Accessibility: Fixed Link annotation is not nested inside a Link structure element (#1664)

adyry · akgn268 · web-flow · commit 0b01ef41461d · 2025-12-18T10:53:27.000-03:00
* Accessibility: Fixed Link annotation is not nested inside a Link structure element

* Accessibility: Fixed Link annotation is not nested inside a Link structure element

* Changelog

* Fix links leakage into subsequent structures

* Prettier

---------

Co-authored-by: akowalczewski &lt;akowalczewski@gn.com&gt;
diff --git a/.gitignore b/.gitignore
@@ -6,6 +6,7 @@ playground/
 build/
 js/
 .vscode
+.idea
 coverage
 package-lock.json
 /examples/browserify/bundle.js
diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -3,6 +3,7 @@
 ### Unreleased
 
 - Fix garbled text copying in Chrome/Edge for PDFs with >256 unique characters (#1659)
+- Fix Link accessibility issues
 
 ### [v0.17.2] - 2025-08-30
 
diff --git a/examples/accessible-links.js b/examples/accessible-links.js
@@ -0,0 +1,87 @@
+var PDFDocument = require('../');
+var fs = require('fs');
+
+// Create a new PDFDocument
+var doc = new PDFDocument({
+  autoFirstPage: true,
+  bufferPages: true,
+  pdfVersion: '1.5',
+  // @ts-ignore PDF/UA needs to be enforced for PAC accessibility checker
+  subset: 'PDF/UA',
+  tagged: true,
+  displayTitle: true,
+  lang: 'en-US',
+  fontSize: 12,
+});
+
+doc.pipe(fs.createWriteStream('accessible-links.pdf'));
+
+// Set some meta data
+doc.info['Title'] = 'Test Document';
+doc.info['Author'] = 'Devon Govett';
+
+// Initialise document logical structure
+var struct = doc.struct('Document');
+doc.addStructure(struct);
+
+// Register a font name for use later
+doc.registerFont('Palatino', 'fonts/PalatinoBold.ttf');
+
+// Set the font and draw some text
+struct.add(
+  doc.struct('P', () => {
+    doc
+      .font('Palatino')
+      .fontSize(25)
+      .text('Some text with an embedded font! ', 100, 100);
+  }),
+);
+
+// Add another page
+doc.addPage();
+
+// Add some text with annotations
+var linkSection = doc.struct('Sect');
+struct.add(linkSection);
+
+var paragraph = doc.struct('P');
+linkSection.add(paragraph);
+
+paragraph.add(
+  doc.struct('Span', () => {
+    doc
+      .font('Palatino')
+      .fillColor('black')
+      .text('This is some text before ', 100, 100, {
+        continued: true,
+      });
+  }),
+);
+
+paragraph.add(
+  doc.struct(
+    'Link',
+    {
+      alt: 'Here is a link! ',
+    },
+    () => {
+      doc.fillColor('blue').text('Here is a link!', {
+        link: 'http://google.com/',
+        underline: true,
+        continued: true,
+      });
+    },
+  ),
+);
+
+paragraph.add(
+  doc.struct('Span', () => {
+    doc.fillColor('black').text(' and this is text after the link.');
+  }),
+);
+
+paragraph.end();
+linkSection.end();
+
+// End and flush the document
+doc.end();
diff --git a/examples/accessible-links.pdf b/examples/accessible-links.pdf
diff --git a/examples/kitchen-sink-accessible.js b/examples/kitchen-sink-accessible.js
@@ -7,7 +7,9 @@ var doc = new PDFDocument({
   pdfVersion: '1.5',
   lang: 'en-US',
   tagged: true,
-  displayTitle: true
+  displayTitle: true,
+  // @ts-ignore PDF/UA needs to be enforced for PAC accessibility checker
+  subset: 'PDF/UA',
 });
 
 doc.pipe(fs.createWriteStream('kitchen-sink-accessible.pdf'));
diff --git a/examples/kitchen-sink-accessible.pdf b/examples/kitchen-sink-accessible.pdf
diff --git a/lib/mixins/annotations.js b/lib/mixins/annotations.js
@@ -1,3 +1,5 @@
+import PDFAnnotationReference from '../structure_annotation';
+
 export default {
   annotate(x, y, w, h, options) {
     options.Type = 'Annot';
@@ -19,6 +21,9 @@ export default {
       options.Dest = new String(options.Dest);
     }
 
+    const structParent = options.structParent;
+    delete options.structParent;
+
     // Capitalize keys
     for (let key in options) {
       const val = options[key];
@@ -27,6 +32,12 @@ export default {
 
     const ref = this.ref(options);
     this.page.annotations.push(ref);
+
+    if (structParent && typeof structParent.add === 'function') {
+      const annotRef = new PDFAnnotationReference(ref);
+      structParent.add(annotRef);
+    }
+
     ref.end();
     return this;
   },
@@ -77,6 +88,10 @@ export default {
       options.A.end();
     }
 
+    if (options.structParent && !options.Contents) {
+      options.Contents = new String('');
+    }
+
     return this.annotate(x, y, w, h, options);
   },
 
diff --git a/lib/mixins/markings.js b/lib/mixins/markings.js
@@ -99,6 +99,13 @@ export default {
   endMarkedContent() {
     this.page.markings.pop();
     this.addContent('EMC');
+    if (this._textOptions) {
+      delete this._textOptions.link;
+      delete this._textOptions.goTo;
+      delete this._textOptions.destination;
+      delete this._textOptions.underline;
+      delete this._textOptions.strike;
+    }
     return this;
   },
 
diff --git a/lib/mixins/text.js b/lib/mixins/text.js
@@ -531,7 +531,21 @@ export default {
 
