selectionobserver.js 9.0 KB

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  1. /**
  2. * @license Copyright (c) 2003-2019, CKSource - Frederico Knabben. All rights reserved.
  3. * For licensing, see LICENSE.md.
  4. */
  5. /**
  6. * @module engine/view/observer/selectionobserver
  7. */
  8. /* global setInterval, clearInterval */
  9. import Observer from './observer';
  10. import MutationObserver from './mutationobserver';
  11. import log from '@ckeditor/ckeditor5-utils/src/log';
  12. import { debounce } from 'lodash-es';
  13. /**
  14. * Selection observer class observes selection changes in the document. If selection changes on the document this
  15. * observer checks if there are any mutations and if DOM selection is different than the
  16. * {@link module:engine/view/document~Document#selection view selection}. Selection observer fires
  17. * {@link module:engine/view/document~Document#event:selectionChange} event only if selection change was the only change in the document
  18. * and DOM selection is different then the view selection.
  19. *
  20. * Note that this observer is attached by the {@link module:engine/view/view~View} and is available by default.
  21. *
  22. * @see module:engine/view/observer/mutationobserver~MutationObserver
  23. * @extends module:engine/view/observer/observer~Observer
  24. */
  25. export default class SelectionObserver extends Observer {
  26. constructor( view ) {
  27. super( view );
  28. /**
  29. * Instance of the mutation observer. Selection observer calls
  30. * {@link module:engine/view/observer/mutationobserver~MutationObserver#flush} to ensure that the mutations will be handled
  31. * before the {@link module:engine/view/document~Document#event:selectionChange} event is fired.
  32. *
  33. * @readonly
  34. * @member {module:engine/view/observer/mutationobserver~MutationObserver}
  35. * module:engine/view/observer/selectionobserver~SelectionObserver#mutationObserver
  36. */
  37. this.mutationObserver = view.getObserver( MutationObserver );
  38. /**
  39. * Reference to the view {@link module:engine/view/documentselection~DocumentSelection} object used to compare
  40. * new selection with it.
  41. *
  42. * @readonly
  43. * @member {module:engine/view/documentselection~DocumentSelection}
  44. * module:engine/view/observer/selectionobserver~SelectionObserver#selection
  45. */
  46. this.selection = this.document.selection;
  47. /* eslint-disable max-len */
  48. /**
  49. * Reference to the {@link module:engine/view/view~View#domConverter}.
  50. *
  51. * @readonly
  52. * @member {module:engine/view/domconverter~DomConverter} module:engine/view/observer/selectionobserver~SelectionObserver#domConverter
  53. */
  54. /* eslint-enable max-len */
  55. this.domConverter = view.domConverter;
  56. /**
  57. * Set of documents which have added "selectionchange" listener to avoid adding listener twice to the same
  58. * document.
  59. *
  60. * @private
  61. * @member {WeakSet.<Document>} module:engine/view/observer/selectionobserver~SelectionObserver#_documents
  62. */
  63. this._documents = new WeakSet();
  64. /**
  65. * Fires debounced event `selectionChangeDone`. It uses `lodash#debounce` method to delay function call.
  66. *
  67. * @private
  68. * @param {Object} data Selection change data.
  69. * @method #_fireSelectionChangeDoneDebounced
  70. */
  71. this._fireSelectionChangeDoneDebounced = debounce( data => this.document.fire( 'selectionChangeDone', data ), 200 );
  72. this._clearInfiniteLoopInterval = setInterval( () => this._clearInfiniteLoop(), 1000 );
  73. /**
  74. * Private property to check if the code does not enter infinite loop.
  75. *
  76. * @private
  77. * @member {Number} module:engine/view/observer/selectionobserver~SelectionObserver#_loopbackCounter
  78. */
  79. this._loopbackCounter = 0;
  80. }
  81. /**
  82. * @inheritDoc
  83. */
  84. observe( domElement ) {
  85. const domDocument = domElement.ownerDocument;
  86. // Add listener once per each document.
  87. if ( this._documents.has( domDocument ) ) {
  88. return;
  89. }
  90. this.listenTo( domDocument, 'selectionchange', () => {
  91. this._handleSelectionChange( domDocument );
  92. } );
  93. this._documents.add( domDocument );
  94. }
  95. /**
  96. * @inheritDoc
  97. */
  98. destroy() {
  99. super.destroy();
  100. clearInterval( this._clearInfiniteLoopInterval );
  101. this._fireSelectionChangeDoneDebounced.cancel();
  102. }
  103. /**
  104. * Selection change listener. {@link module:engine/view/observer/mutationobserver~MutationObserver#flush Flush} mutations, check if
  105. * selection changes and fires {@link module:engine/view/document~Document#event:selectionChange} event on every change
  106. * and {@link module:engine/view/document~Document#event:selectionChangeDone} when selection stop changing.
