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[Annotations] Add some aria-owns in the text layer to link to annotations (bug 1780375)

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This patch doesn't structurally change the text layer: it just adds some aria-owns
attributes to some spans.
The aria-owns attribute expect to have an element id, hence it's why it adds back an
id on the element rendering an annotation, but this id is built in using crypto.randomUUID
to avoid any potential issues with the hash in the url.
The elements in the annotation layer are moved into the DOM in order to have them in the
same "order" as they visually are.
The overall goal is to help screen readers to present to the user the annotations as
they visually are and as they come in the text flow.
It is clearly not perfect, but it should improve readability for some people with visual
disabilities.
This commit is contained in:
Calixte Denizet 2022-07-28 17:59:03 +02:00
parent cef2ac99e5
commit f316300113
23 changed files with 436 additions and 246 deletions
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45
src/display/annotation_layer.js
View file

@ -29,6 +29,7 @@ import {
warn,
} from "../shared/util.js";
import {
AnnotationPrefix,
DOMSVGFactory,
getFilenameFromUrl,
PDFDateString,
@ -1901,7 +1902,8 @@ class PopupElement {
}
if (this.hideElement.hidden) {
this.hideElement.hidden = false;
this.container.style.zIndex += 1;
this.container.style.zIndex =
parseInt(this.container.style.zIndex) + 1000;
}
}
@ -1918,7 +1920,8 @@ class PopupElement {
}
if (!this.hideElement.hidden && !this.pinned) {
this.hideElement.hidden = true;
this.container.style.zIndex -= 1;
this.container.style.zIndex =
parseInt(this.container.style.zIndex) - 1000;
}
}
}
@ -2465,6 +2468,19 @@ class FileAttachmentAnnotationElement extends AnnotationElement {
*/
class AnnotationLayer {
static #appendElement(element, id, div, accessibilityManager) {
const contentElement = element.firstChild || element;
contentElement.id = `${AnnotationPrefix}${id}`;
div.append(element);
accessibilityManager?.moveElementInDOM(
div,
element,
contentElement,
/* isRemovable = */ false
);
}
/**
* Render a new annotation layer with all annotation elements.
*
@ -2473,9 +2489,10 @@ class AnnotationLayer {
* @memberof AnnotationLayer
*/
static render(parameters) {
const { annotations, div, viewport } = parameters;
const { annotations, div, viewport, accessibilityManager } = parameters;
this.#setDimensions(div, viewport);
let zIndex = 0;
for (const data of annotations) {
if (data.annotationType !== AnnotationType.POPUP) {
@ -2508,15 +2525,33 @@ class AnnotationLayer {
}
if (Array.isArray(rendered)) {
for (const renderedElement of rendered) {
div.append(renderedElement);
renderedElement.style.zIndex = zIndex++;
AnnotationLayer.#appendElement(
renderedElement,
data.id,
div,
accessibilityManager
);
}
} else {
// The accessibility manager will move the annotation in the DOM in
// order to match the visual ordering.
// But if an annotation is above an other one, then we must draw it
// after the other one whatever the order is in the DOM, hence the
// use of the z-index.
rendered.style.zIndex = zIndex++;
if (element instanceof PopupAnnotationElement) {
// Popup annotation elements should not be on top of other
// annotation elements to prevent interfering with mouse events.
div.prepend(rendered);
} else {
div.append(rendered);
AnnotationLayer.#appendElement(
rendered,
data.id,
div,
accessibilityManager
);
}
}
}

3
src/display/display_utils.js
View file

@ -23,6 +23,8 @@ import { BaseException, stringToBytes, Util, warn } from "../shared/util.js";
const SVG_NS = "http://www.w3.org/2000/svg";
const AnnotationPrefix = "pdfjs_internal_id_";
class PixelsPerInch {
static CSS = 96.0;
@ -652,6 +654,7 @@ function getCurrentTransformInverse(ctx) {
}
export {
AnnotationPrefix,
binarySearchFirstItem,
deprecated,
DOMCanvasFactory,

