document}
  69. */
  70. this.document = new Document( stylesProcessor );
  71. /**
  72. * Instance of the {@link module:engine/view/domconverter~DomConverter domConverter} used by
  73. * {@link module:engine/view/view~View#_renderer renderer}
  74. * and {@link module:engine/view/observer/observer~Observer observers}.
  75. *
  76. * @readonly
  77. * @type {module:engine/view/domconverter~DomConverter}
  78. */
  79. this.domConverter = new DomConverter( this.document );
  80. /**
  81. * Roots of the DOM tree. Map on the `HTMLElement`s with roots names as keys.
  82. *
  83. * @readonly
  84. * @type {Map.<String, HTMLElement>}
  85. */
  86. this.domRoots = new Map();
  87. /**
  88. * Used to prevent calling {@link #forceRender} and {@link #change} during rendering view to the DOM.
  89. *
  90. * @readonly
  91. * @member {Boolean} #isRenderingInProgress
  92. */
  93. this.set( 'isRenderingInProgress', false );
  94. /**
  95. * Instance of the {@link module:engine/view/renderer~Renderer renderer}.
  96. *
  97. * @protected
  98. * @type {module:engine/view/renderer~Renderer}
  99. */
  100. this._renderer = new Renderer( this.domConverter, this.document.selection );
  101. this._renderer.bind( 'isFocused' ).to( this.document );
  102. /**
  103. * A DOM root attributes cache. It saves the initial values of DOM root attributes before the DOM element
  104. * is {@link module:engine/view/view~View#attachDomRoot attached} to the view so later on, when
  105. * the view is destroyed ({@link module:engine/view/view~View#detachDomRoot}), they can be easily restored.
  106. * This way, the DOM element can go back to the (clean) state as if the editing view never used it.
  107. *
  108. * @private
  109. * @member {WeakMap.<HTMLElement,Object>}
  110. */
  111. this._initialDomRootAttributes = new WeakMap();
  112. /**
  113. * Map of registered {@link module:engine/view/observer/observer~Observer observers}.
  114. *
  115. * @private
  116. * @type {Map.<Function, module:engine/view/observer/observer~Observer>}
  117. */
  118. this._observers = new Map();
  119. /**
  120. * Is set to `true` when {@link #change view changes} are currently in progress.
  121. *
  122. * @private
  123. * @type {Boolean}
  124. */
  125. this._ongoingChange = false;
  126. /**
  127. * Used to prevent calling {@link #forceRender} and {@link #change} during rendering view to the DOM.
  128. *
  129. * @private
  130. * @type {Boolean}
  131. */
  132. this._postFixersInProgress = false;
  133. /**
  134. * Internal flag to temporary disable rendering. See the usage in the {@link #_disableRendering}.
  135. *
  136. * @private
  137. * @type {Boolean}
  138. */
  139. this._renderingDisabled = false;
  140. /**
  141. * Internal flag that disables rendering when there are no changes since the last rendering.
  142. * It stores information about changed selection and changed elements from attached document roots.
  143. *
  144. * @private
  145. * @type {Boolean}
  146. */
  147. this._hasChangedSinceTheLastRendering = false;
  148. /**
  149. * DowncastWriter instance used in {@link #change change method} callbacks.
  150. *
  151. * @private
  152. * @type {module:engine/view/downcastwriter~DowncastWriter}
  153. */
  154. this._writer = new DowncastWriter( this.document );
  155. // Add default observers.
  156. this.addObserver( MutationObserver );
  157. this.addObserver( SelectionObserver );
  158. this.addObserver( FocusObserver );
  159. this.addObserver( KeyObserver );
  160. this.addObserver( FakeSelectionObserver );
  161. this.addObserver( CompositionObserver );
  162. if ( env.isAndroid ) {
  163. this.addObserver( InputObserver );
  164. }
  165. // Inject quirks handlers.
  166. injectQuirksHandling( this );
  167. injectUiElementHandling( this );
  168. // Use 'normal' priority so that rendering is performed as first when using that priority.
  169. this.on( 'render', () => {
  170. this._render();
  171. // Informs that layout has changed after render.
