From ed22684ef239e227693bbf9ab05904a38bf53262 Mon Sep 17 00:00:00 2001
From: Matthias BUSSONNIER <bussonniermatthias@gmail.com>
Date: Tue, 28 May 2013 18:17:12 +0200
Subject: [PATCH] Use different threshold for (auto)scroll in output

Allow, in particular to switch to scolling for longer input (or disable
it) by still keeping the possibility to manually toggle the output to
scroll.
---
 .../notebook/static/notebook/js/notebook.js   |  2 +-
 .../notebook/static/notebook/js/outputarea.js | 77 +++++++++++++++++--
 2 files changed, 71 insertions(+), 8 deletions(-)

diff --git a/IPython/frontend/html/notebook/static/notebook/js/notebook.js b/IPython/frontend/html/notebook/static/notebook/js/notebook.js
index fb6cdf8ea..80ac53622 100644
--- a/IPython/frontend/html/notebook/static/notebook/js/notebook.js
+++ b/IPython/frontend/html/notebook/static/notebook/js/notebook.js
@@ -1242,7 +1242,7 @@ var IPython = (function (IPython) {
         for (var i=0; i<ncells; i++) {
             if (cells[i] instanceof IPython.CodeCell) {
                 cells[i].output_area.expand();
-                cells[i].output_area.scroll_if_long(20);
+                cells[i].output_area.scroll_if_long();
             }
         };
         // this should not be set if the `collapse` key is removed from nbformat
diff --git a/IPython/frontend/html/notebook/static/notebook/js/outputarea.js b/IPython/frontend/html/notebook/static/notebook/js/outputarea.js
index a57ef56ea..2e780dee0 100644
--- a/IPython/frontend/html/notebook/static/notebook/js/outputarea.js
+++ b/IPython/frontend/html/notebook/static/notebook/js/outputarea.js
@@ -1,5 +1,5 @@
 //----------------------------------------------------------------------------
-//  Copyright (C) 2008-2011  The IPython Development Team
+//  Copyright (C) 2008 The IPython Development Team
 //
 //  Distributed under the terms of the BSD License.  The full license is in
 //  the file COPYING, distributed as part of this software.
@@ -9,11 +9,22 @@
 // OutputArea
 //============================================================================
 
+/**
+ * @module IPython
+ * @namespace IPython
+ * @submodule OutputArea
+ */
 var IPython = (function (IPython) {
     "use strict";
 
     var utils = IPython.utils;
 
+    /**
+     * @class OutputArea
+     *
+     * @constructor
+     */
+
     var OutputArea = function (selector, prompt_area) {
         this.selector = selector;
         this.wrapper = $(selector);
@@ -59,8 +70,18 @@ var IPython = (function (IPython) {
         this.collapse();
     };
 
-
+    /**
+     * Should the OutputArea scroll?
+     * Returns whether the height (in lines) exceeds a threshold.
+     *
+     * @private
+     * @method _should_scroll
+     * @param [lines=100]{Integer}
+     * @return {Bool}
+     *
+     */
     OutputArea.prototype._should_scroll = function (lines) {
+        if (lines <=0 ){ return }
         if (!lines) {
             lines = 100;
         }
@@ -84,7 +105,7 @@ var IPython = (function (IPython) {
             }
             // maybe scroll output,
             // if it's grown large enough and hasn't already been scrolled.
-            if ( !that.scrolled && that._should_scroll()) {
+            if ( !that.scrolled && that._should_scroll(OutputArea.auto_scroll_threshold)) {
                 that.scroll_area();
             }
         });
@@ -143,9 +164,51 @@ var IPython = (function (IPython) {
         this.scrolled = false;
     };
 
-
+    /**
+     * Threshold to trigger autoscroll when the OutputArea is resized,
+     * typically when new outputs are added.
+     *
+     * Behavior is undefined if autoscroll is lower than scroll_threshold,
+     * unless it is < 0 then autoscroll will never be triggerd
+     *
+     * @property auto_scroll_threshold
+     * @type Number
+     * @default 20
+     *
+     **/
+    OutputArea.auto_scroll_threshold = 20;
+
+
+    /**
+     * Defautl value for minimal length for output are to be able to switch to
+     * scroll mode
+     *
+     * @property scroll_threshold
+     * @type Number
+     * @default 20
+     *
+     **/
+    OutputArea.scroll_threshold = 20;
+
+
+    /**
+     * Scroll OutputArea if height supperior than a threshold.
+     *
+     * Treshold is exprimed as a number of lines, fallback to a (configurable) default.
+     *
+     * Negative or null (0) threshold will prevent the OutputArea ever to scroll.
+     *
+     * @method scroll_if_long
+     * @param [lines=20,configurable]{Number}
+     *
+     **/
     OutputArea.prototype.scroll_if_long = function (lines) {
-        if (this._should_scroll(lines)) {
+        var n = lines | OutputArea.scroll_threshold;
+        if(n <= 0){
+            return
+        }
+
+        if (this._should_scroll(n)) {
             // only allow scrolling long-enough output
             this.scroll_area();
         }
@@ -157,7 +220,7 @@ var IPython = (function (IPython) {
             this.unscroll_area();
         } else {
             // only allow scrolling long-enough output
-            this.scroll_if_long(20);
+            this.scroll_if_long();
         }
     };
 
@@ -466,7 +529,7 @@ var IPython = (function (IPython) {
         toinsert.append(latex);
         element.append(toinsert);
     };
-    
+
     OutputArea.prototype.append_raw_input = function (content) {
         var that = this;
         this.expand();