From 2cefc5f71a79fa31e509423f46036d943c0ae77e Mon Sep 17 00:00:00 2001
From: Robert Osfield <robert@openscenegraph.com>
Date: Thu, 14 May 2009 15:45:54 +0000
Subject: [PATCH] From Ulrich Hertlein, "please find attached a patch for
 TrackballManipulator to fix zooming using the MBP touchpad.  The old code
 would always zoom-in even when using the gesture to zoom-out.

Also attached are some code and documentation cleanups for GUIEventAdapter that collect related values (e.g. scrolling, tablet pen) in a struct.
"
---
 src/osgGA/TrackballManipulator.cpp | 23 ++++++++++++++++++++++-
 1 file changed, 22 insertions(+), 1 deletion(-)

diff --git a/src/osgGA/TrackballManipulator.cpp b/src/osgGA/TrackballManipulator.cpp
index 8ca46ad00..566481bc6 100644
--- a/src/osgGA/TrackballManipulator.cpp
+++ b/src/osgGA/TrackballManipulator.cpp
@@ -256,7 +256,28 @@ bool TrackballManipulator::calcMovement()
 
     if (_ga_t0->getEventType()==GUIEventAdapter::SCROLL)
     {
-        dy = _ga_t0->getScrollingMotion() == osgGA::GUIEventAdapter::SCROLL_UP ? _zoomDelta : -_zoomDelta;
+        switch (_ga_t0->getScrollingMotion()) {
+        case osgGA::GUIEventAdapter::SCROLL_UP:
+            dy = _zoomDelta;
+            break;
+        case osgGA::GUIEventAdapter::SCROLL_DOWN:
+            dy = -_zoomDelta;
+            break;
+        case osgGA::GUIEventAdapter::SCROLL_LEFT:
+        case osgGA::GUIEventAdapter::SCROLL_RIGHT:
+            // pass
+            break;
+        case osgGA::GUIEventAdapter::SCROLL_2D:
+            // normalize scrolling delta
+            dx = _ga_t0->getScrollingDeltaX() / ((_ga_t0->getXmax()-_ga_t0->getXmin()) * 0.5f);
+            dy = _ga_t0->getScrollingDeltaY() / ((_ga_t0->getYmax()-_ga_t0->getYmin()) * 0.5f);
+
+            dx *= _zoomDelta;
+            dy *= _zoomDelta;
+            break;
+        default:
+            break;
+        }
         buttonMask=GUIEventAdapter::SCROLL;
     } 
     else