From 83b25c091bed90accd233ca95bf880689c352348 Mon Sep 17 00:00:00 2001
From: Lu Wang <coolwanglu@gmail.com>
Date: Thu, 2 May 2013 16:45:00 +0800
Subject: [PATCH] pdf2htmlEX.js: reveal prev and next page for a better reading
 experience

---
 share/pdf2htmlEX.js.in | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/share/pdf2htmlEX.js.in b/share/pdf2htmlEX.js.in
index 9069eb1..6c1a432 100644
--- a/share/pdf2htmlEX.js.in
+++ b/share/pdf2htmlEX.js.in
@@ -84,10 +84,19 @@ var pdf2htmlEX = (function(){
       this.p.height(this.b.height() * this.set_r);
       this.p.width(this.b.width() * this.set_r);
     },
+    /* return if any part of this page is shown in the container */
     is_visible : function() {
       var off = this.position();
       return !((off[1] > this.height()) || (off[1] + this.container.height() < 0));
     },
+    /* return if this page or any neighbor of it is visible */
+    is_nearly_visible : function() {
+      var off = this.position();
+      /* I should use the height of the previous page or the next page here
+       * but since they are not easily available, just use '*2', which should be a good estimate in most cases
+       */
+      return !((off[1] > this.height() * 2) || (off[1] + this.container.height() * 2 < 0));
+    },
     /* return the coordinate of the top-left corner of container
      * in our cooridnate system
      */
@@ -199,7 +208,7 @@ var pdf2htmlEX = (function(){
       var pl = this.pages;
       for(var i in pl) {
         var p = pl[i];
-        if(p.is_visible()){
+        if(p.is_nearly_visible()){
           p.show();
         } else {
           p.hide();