  172. this.document.fire( 'layoutChanged' );
  173. // Reset the `_hasChangedSinceTheLastRendering` flag after rendering.
  174. this._hasChangedSinceTheLastRendering = false;
  175. } );
  176. // Listen to the document selection changes directly.
  177. this.listenTo( this.document.selection, 'change', () => {
  178. this._hasChangedSinceTheLastRendering = true;
  179. } );
  180. }
  181. /**
  182. * Attaches a DOM root element to the view element and enable all observers on that element.
  183. * Also {@link module:engine/view/renderer~Renderer#markToSync mark element} to be synchronized
  184. * with the view what means that all child nodes will be removed and replaced with content of the view root.
  185. *
  186. * This method also will change view element name as the same as tag name of given dom root.
  187. * Name is always transformed to lower case.
  188. *
  189. * **Note:** Use {@link #detachDomRoot `detachDomRoot()`} to revert this action.
  190. *
  191. * @param {Element} domRoot DOM root element.
  192. * @param {String} [name='main'] Name of the root.
  193. */
  194. attachDomRoot( domRoot, name = 'main' ) {
  195. const viewRoot = this.document.getRoot( name );
  196. // Set view root name the same as DOM root tag name.
  197. viewRoot._name = domRoot.tagName.toLowerCase();
  198. const initialDomRootAttributes = {};
  199. // 1. Copy and cache the attributes to remember the state of the element before attaching.
  200. // The cached attributes will be restored in detachDomRoot() so the element goes to the
  201. // clean state as if the editing view never used it.
  202. // 2. Apply the attributes using the view writer, so they all go under the control of the engine.
  203. // The editing view takes over the attribute management completely because various
  204. // features (e.g. addPlaceholder()) require dynamic changes of those attributes and they
  205. // cannot be managed by the engine and the UI library at the same time.
  206. for ( const { name, value } of Array.from( domRoot.attributes ) ) {
  207. initialDomRootAttributes[ name ] = value;
  208. // Do not use writer.setAttribute() for the class attribute. The EditableUIView class
  209. // and its descendants could have already set some using the writer.addClass() on the view
  210. // document root. They haven't been rendered yet so they are not present in the DOM root.
  211. // Using writer.setAttribute( 'class', ... ) would override them completely.
  212. if ( name === 'class' ) {
  213. this._writer.addClass( value.split( ' ' ), viewRoot );
  214. } else {
  215. this._writer.setAttribute( name, value, viewRoot );
  216. }
  217. }
  218. this._initialDomRootAttributes.set( domRoot, initialDomRootAttributes );
  219. const updateContenteditableAttribute = () => {
  220. this._writer.setAttribute( 'contenteditable', !viewRoot.isReadOnly, viewRoot );
  221. if ( viewRoot.isReadOnly ) {
  222. this._writer.addClass( 'ck-read-only', viewRoot );
  223. } else {
  224. this._writer.removeClass( 'ck-read-only', viewRoot );
  225. }
  226. };
  227. // Set initial value.
  228. updateContenteditableAttribute();
  229. this.domRoots.set( name, domRoot );
  230. this.domConverter.bindElements( domRoot, viewRoot );
  231. this._renderer.markToSync( 'children', viewRoot );
  232. this._renderer.markToSync( 'attributes', viewRoot );
  233. this._renderer.domDocuments.add( domRoot.ownerDocument );
  234. viewRoot.on( 'change:children', ( evt, node ) => this._renderer.markToSync( 'children', node ) );
  235. viewRoot.on( 'change:attributes', ( evt, node ) => this._renderer.markToSync( 'attributes', node ) );
  236. viewRoot.on( 'change:text', ( evt, node ) => this._renderer.markToSync( 'text', node ) );
  237. viewRoot.on( 'change:isReadOnly', () => this.change( updateContenteditableAttribute ) );
  238. viewRoot.on( 'change', () => {
  239. this._hasChangedSinceTheLastRendering = true;
  240. } );
  241. for ( const observer of this._observers.values() ) {
  242. observer.observe( domRoot, name );
  243. }
  244. }
  245. /**
  246. * Detaches a DOM root element from the view element and restores its attributes to the state before
  247. * {@link #attachDomRoot `attachDomRoot()`}.