     // create link annotations if the link option is given
     if (options.link != null) {
-      this.link(x, y, renderedWidth, this.currentLineHeight(), options.link);
+      const linkOptions = {};
+      if (
+        this._currentStructureElement &&
+        this._currentStructureElement.dictionary.data.S === 'Link'
+      ) {
+        linkOptions.structParent = this._currentStructureElement;
+      }
+      this.link(
+        x,
+        y,
+        renderedWidth,
+        this.currentLineHeight(),
+        options.link,
+        linkOptions,
+      );
     }
     if (options.goTo != null) {
       this.goTo(x, y, renderedWidth, this.currentLineHeight(), options.goTo);
diff --git a/lib/structure_annotation.js b/lib/structure_annotation.js
@@ -0,0 +1,7 @@
+class PDFAnnotationReference {
+  constructor(annotationRef) {
+    this.annotationRef = annotationRef;
+  }
+}
+
+export default PDFAnnotationReference;
diff --git a/lib/structure_element.js b/lib/structure_element.js
@@ -4,6 +4,7 @@ By Ben Schmidt
 */
 
 import PDFStructureContent from './structure_content';
+import PDFAnnotationReference from './structure_annotation';
 
 class PDFStructureElement {
   constructor(document, type, options = {}, children = null) {
@@ -71,6 +72,10 @@ class PDFStructureElement {
       this._addContentToParentTree(child);
     }
 
+    if (child instanceof PDFAnnotationReference) {
+      this._addAnnotationToParentTree(child.annotationRef);
+    }
+
     if (typeof child === 'function' && this._attached) {
       // _contentForClosure() adds the content to the parent tree
       child = this._contentForClosure(child);
@@ -90,6 +95,15 @@ class PDFStructureElement {
     });
   }
 
+  _addAnnotationToParentTree(annotRef) {
+    const parentTreeKey = this.document.createStructParentTreeNextKey();
+
+    annotRef.data.StructParent = parentTreeKey;
+
+    const parentTree = this.document.getStructParentTree();
+    parentTree.add(parentTreeKey, this.dictionary);
+  }
+
   setParent(parentRef) {
     if (this.dictionary.data.P) {
       throw new Error(`Structure element added to more than one parent`);
@@ -137,13 +151,25 @@ class PDFStructureElement {
     return (
       child instanceof PDFStructureElement ||
       child instanceof PDFStructureContent ||
+      child instanceof PDFAnnotationReference ||
       typeof child === 'function'
     );
   }
 
   _contentForClosure(closure) {
     const content = this.document.markStructureContent(this.dictionary.data.S);
+
+    const prevStructElement = this.document._currentStructureElement;
+    this.document._currentStructureElement = this;
+
+    const wasEnded = this._ended;
+    this._ended = false;
+
     closure();
+
+    this._ended = wasEnded;
+
+    this.document._currentStructureElement = prevStructElement;
     this.document.endMarkedContent();
 
     this._addContentToParentTree(content);
@@ -209,6 +235,16 @@ class PDFStructureElement {
         }
       });
     }
+
+    if (child instanceof PDFAnnotationReference) {
+      const pageRef = this.document.page.dictionary;
+      const objr = {
+        Type: 'OBJR',
+        Obj: child.annotationRef,
+        Pg: pageRef,
+      };
+      this.dictionary.data.K.push(objr);
+    }
   }
 }
 
diff --git a/tests/unit/annotations.spec.js b/tests/unit/annotations.spec.js
@@ -178,4 +178,41 @@ describe('Annotations', () => {
       ]);
     });
   });
+
+  describe('annotations with structure parent', () => {
+    test('should add structParent to link annotations', () => {
+      document = new PDFDocument({
+        info: { CreationDate: new Date(Date.UTC(2018, 1, 1)) },
+        compress: false,
+        tagged: true,
+      });
+
+      const docData = logData(document);
+
+      const linkElement = document.struct('Link');
+      document.addStructure(linkElement);
+
+      document.link(100, 100, 100, 20, 'http://example.com', {
+        structParent: linkElement,
+      });
+
+      linkElement.end();
+      document.end();
+
+      const dataStr = docData.join('\n');
+      expect(dataStr).toContain('/StructParent 0');
+      expect(dataStr).toContain('/Contents ()');
+    });
+
+    test('should work without structParent (backwards compatibility)', () => {
+      const docData = logData(document);
+
+      document.link(100, 100, 100, 20, 'http://example.com');
+      document.end();
+
+      const dataStr = docData.join('\n');
+      expect(dataStr).toContain('/Subtype /Link');
+      expect(dataStr).not.toContain('/StructParent');
+    });
+  });
 });
diff --git a/tests/unit/markings.spec.js b/tests/unit/markings.spec.js
@@ -525,6 +525,23 @@ EMC
         document.struct('Foo', [1]);
       }).toThrow();
     });
+
+    test('_currentStructureElement tracking with closures', () => {
+      const section = document.struct('Sect');
+      document.addStructure(section);
+
+      let capturedStructElement = null;
+
+      const paragraph = document.struct('P', () => {
+        capturedStructElement = document._currentStructureElement;
+      });
+
+      section.add(paragraph);
+      section.end();
+      document.end();
+
+      expect(capturedStructElement).toBe(paragraph);
+    });
   });
 
   describe('accessible document', () => {
diff --git a/tests/unit/structure_annotation.spec.js b/tests/unit/structure_annotation.spec.js
diff --git a/tests/unit/text.spec.js b/tests/unit/text.spec.js
