From 9a5ecae2a379e6186ecf2a9db1ae91b44094887b Mon Sep 17 00:00:00 2001
From: Yury Delendik <ydelendik@mozilla.com>
Date: Fri, 25 Jan 2013 13:58:49 -0600
Subject: [PATCH] Wait for animation frame before displaying stuff

---
 web/viewer.js | 24 +++++++++++++++++++++++-
 1 file changed, 23 insertions(+), 1 deletion(-)

diff --git a/web/viewer.js b/web/viewer.js
index 944ef0f76..57b147101 100644
--- a/web/viewer.js
+++ b/web/viewer.js
@@ -59,7 +59,13 @@ function getFileName(url) {
 }
 
 function scrollIntoView(element, spot) {
+  // Assuming offsetParent is available (it's not available when viewer is in
+  // hidden iframe or object). We have to scroll: if the offsetParent is not set
+  // producing the error. See also animationStartedClosure.
   var parent = element.offsetParent, offsetY = element.offsetTop;
+  if (!parent) {
+    error('offsetParent is not set -- cannot scroll');
+  }
   while (parent.clientHeight == parent.scrollHeight) {
     offsetY += parent.offsetTop;
     parent = parent.offsetParent;
@@ -1286,7 +1292,8 @@ var PDFView = {
     });
 
     // outline and initial view depends on destinations and pagesRefMap
-    var promises = [pagesPromise, destinationsPromise, storePromise];
+    var promises = [pagesPromise, destinationsPromise, storePromise,
+                    PDFView.animationStartedPromise];
     PDFJS.Promise.all(promises).then(function() {
       pdfDocument.getOutline().then(function(outline) {
         self.outline = new DocumentOutlineView(outline);
@@ -3311,6 +3318,21 @@ window.addEventListener('afterprint', function afterPrint(evt) {
   window.addEventListener('webkitfullscreenchange', fullscreenChange, false);
 })();
 
+(function animationStartedClosure() {
+  // The offsetParent is not set until the pdf.js iframe or object is visible.
+  // Waiting for first animation.
+  var requestAnimationFrame = window.requestAnimationFrame ||
+                              window.mozRequestAnimationFrame ||
+                              window.webkitRequestAnimationFrame ||
+                              window.oRequestAnimationFrame ||
+                              window.msRequestAnimationFrame ||
+                              function startAtOnce(callback) { callback(); };
+  PDFView.animationStartedPromise = new PDFJS.Promise();
+  requestAnimationFrame(function onAnimationFrame() {
+    PDFView.animationStartedPromise.resolve();
+  });
+})();
+
 //#if B2G
 //window.navigator.mozSetMessageHandler('activity', function(activity) {
 //  var url = activity.source.data.url;