Expose the optional UserUnit entry as a page property

src/core/document.js

@@ -138,6 +138,15 @@ var Page = (function PageClosure() {
       return shadow(this, 'mediaBox', obj);
     },
 
+    get userUnit() {
+      var obj = this.getPageProp('UserUnit');
+      // Optional according to the spec with a default value of 1.0.
+      if (typeof obj !== 'number') {
+        obj = 1.0;
+      }
+      return shadow(this, 'userUnit', obj);
+    },
+
     get view() {
       var mediaBox = this.mediaBox;
       var cropBox = this.getInheritedPageProp('CropBox');

src/core/worker.js

@@ -747,14 +747,17 @@ var WorkerMessageHandler = {
       return pdfManager.getPage(data.pageIndex).then(function(page) {
         var rotatePromise = pdfManager.ensure(page, 'rotate');
         var refPromise = pdfManager.ensure(page, 'ref');
+        var userUnitPromise = pdfManager.ensure(page, 'userUnit');
         var viewPromise = pdfManager.ensure(page, 'view');
 
-        return Promise.all([rotatePromise, refPromise, viewPromise]).then(
-            function(results) {
+        return Promise.all([
+          rotatePromise, refPromise, userUnitPromise, viewPromise
+        ]).then(function(results) {
           return {
             rotate: results[0],
             ref: results[1],
-            view: results[2]
+            userUnit: results[2],
+            view: results[3]
           };
         });
       });

src/display/api.js

@@ -747,6 +747,12 @@ var PDFPageProxy = (function PDFPageProxyClosure() {
     get ref() {
       return this.pageInfo.ref;
     },
+    /**
+     * @return {number} The default size of units in 1/72nds of an inch.
+     */
+    get userUnit() {
+      return this.pageInfo.userUnit;
+    },
     /**
      * @return {Array} An array of the visible portion of the PDF page in the
      * user space units - [x1, y1, x2, y2].

test/unit/api_spec.js

@@ -769,6 +769,9 @@ describe('api', function() {
     it('gets ref', function () {
       expect(page.ref).toEqual({ num: 15, gen: 0 });
     });
+    it('gets userUnit', function () {
+      expect(page.userUnit).toEqual(1.0);
+    });
     it('gets view', function () {
       expect(page.view).toEqual([0, 0, 595.28, 841.89]);
     });