Merge pull request #4200 from timvandermeij/ie-mousewheel

Implements mouse wheel behaviour for non-Firefox browsers

web/viewer.js

@@ -2049,19 +2049,22 @@ window.addEventListener('pagechange', function pagechange(evt) {
   document.getElementById('next').disabled = (page >= PDFView.pages.length);
 }, true);
 
-// Firefox specific event, so that we can prevent browser from zooming
+function handleMouseWheel(evt) {
-window.addEventListener('DOMMouseScroll', function(evt) {
+  var MOUSE_WHEEL_DELTA_FACTOR = 40;
-  if (evt.ctrlKey) {
+  var ticks = (evt.type === 'DOMMouseScroll') ? -evt.detail :
-    evt.preventDefault();
+              evt.wheelDelta / MOUSE_WHEEL_DELTA_FACTOR;
+  var direction = (ticks < 0) ? 'zoomOut' : 'zoomIn';
 
-    var ticks = evt.detail;
+  if (evt.ctrlKey) { // Only zoom the pages, not the entire viewer
-    var direction = (ticks > 0) ? 'zoomOut' : 'zoomIn';
+    evt.preventDefault();
     PDFView[direction](Math.abs(ticks));
   } else if (PresentationMode.active) {
-    var FIREFOX_DELTA_FACTOR = -40;
+    PDFView.mouseScroll(ticks * MOUSE_WHEEL_DELTA_FACTOR);
-    PDFView.mouseScroll(evt.detail * FIREFOX_DELTA_FACTOR);
   }
-}, false);
+}
+
+window.addEventListener('DOMMouseScroll', handleMouseWheel);
+window.addEventListener('mousewheel', handleMouseWheel);
 
 window.addEventListener('click', function click(evt) {
   if (!PresentationMode.active) {