8
0

view.js 26 KB

123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171172173174175176177178179180181182183184185186187188189190191192193194195196197198199200201202203204205206207208209210211212213214215216217218219220221222223224225226227228229230231232233234235236237238239240241242243244245246247248249250251252253254255256257258259260261262263264265266267268269270271272273274275276277278279280281282283284285286287288289290291292293294295296297298299300301302303304305306307308309310311312313314315316317318319320321322323324325326327328329330331332333334335336337338339340341342343344345346347348349350351352353354355356357358359360361362363364365366367368369370371372373374375376377378379380381382383384385386387388389390391392393394395396397398399400401402403404405406407408409410411412413414415416417418419420421422423424425426427428429430431432433434435436437438439440441442443444445446447448449450451452453454455456457458459460461462463464465466467468469470471472473474475476477478479480481482483484485486487488489490491492493494495496497498499500501502503504505506507508509510511512513514515516517518519520521522523524525526527528529530531532533534535536537538539540541542543544545546547548549550551552553554555556557558559560561562563564565566567568569570571572573574575576577578579580581582583584585586587588589590591592593594595596597598599600601602603604605606607608609610611612613614615616617618619620621622623624625626627628629630631632633634635636637638639640641642643644645646647648649650651652653654655656657658659660661662663664665666667668669670671672673674675676677678679680681682683684685686687688689690691692693694695696697698699700
  1. /**
  2. * @license Copyright (c) 2003-2019, 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. constructor() {
  61. /**
  62. * Instance of the {@link module:engine/view/document~Document} associated with this view controller.
  63. *
  64. * @readonly
  65. * @type {module:engine/view/document~Document}
  66. */
  67. this.document = new Document();
  68. /**
  69. * Instance of the {@link module:engine/view/domconverter~DomConverter domConverter} used by
  70. * {@link module:engine/view/view~View#_renderer renderer}
  71. * and {@link module:engine/view/observer/observer~Observer observers}.
  72. *
  73. * @readonly
  74. * @type {module:engine/view/domconverter~DomConverter}
  75. */
  76. this.domConverter = new DomConverter();
  77. /**
  78. * Roots of the DOM tree. Map on the `HTMLElement`s with roots names as keys.
  79. *
  80. * @readonly
  81. * @type {Map.<String, HTMLElement>}
  82. */
  83. this.domRoots = new Map();
  84. /**
  85. * Used to prevent calling {@link #forceRender} and {@link #change} during rendering view to the DOM.
  86. *
  87. * @readonly
  88. * @member {Boolean} #isRenderingInProgress
  89. */
  90. this.set( 'isRenderingInProgress', false );
  91. /**
  92. * Instance of the {@link module:engine/view/renderer~Renderer renderer}.
  93. *
  94. * @protected
  95. * @type {module:engine/view/renderer~Renderer}
  96. */
  97. this._renderer = new Renderer( this.domConverter, this.document.selection );
  98. this._renderer.bind( 'isFocused' ).to( this.document );
  99. this._renderer.bind( 'isComposing' ).to( this.document );
  100. /**
  101. * A DOM root attributes cache. It saves the initial values of DOM root attributes before the DOM element
  102. * is {@link module:engine/view/view~View#attachDomRoot attached} to the view so later on, when
  103. * the view is destroyed ({@link module:engine/view/view~View#detachDomRoot}), they can be easily restored.
  104. * This way, the DOM element can go back to the (clean) state as if the editing view never used it.
  105. *
  106. * @private
  107. * @member {WeakMap.<HTMLElement,Object>}
  108. */
  109. this._initialDomRootAttributes = new WeakMap();
  110. /**
  111. * Map of registered {@link module:engine/view/observer/observer~Observer observers}.
  112. *
  113. * @private
  114. * @type {Map.<Function, module:engine/view/observer/observer~Observer>}
  115. */
  116. this._observers = new Map();
  117. /**
  118. * Is set to `true` when {@link #change view changes} are currently in progress.
  119. *
  120. * @private
  121. * @type {Boolean}
  122. */
  123. this._ongoingChange = false;
  124. /**
  125. * Used to prevent calling {@link #forceRender} and {@link #change} during rendering view to the DOM.
  126. *
  127. * @private
  128. * @type {Boolean}
  129. */
  130. this._postFixersInProgress = false;
  131. /**
  132. * Internal flag to temporary disable rendering. See the usage in the {@link #_disableRendering}.
