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authortoasted-nutbread <toasted-nutbread@users.noreply.github.com>2022-09-24 22:44:40 -0400
committerGitHub <noreply@github.com>2022-09-24 22:44:40 -0400
commit8240482e9d0b6da7a996bc581c9b5304ebcf22aa (patch)
tree4d1621193b9990f6cb710a72f9b761aa2b471de6 /ext/js/accessibility/google-docs-util.js
parentda52caa15247f82377e5d914306de1713ed63cea (diff)
Google Docs accessibility update (#2235)
* Update Google Docs injection script * Create GoogleDocsUtil * Update Frontend.js to register GoogleDocsUtil's getRangeFromPoint handler * Update setting name and description * Add comment * Fix Firefox support
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+/*
+ * Copyright (C) 2022 Yomichan Authors
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <https://www.gnu.org/licenses/>.
+ */
+
+/* global
+ * DocumentUtil
+ * TextSourceRange
+ */
+
+/**
+ * This class is a helper for handling Google Docs content in content scripts.
+ */
+class GoogleDocsUtil {
+ /**
+ * Scans the document for text or elements with text information at the given coordinate.
+ * Coordinates are provided in [client space](https://developer.mozilla.org/en-US/docs/Web/CSS/CSSOM_View/Coordinate_systems).
+ * @param {number} x The x coordinate to search at.
+ * @param {number} y The y coordinate to search at.
+ * @param {GetRangeFromPointOptions} options Options to configure how element detection is performed.
+ * @returns {?TextSourceRange|TextSourceElement} A range for the hovered text or element, or `null` if no applicable content was found.
+ */
+ static getRangeFromPoint(x, y, {normalizeCssZoom}) {
+ const selector = '.kix-canvas-tile-content svg>g>rect';
+ const styleNode = this._getStyleNode(selector);
+ styleNode.disabled = false;
+ const elements = document.elementsFromPoint(x, y);
+ styleNode.disabled = true;
+ for (const element of elements) {
+ if (!element.matches(selector)) { continue; }
+ const ariaLabel = element.getAttribute('aria-label');
+ if (typeof ariaLabel !== 'string' || ariaLabel.length === 0) { continue; }
+ return this._createRange(element, ariaLabel, x, y, normalizeCssZoom);
+ }
+ return null;
+ }
+
+ static _getStyleNode(selector) {
+ // This <style> node is necessary to force the SVG <rect> elements to have a fill,
+ // which allows them to be included in document.elementsFromPoint's return value.
+ if (this._styleNode === null) {
+ const style = document.createElement('style');
+ style.textContent = `${selector}{fill:#0000 !important;}`;
+ const parent = document.head || document.documentElement;
+ if (parent !== null) {
+ parent.appendChild(style);
+ }
+ this._styleNode = style;
+ }
+ return this._styleNode;
+ }
+
+ static _createRange(element, text, x, y, normalizeCssZoom) {
+ // Create imposter
+ const content = document.createTextNode(text);
+ const svgText = document.createElementNS('http://www.w3.org/2000/svg', 'text');
+ const transform = element.getAttribute('transform') || '';
+ svgText.setAttribute('x', element.getAttribute('x'));
+ svgText.setAttribute('y', element.getAttribute('y'));
+ svgText.appendChild(content);
+ const textStyle = svgText.style;
+ this._setImportantStyle(textStyle, 'all', 'initial');
+ this._setImportantStyle(textStyle, 'transform', transform);
+ this._setImportantStyle(textStyle, 'font', element.dataset.fontCss);
+ this._setImportantStyle(textStyle, 'text-anchor', 'start');
+ element.parentNode.appendChild(svgText);
+
+ // Adjust offset
+ const elementRect = element.getBoundingClientRect();
+ const textRect = svgText.getBoundingClientRect();
+ const yOffset = ((elementRect.top - textRect.top) + (elementRect.bottom - textRect.bottom)) * 0.5;
+ this._setImportantStyle(textStyle, 'transform', `translate(0px,${yOffset}px) ${transform}`);
+
+ // Create range
+ const range = this._getRangeWithPoint(content, x, y, normalizeCssZoom);
+ this._setImportantStyle(textStyle, 'pointer-events', 'none');
+ this._setImportantStyle(textStyle, 'opacity', '0');
+ return new TextSourceRange(range, '', svgText, element);
+ }
+
+ static _getRangeWithPoint(textNode, x, y, normalizeCssZoom) {
+ if (normalizeCssZoom) {
+ const scale = DocumentUtil.computeZoomScale(textNode);
+ x /= scale;
+ y /= scale;
+ }
+ const range = document.createRange();
+ let start = 0;
+ let end = textNode.nodeValue.length;
+ while (end - start > 1) {
+ const mid = Math.floor((start + end) / 2);
+ range.setStart(textNode, mid);
+ range.setEnd(textNode, end);
+ if (DocumentUtil.isPointInAnyRect(x, y, range.getClientRects())) {
+ start = mid;
+ } else {
+ end = mid;
+ }
+ }
+ range.setStart(textNode, start);
+ range.setEnd(textNode, end);
+ return range;
+ }
+
+ static _setImportantStyle(style, propertyName, value) {
+ style.setProperty(propertyName, value, 'important');
+ }
+}
+// eslint-disable-next-line no-underscore-dangle
+GoogleDocsUtil._styleNode = null;