Google Maps API 2.0解析(11-GKeyboardHandler支持键盘操作的类)

        //滑动地图操作的键码值
        var moveKeyCodes=[37,38,39,40];
        //每个码值对应的方向
        var moveKeyDirection=
        {
            38:[0,1],40:[0,-1],37:[1,0],39:[-1,0]
        };
        //支持键盘操作的类，b参数是要将事件绑定到的层，默认是document
        function GKeyboardHandler(map,b)
        {
            this.map=map;
            bindDom(window,"blur",this,this.onBlur);
            this.addKeyboardEvent(b)
        }
        GKeyboardHandler.prototype.addKeyboardEvent=function(a)
        {
            var b=a||document;
            if(browser.isFirefox()&&browser.os==1)
            {
                bindDom(b,"keydown",this,this.onKeyPress);
                bindDom(b,"keypress",this,this.onKeyDown)
            }
            else
            {
                bindDom(b,"keydown",this,this.onKeyDown);
                bindDom(b,"keypress",this,this.onKeyPress)
            }
            bindDom(b,"keyup",this,this.onKeyUp);
            this.moveDirection=
            {
            }
        };
        GKeyboardHandler.prototype.onKeyDown=function(a)
        {
            if(this.isMapEvent(a))
            {
                return true
            }
            var b=this.map;
            switch(a.keyCode)
            {
                //方向键,记录下移动方向，然后开始移动
                case 38:case 40:case 37:case 39:this.moveDirection[a.keyCode]=1;
                this.startMove();
                PreventEventDefault(a);
                return false;
                //pageUp,pageDown,home,end四个键,直接移动地图
                case 34:b.panBy(new GSize(0,-getMathRound(b.getSize().height*0.75)));
                PreventEventDefault(a);
                return false;
                case 33:b.panBy(new GSize(0,getMathRound(b.getSize().height*0.75)));
                PreventEventDefault(a);
                return false;
                case 36:b.panBy(new GSize(getMathRound(b.getSize().width*0.75),0));
                PreventEventDefault(a);
                return false;
                case 35:b.panBy(new GSize(-getMathRound(b.getSize().width*0.75),0));
                PreventEventDefault(a);
                return false;
                //大小键盘上的+-
                case 187:case 107:b.zoomIn();
                PreventEventDefault(a);
                return false;
                case 189:case 109:b.zoomOut();
                PreventEventDefault(a);
                return false
            }
            switch(a.which)//fireFox键的支持
            {
                case 61:case 43:b.zoomIn();
                PreventEventDefault(a);
                return false;
                case 45:case 95:b.zoomOut();
                PreventEventDefault(a);
                return false
            }
            return true
        };
        GKeyboardHandler.prototype.onKeyPress=function(a)
        {
            if(this.isMapEvent(a))
            {
                return true
            }
            switch(a.keyCode)
            {
                case 38:case 40:case 37:case 39:case 34:case 33:case 36:case 35:case 187:case 107:case 189:case 109:PreventEventDefault(a);
                return false
            }
            switch(a.which)
            {
                case 61:case 43:case 45:case 95:PreventEventDefault(a);
                return false
            }
            return true
        };
        //键盘放开的时候停止移动
        GKeyboardHandler.prototype.onKeyUp=function(a)
        {
            switch(a.keyCode)
            {
                case 38:case 40:case 37:case 39:this.moveDirection[a.keyCode]=null;
                return false
            }
            return true
        };
        //判断改键盘事件是否应该由地图处理
        GKeyboardHandler.prototype.isMapEvent=function(a)
        {
            if(a.ctrlKey||a.altKey||a.metaKey)
            {
                return true
            }
            var b=GetEventElement(a);
            if(b&&(b.nodeName=="INPUT"&&b.getAttribute("type").toLowerCase()=="text"||b.nodeName=="TEXTAREA"))
            {
                return true
            }
            return false
        };
        //开始滑动地图
        GKeyboardHandler.prototype.startMove=function()
        {
            var a=this.map;
            if(!a.isLoaded())return;
            a.endMove();//如果地图已经正在滑动，则先停止
            trigger(a,GEvent_movestart);
            if(!this.zc)
            {
                this.ticks=new GTicks(100);
                this.moveMap()
            }
        };
        //不停的调用该方法会滑动地图
        GKeyboardHandler.prototype.moveMap=function()
        {
            var a=this.moveDirection;
            var b=0;
            var c=0;
            var d=false;
            //根据当前已经按下的键确定华东方向
            for(var e=0;e<moveKeyCodes.length;e++)
            {
                if(a[moveKeyCodes[e]])
                {
                    var f=moveKeyDirection[moveKeyCodes[e]];
                    b+=f[0];
                    c+=f[1];
                    d=true
                }
            }
            var g=this.map;
            //向在指定方向滑动
            if(d)
            {
                var h=1;
                var i=browser.type!=0||browser.os!=1;
                if(i&&this.ticks.more())
                {
                    h=this.ticks.next()
                }
                var l=getMathRound(7*h*5*b);
                var n=getMathRound(7*h*5*c);
                var p=g.getDragObject();
                p.moveTo(p.left+l,p.top+n);
                //0.01秒之后再次运行移动过程
                this.zc=setWindowTimeOut(this,this.moveMap,10)
            }
            else//如果当前没有任何键被按下，则完成滑动
            {
                this.zc=null;
                trigger(g,GEvent_moveend)
            }
        };
        //用户窗口失去焦点的时候停止滑动
        GKeyboardHandler.prototype.onBlur=function(a)
        {
            this.moveDirection=
            {
            }
        };