208
src/display/editor/annotation_editor_layer.js
View file

@ -18,11 +18,12 @@
/** @typedef {import("./tools.js").AnnotationEditorUIManager} AnnotationEditorUIManager */
// eslint-disable-next-line max-len
/** @typedef {import("../annotation_storage.js").AnnotationStorage} AnnotationStorage */
// eslint-disable-next-line max-len
/** @typedef {import("../../web/text_accessibility.js").TextAccessibilityManager} TextAccessibilityManager */
/** @typedef {import("../../web/interfaces").IL10n} IL10n */
import { AnnotationEditorType, shadow } from "../../shared/util.js";
import { bindEvents, KeyboardManager } from "./tools.js";
import { binarySearchFirstItem } from "../display_utils.js";
import { AnnotationEditorType } from "../../shared/util.js";
import { FreeTextEditor } from "./freetext.js";
import { InkEditor } from "./ink.js";
@ -33,6 +34,7 @@ import { InkEditor } from "./ink.js";
* @property {AnnotationEditorUIManager} uiManager
* @property {boolean} enabled
* @property {AnnotationStorage} annotationStorage
* @property {TextAccessibilityManager} [accessibilityManager]
* @property {number} pageIndex
* @property {IL10n} l10n
*/
@ -41,6 +43,8 @@ import { InkEditor } from "./ink.js";
* Manage all the different editors on a page.
*/
class AnnotationEditorLayer {
#accessibilityManager;
#allowClick = false;
#boundPointerup = this.pointerup.bind(this);
@ -53,14 +57,8 @@ class AnnotationEditorLayer {
#isCleaningUp = false;
#textLayerMap = new WeakMap();
#textNodes = new Map();
#uiManager;
#waitingEditors = new Set();
static _initialized = false;
/**
@ -78,43 +76,11 @@ class AnnotationEditorLayer {
this.annotationStorage = options.annotationStorage;
this.pageIndex = options.pageIndex;
this.div = options.div;
this.#accessibilityManager = options.accessibilityManager;
this.#uiManager.addLayer(this);
}
get textLayerElements() {
// When zooming the text layer is removed from the DOM and sometimes
// it's rebuilt hence the nodes are no longer valid.
const textLayer = this.div.parentNode
.getElementsByClassName("textLayer")
.item(0);
if (!textLayer) {
return shadow(this, "textLayerElements", null);
}
let textChildren = this.#textLayerMap.get(textLayer);
if (textChildren) {
return textChildren;
}
textChildren = textLayer.querySelectorAll(`span[role="presentation"]`);
if (textChildren.length === 0) {
return shadow(this, "textLayerElements", null);
}
textChildren = Array.from(textChildren);
textChildren.sort(AnnotationEditorLayer.#compareElementPositions);
this.#textLayerMap.set(textLayer, textChildren);
return textChildren;
}
get #hasTextLayer() {
return !!this.div.parentNode.querySelector(".textLayer .endOfContent");
}
/**
* Update the toolbar if it's required to reflect the tool currently used.
* @param {number} mode
@ -228,7 +194,7 @@ class AnnotationEditorLayer {
detach(editor) {
this.#editors.delete(editor.id);
this.removePointerInTextLayer(editor);
this.#accessibilityManager?.removePointerInTextLayer(editor.contentDiv);
}
/**
@ -281,147 +247,6 @@ class AnnotationEditorLayer {
}
}
/**
* Compare the positions of two elements, it must correspond to
* the visual ordering.
*
* @param {HTMLElement} e1
* @param {HTMLElement} e2
* @returns {number}
*/
static #compareElementPositions(e1, e2) {
const rect1 = e1.getBoundingClientRect();
const rect2 = e2.getBoundingClientRect();
if (rect1.y + rect1.height <= rect2.y) {
return -1;
}
if (rect2.y + rect2.height <= rect1.y) {
return +1;
}
const centerX1 = rect1.x + rect1.width / 2;
const centerX2 = rect2.x + rect2.width / 2;
return centerX1 - centerX2;
}
/**
* Function called when the text layer has finished rendering.
*/
onTextLayerRendered() {
this.#textNodes.clear();
for (const editor of this.#waitingEditors) {
if (editor.isAttachedToDOM) {
this.addPointerInTextLayer(editor);
}
}
this.#waitingEditors.clear();
}
/**
* Remove an aria-owns id from a node in the text layer.
* @param {AnnotationEditor} editor
*/
removePointerInTextLayer(editor) {
if (!this.#hasTextLayer) {
this.#waitingEditors.delete(editor);
return;
}
const { id } = editor;
const node = this.#textNodes.get(id);
if (!node) {
return;
}
this.#textNodes.delete(id);
let owns = node.getAttribute("aria-owns");
if (owns?.includes(id)) {
owns = owns
.split(" ")
.filter(x => x !== id)
.join(" ");
if (owns) {
node.setAttribute("aria-owns", owns);
} else {
node.removeAttribute("aria-owns");
node.setAttribute("role", "presentation");
}
}
}
/**
* Find the text node which is the nearest and add an aria-owns attribute
* in order to correctly position this editor in the text flow.
* @param {AnnotationEditor} editor
*/
addPointerInTextLayer(editor) {
if (!this.#hasTextLayer) {
// The text layer needs to be there, so we postpone the association.
this.#waitingEditors.add(editor);
return;
}
this.removePointerInTextLayer(editor);
const children = this.textLayerElements;
if (!children) {
return;
}
const { contentDiv } = editor;
const id = editor.getIdForTextLayer();
const index = binarySearchFirstItem(
children,
node =>
AnnotationEditorLayer.#compareElementPositions(contentDiv, node) < 0
);
const node = children[Math.max(0, index - 1)];
const owns = node.getAttribute("aria-owns");
if (!owns?.includes(id)) {
node.setAttribute("aria-owns", owns ? `${owns} ${id}` : id);
}
node.removeAttribute("role");
this.#textNodes.set(id, node);
}
/**
* Move a div in the DOM in order to respect the visual order.
* @param {HTMLDivElement} div
*/
moveDivInDOM(editor) {
this.addPointerInTextLayer(editor);
const { div, contentDiv } = editor;
if (!this.div.hasChildNodes()) {
this.div.append(div);
return;
}
const children = Array.from(this.div.childNodes).filter(
node => node !== div
);
if (children.length === 0) {
return;
}
const index = binarySearchFirstItem(
children,
node =>
AnnotationEditorLayer.#compareElementPositions(contentDiv, node) < 0
);
if (index === 0) {
children[0].before(div);
} else {
children[index - 1].after(div);
}
}
/**
* Add a new editor in the current view.
* @param {AnnotationEditor} editor
@ -437,11 +262,20 @@ class AnnotationEditorLayer {
editor.isAttachedToDOM = true;
}
this.moveDivInDOM(editor);
this.moveEditorInDOM(editor);
editor.onceAdded();
this.addToAnnotationStorage(editor);
}
moveEditorInDOM(editor) {
this.#accessibilityManager?.moveElementInDOM(
this.div,
editor.div,
editor.contentDiv,
/* isRemovable = */ true
);
}
/**
* Add an editor in the annotation storage.
* @param {AnnotationEditor} editor
@ -658,7 +492,7 @@ class AnnotationEditorLayer {
const endY = event.clientY - rect.y;
editor.translate(endX - editor.startX, endY - editor.startY);
this.moveDivInDOM(editor);
this.moveEditorInDOM(editor);
editor.div.focus();
}
@ -679,15 +513,13 @@ class AnnotationEditorLayer {
}
for (const editor of this.#editors.values()) {
this.removePointerInTextLayer(editor);
this.#accessibilityManager?.removePointerInTextLayer(editor.contentDiv);
editor.isAttachedToDOM = false;
editor.div.remove();
editor.parent = null;
}
this.#textNodes.clear();
this.div = null;
this.#editors.clear();
this.#waitingEditors.clear();
this.#uiManager.removeLayer(this);
}

