Fix Firefox scanning when some combining characters are present

ext/js/accessibility/google-docs-util.js

@@ -137,7 +137,7 @@ export class GoogleDocsUtil {
             const mid = Math.floor((start + end) / 2);
             range.setStart(textNode, mid);
             range.setEnd(textNode, end);
-            if (isPointInAnyRect(x, y, range.getClientRects())) {
+            if (isPointInAnyRect(x, y, range.getClientRects(), null)) {
                 start = mid;
             } else {
                 end = mid;

ext/js/dom/document-util.js

@@ -22,6 +22,9 @@
  */
 let cssZoomSupported = null;
 
+/** @type {Set<?string>} */
+const FIREFOX_RECT_EXCLUDED_LANGUAGES = new Set(['th']);
+
 /**
  * Computes the scaling adjustment that is necessary for client space coordinates based on the
  * CSS zoom level.
@@ -107,9 +110,18 @@ export function isPointInRect(x, y, rect) {
  * @param {number} x The horizontal coordinate.
  * @param {number} y The vertical coordinate.
  * @param {DOMRect[]|DOMRectList} rects The rect to check.
+ * @param {?string} language
  * @returns {boolean} `true` if the point is inside any of the rects, `false` otherwise.
  */
-export function isPointInAnyRect(x, y, rects) {
+export function isPointInAnyRect(x, y, rects, language) {
+    // Always return true for Firefox due to inconsistencies with Range.getClientRects() implementation from unclear W3C spec
+    // https://drafts.csswg.org/cssom-view/#dom-range-getclientrects
+    // https://bugzilla.mozilla.org/show_bug.cgi?id=816238
+    // Firefox returns only the first level nodes, Chromium returns every text node
+    // This only affects specific languages
+    if (typeof browser !== 'undefined' && FIREFOX_RECT_EXCLUDED_LANGUAGES.has(language)) {
+        return true;
+    }
     for (const rect of rects) {
         if (isPointInRect(x, y, rect)) {
             return true;
@@ -123,12 +135,13 @@ export function isPointInAnyRect(x, y, rects) {
  * @param {number} x The horizontal coordinate.
  * @param {number} y The vertical coordinate.
  * @param {Selection} selection The selection to check.
+ * @param {string} language
  * @returns {boolean} `true` if the point is inside the selection, `false` otherwise.
  */
-export function isPointInSelection(x, y, selection) {
+export function isPointInSelection(x, y, selection, language) {
     for (let i = 0; i < selection.rangeCount; ++i) {
         const range = selection.getRangeAt(i);
-        if (isPointInAnyRect(x, y, range.getClientRects())) {
+        if (isPointInAnyRect(x, y, range.getClientRects(), language)) {
             return true;
         }
     }

ext/js/dom/text-source-generator.js

@@ -187,7 +187,7 @@ export class TextSourceGenerator {
      * @returns {?import('text-source').TextSource} A range for the hovered text or element, or `null` if no applicable content was found.
      */
     _getRangeFromPointInternal(x, y, options) {
-        const {deepContentScan, normalizeCssZoom} = options;
+        const {deepContentScan, normalizeCssZoom, language} = options;
 
         const elements = this._getElementsFromPoint(x, y, deepContentScan);
         /** @type {?HTMLDivElement} */
@@ -216,7 +216,7 @@ export class TextSourceGenerator {
             }
         }
 
