Add accessibilty tagging

package.json

@@ -1,6 +1,6 @@
 {
-  "name": "pdfmake",
-  "version": "0.2.23",
+  "name": "@wellcometrust/pdfmake",
+  "version": "2.1.0",
   "description": "Client/server side PDF printing in pure JavaScript",
   "main": "src/printer.js",
   "browser": "build/pdfmake.js",

src/accessibilityMetadata.js

@@ -0,0 +1,96 @@
+'use strict';
+
+/**
+ * Utility module to extract accessibility-relevant properties from document nodes
+ * and determine their PDF structure type.
+ */
+
+/**
+ * Returns the PDF structure tag for a node based on its properties.
+ *
+ * @param {Object} node - A pdfmake document node
+ * @param {Object} [context] - Optional context about the node's position in the document tree
+ * @param {boolean} [context.inList] - Whether the node is inside a list
+ * @param {boolean} [context.inTable] - Whether the node is inside a table
+ * @returns {string} The PDF structure type (e.g. 'P', 'H1', 'Figure', 'Artifact')
+ */
+function getAccessibilityRole(node, context) {
+	if (!node) {
+		return 'Artifact';
+	}
+
+	// Explicit accessibilityTag takes precedence
+	if (node.accessibilityTag) {
+		return node.accessibilityTag;
+	}
+
+	// Headings via headlineLevel
+	if (node.headlineLevel && node.headlineLevel >= 1 && node.headlineLevel <= 6) {
+		return 'H' + node.headlineLevel;
+	}
+
+	// Images and SVGs - Figure if alt/actualText present, otherwise Artifact
+	if (node.image || node.svg) {
+		if (node.alt || node.actualText) {
+			return 'Figure';
+		}
+		return 'Artifact';
+	}
+
+	// Canvas / vectors are always artifacts
+	if (node.canvas) {
+		return 'Artifact';
+	}
+
+	// Tables - only tagged if explicitly marked
+	if (node.table) {
+		if (node.accessibilityTag === 'Table' || node.accessibilityTag === 'TOC') {
+			return node.accessibilityTag;
+		}
+		return null; // no structural tagging for unmarked tables
+	}
+
+	// Text nodes default to P (paragraph)
+	if (node.text !== undefined) {
+		return 'P';
+	}
+
+	return null;
+}
+
+/**
+ * Returns options for pdfKitDoc.struct() based on node properties.
+ */
+function getStructureOptions(node) {
+	var options = {};
+
+	if (node.alt) {
+		options.alt = node.alt;
+	}
+	if (node.actualText) {
+		options.actual = node.actualText;
+	}
+
+	return options;
+}
+
+/**
+ * Checks if a table node should be structurally tagged.
+ */
+function shouldTagTable(node) {
+	return node && (node.accessibilityTag === 'Table' || node.accessibilityTag === 'TOC');
+}
+
+/**
+ * Checks if a table node is a Table of Contents.
+ */
+function isTOC(node) {
+	return node && node.accessibilityTag === 'TOC';
+}
+
+module.exports = {
+	getAccessibilityRole: getAccessibilityRole,
+	getStructureOptions: getStructureOptions,
+	shouldTagTable: shouldTagTable,
+	isTOC: isTOC
+};