Added 'wheel' Event Support

Also improved OpenSeadragon.addEvent()/OpenSeadragon.removeEvent()

changelog.txt

@@ -5,7 +5,7 @@ OPENSEADRAGON CHANGELOG
 
 * BREAKING CHANGE: All EventSource and MouseTracker event handler method signatures changed to 'handlerMethod(event)' where event == { eventSource, userData, ... } (#251) (Also fixes #23, #224, #239)
     * The new eventSource property in the event object replaces the old eventSource parameter that was passed to handler methods.
-    * Where the event object duplicated the eventSource value, those properties have been removed. This effects the following events:
+    * Where the event object duplicated the eventSource value, those properties have been removed. This affects the following events:
         * All Button events - 'button' property removed
         * All Viewer (Viewer, Drawer, Viewport) events - 'viewer' property removed
 * BREAKING CHANGE: Renamed EventHandler to EventSource (#225)
@@ -34,6 +34,7 @@ OPENSEADRAGON CHANGELOG
     * Viewer: 'canvas-release', 'canvas-click', 'canvas-drag', 'canvas-scroll', 'container-enter', 'container-exit', 'container-release'
     * Button: 'enter', 'exit', 'press', 'release', 'focus', 'blur', 'click'
 * Fixed: IE 10 not reading DZI file correctly in certain circumstances (#218)
+* Added support for the 'wheel' DOM mousewheel event (#261)
 
 0.9.131:
 

src/mousetracker.js

@@ -157,8 +157,9 @@
             mouseup:               function ( event ) { onMouseUp( _this, event, false ); },
             mousemove:             function ( event ) { onMouseMove( _this, event ); },
             click:                 function ( event ) { onMouseClick( _this, event ); },
-            DOMMouseScroll:        function ( event ) { onMouseWheelSpin( _this, event, false ); },
+            wheel:                 function ( event ) { onWheel( _this, event ); },
-            mousewheel:            function ( event ) { onMouseWheelSpin( _this, event, false ); },
+            mousewheel:            function ( event ) { onMouseWheel( _this, event ); },
+            DOMMouseScroll:        function ( event ) { onMouseWheel( _this, event ); },
             mouseupie:             function ( event ) { onMouseUpIE( _this, event ); },
             mousemovecapturedie:   function ( event ) { onMouseMoveCapturedIE( _this, event ); },
             mouseupcaptured:       function ( event ) { onMouseUpCaptured( _this, event ); },
@@ -436,6 +437,13 @@
         blurHandler: function () { }
     };
 
+    /**
+     * Detect available mouse wheel event.
+     */
+    $.MouseTracker.wheelEventName = (($.Browser.vendor == $.BROWSERS.IE && $.Browser.version > 8) || ("onwheel" in document.createElement("div"))) ? "wheel" : // Modern browsers support "wheel"
+                                    document.onmousewheel !== undefined ? "mousewheel" :   // Webkit and IE support at least "mousewheel"
+                                    "DOMMouseScroll";                                      // Assume old Firefox
+
     /**
      * Starts tracking mouse events on this element.
      * @private
@@ -445,7 +453,7 @@
         var events = [
                 "mouseover", "mouseout", "mousedown", "mouseup", "mousemove",
                 "click",
-                "DOMMouseScroll", "mousewheel",
+                $.MouseTracker.wheelEventName,
                 "touchstart", "touchmove", "touchend",
                 "keypress",
                 "focus", "blur"
@@ -478,7 +486,7 @@
         var events = [
                 "mouseover", "mouseout", "mousedown", "mouseup", "mousemove",
                 "click",
-                "DOMMouseScroll", "mousewheel",
+                $.MouseTracker.wheelEventName,
                 "touchstart", "touchmove", "touchend",
                 "keypress",
                 "focus", "blur"
@@ -1071,41 +1079,80 @@
      * @private
      * @inner
      */
-    function onMouseWheelSpin( tracker, event, isTouch ) {
+    function onWheel( tracker, event ) {
+        handleWheelEvent( tracker, event, event, false );
+    }
+
+
+    /**
+     * @private
+     * @inner
+     */
+    function onMouseWheel( tracker, originalEvent ) {
+        // For legacy IE, access the global (window) event object
+        originalEvent = originalEvent || window.event;
+
+        // Simulate a 'wheel' event
+        var event = {
+            target:         originalEvent.target || originalEvent.srcElement,
+            type:           "wheel",
+            shiftKey:       originalEvent.shiftKey || false,
+            clientX:        originalEvent.clientX,
+            clientY:        originalEvent.clientY,
+            pageX:          originalEvent.pageX ? originalEvent.pageX : originalEvent.clientX,
+            pageY:          originalEvent.pageY ? originalEvent.pageY : originalEvent.clientY,
+            deltaMode:      originalEvent.type == "MozMousePixelScroll" ? 0 : 1, // 0=pixel, 1=line, 2=page
+            deltaX:         0,
+            deltaZ:         0,
+            preventDefault: function() {
+                if ( originalEvent.preventDefault ) {
+                    originalEvent.preventDefault();
+                } else {
+                    originalEvent.returnValue = false;
+                }
+            }
+        };
+
+        // Calculate event.deltaY
+        if ( $.MouseTracker.wheelEventName == "mousewheel" ) {
+            event.deltaY = - 1 / $.DEFAULT_SETTINGS.pixelsPerWheelLine * originalEvent.wheelDelta;
+        } else {
+            event.deltaY = originalEvent.detail;
+        }
+
+        handleWheelEvent( tracker, event, originalEvent, false );
+    }
+
+
+    /**
+     * Handles 'wheel' events. 
+     * The event may be simulated by the legacy mouse wheel event handler (onMouseWheel()) or onTouchMove().
+     *
+     * @private
+     * @inner
+     */
+    function handleWheelEvent( tracker, event, originalEvent, isTouch ) {
         var nDelta = 0,
             propagate;
 