  248. *
  249. * @param {String} name Name of the root to detach.
  250. */
  251. detachDomRoot( name ) {
  252. const domRoot = this.domRoots.get( name );
  253. // Remove all root attributes so the DOM element is "bare".
  254. Array.from( domRoot.attributes ).forEach( ( { name } ) => domRoot.removeAttribute( name ) );
  255. const initialDomRootAttributes = this._initialDomRootAttributes.get( domRoot );
  256. // Revert all view root attributes back to the state before attachDomRoot was called.
  257. for ( const attribute in initialDomRootAttributes ) {
  258. domRoot.setAttribute( attribute, initialDomRootAttributes[ attribute ] );
  259. }
  260. this.domRoots.delete( name );
  261. this.domConverter.unbindDomElement( domRoot );
  262. }
  263. /**
  264. * Gets DOM root element.
  265. *
  266. * @param {String} [name='main'] Name of the root.
  267. * @returns {Element} DOM root element instance.
  268. */
  269. getDomRoot( name = 'main' ) {
  270. return this.domRoots.get( name );
  271. }
  272. /**
  273. * Creates observer of the given type if not yet created, {@link module:engine/view/observer/observer~Observer#enable enables} it
  274. * and {@link module:engine/view/observer/observer~Observer#observe attaches} to all existing and future
  275. * {@link #domRoots DOM roots}.
  276. *
  277. * Note: Observers are recognized by their constructor (classes). A single observer will be instantiated and used only
  278. * when registered for the first time. This means that features and other components can register a single observer
  279. * multiple times without caring whether it has been already added or not.
  280. *
  281. * @param {Function} Observer The constructor of an observer to add.
  282. * Should create an instance inheriting from {@link module:engine/view/observer/observer~Observer}.
  283. * @returns {module:engine/view/observer/observer~Observer} Added observer instance.
  284. */
  285. addObserver( Observer ) {
  286. let observer = this._observers.get( Observer );
  287. if ( observer ) {
  288. return observer;
  289. }
  290. observer = new Observer( this );
  291. this._observers.set( Observer, observer );
  292. for ( const [ name, domElement ] of this.domRoots ) {
  293. observer.observe( domElement, name );
  294. }
  295. observer.enable();
  296. return observer;
  297. }
  298. /**
  299. * Returns observer of the given type or `undefined` if such observer has not been added yet.
  300. *
  301. * @param {Function} Observer The constructor of an observer to get.
  302. * @returns {module:engine/view/observer/observer~Observer|undefined} Observer instance or undefined.
  303. */
  304. getObserver( Observer ) {
  305. return this._observers.get( Observer );
  306. }
  307. /**
  308. * Disables all added observers.
  309. */
  310. disableObservers() {
  311. for ( const observer of this._observers.values() ) {
  312. observer.disable();
  313. }
  314. }
  315. /**
  316. * Enables all added observers.
  317. */
  318. enableObservers() {
  319. for ( const observer of this._observers.values() ) {
  320. observer.enable();
  321. }
  322. }
  323. /**
  324. * Scrolls the page viewport and {@link #domRoots} with their ancestors to reveal the
  325. * caret, if not already visible to the user.
  326. */
  327. scrollToTheSelection() {
  328. const range = this.document.selection.getFirstRange();
  329. if ( range ) {
  330. scrollViewportToShowTarget( {
  331. target: this.domConverter.viewRangeToDom( range ),
  332. viewportOffset: 20
  333. } );
  334. }
  335. }
  336. /**
  337. * It will focus DOM element representing {@link module:engine/view/editableelement~EditableElement EditableElement}
  338. * that is currently having selection inside.
  339. */
  340. focus() {
  341. if ( !this.document.isFocused ) {
  342. const editable = this.document.selection.editableElement;
  343. if ( editable ) {
  344. this.domConverter.focus( editable );
  345. this.forceRender();
  346. } else {
  347. // Before focusing view document, selection should be placed inside one of the view's editables.
