From 870d9df77960e05ed853b3779023ff954f66c642 Mon Sep 17 00:00:00 2001
From: Mark Salsbery <>
Date: Tue, 16 Mar 2021 19:47:08 -0700
Subject: [PATCH] Code cleanup, better scrollHandler handling in Viewer

---
 src/mousetracker.js |  1 -
 src/viewer.js       | 10 +++++++---
 2 files changed, 7 insertions(+), 4 deletions(-)

diff --git a/src/mousetracker.js b/src/mousetracker.js
index abd33fdd..f4214a27 100644
--- a/src/mousetracker.js
+++ b/src/mousetracker.js
@@ -2089,7 +2089,6 @@
         if ( eventInfo.stopPropagation ) {
             $.stopEvent( originalEvent );
         }
-        //if ( eventInfo.preventDefault && !eventInfo.defaultPrevented ) {
         if ( ( eventArgs && eventArgs.preventDefault ) || ( eventInfo.preventDefault && !eventInfo.defaultPrevented ) ) {
                 $.cancelEvent( originalEvent );
         }
diff --git a/src/viewer.js b/src/viewer.js
index 4c0465e3..29b2054a 100644
--- a/src/viewer.js
+++ b/src/viewer.js
@@ -3224,7 +3224,8 @@ function onCanvasScroll( event ) {
             scroll: event.scroll,
             shift: event.shift,
             originalEvent: event.originalEvent,
-            preventDefaultAction: false
+            preventDefaultAction: false,
+            preventDefault: true
         };
 
         /**
@@ -3240,6 +3241,7 @@ function onCanvasScroll( event ) {
          * @property {Boolean} shift - True if the shift key was pressed during this event.
          * @property {Object} originalEvent - The original DOM event.
          * @property {Boolean} preventDefaultAction - Set to true to prevent default scroll to zoom behaviour. Default: false.
+         * @property {Boolean} preventDefault - Set to true to prevent the default user-agent's handling of the wheel event. Default: true.
          * @property {?Object} userData - Arbitrary subscriber-defined object.
          */
          this.raiseEvent('canvas-scroll', canvasScrollEventArgs );
@@ -3259,9 +3261,11 @@ function onCanvasScroll( event ) {
                 this.viewport.applyConstraints();
             }
         }
-    }
 
-    event.preventDefault = true;
+        event.preventDefault = canvasScrollEventArgs.preventDefault;
+    } else {
+        event.preventDefault = true;
+    }
 }
 
 function onContainerEnter( event ) {