From 472bbf45922b7509541e25589cbfcfa8c4a92b12 Mon Sep 17 00:00:00 2001
From: Jonas Jenwald <jonas.jenwald@gmail.com>
Date: Sat, 18 Dec 2021 19:04:38 +0100
Subject: [PATCH] Unblock the "load" event in inactive windows/tabs (bug
 1746213, PR 11646 follow-up)

Given that `requestAnimationFrame` is being used, see the `src/diplay/api.js` file, an inactive window/tab means that rendering will not run and we'll thus not fetch all pages. The latter is a requirement for the "load" event to be unblocked, in the MOZCENTRAL-version of, the default viewer.

This patch is a *partial* solution, since it only addresses the following situations:
 - A *background*  tab (containing the viewer) is reloaded, e.g. via the tab-bar context menu.
 - The viewer is loaded in a active tab, but the user switches away from it (or switches to another program window) *before* rendering has started.
---
 web/base_viewer.js | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/web/base_viewer.js b/web/base_viewer.js
index 993c869c7..1f26fe2fd 100644
--- a/web/base_viewer.js
+++ b/web/base_viewer.js
@@ -533,11 +533,14 @@ class BaseViewer {
     // `this._onePageRenderedCapability` thus won't be resolved.
     // To ensure that automatic printing, on document load, still works even in
     // those cases we force-allow fetching of all pages when:
+    //  - The current window/tab is inactive, which will prevent rendering since
+    //    `requestAnimationFrame` is being used; fixes bug 1746213.
     //  - The viewer is hidden in the DOM, e.g. in a `display: none` <iframe>
     //    element; fixes bug 1618621.
     //  - The viewer is visible, but none of the pages are (e.g. if the
     //    viewer is very small); fixes bug 1618955.
     if (
+      document.visibilityState === "hidden" ||
       !this.container.offsetParent ||
       this._getVisiblePages().views.length === 0
     ) {