  348. // Normally its selection will be converted from model document (which have default selection), but
  349. // when using view document on its own, we need to manually place selection before focusing it.
  350. //
  351. // @if CK_DEBUG // console.warn( 'There is no selection in any editable to focus.' );
  352. }
  353. }
  354. }
  355. /**
  356. * The `change()` method is the primary way of changing the view. You should use it to modify any node in the view tree.
  357. * It makes sure that after all changes are made the view is rendered to the DOM (assuming that the view will be changed
  358. * inside the callback). It prevents situations when the DOM is updated when the view state is not yet correct. It allows
  359. * to nest calls one inside another and still performs a single rendering after all those changes are made.
  360. * It also returns the return value of its callback.
  361. *
  362. * const text = view.change( writer => {
  363. * const newText = writer.createText( 'foo' );
  364. * writer.insert( position1, newText );
  365. *
  366. * view.change( writer => {
  367. * writer.insert( position2, writer.createText( 'bar' ) );
  368. * } );
  369. *
  370. * writer.remove( range );
  371. *
  372. * return newText;
  373. * } );
  374. *
  375. * When the outermost change block is done and rendering to the DOM is over the
  376. * {@link module:engine/view/view~View#event:render `View#render`} event is fired.
  377. *
  378. * This method throws a `applying-view-changes-on-rendering` error when
  379. * the change block is used after rendering to the DOM has started.
  380. *
  381. * @param {Function} callback Callback function which may modify the view.
  382. * @returns {*} Value returned by the callback.
  383. */
  384. change( callback ) {
  385. if ( this.isRenderingInProgress || this._postFixersInProgress ) {
  386. /**
  387. * Thrown when there is an attempt to make changes to the view tree when it is in incorrect state. This may
  388. * cause some unexpected behaviour and inconsistency between the DOM and the view.
  389. * This may be caused by:
  390. *
  391. * * calling {@link #change} or {@link #forceRender} during rendering process,
  392. * * calling {@link #change} or {@link #forceRender} inside of
  393. * {@link module:engine/view/document~Document#registerPostFixer post-fixer function}.
  394. *
  395. * @error cannot-change-view-tree
  396. */
  397. throw new CKEditorError(
  398. 'cannot-change-view-tree: ' +
  399. 'Attempting to make changes to the view when it is in an incorrect state: rendering or post-fixers are in progress. ' +
  400. 'This may cause some unexpected behavior and inconsistency between the DOM and the view.',
  401. this
  402. );
  403. }
  404. try {
  405. // Recursive call to view.change() method - execute listener immediately.
  406. if ( this._ongoingChange ) {
  407. return callback( this._writer );
  408. }
  409. // This lock will assure that all recursive calls to view.change() will end up in same block - one "render"
  410. // event for all nested calls.
  411. this._ongoingChange = true;
  412. const callbackResult = callback( this._writer );
  413. this._ongoingChange = false;
  414. // This lock is used by editing controller to render changes from outer most model.change() once. As plugins might call
  415. // view.change() inside model.change() block - this will ensures that postfixers and rendering are called once after all
  416. // changes. Also, we don't need to render anything if there're no changes since last rendering.
  417. if ( !this._renderingDisabled && this._hasChangedSinceTheLastRendering ) {
  418. this._postFixersInProgress = true;
  419. this.document._callPostFixers( this._writer );
  420. this._postFixersInProgress = false;
  421. this.fire( 'render' );
  422. }
  423. return callbackResult;
  424. } catch ( err ) {
  425. // @if CK_DEBUG // throw err;
  426. /* istanbul ignore next */
  427. CKEditorError.rethrowUnexpectedError( err, this );
  428. }
  429. }
  430. /**
  431. * Forces rendering {@link module:engine/view/document~Document view document} to DOM. If any view changes are
  432. * currently in progress, rendering will start after all {@link #change change blocks} are processed.
  433. *
  434. * Note that this method is dedicated for special cases. All view changes should be wrapped in the {@link #change}
  435. * block and the view will automatically check whether it needs to render DOM or not.
