From d9743e462dd27d3f01674449e5ccec0eab2afd59 Mon Sep 17 00:00:00 2001
From: Jonas Jenwald <jonas.jenwald@gmail.com>
Date: Thu, 29 Nov 2018 11:31:49 +0100
Subject: [PATCH 1/2] Replace the `OVERRIDES` list in
 `PDFViewerApplication._readPreferences` with a `disablePreferences`, in
 `GENERIC` builds, `AppOption instead

Rather than having a (somewhat) randomly choosen list of Preferences which `AppOptions` are allowed to override, it makes much more sense to simply add an AppOption to allow custom implementations to ignore Preferences altogether (it's also inline with the AppOption that allows the `ViewHistory` to be bypassed on load).
---
 web/app.js         | 19 ++++++-------------
 web/app_options.js |  8 ++++++++
 2 files changed, 14 insertions(+), 13 deletions(-)

diff --git a/web/app.js b/web/app.js
index e9ba568b6..5358e5810 100644
--- a/web/app.js
+++ b/web/app.js
@@ -169,21 +169,14 @@ let PDFViewerApplication = {
    * @private
    */
   async _readPreferences() {
-    // A subset of the Preferences that `AppOptions`, for compatibility reasons,
-    // is allowed to override if the `AppOptions` values matches the ones below.
-    const OVERRIDES = {
-      disableFontFace: true,
-      disableRange: true,
-      disableStream: true,
-      textLayerMode: TextLayerMode.DISABLE,
-    };
-
+    if (AppOptions.get('disablePreferences') === true) {
+      // Give custom implementations of the default viewer a simpler way to
+      // opt-out of having the `Preferences` override existing `AppOptions`.
+      return;
+    }
     try {
       const prefs = await this.preferences.getAll();
-      for (let name in prefs) {
-        if ((name in OVERRIDES) && AppOptions.get(name) === OVERRIDES[name]) {
-          continue;
-        }
+      for (const name in prefs) {
         AppOptions.set(name, prefs[name]);
       }
     } catch (reason) { }
diff --git a/web/app_options.js b/web/app_options.js
index 08fb28848..220b28455 100644
--- a/web/app_options.js
+++ b/web/app_options.js
@@ -58,6 +58,9 @@ const defaultOptions = {
     value: false,
     kind: OptionKind.VIEWER,
   },
+  /**
+   * The `disablePreferences` is, conditionally, defined below.
+   */
   enablePrintAutoRotate: {
     /** @type {boolean} */
     value: false,
@@ -218,6 +221,11 @@ const defaultOptions = {
 };
 if (typeof PDFJSDev === 'undefined' ||
     PDFJSDev.test('!PRODUCTION || GENERIC')) {
+  defaultOptions.disablePreferences = {
+    /** @type {boolean} */
+    value: false,
+    kind: OptionKind.VIEWER,
+  };
   defaultOptions.locale = {
     /** @type {string} */
     value: (typeof navigator !== 'undefined' ? navigator.language : 'en-US'),

From 0dc995c7e0c3368929e01ae8555b3f04795a8e0a Mon Sep 17 00:00:00 2001
From: Jonas Jenwald <jonas.jenwald@gmail.com>
Date: Thu, 29 Nov 2018 11:32:48 +0100
Subject: [PATCH 2/2] In `GENERIC` builds, dispatch a "webviewerloaded" event
 (from the `webViewerLoad` function) before initializing the viewer

With the removal of the global `PDFJS` object, in PDF.js version `2.0`, the viewer options are no longer as easily accessible as they previously were (and issues have been filed about this).
In particular, since the viewer files aren't necessarily loaded *immediately*, this means that `PDFViewerApplication`/`PDFViewerApplicationOptions` aren't necessarily available directly. By dispatching an event once all viewer files are loaded but *before* the viewer initialization has run, setting `AppOptions` during load (in custom implementations of the default viewer) should hopefully become a little bit easier[1].

---
[1] In hindsight, this should probably have been implemented when the global `PDFJS` object was removed...
---
 web/viewer.js | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/web/viewer.js b/web/viewer.js
index 8885162b2..2254731fc 100644
--- a/web/viewer.js
+++ b/web/viewer.js
@@ -203,6 +203,16 @@ function webViewerLoad() {
 
     window.PDFViewerApplication = pdfjsWebApp.PDFViewerApplication;
     window.PDFViewerApplicationOptions = pdfjsWebAppOptions.AppOptions;
+
+    if (typeof PDFJSDev !== 'undefined' && PDFJSDev.test('GENERIC')) {
+      // Give custom implementations of the default viewer a simpler way to
+      // set various `AppOptions`, by dispatching an event once all viewer
+      // files are loaded but *before* the viewer initialization has run.
+      const event = document.createEvent('CustomEvent');
+      event.initCustomEvent('webviewerloaded', true, true, {});
+      document.dispatchEvent(event);
+    }
+
     pdfjsWebApp.PDFViewerApplication.run(config);
   }
 }