From 9273350c6b7c7bff4b6c748eb84f226240285dda Mon Sep 17 00:00:00 2001
From: Jonas Jenwald <jonas.jenwald@gmail.com>
Date: Thu, 17 Aug 2017 14:12:42 +0200
Subject: [PATCH] Attempt to delay disabling of the attachment view until
 FileAttachment annotations of the *initial* page has been parsed

As discussed in PR 8673, we cannot solve the general issue (since that would require parsing every single page). However, we can mitigate the effect somewhat, by waiting for the FileAttachment annotations of the initially rendered page.
---
 web/pdf_attachment_viewer.js |  4 ++--
 web/pdf_sidebar.js           | 30 ++++++++++++++++++++++--------
 2 files changed, 24 insertions(+), 10 deletions(-)

diff --git a/web/pdf_attachment_viewer.js b/web/pdf_attachment_viewer.js
index 8223cbd4a..27d1b4eab 100644
--- a/web/pdf_attachment_viewer.js
+++ b/web/pdf_attachment_viewer.js
@@ -62,12 +62,12 @@ class PDFAttachmentViewer {
    * @private
    */
   _dispatchEvent(attachmentsCount) {
+    this._renderedCapability.resolve();
+
     this.eventBus.dispatch('attachmentsloaded', {
       source: this,
       attachmentsCount,
     });
-
-    this._renderedCapability.resolve();
   }
 
   /**
diff --git a/web/pdf_sidebar.js b/web/pdf_sidebar.js
index f3a7a26f6..caabedd57 100644
--- a/web/pdf_sidebar.js
+++ b/web/pdf_sidebar.js
@@ -420,17 +420,31 @@ class PDFSidebar {
     });
 
     this.eventBus.on('attachmentsloaded', (evt) => {
-      let attachmentsCount = evt.attachmentsCount;
+      if (evt.attachmentsCount) {
+        this.attachmentsButton.disabled = false;
 
-      this.attachmentsButton.disabled = !attachmentsCount;
-
-      if (attachmentsCount) {
         this._showUINotification(SidebarView.ATTACHMENTS);
-      } else if (this.active === SidebarView.ATTACHMENTS) {
-        // If the attachment view was opened during document load, switch away
-        // from it if it turns out that the document has no attachments.
-        this.switchView(SidebarView.THUMBS);
+        return;
       }
+
+      // Attempt to avoid temporarily disabling, and switching away from, the
+      // attachment view for documents that do not contain proper attachments
+      // but *only* FileAttachment annotations. Hence we defer those operations
+      // slightly to allow time for parsing any FileAttachment annotations that
+      // may be present on the *initially* rendered page of the document.
+      Promise.resolve().then(() => {
+        if (this.attachmentsView.hasChildNodes()) {
+          // FileAttachment annotations were appended to the attachment view.
+          return;
+        }
+        this.attachmentsButton.disabled = true;
+
+        if (this.active === SidebarView.ATTACHMENTS) {
+          // If the attachment view was opened during document load, switch away
+          // from it if it turns out that the document has no attachments.
+          this.switchView(SidebarView.THUMBS);
+        }
+      });
     });
 
     // Update the thumbnailViewer, if visible, when exiting presentation mode.