  436. *
  437. * Throws {@link module:utils/ckeditorerror~CKEditorError CKEditorError} `applying-view-changes-on-rendering` when
  438. * trying to re-render when rendering to DOM has already started.
  439. */
  440. forceRender() {
  441. this._hasChangedSinceTheLastRendering = true;
  442. this.change( () => {} );
  443. }
  444. /**
  445. * Destroys this instance. Makes sure that all observers are destroyed and listeners removed.
  446. */
  447. destroy() {
  448. for ( const observer of this._observers.values() ) {
  449. observer.destroy();
  450. }
  451. this.document.destroy();
  452. this.stopListening();
  453. }
  454. /**
  455. * Creates position at the given location. The location can be specified as:
  456. *
  457. * * a {@link module:engine/view/position~Position position},
  458. * * parent element and offset (offset defaults to `0`),
  459. * * parent element and `'end'` (sets position at the end of that element),
  460. * * {@link module:engine/view/item~Item view item} and `'before'` or `'after'` (sets position before or after given view item).
  461. *
  462. * This method is a shortcut to other constructors such as:
  463. *
  464. * * {@link #createPositionBefore},
  465. * * {@link #createPositionAfter},
  466. *
  467. * @param {module:engine/view/item~Item|module:engine/model/position~Position} itemOrPosition
  468. * @param {Number|'end'|'before'|'after'} [offset] Offset or one of the flags. Used only when
  469. * first parameter is a {@link module:engine/view/item~Item view item}.
  470. */
  471. createPositionAt( itemOrPosition, offset ) {
  472. return Position._createAt( itemOrPosition, offset );
  473. }
  474. /**
  475. * Creates a new position after given view item.
  476. *
  477. * @param {module:engine/view/item~Item} item View item after which the position should be located.
  478. * @returns {module:engine/view/position~Position}
  479. */
  480. createPositionAfter( item ) {
  481. return Position._createAfter( item );
  482. }
  483. /**
  484. * Creates a new position before given view item.
  485. *
  486. * @param {module:engine/view/item~Item} item View item before which the position should be located.
  487. * @returns {module:engine/view/position~Position}
  488. */
  489. createPositionBefore( item ) {
  490. return Position._createBefore( item );
  491. }
  492. /**
  493. * Creates a range spanning from `start` position to `end` position.
  494. *
  495. * **Note:** This factory method creates it's own {@link module:engine/view/position~Position} instances basing on passed values.
  496. *
  497. * @param {module:engine/view/position~Position} start Start position.
  498. * @param {module:engine/view/position~Position} [end] End position. If not set, range will be collapsed at `start` position.
  499. * @returns {module:engine/view/range~Range}
  500. */
  501. createRange( start, end ) {
  502. return new Range( start, end );
  503. }
  504. /**
  505. * Creates a range that starts before given {@link module:engine/view/item~Item view item} and ends after it.
  506. *
  507. * @param {module:engine/view/item~Item} item
  508. * @returns {module:engine/view/range~Range}
  509. */
  510. createRangeOn( item ) {
  511. return Range._createOn( item );
  512. }
  513. /**
  514. * Creates a range inside an {@link module:engine/view/element~Element element} which starts before the first child of
  515. * that element and ends after the last child of that element.
  516. *
  517. * @param {module:engine/view/element~Element} element Element which is a parent for the range.
  518. * @returns {module:engine/view/range~Range}
  519. */
  520. createRangeIn( element ) {
  521. return Range._createIn( element );
  522. }
  523. /**
  524. Creates new {@link module:engine/view/selection~Selection} instance.
  525. *
  526. * // Creates empty selection without ranges.
  527. * const selection = view.createSelection();
  528. *
  529. * // Creates selection at the given range.
  530. * const range = view.createRange( start, end );
  531. * const selection = view.createSelection( range );
  532. *
  533. * // Creates selection at the given ranges
  534. * const ranges = [ view.createRange( start1, end2 ), view.createRange( star2, end2 ) ];
  535. * const selection = view.createSelection( ranges );
  536. *
  537. * // Creates selection from the other selection.
  538. * const otherSelection = view.createSelection();
  539. * const selection = view.createSelection( otherSelection );
  540. *
  541. * // Creates selection from the document selection.