  133. *
  134. * @private
  135. * @type {Boolean}
  136. */
  137. this._renderingDisabled = false;
  138. /**
  139. * Internal flag that disables rendering when there are no changes since the last rendering.
  140. * It stores information about changed selection and changed elements from attached document roots.
  141. *
  142. * @private
  143. * @type {Boolean}
  144. */
  145. this._hasChangedSinceTheLastRendering = false;
  146. /**
  147. * DowncastWriter instance used in {@link #change change method} callbacks.
  148. *
  149. * @private
  150. * @type {module:engine/view/downcastwriter~DowncastWriter}
  151. */
  152. this._writer = new DowncastWriter( this.document );
  153. // Add default observers.
  154. this.addObserver( MutationObserver );
  155. this.addObserver( SelectionObserver );
  156. this.addObserver( FocusObserver );
  157. this.addObserver( KeyObserver );
  158. this.addObserver( FakeSelectionObserver );
  159. this.addObserver( CompositionObserver );
  160. if ( env.isAndroid ) {
  161. this.addObserver( InputObserver );
  162. }
  163. // Inject quirks handlers.
  164. injectQuirksHandling( this );
  165. injectUiElementHandling( this );
  166. // Use 'normal' priority so that rendering is performed as first when using that priority.
  167. this.on( 'render', () => {
  168. this._render();
  169. // Informs that layout has changed after render.
  170. this.document.fire( 'layoutChanged' );
  171. // Reset the `_hasChangedSinceTheLastRendering` flag after rendering.
  172. this._hasChangedSinceTheLastRendering = false;
  173. } );
  174. // Listen to the document selection changes directly.
  175. this.listenTo( this.document.selection, 'change', () => {
  176. this._hasChangedSinceTheLastRendering = true;
  177. } );
  178. }
  179. /**
  180. * Attaches a DOM root element to the view element and enable all observers on that element.
  181. * Also {@link module:engine/view/renderer~Renderer#markToSync mark element} to be synchronized
  182. * with the view what means that all child nodes will be removed and replaced with content of the view root.
  183. *
  184. * This method also will change view element name as the same as tag name of given dom root.
  185. * Name is always transformed to lower case.
  186. *
  187. * **Note:** Use {@link #detachDomRoot `detachDomRoot()`} to revert this action.
  188. *
  189. * @param {Element} domRoot DOM root element.
  190. * @param {String} [name='main'] Name of the root.
  191. */
  192. attachDomRoot( domRoot, name = 'main' ) {
  193. const viewRoot = this.document.getRoot( name );
  194. // Set view root name the same as DOM root tag name.
  195. viewRoot._name = domRoot.tagName.toLowerCase();
  196. const initialDomRootAttributes = {};
  197. // 1. Copy and cache the attributes to remember the state of the element before attaching.
  198. // The cached attributes will be restored in detachDomRoot() so the element goes to the
  199. // clean state as if the editing view never used it.
  200. // 2. Apply the attributes using the view writer, so they all go under the control of the engine.
  201. // The editing view takes over the attribute management completely because various
  202. // features (e.g. addPlaceholder()) require dynamic changes of those attributes and they
  203. // cannot be managed by the engine and the UI library at the same time.
  204. for ( const { name, value } of Array.from( domRoot.attributes ) ) {
  205. initialDomRootAttributes[ name ] = value;
  206. // Do not use writer.setAttribute() for the class attribute. The EditableUIView class
  207. // and its descendants could have already set some using the writer.addClass() on the view
  208. // document root. They haven't been rendered yet so they are not present in the DOM root.
  209. // Using writer.setAttribute( 'class', ... ) would override them completely.
  210. if ( name === 'class' ) {
  211. this._writer.addClass( value.split( ' ' ), viewRoot );
  212. } else {
  213. this._writer.setAttribute( name, value, viewRoot );
  214. }
  215. }
  216. this._initialDomRootAttributes.set( domRoot, initialDomRootAttributes );
  217. const updateContenteditableAttribute = () => {
  218. this._writer.setAttribute( 'contenteditable', !viewRoot.isReadOnly, viewRoot );
  219. if ( viewRoot.isReadOnly ) {
  220. this._writer.addClass( 'ck-read-only', viewRoot );
  221. } else {
  222. this._writer.removeClass( 'ck-read-only', viewRoot );
  223. }
  224. };
  225. // Set initial value.