-        const range = this._caretRangeFromPointExt(x, y, deepContentScan ? elements : [], normalizeCssZoom);
+        const range = this._caretRangeFromPointExt(x, y, deepContentScan ? elements : [], normalizeCssZoom, language);
         if (range !== null) {
             if (imposter !== null) {
                 this._setImposterStyle(/** @type {HTMLDivElement} */ (imposterContainer).style, 'z-index', '-2147483646');
@@ -347,9 +347,10 @@ export class TextSourceGenerator {
      * @param {number} y
      * @param {Range} range
      * @param {boolean} normalizeCssZoom
+     * @param {?string} language
      * @returns {boolean}
      */
-    _isPointInRange(x, y, range, normalizeCssZoom) {
+    _isPointInRange(x, y, range, normalizeCssZoom, language) {
         // Require a text node to start
         const {startContainer} = range;
         if (startContainer.nodeType !== Node.TEXT_NODE) {
@@ -370,7 +371,7 @@ export class TextSourceGenerator {
             const {node, offset, content} = new DOMTextScanner(nodePre, offsetPre, true, false).seek(1);
             range.setEnd(node, offset);
 
-            if (!this._isWhitespace(content) && isPointInAnyRect(x, y, range.getClientRects())) {
+            if (!this._isWhitespace(content) && isPointInAnyRect(x, y, range.getClientRects(), language)) {
                 return true;
             }
         } finally {
@@ -381,7 +382,7 @@ export class TextSourceGenerator {
         const {node, offset, content} = new DOMTextScanner(startContainer, range.startOffset, true, false).seek(-1);
         range.setStart(node, offset);
 
-        if (!this._isWhitespace(content) && isPointInAnyRect(x, y, range.getClientRects())) {
+        if (!this._isWhitespace(content) && isPointInAnyRect(x, y, range.getClientRects(), language)) {
             // This purposefully leaves the starting offset as modified and sets the range length to 0.
             range.setEnd(node, offset);
             return true;
@@ -522,9 +523,10 @@ export class TextSourceGenerator {
      * @param {number} y
      * @param {Element[]} elements
      * @param {boolean} normalizeCssZoom
+     * @param {?string} language
      * @returns {?Range}
      */
-    _caretRangeFromPointExt(x, y, elements, normalizeCssZoom) {
+    _caretRangeFromPointExt(x, y, elements, normalizeCssZoom, language) {
         /** @type {?Map<Element, ?string>} */
         let previousStyles = null;
         try {
@@ -538,7 +540,7 @@ export class TextSourceGenerator {
 
                 const startContainer = range.startContainer;
                 if (startContinerPre !== startContainer) {
-                    if (this._isPointInRange(x, y, range, normalizeCssZoom)) {
+                    if (this._isPointInRange(x, y, range, normalizeCssZoom, language)) {
                         return range;
                     }
                     startContinerPre = startContainer;

ext/js/language/text-scanner.js

@@ -731,8 +731,9 @@ export class TextScanner extends EventDispatcher {
         this._preventNextClick = false;
         this._touchTapValid = true;
 
+        const languageNotNull = this._language !== null ? this._language : '';
         const selection = window.getSelection();
-        if (selection !== null && isPointInSelection(x, y, selection)) {
+        if (selection !== null && isPointInSelection(x, y, selection, languageNotNull)) {
             return;
         }
 
@@ -1356,6 +1357,7 @@ export class TextScanner extends EventDispatcher {
             const textSource = this._textSourceGenerator.getRangeFromPoint(x, y, {
                 deepContentScan: this._deepContentScan,
                 normalizeCssZoom: this._normalizeCssZoom,
+                language: this._language,
             });
             if (textSource !== null) {
                 try {

test/document-util.test.js

@@ -187,6 +187,7 @@ describe('Document utility tests', () => {
                     const source = textSourceGenerator.getRangeFromPoint(0, 0, {
                         deepContentScan: false,
                         normalizeCssZoom: true,
+                        language: null,
                     });
                     switch (resultType) {
                         case 'TextSourceRange':

types/ext/document-util.d.ts

@@ -30,6 +30,10 @@ export type GetRangeFromPointOptions = {
      * Whether or not zoom coordinates should be normalized.
      */
     normalizeCssZoom: boolean;
+    /**
+     * ISO-639 code of the language.
+     */
+    language: string | null;
 };
 
 export type ToNumberConstraints = {