  542. * const selection = view.createSelection( editor.editing.view.document.selection );
  543. *
  544. * // Creates selection at the given position.
  545. * const position = view.createPositionFromPath( root, path );
  546. * const selection = view.createSelection( position );
  547. *
  548. * // Creates collapsed selection at the position of given item and offset.
  549. * const paragraph = view.createContainerElement( 'paragraph' );
  550. * const selection = view.createSelection( paragraph, offset );
  551. *
  552. * // Creates a range inside an {@link module:engine/view/element~Element element} which starts before the
  553. * // first child of that element and ends after the last child of that element.
  554. * const selection = view.createSelection( paragraph, 'in' );
  555. *
  556. * // Creates a range on an {@link module:engine/view/item~Item item} which starts before the item and ends
  557. * // just after the item.
  558. * const selection = view.createSelection( paragraph, 'on' );
  559. *
  560. * `Selection`'s factory method allow passing additional options (`backward`, `fake` and `label`) as the last argument.
  561. *
  562. * // Creates backward selection.
  563. * const selection = view.createSelection( range, { backward: true } );
  564. *
  565. * Fake selection does not render as browser native selection over selected elements and is hidden to the user.
  566. * This way, no native selection UI artifacts are displayed to the user and selection over elements can be
  567. * represented in other way, for example by applying proper CSS class.
  568. *
  569. * Additionally fake's selection label can be provided. It will be used to describe fake selection in DOM
  570. * (and be properly handled by screen readers).
  571. *
  572. * // Creates fake selection with label.
  573. * const selection = view.createSelection( range, { fake: true, label: 'foo' } );
  574. *
  575. * @param {module:engine/view/selection~Selectable} [selectable=null]
  576. * @param {Number|'before'|'end'|'after'|'on'|'in'} [placeOrOffset] Offset or place when selectable is an `Item`.
  577. * @param {Object} [options]
  578. * @param {Boolean} [options.backward] Sets this selection instance to be backward.
  579. * @param {Boolean} [options.fake] Sets this selection instance to be marked as `fake`.
  580. * @param {String} [options.label] Label for the fake selection.
  581. * @returns {module:engine/view/selection~Selection}
  582. */
  583. createSelection( selectable, placeOrOffset, options ) {
  584. return new Selection( selectable, placeOrOffset, options );
  585. }
  586. /**
  587. * Disables or enables rendering. If the flag is set to `true` then the rendering will be disabled.
  588. * If the flag is set to `false` and if there was some change in the meantime, then the rendering action will be performed.
  589. *
  590. * @protected
  591. * @param {Boolean} flag A flag indicates whether the rendering should be disabled.
  592. */
  593. _disableRendering( flag ) {
  594. this._renderingDisabled = flag;
  595. if ( flag == false ) {
  596. // Render when you stop blocking rendering.
  597. this.change( () => {} );
  598. }
  599. }
  600. /**
  601. * Renders all changes. In order to avoid triggering the observers (e.g. mutations) all observers are disabled
  602. * before rendering and re-enabled after that.
  603. *
  604. * @private
  605. */
  606. _render() {
  607. this.isRenderingInProgress = true;
  608. this.disableObservers();
  609. this._renderer.render();
  610. this.enableObservers();
  611. this.isRenderingInProgress = false;
  612. }
  613. /**
  614. * Fired after a topmost {@link module:engine/view/view~View#change change block} and all
  615. * {@link module:engine/view/document~Document#registerPostFixer post-fixers} are executed.
  616. *
  617. * Actual rendering is performed as a first listener on 'normal' priority.
  618. *
  619. * view.on( 'render', () => {
  620. * // Rendering to the DOM is complete.
  621. * } );
  622. *
  623. * This event is useful when you want to update interface elements after the rendering, e.g. position of the
  624. * balloon panel. If you wants to change view structure use
  625. * {@link module:engine/view/document~Document#registerPostFixer post-fixers}.
  626. *
  627. * @event module:engine/view/view~View#event:render
  628. */
  629. }
  630. mix( View, ObservableMixin );