  226. updateContenteditableAttribute();
  227. this.domRoots.set( name, domRoot );
  228. this.domConverter.bindElements( domRoot, viewRoot );
  229. this._renderer.markToSync( 'children', viewRoot );
  230. this._renderer.markToSync( 'attributes', viewRoot );
  231. this._renderer.domDocuments.add( domRoot.ownerDocument );
  232. viewRoot.on( 'change:children', ( evt, node ) => this._renderer.markToSync( 'children', node ) );
  233. viewRoot.on( 'change:attributes', ( evt, node ) => this._renderer.markToSync( 'attributes', node ) );
  234. viewRoot.on( 'change:text', ( evt, node ) => this._renderer.markToSync( 'text', node ) );
  235. viewRoot.on( 'change:isReadOnly', () => this.change( updateContenteditableAttribute ) );
  236. viewRoot.on( 'change', () => {
  237. this._hasChangedSinceTheLastRendering = true;
  238. } );
  239. for ( const observer of this._observers.values() ) {
  240. observer.observe( domRoot, name );
  241. }
  242. }
  243. /**
  244. * Detaches a DOM root element from the view element and restores its attributes to the state before
  245. * {@link #attachDomRoot `attachDomRoot()`}.
  246. *
  247. * @param {String} name Name of the root to detach.
  248. */
  249. detachDomRoot( name ) {
  250. const domRoot = this.domRoots.get( name );
  251. // Remove all root attributes so the DOM element is "bare".
  252. Array.from( domRoot.attributes ).forEach( ( { name } ) => domRoot.removeAttribute( name ) );
  253. const initialDomRootAttributes = this._initialDomRootAttributes.get( domRoot );
  254. // Revert all view root attributes back to the state before attachDomRoot was called.
  255. for ( const attribute in initialDomRootAttributes ) {
  256. domRoot.setAttribute( attribute, initialDomRootAttributes[ attribute ] );
  257. }
  258. this.domRoots.delete( name );
  259. this.domConverter.unbindDomElement( domRoot );
  260. }
  261. /**
  262. * Gets DOM root element.
  263. *
  264. * @param {String} [name='main'] Name of the root.
  265. * @returns {Element} DOM root element instance.
  266. */
  267. getDomRoot( name = 'main' ) {
  268. return this.domRoots.get( name );
  269. }
  270. /**
  271. * Creates observer of the given type if not yet created, {@link module:engine/view/observer/observer~Observer#enable enables} it
  272. * and {@link module:engine/view/observer/observer~Observer#observe attaches} to all existing and future
  273. * {@link #domRoots DOM roots}.
  274. *
  275. * Note: Observers are recognized by their constructor (classes). A single observer will be instantiated and used only
  276. * when registered for the first time. This means that features and other components can register a single observer
  277. * multiple times without caring whether it has been already added or not.
  278. *
  279. * @param {Function} Observer The constructor of an observer to add.
  280. * Should create an instance inheriting from {@link module:engine/view/observer/observer~Observer}.
  281. * @returns {module:engine/view/observer/observer~Observer} Added observer instance.
  282. */
  283. addObserver( Observer ) {
  284. let observer = this._observers.get( Observer );
  285. if ( observer ) {
  286. return observer;
  287. }
  288. observer = new Observer( this );
  289. this._observers.set( Observer, observer );
  290. for ( const [ name, domElement ] of this.domRoots ) {
  291. observer.observe( domElement, name );
  292. }
  293. observer.enable();
  294. return observer;
  295. }
  296. /**
  297. * Returns observer of the given type or `undefined` if such observer has not been added yet.
  298. *
  299. * @param {Function} Observer The constructor of an observer to get.
  300. * @returns {module:engine/view/observer/observer~Observer|undefined} Observer instance or undefined.
  301. */
  302. getObserver( Observer ) {
  303. return this._observers.get( Observer );
  304. }
  305. /**
  306. * Disables all added observers.
  307. */
  308. disableObservers() {
  309. for ( const observer of this._observers.values() ) {
  310. observer.disable();
  311. }
  312. }
  313. /**
  314. * Enables all added observers.
