Chore: track encoding type for documents

src/lib/Preview.js

@@ -1250,7 +1250,7 @@ class Preview extends EventEmitter {
         }
 
         // Log now that loading is finished
-        this.emitLoadMetrics();
+        this.emitLoadMetrics(data);
 
         // Show download and print buttons if user can download
         if (canDownload(this.file, this.options)) {
@@ -1522,9 +1522,10 @@ class Preview extends EventEmitter {
      * A value of 0 means that the load milestone was never reached.
      *
      * @private
+     * @param {string} [encoding] - Type of encoding applied to the downloaded content. ie) GZIP
      * @return {void}
      */
-    emitLoadMetrics() {
+    emitLoadMetrics({ encoding } = {}) {
         if (!this.file || !this.file.id) {
             return;
         }
@@ -1544,6 +1545,7 @@ class Preview extends EventEmitter {
         const total = times.reduce((acc, current) => acc + current);
 
         const event = {
+            encoding,
             event_name: LOAD_METRIC.previewLoadEvent,
             value: total, // Sum of all available load times.
             [LOAD_METRIC.fileInfoTime]: times[0],

src/lib/__tests__/Preview-test.js

@@ -8,7 +8,7 @@ import PreviewError from '../PreviewError';
 import DownloadReachability from '../DownloadReachability';
 import * as file from '../file';
 import * as util from '../util';
-import { API_HOST, CLASS_NAVIGATION_VISIBILITY, PERMISSION_PREVIEW } from '../constants';
+import { API_HOST, CLASS_NAVIGATION_VISIBILITY, PERMISSION_PREVIEW, ENCODING_TYPES } from '../constants';
 import { VIEWER_EVENT, ERROR_CODE, LOAD_METRIC, PREVIEW_METRIC } from '../events';
 import Timer from '../Timer';
 
@@ -2387,6 +2387,14 @@ describe('lib/Preview', () => {
             });
             preview.emitLoadMetrics();
         });
+
+        it('should append encoding field to load metric, when provided', (done) => {
+            preview.once(PREVIEW_METRIC, (metric) => {
+                expect(metric.encoding).to.equal(ENCODING_TYPES.GZIP);
+                done();
+            });
+            preview.emitLoadMetrics({ encoding: ENCODING_TYPES.GZIP });
+        });
     });
 
     describe('getRequestHeaders()', () => {

src/lib/viewers/doc/DocBaseViewer.js

@@ -60,6 +60,9 @@ class DocBaseViewer extends BaseViewer {
     // Public
     //--------------------------------------------------------------------------
 
+    /** @property {string} - Tracks the type of encoding, if applicable, that was requested for the viewable content */
+    encoding;
+
     /**
      * @inheritdoc
      */
@@ -571,6 +574,9 @@ class DocBaseViewer extends BaseViewer {
         // Use chunk size set in viewer options if available
         let rangeChunkSize = this.getViewerOption('rangeChunkSize');
 
+        // If range requests are disabled, request the gzip compressed version of the representation
+        this.encoding = PDFJS.disableRange ? ENCODING_TYPES.GZIP : undefined;
+
         // Otherwise, use large chunk size if locale is en-US and the default,
         // smaller chunk size if not. This is using a rough assumption that
         // en-US users have higher bandwidth to Box.
@@ -583,10 +589,10 @@ class DocBaseViewer extends BaseViewer {
 
         let url = pdfUrl;
 
-        // If range requests are disabled, request the gzip compressed version of the representation
-        if (PDFJS.disableRange) {
+        // Apply encoding request to the content request
+        if (this.encoding) {
             url = appendQueryParams(url, {
-                [QUERY_PARAM_ENCODING]: ENCODING_TYPES.GZIP
+                [QUERY_PARAM_ENCODING]: this.encoding
             });
         }
 
@@ -996,6 +1002,7 @@ class DocBaseViewer extends BaseViewer {
         if (!this.loaded) {
             this.loaded = true;
             this.emit(VIEWER_EVENT.load, {
+                encoding: this.encoding,
                 numPages: pagesCount,
                 endProgress: false, // Indicate that viewer will end progress later
                 scale: currentScale

src/lib/viewers/doc/__tests__/DocBaseViewer-test.js

@@ -1569,9 +1569,11 @@ describe('src/lib/viewers/doc/DocBaseViewer', () => {
             };
             docBase.loaded = false;
             docBase.pdfViewer.pagesCount = 5;
+            docBase.encoding = 'gzip';
 
             docBase.pagesinitHandler();
             expect(stubs.emit).to.be.calledWith(VIEWER_EVENT.load, {
+                encoding: docBase.encoding,
                 endProgress: false,
                 numPages: 5,
                 scale: sinon.match.any