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/* Copyright 2021 Mozilla Foundation
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/** @typedef {import("../src/display/api").PDFPageProxy} PDFPageProxy */
const PDF_ROLE_TO_HTML_ROLE = {
// Document level structure types
Document: null, // There's a "document" role, but it doesn't make sense here.
DocumentFragment: null,
// Grouping level structure types
Part: "group",
Sect: "group", // XXX: There's a "section" role, but it's abstract.
Div: "group",
Aside: "note",
NonStruct: "none",
// Block level structure types
P: null,
// H<n>,
H: "heading",
Title: null,
FENote: "note",
// Sub-block level structure type
Sub: "group",
// General inline level structure types
Lbl: null,
Span: null,
Em: null,
Strong: null,
Link: "link",
Annot: "note",
Form: "form",
// Ruby and Warichu structure types
Ruby: null,
RB: null,
RT: null,
RP: null,
Warichu: null,
WT: null,
WP: null,
// List standard structure types
L: "list",
LI: "listitem",
LBody: null,
// Table standard structure types
Table: "table",
TR: "row",
TH: "columnheader",
TD: "cell",
THead: "columnheader",
TBody: null,
TFoot: null,
// Standard structure type Caption
Caption: null,
// Standard structure type Figure
Figure: "figure",
// Standard structure type Formula
Formula: null,
// standard structure type Artifact
Artifact: null,
};
const HEADING_PATTERN = /^H(\d+)$/;
/**
* @typedef {Object} StructTreeLayerBuilderOptions
* @property {PDFPageProxy} pdfPage
*/
class StructTreeLayerBuilder {
/**
* @param {StructTreeLayerBuilderOptions} options
*/
constructor({ pdfPage }) {
this.pdfPage = pdfPage;
}
render(structTree) {
return this._walk(structTree);
}
_setAttributes(structElement, htmlElement) {
if (structElement.alt !== undefined) {
htmlElement.setAttribute("aria-label", structElement.alt);
}
if (structElement.id !== undefined) {
htmlElement.setAttribute("aria-owns", structElement.id);
}
if (structElement.lang !== undefined) {
htmlElement.setAttribute("lang", structElement.lang);
}
}
_walk(node) {
if (!node) {
return null;
}
const element = document.createElement("span");
if ("role" in node) {
const { role } = node;
const match = role.match(HEADING_PATTERN);
if (match) {
element.setAttribute("role", "heading");
element.setAttribute("aria-level", match[1]);
} else if (PDF_ROLE_TO_HTML_ROLE[role]) {
element.setAttribute("role", PDF_ROLE_TO_HTML_ROLE[role]);
}
}
this._setAttributes(node, element);
if (node.children) {
if (node.children.length === 1 && "id" in node.children[0]) {
// Often there is only one content node so just set the values on the
// parent node to avoid creating an extra span.
this._setAttributes(node.children[0], element);
} else {
for (const kid of node.children) {
element.appendChild(this._walk(kid));
}
}
}
return element;
}
}
export { StructTreeLayerBuilder };
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