  315. */
  316. enableObservers() {
  317. for ( const observer of this._observers.values() ) {
  318. observer.enable();
  319. }
  320. }
  321. /**
  322. * Scrolls the page viewport and {@link #domRoots} with their ancestors to reveal the
  323. * caret, if not already visible to the user.
  324. */
  325. scrollToTheSelection() {
  326. const range = this.document.selection.getFirstRange();
  327. if ( range ) {
  328. scrollViewportToShowTarget( {
  329. target: this.domConverter.viewRangeToDom( range ),
  330. viewportOffset: 20
  331. } );
  332. }
  333. }
  334. /**
  335. * It will focus DOM element representing {@link module:engine/view/editableelement~EditableElement EditableElement}
  336. * that is currently having selection inside.
  337. */
  338. focus() {
  339. if ( !this.document.isFocused ) {
  340. const editable = this.document.selection.editableElement;
  341. if ( editable ) {
  342. this.domConverter.focus( editable );
  343. this.forceRender();
  344. } else {
  345. // Before focusing view document, selection should be placed inside one of the view's editables.
  346. // Normally its selection will be converted from model document (which have default selection), but
  347. // when using view document on its own, we need to manually place selection before focusing it.
  348. //
  349. // @if CK_DEBUG // console.warn( 'There is no selection in any editable to focus.' );
  350. }
  351. }
  352. }
  353. /**
  354. * The `change()` method is the primary way of changing the view. You should use it to modify any node in the view tree.
  355. * It makes sure that after all changes are made the view is rendered to the DOM (assuming that the view will be changed
  356. * inside the callback). It prevents situations when the DOM is updated when the view state is not yet correct. It allows
  357. * to nest calls one inside another and still performs a single rendering after all those changes are made.
  358. * It also returns the return value of its callback.
  359. *
  360. * const text = view.change( writer => {
  361. * const newText = writer.createText( 'foo' );
  362. * writer.insert( position1, newText );
  363. *
  364. * view.change( writer => {
  365. * writer.insert( position2, writer.createText( 'bar' ) );
  366. * } );
  367. *
  368. * writer.remove( range );
  369. *
  370. * return newText;
  371. * } );
  372. *
  373. * When the outermost change block is done and rendering to the DOM is over the
  374. * {@link module:engine/view/view~View#event:render `View#render`} event is fired.
  375. *
  376. * This method throws a `applying-view-changes-on-rendering` error when
  377. * the change block is used after rendering to the DOM has started.
  378. *
  379. * @param {Function} callback Callback function which may modify the view.
  380. * @returns {*} Value returned by the callback.
  381. */
  382. change( callback ) {
  383. if ( this.isRenderingInProgress || this._postFixersInProgress ) {
  384. /**
  385. * Thrown when there is an attempt to make changes to the view tree when it is in incorrect state. This may
  386. * cause some unexpected behaviour and inconsistency between the DOM and the view.
  387. * This may be caused by:
  388. *
  389. * * calling {@link #change} or {@link #forceRender} during rendering process,
  390. * * calling {@link #change} or {@link #forceRender} inside of
  391. * {@link module:engine/view/document~Document#registerPostFixer post-fixer function}.
  392. *
  393. * @error cannot-change-view-tree
  394. */
  395. throw new CKEditorError(
  396. 'cannot-change-view-tree: ' +
  397. 'Attempting to make changes to the view when it is in an incorrect state: rendering or post-fixers are in progress. ' +
  398. 'This may cause some unexpected behavior and inconsistency between the DOM and the view.',
  399. this
  400. );
  401. }
  402. // Recursive call to view.change() method - execute listener immediately.
  403. if ( this._ongoingChange ) {
  404. return callback( this._writer );
  405. }
  406. // This lock will assure that all recursive calls to view.change() will end up in same block - one "render"
  407. // event for all nested calls.
  408. this._ongoingChange = true;
  409. const callbackResult = callback( this._writer );
  410. this._ongoingChange = false;
  411. // This lock is used by editing controller to render changes from outer most model.change() once. As plugins might call
  412. // view.change() inside model.change() block - this will ensures that postfixers and rendering are called once after all changes.
  413. // Also, we don't need to render anything if there're no changes since last rendering.
  414. if ( !this._renderingDisabled && this._hasChangedSinceTheLastRendering ) {
  415. this._postFixersInProgress = true;
  416. this.document._callPostFixers( this._writer );
  417. this._postFixersInProgress = false;
  418. this.fire( 'render' );
  419. }
  420. return callbackResult;
  421. }
  422. /**
  423. * Forces rendering {@link module:engine/view/document~Document view document} to DOM. If any view changes are
  424. * currently in progress, rendering will start after all {@link #change change blocks} are processed.