         isTouch = isTouch || false;
 
-        if ( !event ) { // For IE, access the global (window) event object
+        // The nDelta variable is gated to provide smooth z-index scrolling
-            event = window.event;
+        //   since the mouse wheel allows for substantial deltas meant for rapid
-        }
+        //   y-index scrolling.
-
+        // event.deltaMode: 0=pixel, 1=line, 2=page
-        if ( event.wheelDelta ) { // IE and Opera
+        // TODO: Deltas in pixel mode should be accumulated then a scroll value computed after $.DEFAULT_SETTINGS.pixelsPerWheelLine threshold reached
-            nDelta = event.wheelDelta;
+        nDelta = event.deltaY < 0 ? 1 : -1;
-            if ( window.opera ) {  // Opera has the values reversed
-                nDelta = -nDelta;
-            }
-        } else if ( event.detail ) { // Mozilla FireFox
-            nDelta = -event.detail;
-        }
-        //The nDelta variable is gated to provide smooth z-index scrolling
-        //since the mouse wheel allows for substantial deltas meant for rapid
-        //y-index scrolling.
-        nDelta = nDelta > 0 ? 1 : -1;
 
         if ( tracker.scrollHandler ) {
             propagate = tracker.scrollHandler(
                 {
                     eventSource:   tracker,
-                    // Note: Ok to call getMouseRelative on passed event for isTouch==true since 
-                    //   event.pageX/event.pageY are added to the original touchmove event in
-                    //   onTouchMove().
                     position:      getMouseRelative( event, tracker.element ),
                     scroll:        nDelta,
                     shift:         event.shiftKey,
                     isTouchEvent:  isTouch,
-                    originalEvent: event,
+                    originalEvent: originalEvent,
                     userData:      tracker.userData
                 }
             );
@@ -1229,15 +1276,29 @@
             if ( Math.abs( THIS[ tracker.hash ].lastPinchDelta - pinchDelta ) > 75 ) {
                 //$.console.debug( "pinch delta : " + pinchDelta + " | previous : " + THIS[ tracker.hash ].lastPinchDelta);
 
-                // Simulate a mouse wheel scroll event
+                // Simulate a 'wheel' event
                 var simulatedEvent = {
+                    target:         event.target || event.srcElement,
+                    type:           "wheel",
                     shiftKey:       event.shiftKey || false,
-                    pageX:    THIS[ tracker.hash ].pinchMidpoint.x,
+                    clientX:        event.clientX,
-                    pageY:    THIS[ tracker.hash ].pinchMidpoint.y,
+                    clientY:        event.clientY,
-                    detail:   ( THIS[ tracker.hash ].lastPinchDelta > pinchDelta ) ? 1 : -1
+                    pageX:          event.pageX ? event.pageX : event.clientX,
+                    pageY:          event.pageY ? event.pageY : event.clientY,
+                    deltaMode:      1, // 0=pixel, 1=line, 2=page
+                    deltaX:         0,
+                    deltaY:         ( THIS[ tracker.hash ].lastPinchDelta > pinchDelta ) ? 1 : -1,
+                    deltaZ:         0,
+                    preventDefault: function() {
+                        if ( event.preventDefault ) {
+                            event.preventDefault();
+                        } else {
+                            event.returnValue = false;
+                        }
+                    }
                 };
 
-                onMouseWheelSpin( tracker, simulatedEvent, true );
+                handleWheelEvent( tracker, simulatedEvent, event, true );
 
