From f11bf04aaa4bb3d358f9662a44ad43c6638c97a3 Mon Sep 17 00:00:00 2001
From: Boris Sergeev <bs@4xxi.com>
Date: Thu, 21 Apr 2016 19:38:00 +0300
Subject: [PATCH 1/2] Add option for custom autoscrolling function

---
 Sortable.js | 20 ++++++++++++++++----
 1 file changed, 16 insertions(+), 4 deletions(-)

diff --git a/Sortable.js b/Sortable.js
index 24664b7..d8445c5 100644
--- a/Sortable.js
+++ b/Sortable.js
@@ -39,6 +39,7 @@
 
 		scrollEl,
 		scrollParentEl,
+		scrollCustomFn,
 
 		lastEl,
 		lastCSS,
@@ -99,13 +100,17 @@
 					winHeight = window.innerHeight,
 
 					vx,
-					vy
+					vy,
+
+					scrollOffsetX,
+					scrollOffsetY
 				;
 
 				// Delect scrollEl
 				if (scrollParentEl !== rootEl) {
 					scrollEl = options.scroll;
 					scrollParentEl = rootEl;
+					scrollCustomFn = options.scrollFn;
 
 					if (scrollEl === true) {
 						scrollEl = rootEl;
@@ -147,11 +152,18 @@
 
 					if (el) {
 						autoScroll.pid = setInterval(function () {
+							scrollOffsetY = vy ? vy * speed : 0;
+							scrollOffsetX = vx ? vx * speed : 0;
+
+							if ('function' === typeof(scrollCustomFn)) {
+								return scrollCustomFn.call(_this, scrollOffsetX, scrollOffsetY, evt);
+							}
+
 							if (el === win) {
-								win.scrollTo(win.pageXOffset + vx * speed, win.pageYOffset + vy * speed);
+								win.scrollTo(win.pageXOffset + scrollOffsetX, win.pageYOffset + scrollOffsetY);
 							} else {
-								vy && (el.scrollTop += vy * speed);
-								vx && (el.scrollLeft += vx * speed);
+								el.scrollTop += scrollOffsetY;
+								el.scrollLeft += scrollOffsetX;
 							}
 						}, 24);
 					}

From b11772918e624c5b70b56fa29d5a7f96b74fff9d Mon Sep 17 00:00:00 2001
From: Boris Sergeev <bs@4xxi.com>
Date: Thu, 21 Apr 2016 19:39:34 +0300
Subject: [PATCH 2/2] Update README.md: info about custom autoscrolling
 function

---
 README.md | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/README.md b/README.md
index 02faa6e..d038483 100644
--- a/README.md
+++ b/README.md
@@ -74,6 +74,7 @@ var sortable = new Sortable(el, {
 	fallbackTolerance: 0 // Specify in pixels how far the mouse should move before it's considered as a drag.        
 	
 	scroll: true, // or HTMLElement
+	scrollFn: function(offsetX, offsetY, originalEvent) { ... }, // if you have custom scrollbar scrollFn may be used for autoscrolling
 	scrollSensitivity: 30, // px, how near the mouse must be to an edge to start scrolling.
 	scrollSpeed: 10, // px
 	
@@ -336,6 +337,14 @@ Demo:
 ---
 
 
+#### `scrollFn` option
+Defines function that will be used for autoscrolling. el.scrollTop/el.scrollLeft is used by default.
+Useful when you have custom scrollbar with dedicated scroll function.
+
+
+---
+
+
 #### `scrollSensitivity` option
 Defines how near the mouse must be to an edge to start scrolling.