From bb309fb72e05b2ae8bd594bb6ac7074facaa7519 Mon Sep 17 00:00:00 2001
From: David Capello <davidcapello@gmail.com>
Date: Mon, 25 Aug 2014 23:30:27 -0300
Subject: [PATCH] Improve Editor::autoScroll() scroll

Avoid a bad user experience when he/she tries to put back the mouse
position into the editor viewport.
---
 src/app/ui/editor/editor.cpp | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/src/app/ui/editor/editor.cpp b/src/app/ui/editor/editor.cpp
index 5e78b579b..f6a6cf630 100644
--- a/src/app/ui/editor/editor.cpp
+++ b/src/app/ui/editor/editor.cpp
@@ -712,8 +712,18 @@ gfx::Point Editor::autoScroll(MouseMessage* msg)
   gfx::Point mousePos = msg->position();
 
   if (!vp.contains(mousePos)) {
+    gfx::Point delta = (mousePos - m_oldPos);
+
+    if (!((mousePos.x <  vp.x      && delta.x < 0) ||
+          (mousePos.x >= vp.x+vp.w && delta.x > 0)))
+      delta.x = 0;
+
+    if (!((mousePos.y <  vp.y      && delta.y < 0) ||
+          (mousePos.y >= vp.y+vp.h && delta.y > 0)))
+      delta.y = 0;
+
     gfx::Point scroll = view->getViewScroll();
-    scroll += (mousePos - m_oldPos);
+    scroll += delta;
     setEditorScroll(scroll.x, scroll.y, true);
 
     m_oldPos = mousePos;