                 THIS[ tracker.hash ].lastPinchDelta = pinchDelta;
             }

src/openseadragon.js

@@ -386,6 +386,50 @@ window.OpenSeadragon = window.OpenSeadragon || function( options ){
     };
 
 
+    /**
+     * Detect event model and create appropriate _addEvent/_removeEvent methods
+     */
+    if ( window.addEventListener ) {
+        //$._addEventListener = 'addEventListener';
+        //$._eventNamePrefix  = '';
+        $._addEvent = function ( element, eventName, handler, useCapture ) {
+            element = $.getElement( element );
+            element.addEventListener( eventName, handler, useCapture );
+        };
+    } else if ( window.attachEvent ) {
+        //$._addEventListener = 'attachEvent';
+        //$._eventNamePrefix  = 'on';
+        $._addEvent = function ( element, eventName, handler, useCapture ) {
+            element = $.getElement( element );
+            element.attachEvent( 'on' + eventName, handler );
+            if ( useCapture && element.setCapture ) {
+                element.setCapture();
+            }
+        };
+    } else {
+        throw new Error( "No known event model." );
+    }
+
+    if ( window.removeEventListener ) {
+        //$._removeEventListener = 'removeEventListener';
+        $._removeEvent = function ( element, eventName, handler, useCapture ) {
+            element = $.getElement( element );
+            element.removeEventListener( eventName, handler, useCapture );
+        };
+    } else if ( window.detachEvent ) {
+        //$._removeEventListener = 'detachEvent';
+        $._removeEvent = function( element, eventName, handler, useCapture ) {
+            element = $.getElement( element );
+            element.detachEvent( 'on' + eventName, handler );
+            if ( useCapture && element.releaseCapture ) {
+                element.releaseCapture();
+            }
+        };
+    } else {
+        throw new Error( "No known event model." );
+    }
+
+
 }( OpenSeadragon ));
 
 /**
@@ -517,6 +561,7 @@ window.OpenSeadragon = window.OpenSeadragon || function( options ){
             immediateRender:        false,
             minZoomImageRatio:      0.9, //-> closer to 0 allows zoom out to infinity
             maxZoomPixelRatio:      1.1, //-> higher allows 'over zoom' into pixels
+            pixelsPerWheelLine:     40,
 
             //DEFAULT CONTROL SETTINGS
             showSequenceControl:    true,  //SEQUENCE
@@ -1142,33 +1187,9 @@ window.OpenSeadragon = window.OpenSeadragon || function( options ){
          * @param {String} eventName
          * @param {Function} handler
          * @param {Boolean} [useCapture]
-         * @throws {Error}
          */
         addEvent: function( element, eventName, handler, useCapture ) {
-            element = $.getElement( element );
+            return $._addEvent( element, eventName, handler, useCapture );
-
-            //TODO: Why do this if/else on every method call instead of just
-            //      defining this function once based on the same logic
-            if ( element.addEventListener ) {
-                $.addEvent = function( element, eventName, handler, useCapture ){
-                    element = $.getElement( element );
-                    element.addEventListener( eventName, handler, useCapture );
-                };
-            } else if ( element.attachEvent ) {
-                $.addEvent = function( element, eventName, handler, useCapture ){
-                    element = $.getElement( element );
-                    element.attachEvent( "on" + eventName, handler );
-                    if ( useCapture && element.setCapture ) {
-                        element.setCapture();
-                    }
-                };
-            } else {
-                throw new Error(
-                    "Unable to attach event handler, no known technique."
-                );
-            }
-
-            return $.addEvent( element, eventName, handler, useCapture );
         },
 
 
@@ -1181,32 +1202,9 @@ window.OpenSeadragon = window.OpenSeadragon || function( options ){
          * @param {String} eventName
          * @param {Function} handler
          * @param {Boolean} [useCapture]
-         * @throws {Error}
          */
         removeEvent: function( element, eventName, handler, useCapture ) {
-            element = $.getElement( element );
+            return $._removeEvent( element, eventName, handler, useCapture );
-
-            //TODO: Why do this if/else on every method call instead of just
-            //      defining this function once based on the same logic
-            if ( element.removeEventListener ) {
-                $.removeEvent = function( element, eventName, handler, useCapture ) {
-                    element = $.getElement( element );
-                    element.removeEventListener( eventName, handler, useCapture );
-                };
-            } else if ( element.detachEvent ) {
-                $.removeEvent = function( element, eventName, handler, useCapture ) {
-                    element = $.getElement( element );
-                    element.detachEvent("on" + eventName, handler);
-                    if ( useCapture && element.releaseCapture ) {
-                        element.releaseCapture();
-                    }
-                };
-            } else {
-                throw new Error(
-                    "Unable to detach event handler, no known technique."
-                );
-            }
-            return $.removeEvent( element, eventName, handler, useCapture );
         },