  425. *
  426. * Note that this method is dedicated for special cases. All view changes should be wrapped in the {@link #change}
  427. * block and the view will automatically check whether it needs to render DOM or not.
  428. *
  429. * Throws {@link module:utils/ckeditorerror~CKEditorError CKEditorError} `applying-view-changes-on-rendering` when
  430. * trying to re-render when rendering to DOM has already started.
  431. */
  432. forceRender() {
  433. this._hasChangedSinceTheLastRendering = true;
  434. this.change( () => {} );
  435. }
  436. /**
  437. * Destroys this instance. Makes sure that all observers are destroyed and listeners removed.
  438. */
  439. destroy() {
  440. for ( const observer of this._observers.values() ) {
  441. observer.destroy();
  442. }
  443. this.document.destroy();
  444. this.stopListening();
  445. }
  446. /**
  447. * Creates position at the given location. The location can be specified as:
  448. *
  449. * * a {@link module:engine/view/position~Position position},
  450. * * parent element and offset (offset defaults to `0`),
  451. * * parent element and `'end'` (sets position at the end of that element),
  452. * * {@link module:engine/view/item~Item view item} and `'before'` or `'after'` (sets position before or after given view item).
  453. *
  454. * This method is a shortcut to other constructors such as:
  455. *
  456. * * {@link #createPositionBefore},
  457. * * {@link #createPositionAfter},
  458. *
  459. * @param {module:engine/view/item~Item|module:engine/model/position~Position} itemOrPosition
  460. * @param {Number|'end'|'before'|'after'} [offset] Offset or one of the flags. Used only when
  461. * first parameter is a {@link module:engine/view/item~Item view item}.
  462. */
  463. createPositionAt( itemOrPosition, offset ) {
  464. return Position._createAt( itemOrPosition, offset );
  465. }
  466. /**
  467. * Creates a new position after given view item.
  468. *
  469. * @param {module:engine/view/item~Item} item View item after which the position should be located.
  470. * @returns {module:engine/view/position~Position}
  471. */
  472. createPositionAfter( item ) {
  473. return Position._createAfter( item );
  474. }
  475. /**
  476. * Creates a new position before given view item.
  477. *
  478. * @param {module:engine/view/item~Item} item View item before which the position should be located.
  479. * @returns {module:engine/view/position~Position}
  480. */
  481. createPositionBefore( item ) {
  482. return Position._createBefore( item );
  483. }
  484. /**
  485. * Creates a range spanning from `start` position to `end` position.
  486. *
  487. * **Note:** This factory method creates it's own {@link module:engine/view/position~Position} instances basing on passed values.
  488. *
  489. * @param {module:engine/view/position~Position} start Start position.
  490. * @param {module:engine/view/position~Position} [end] End position. If not set, range will be collapsed at `start` position.
  491. * @returns {module:engine/view/range~Range}
  492. */
  493. createRange( start, end ) {
  494. return new Range( start, end );
  495. }
  496. /**
  497. * Creates a range that starts before given {@link module:engine/view/item~Item view item} and ends after it.
  498. *
  499. * @param {module:engine/view/item~Item} item
  500. * @returns {module:engine/view/range~Range}
  501. */
  502. createRangeOn( item ) {
  503. return Range._createOn( item );
  504. }
  505. /**
  506. * Creates a range inside an {@link module:engine/view/element~Element element} which starts before the first child of
  507. * that element and ends after the last child of that element.
  508. *
  509. * @param {module:engine/view/element~Element} element Element which is a parent for the range.
  510. * @returns {module:engine/view/range~Range}
  511. */
  512. createRangeIn( element ) {
  513. return Range._createIn( element );
  514. }
  515. /**
  516. Creates new {@link module:engine/view/selection~Selection} instance.
  517. *
  518. * // Creates empty selection without ranges.
  519. * const selection = view.createSelection();
  520. *
  521. * // Creates selection at the given range.
  522. * const range = view.createRange( start, end );
  523. * const selection = view.createSelection( range );
  524. *
  525. * // Creates selection at the given ranges
  526. * const ranges = [ view.createRange( start1, end2 ), view.createRange( star2, end2 ) ];
  527. * const selection = view.createSelection( ranges );
  528. *
  529. * // Creates selection from the other selection.
