Use the mouse wheel to zoom in or out the mxgraph drawing Area

// Override the mouse wheel event mxevent. addmousewheellistener = function (funct) {}// adds the window for the first loading event. onload = function () {var element = document. getelementbyid ('graph'); addscrolllistener (element, wheelhandle);} function addscrolllistener (element, wheelhandle) {If (typeof element! = 'Object') return; If (typeof wheelhandle! = 'Function') return; // monitor the browser if (typeof arguments. callee. browser = 'undefined') {var user = navigator. useragent; var B ={}; B. opera = user. indexof ("Opera")>-1 & typeof window. opera = "object"; B. khtml = (user. indexof ("khtml")>-1 | user. indexof ("applewebkit")>-1 | user. indexof ("Konqueror")>-1 )&&! B. Opera; B. Ie = user. indexof ("MSIE")>-1 &&! B. Opera; B. Gecko = user. indexof ("gecko")>-1 &&! B. khtml; arguments. callee. browser = B;} If (element = Window) element = document; if (arguments. callee. browser. IE) element. attachevent ('onmousewheel ', wheelhandle); else element. addeventlistener (arguments. callee. browser. gecko? 'Dommousescroll': 'mousewheel', wheelhandle, false);} function wheelhandle (e) {var upcheck; If (E. wheeldelta) {upcheck = E. wheeldelta> 0? 1: 0;} else {upcheck = E. Detail <0? 1: 0;} If (upcheck) {mygraph. zoomin ();} else {mygraph. zoomout ();} If (window. event) {e. returnvalue = false; window. event. cancelbubble = true;} else {e. preventdefault (); E. stoppropagation ();}}

PS: mygraph is a global variable, an mxgraph instance.