Merge pull request #13171 from brendandahl/struct-tree

[api-minor] Add support for basic structure tree for accessibility.

test/driver.js

@@ -572,6 +572,7 @@ var Driver = (function DriverClosure() {
                 initPromise = page
                   .getTextContent({
                     normalizeWhitespace: true,
+                    includeMarkedContent: true,
                   })
                   .then(function (textContent) {
                     return rasterizeTextLayer(

test/integration-boot.js

@@ -24,7 +24,11 @@ async function runTests(results) {
   jasmine.loadConfig({
     random: false,
     spec_dir: "integration",
-    spec_files: ["scripting_spec.js", "annotation_spec.js"],
+    spec_files: [
+      "scripting_spec.js",
+      "annotation_spec.js",
+      "accessibility_spec.js",
+    ],
   });
 
   jasmine.addReporter({

test/integration/accessibility_spec.js

@@ -0,0 +1,69 @@
+/* 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.
+ */
+
+const { closePages, loadAndWait } = require("./test_utils.js");
+
+describe("accessibility", () => {
+  describe("structure tree", () => {
+    let pages;
+
+    beforeAll(async () => {
+      pages = await loadAndWait("structure_simple.pdf", ".structTree");
+    });
+
+    afterAll(async () => {
+      await closePages(pages);
+    });
+
+    it("must build structure that maps to text layer", async () => {
+      await Promise.all(
+        pages.map(async ([browserName, page]) => {
+          await page.waitForSelector(".structTree");
+
+          // Check the headings match up.
+          const head1 = await page.$eval(
+            ".structTree [role='heading'][aria-level='1'] span",
+            el =>
+              document.getElementById(el.getAttribute("aria-owns")).textContent
+          );
+          expect(head1).withContext(`In ${browserName}`).toEqual("Heading 1");
+          const head2 = await page.$eval(
+            ".structTree [role='heading'][aria-level='2'] span",
+            el =>
+              document.getElementById(el.getAttribute("aria-owns")).textContent
+          );
+          expect(head2).withContext(`In ${browserName}`).toEqual("Heading 2");
+
+          // Check the order of the content.
+          const texts = await page.$$eval(".structTree [aria-owns]", nodes =>
+            nodes.map(
+              el =>
+                document.getElementById(el.getAttribute("aria-owns"))
+                  .textContent
+            )
+          );
+          expect(texts)
+            .withContext(`In ${browserName}`)
+            .toEqual([
+              "Heading 1",
+              "This paragraph 1.",
+              "Heading 2",
+              "This paragraph 2.",
+            ]);
+        })
+      );
+    });
+  });
+});

test/pdfs/.gitignore

@@ -71,6 +71,7 @@
 !issue8570.pdf
 !issue8697.pdf
 !issue8702.pdf
+!structure_simple.pdf
 !issue12823.pdf
 !issue8707.pdf
 !issue8798r.pdf

test/text_layer_test.css

@@ -23,7 +23,7 @@
   bottom: 0;
   line-height: 1;
 }
-.textLayer > span {
+.textLayer span {
   position: absolute;
   white-space: pre;
   -webkit-transform-origin: 0% 0%;
@@ -37,3 +37,8 @@
   -moz-box-sizing: border-box;
   box-sizing: border-box;
 }
+
+.textLayer .markedContent {
+  border: none;
+  background-color: transparent;
+}

test/unit/clitests.json

@@ -34,6 +34,7 @@
     "pdf_history_spec.js",
     "primitives_spec.js",
     "stream_spec.js",
+    "struct_tree_spec.js",
     "type1_parser_spec.js",
     "ui_utils_spec.js",
     "unicode_spec.js",

test/unit/jasmine-boot.js

@@ -80,6 +80,7 @@ async function initializePDFJS(callback) {
       "pdfjs-test/unit/primitives_spec.js",
       "pdfjs-test/unit/scripting_spec.js",
       "pdfjs-test/unit/stream_spec.js",
+      "pdfjs-test/unit/struct_tree_spec.js",
       "pdfjs-test/unit/type1_parser_spec.js",
       "pdfjs-test/unit/ui_utils_spec.js",
       "pdfjs-test/unit/unicode_spec.js",

test/unit/struct_tree_spec.js

@@ -0,0 +1,108 @@
+/* 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.
+ */
+
+import { buildGetDocumentParams } from "./test_utils.js";
+import { getDocument } from "../../src/display/api.js";
+
+function equalTrees(rootA, rootB) {
+  function walk(a, b) {
+    expect(a.role).toEqual(b.role);
+    expect(a.type).toEqual(b.type);
+    expect("children" in a).toEqual("children" in b);
+    if (!a.children) {
+      return;
+    }
+    expect(a.children.length).toEqual(b.children.length);
+    for (let i = 0; i < rootA.children.length; i++) {
+      walk(a.children[i], b.children[i]);
+    }
+  }
+  return walk(rootA, rootB);
+}
+
+describe("struct tree", function () {
+  describe("getStructTree", function () {
+    it("parses basic structure", async function () {
+      const filename = "structure_simple.pdf";
+      const params = buildGetDocumentParams(filename);
+      const loadingTask = getDocument(params);
+      const doc = await loadingTask.promise;
+      const page = await doc.getPage(1);
+      const struct = await page.getStructTree();
+      equalTrees(
+        {
+          role: "Root",
+          children: [
+            {
+              role: "Document",
+              children: [
+                {
+                  role: "H1",
+                  children: [
+                    { role: "NonStruct", children: [{ type: "content" }] },
+                  ],
+                },
+                {
+                  role: "P",
+                  children: [
+                    { role: "NonStruct", children: [{ type: "content" }] },
+                  ],
+                },
+                {
+                  role: "H2",
+                  children: [
+                    { role: "NonStruct", children: [{ type: "content" }] },
+                  ],
+                },
+                {
+                  role: "P",
+                  children: [
+                    { role: "NonStruct", children: [{ type: "content" }] },
+                  ],
+                },
+              ],
+            },
+          ],
+        },
+        struct
+      );
+      await loadingTask.destroy();
+    });
+
+    it("parses structure with marked content reference", async function () {
+      const filename = "issue6782.pdf";
+      const params = buildGetDocumentParams(filename);
+      const loadingTask = getDocument(params);
+      const doc = await loadingTask.promise;
+      const page = await doc.getPage(1);
+      const struct = await page.getStructTree();
+      equalTrees(
+        {
+          role: "Root",
+          children: [
+            {
+              role: "Part",
+              children: [
+                { role: "P", children: Array(27).fill({ type: "content" }) },
+              ],
+            },
+          ],
+        },
+        struct
+      );
+      await loadingTask.destroy();
+    });
+  });
+});