  530. * const otherSelection = view.createSelection();
  531. * const selection = view.createSelection( otherSelection );
  532. *
  533. * // Creates selection from the document selection.
  534. * const selection = view.createSelection( editor.editing.view.document.selection );
  535. *
  536. * // Creates selection at the given position.
  537. * const position = view.createPositionFromPath( root, path );
  538. * const selection = view.createSelection( position );
  539. *
  540. * // Creates collapsed selection at the position of given item and offset.
  541. * const paragraph = view.createContainerElement( 'paragraph' );
  542. * const selection = view.createSelection( paragraph, offset );
  543. *
  544. * // Creates a range inside an {@link module:engine/view/element~Element element} which starts before the
  545. * // first child of that element and ends after the last child of that element.
  546. * const selection = view.createSelection( paragraph, 'in' );
  547. *
  548. * // Creates a range on an {@link module:engine/view/item~Item item} which starts before the item and ends
  549. * // just after the item.
  550. * const selection = view.createSelection( paragraph, 'on' );
  551. *
  552. * `Selection`'s factory method allow passing additional options (`backward`, `fake` and `label`) as the last argument.
  553. *
  554. * // Creates backward selection.
  555. * const selection = view.createSelection( range, { backward: true } );
  556. *
  557. * Fake selection does not render as browser native selection over selected elements and is hidden to the user.
  558. * This way, no native selection UI artifacts are displayed to the user and selection over elements can be
  559. * represented in other way, for example by applying proper CSS class.
  560. *
  561. * Additionally fake's selection label can be provided. It will be used to describe fake selection in DOM
  562. * (and be properly handled by screen readers).
  563. *
  564. * // Creates fake selection with label.
  565. * const selection = view.createSelection( range, { fake: true, label: 'foo' } );
  566. *
  567. * @param {module:engine/view/selection~Selectable} [selectable=null]
  568. * @param {Number|'before'|'end'|'after'|'on'|'in'} [placeOrOffset] Offset or place when selectable is an `Item`.
  569. * @param {Object} [options]
  570. * @param {Boolean} [options.backward] Sets this selection instance to be backward.
  571. * @param {Boolean} [options.fake] Sets this selection instance to be marked as `fake`.
  572. * @param {String} [options.label] Label for the fake selection.
  573. * @returns {module:engine/view/selection~Selection}
  574. */
  575. createSelection( selectable, placeOrOffset, options ) {
  576. return new Selection( selectable, placeOrOffset, options );
  577. }
  578. /**
  579. * Disables or enables rendering. If the flag is set to `true` then the rendering will be disabled.
  580. * If the flag is set to `false` and if there was some change in the meantime, then the rendering action will be performed.
  581. *
  582. * @protected
  583. * @param {Boolean} flag A flag indicates whether the rendering should be disabled.
  584. */
  585. _disableRendering( flag ) {
  586. this._renderingDisabled = flag;
  587. if ( flag == false ) {
  588. // Render when you stop blocking rendering.
  589. this.change( () => {} );
  590. }
  591. }
  592. /**
  593. * Renders all changes. In order to avoid triggering the observers (e.g. mutations) all observers are disabled
  594. * before rendering and re-enabled after that.
  595. *
  596. * @private
  597. */
  598. _render() {
  599. this.isRenderingInProgress = true;
  600. this.disableObservers();
  601. this._renderer.render();
  602. this.enableObservers();
  603. this.isRenderingInProgress = false;
  604. }
  605. /**
  606. * Fired after a topmost {@link module:engine/view/view~View#change change block} and all
  607. * {@link module:engine/view/document~Document#registerPostFixer post-fixers} are executed.
  608. *
  609. * Actual rendering is performed as a first listener on 'normal' priority.
  610. *
  611. * view.on( 'render', () => {
  612. * // Rendering to the DOM is complete.
  613. * } );
  614. *
  615. * This event is useful when you want to update interface elements after the rendering, e.g. position of the
  616. * balloon panel. If you wants to change view structure use
  617. * {@link module:engine/view/document~Document#registerPostFixer post-fixers}.
  618. *
  619. * @event module:engine/view/view~View#event:render
  620. */
  621. }
  622. mix( View, ObservableMixin );