  107. *
  108. * @private
  109. * @param {Document} domDocument DOM document.
  110. */
  111. _handleSelectionChange( domDocument ) {
  112. // Selection is handled when document is not focused but is read-only. This is because in read-only
  113. // mode contenteditable is set as false and editor won't receive focus but we still need to know
  114. // selection position.
  115. if ( !this.isEnabled || ( !this.document.isFocused && !this.document.isReadOnly ) ) {
  116. return;
  117. }
  118. // Ensure the mutation event will be before selection event on all browsers.
  119. this.mutationObserver.flush();
  120. // If there were mutations then the view will be re-rendered by the mutation observer and selection
  121. // will be updated, so selections will equal and event will not be fired, as expected.
  122. const domSelection = domDocument.defaultView.getSelection();
  123. const newViewSelection = this.domConverter.domSelectionToView( domSelection );
  124. if ( this.selection.isEqual( newViewSelection ) && this.domConverter.isDomSelectionCorrect( domSelection ) ) {
  125. return;
  126. }
  127. // Ensure we are not in the infinite loop (#400).
  128. // This counter is reset each second. 60 selection changes in 1 second is enough high number
  129. // to be very difficult (impossible) to achieve using just keyboard keys (during normal editor use).
  130. if ( ++this._loopbackCounter > 60 ) {
  131. /**
  132. * Selection change observer detected an infinite rendering loop.
  133. * Most probably you try to put the selection in the position which is not allowed
  134. * by the browser and browser fixes it automatically what causes `selectionchange` event on
  135. * which a loopback through a model tries to re-render the wrong selection and again.
  136. *
  137. * @error selectionchange-infinite-loop
  138. */
  139. log.warn( 'selectionchange-infinite-loop: Selection change observer detected an infinite rendering loop.' );
  140. return;
  141. }
  142. if ( this.selection.isSimilar( newViewSelection ) ) {
  143. // If selection was equal and we are at this point of algorithm, it means that it was incorrect.
  144. // Just re-render it, no need to fire any events, etc.
  145. this.view.render();
  146. } else {
  147. const data = {
  148. oldSelection: this.selection,
  149. newSelection: newViewSelection,
  150. domSelection
  151. };
  152. // Prepare data for new selection and fire appropriate events.
  153. this.document.fire( 'selectionChange', data );
  154. // Call` #_fireSelectionChangeDoneDebounced` every time when `selectionChange` event is fired.
  155. // This function is debounced what means that `selectionChangeDone` event will be fired only when
  156. // defined int the function time will elapse since the last time the function was called.
  157. // So `selectionChangeDone` will be fired when selection will stop changing.
  158. this._fireSelectionChangeDoneDebounced( data );
  159. }
  160. }
  161. /**
  162. * Clears `SelectionObserver` internal properties connected with preventing infinite loop.
  163. *
  164. * @protected
  165. */
  166. _clearInfiniteLoop() {
  167. this._loopbackCounter = 0;
  168. }
  169. }
  170. /**
  171. * Fired when selection has changed. This event is fired only when the selection change was the only change that happened
  172. * in the document, and old selection is different then the new selection.
  173. *
  174. * Introduced by {@link module:engine/view/observer/selectionobserver~SelectionObserver}.
  175. *
  176. * Note that because {@link module:engine/view/observer/selectionobserver~SelectionObserver} is attached by the
  177. * {@link module:engine/view/view~View} this event is available by default.
  178. *
  179. * @see module:engine/view/observer/selectionobserver~SelectionObserver
  180. * @event module:engine/view/document~Document#event:selectionChange
  181. * @param {Object} data
  182. * @param {module:engine/view/documentselection~DocumentSelection} data.oldSelection Old View selection which is
  183. * {@link module:engine/view/document~Document#selection}.
  184. * @param {module:engine/view/selection~Selection} data.newSelection New View selection which is converted DOM selection.
  185. * @param {Selection} data.domSelection Native DOM selection.
  186. */
  187. /**
  188. * Fired when selection stops changing.
  189. *
  190. * Introduced by {@link module:engine/view/observer/selectionobserver~SelectionObserver}.
  191. *
  192. * Note that because {@link module:engine/view/observer/selectionobserver~SelectionObserver} is attached by the
  193. * {@link module:engine/view/view~View} this event is available by default.
  194. *
  195. * @see module:engine/view/observer/selectionobserver~SelectionObserver
  196. * @event module:engine/view/document~Document#event:selectionChangeDone
  197. * @param {Object} data
  198. * @param {module:engine/view/documentselection~DocumentSelection} data.oldSelection Old View selection which is
  199. * {@link module:engine/view/document~Document#selection}.
  200. * @param {module:engine/view/selection~Selection} data.newSelection New View selection which is converted DOM selection.
  201. * @param {Selection} data.domSelection Native DOM selection.
  202. */