8
src/display/editor/editor.js
View file

@ -489,14 +489,6 @@ class AnnotationEditor {
*/
enableEditing() {}
/**
* Get the id to use in aria-owns when a link is done in the text layer.
* @returns {string}
*/
getIdForTextLayer() {
return this.id;
}
/**
* Get some properties to update in the UI.
* @returns {Object}

5
src/display/editor/freetext.js
View file

@ -385,11 +385,6 @@ class FreeTextEditor extends AnnotationEditor {
this.editorDiv.setAttribute("aria-multiline", true);
}
/** @inheritdoc */
getIdForTextLayer() {
return this.editorDiv.id;
}
/** @inheritdoc */
render() {
if (this.div) {

2
src/display/editor/ink.js
View file

@ -488,7 +488,7 @@ class InkEditor extends AnnotationEditor {
// When commiting, the position of this editor is changed, hence we must
// move it to the right position in the DOM.
this.parent.moveDivInDOM(this);
this.parent.moveEditorInDOM(this);
// After the div has been moved in the DOM, the focus may have been stolen
// by document.body, hence we just keep it here.
this.div.focus();

10
src/display/editor/tools.js
View file

@ -428,8 +428,6 @@ class AnnotationEditorUIManager {
#boundOnPageChanging = this.onPageChanging.bind(this);
#boundOnTextLayerRendered = this.onTextLayerRendered.bind(this);
#previousStates = {
isEditing: false,
isEmpty: true,
@ -474,14 +472,12 @@ class AnnotationEditorUIManager {
this.#eventBus = eventBus;
this.#eventBus._on("editingaction", this.#boundOnEditingAction);
this.#eventBus._on("pagechanging", this.#boundOnPageChanging);
this.#eventBus._on("textlayerrendered", this.#boundOnTextLayerRendered);
}
destroy() {
this.#removeKeyboardManager();
this.#eventBus._off("editingaction", this.#boundOnEditingAction);
this.#eventBus._off("pagechanging", this.#boundOnPageChanging);
this.#eventBus._off("textlayerrendered", this.#boundOnTextLayerRendered);
for (const layer of this.#allLayers.values()) {
layer.destroy();
}
@ -497,12 +493,6 @@ class AnnotationEditorUIManager {
this.#currentPageIndex = pageNumber - 1;
}
onTextLayerRendered({ pageNumber }) {
const pageIndex = pageNumber - 1;
const layer = this.#allLayers.get(pageIndex);
layer?.onTextLayerRendered();
}
focusMainContainer() {
this.#container.focus();
}