From c5b0b5c754b1b925b1e3b6cff52823e1364c1f5d Mon Sep 17 00:00:00 2001
From: Jonas Jenwald <jonas.jenwald@gmail.com>
Date: Tue, 24 Mar 2020 12:58:34 +0100
Subject: [PATCH 1/2] Ensure that automatic printing still works when the
 viewer and/or its pages are hidden (bug 1618621, bug 1618955)

Please note that this patch, on its own, won't magically fix all of these printing bugs without [bug 1618553](https://bugzilla.mozilla.org/show_bug.cgi?id=1618553) also being fixed.
(However I don't foresee that being too difficult, famous last words :-), but it will as suggested require a platform API that we can notify when the viewer is ready.)

Fixes https://bugzilla.mozilla.org/show_bug.cgi?id=1618621
Fixes https://bugzilla.mozilla.org/show_bug.cgi?id=1618955
Fixes 8208
---
 web/base_viewer.js | 23 ++++++++++++++++++++++-
 web/ui_utils.js    |  2 +-
 2 files changed, 23 insertions(+), 2 deletions(-)

diff --git a/web/base_viewer.js b/web/base_viewer.js
index 4b2fbe734..3b07953b2 100644
--- a/web/base_viewer.js
+++ b/web/base_viewer.js
@@ -396,6 +396,27 @@ class BaseViewer {
     throw new Error("Not implemented: _setDocumentViewerElement");
   }
 
+  /**
+   * @private
+   */
+  _onePageRenderedOrForceFetch() {
+    // Unless the viewer *and* its pages are visible, rendering won't start and
+    // `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 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 (
+      !this.container.offsetParent ||
+      this._getVisiblePages().views.length === 0
+    ) {
+      return Promise.resolve();
+    }
+    return this._onePageRenderedCapability.promise;
+  }
+
   /**
    * @param pdfDocument {PDFDocument}
    */
@@ -492,7 +513,7 @@ class BaseViewer {
         // Fetch all the pages since the viewport is needed before printing
         // starts to create the correct size canvas. Wait until one page is
         // rendered so we don't tie up too many resources early on.
-        this._onePageRenderedCapability.promise.then(() => {
+        this._onePageRenderedOrForceFetch().then(() => {
           if (this.findController) {
             this.findController.setDocument(pdfDocument); // Enable searching.
           }
diff --git a/web/ui_utils.js b/web/ui_utils.js
index e456beda3..1ef9c45ef 100644
--- a/web/ui_utils.js
+++ b/web/ui_utils.js
@@ -229,7 +229,7 @@ function binarySearchFirstItem(items, condition) {
   let minIndex = 0;
   let maxIndex = items.length - 1;
 
-  if (items.length === 0 || !condition(items[maxIndex])) {
+  if (maxIndex < 0 || !condition(items[maxIndex])) {
     return items.length;
   }
   if (condition(items[minIndex])) {

From a24ad28d751f82ed1d3777d1a336a3b76c915d15 Mon Sep 17 00:00:00 2001
From: Jonas Jenwald <jonas.jenwald@gmail.com>
Date: Tue, 24 Mar 2020 14:12:10 +0100
Subject: [PATCH 2/2] Rename `BaseViewer._setDocumentViewerElement` to
 `BaseViewer._viewerElement`

It was pointed out the the old name felt confusing, so let's just rename the getter since it's an internal property anyway.
---
 web/base_viewer.js            | 6 +++---
 web/pdf_single_page_viewer.js | 4 ++--
 web/pdf_viewer.js             | 4 ++--
 3 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/web/base_viewer.js b/web/base_viewer.js
index 3b07953b2..f57cafe66 100644
--- a/web/base_viewer.js
+++ b/web/base_viewer.js
@@ -391,9 +391,9 @@ class BaseViewer {
   /**
    * @private
    */
-  get _setDocumentViewerElement() {
+  get _viewerElement() {
     // In most viewers, e.g. `PDFViewer`, this should return `this.viewer`.
-    throw new Error("Not implemented: _setDocumentViewerElement");
+    throw new Error("Not implemented: _viewerElement");
   }
 
   /**
@@ -479,7 +479,7 @@ class BaseViewer {
 
         for (let pageNum = 1; pageNum <= pagesCount; ++pageNum) {
           const pageView = new PDFPageView({
-            container: this._setDocumentViewerElement,
+            container: this._viewerElement,
             eventBus: this.eventBus,
             id: pageNum,
             scale,
diff --git a/web/pdf_single_page_viewer.js b/web/pdf_single_page_viewer.js
index 3db66f3b1..1e835897d 100644
--- a/web/pdf_single_page_viewer.js
+++ b/web/pdf_single_page_viewer.js
@@ -27,12 +27,12 @@ class PDFSinglePageViewer extends BaseViewer {
     });
   }
 
-  get _setDocumentViewerElement() {
+  get _viewerElement() {
     // Since we only want to display *one* page at a time when using the
     // `PDFSinglePageViewer`, we cannot append them to the `viewer` DOM element.
     // Instead, they are placed in a `DocumentFragment`, and only the current
     // page is displayed in the viewer (refer to `this._ensurePageViewVisible`).
-    return shadow(this, "_setDocumentViewerElement", this._shadowViewer);
+    return shadow(this, "_viewerElement", this._shadowViewer);
   }
 
   _resetView() {
diff --git a/web/pdf_viewer.js b/web/pdf_viewer.js
index fcf0e1ac5..e7965f37b 100644
--- a/web/pdf_viewer.js
+++ b/web/pdf_viewer.js
@@ -17,8 +17,8 @@ import { BaseViewer } from "./base_viewer.js";
 import { shadow } from "pdfjs-lib";
 
 class PDFViewer extends BaseViewer {
-  get _setDocumentViewerElement() {
-    return shadow(this, "_setDocumentViewerElement", this.viewer);
+  get _viewerElement() {
+    return shadow(this, "_viewerElement", this.viewer);
   }
 
   _scrollIntoView({ pageDiv, pageSpot = null, pageNumber = null }) {