[api-minor] Fix various issues related to the pageSize information

The `getPageSizeInches` method was implemented on `PDFDocumentProxy`, which seems conceptually wrong since the size property isn't global to the document but rather specific to each page. Hence the method is moved into `PDFPageProxy`, as `get pageSizeInches` instead to address this.

Despite the fact that new API functionality was implemented, no unit-tests were added. To prevent issues later on, we should *always* ensure that new functionality has at least some test-coverage; something that this patch also takes care of.

The new `PDFDocumentProperties._parsePageSize` method seemed unnecessary convoluted. Furthermore, in the "no data provided"-case it even returned incorrect data (an array, rather than the expected object).
Finally, the fallback strings didn't actually agree with the `en-US` locale. This inconsistency doesn't look too great, and it's thus addressed here as well.

src/display/api.js

@@ -692,23 +692,6 @@ var PDFDocumentProxy = (function PDFDocumentProxyClosure() {
     getMetadata: function PDFDocumentProxy_getMetadata() {
       return this.transport.getMetadata();
     },
-    /**
-     * @param {number} pageNumber The page number to get the page size from.
-     * The first page is 1, which is also the default page used.
-     * @return {Promise} A promise that is resolved with an dict containing the
-     * width and height in inches.
-     */
-    getPageSizeInches(pageNumber) {
-      pageNumber = pageNumber || 1;
-      return this.getPage(pageNumber).then((page) => {
-        const [x1, y1, x2, y2] = page.view;
-        // convert values from user units to inches
-        return {
-          width: (x2 - x1) / 72 * page.userUnit,
-          height: (y2 - y1) / 72 * page.userUnit,
-        };
-      });
-    },
     /**
      * @return {Promise} A promise that is resolved with a TypedArray that has
      * the raw data from the PDF.
@@ -890,6 +873,20 @@ var PDFPageProxy = (function PDFPageProxyClosure() {
     get view() {
       return this.pageInfo.view;
     },
+
+    /**
+     * The size of the current page, converted from PDF units to inches.
+     * @return {Object} An Object containing the properties: {number} `width`
+     *   and {number} `height`, given in inches.
+     */
+    get pageSizeInches() {
+      const [x1, y1, x2, y2] = this.view, userUnit = this.userUnit;
+      return {
+        width: (x2 - x1) / 72 * userUnit,
+        height: (y2 - y1) / 72 * userUnit,
+      };
+    },
+
     /**
      * @param {number} scale The desired scale of the viewport.
      * @param {number} rotate Degrees to rotate the viewport. If omitted this

test/unit/api_spec.js

@@ -964,6 +964,14 @@ describe('api', function() {
     it('gets view', function () {
       expect(page.view).toEqual([0, 0, 595.28, 841.89]);
     });
+
+    it('gets page size (in inches)', function() {
+      const { width, height, } = page.pageSizeInches;
+
+      expect(+width.toPrecision(3)).toEqual(8.27);
+      expect(+height.toPrecision(4)).toEqual(11.69);
+    });
+
     it('gets viewport', function () {
       var viewport = page.getViewport(1.5, 90);
       expect(viewport.viewBox).toEqual(page.view);

web/pdf_document_properties.js

@@ -80,13 +80,12 @@ class PDFDocumentProperties {
           this._parseFileSize(this.maybeFileSize),
           this._parseDate(info.CreationDate),
           this._parseDate(info.ModDate),
-          this.pdfDocument.getPageSizeInches().then((pageSizeInches) => {
-            return this._parsePageSize(pageSizeInches);
+          this.pdfDocument.getPage(1).then((pdfPage) => {
+            return this._parsePageSize(pdfPage.pageSizeInches);
           }),
-
         ]);
-      }).then(([info, metadata, fileName, fileSize,
-                creationDate, modDate, pageSize]) => {
+      }).then(([info, metadata, fileName, fileSize, creationDate, modDate,
+                pageSizes]) => {
         freezeFieldData({
           'fileName': fileName,
           'fileSize': fileSize,
@@ -100,8 +99,8 @@ class PDFDocumentProperties {
           'producer': info.Producer,
           'version': info.PDFFormatVersion,
           'pageCount': this.pdfDocument.numPages,
-          'pageSizeInch': pageSize.inch,
-          'pageSizeMM': pageSize.mm,
+          'pageSizeInch': pageSizes.inch,
+          'pageSizeMM': pageSizes.mm,
         });
         this._updateUI();
 
@@ -224,25 +223,25 @@ class PDFDocumentProperties {
    */
   _parsePageSize(pageSizeInches) {
     if (!pageSizeInches) {
-      return Promise.resolve([undefined, undefined]);
+      return Promise.resolve({ inch: undefined, mm: undefined, });
     }
-    const sizes_two_units = {
-      'width_in': Math.round(pageSizeInches.width * 100) / 100,
-      'height_in': Math.round(pageSizeInches.height * 100) / 100,
-      // 1in = 25.4mm; no need to round to 2 decimals for mm
-      'width_mm': Math.round(pageSizeInches.width * 25.4 * 10) / 10,
-      'height_mm': Math.round(pageSizeInches.height * 25.4 * 10) / 10,
-    };
+    const { width, height, } = pageSizeInches;
+
     return Promise.all([
-      this.l10n.get('document_properties_page_size_in',
-        sizes_two_units, '{{width_in}} in × {{height_in}} in'),
-      this.l10n.get('document_properties_page_size_mm',
-        sizes_two_units, '{{width_mm}} mm × {{height_mm}} mm'),
-    ]).then(([parsedPageSizeInches, parsedPageSizeMM]) => {
-      return Promise.resolve({
-        inch: parsedPageSizeInches,
-        mm: parsedPageSizeMM,
-      });
+      this.l10n.get('document_properties_page_size_in', {
+          width_in: Math.round(width * 100) / 100,
+          height_in: Math.round(height * 100) / 100,
+        }, '{{width_in}}in × {{height_in}}in'),
+      // 1in = 25.4mm; no need to round to 2 decimals for millimeters.
+      this.l10n.get('document_properties_page_size_mm', {
+          width_mm: Math.round(width * 25.4 * 10) / 10,
+          height_mm: Math.round(height * 25.4 * 10) / 10,
+        }, '{{width_mm}}mm × {{height_mm}}mm'),
+    ]).then((sizes) => {
+      return {
+        inch: sizes[0],
+        mm: sizes[1],
+      };
     });
   }