function UpdateHelper(thresholdRange){this._screens=[];if(typeof thresholdRange!="undefined"){this._thresholdRange=thresholdRange;}else{this._thresholdRange=.75;}}
UpdateHelper.prototype.reset=function(){this._screens=[];}
UpdateHelper.prototype.addScreen=function(gBounds,zoomLevel,isPruned){if(gBounds.isEmpty())return;var mapScreen=new MapScreen();mapScreen.bounds=gBounds;mapScreen.pruned=isPruned;mapScreen.zoomLevel=zoomLevel;this._screens.push(mapScreen);}
UpdateHelper.prototype.needsUpdate=function(gBounds,zoomLevel){var window=new MapWindow(gBounds,this._thresholdRange);if(this._screens.length==0){return"NOTINITIALIZED";}
if(isDefined(this._limitPages)&&this._limitPages<this._screens.length){return"ERASE";}
this._screens.sort(orderByZoomLevel);if(this._screens[0].zoomLevel>zoomLevel+1)return"ERASE";for(var i=0;i<this._screens.length;i++){window.blockout(this._screens[i].bounds);if(window.isCovered()){if(this._screens[i].pruned){if(this._screens[i].zoomLevel<zoomLevel){return"UPDATE_PRUNED";}else{return"NOUPDATE_PRUNED";}}
return"NOUPDATE";}}
return"UPDATE";}
function MapWindow(gBounds){this.bounds=gBounds;this.ne=gBounds.getNorthEast();this.sw=gBounds.getSouthWest();this.nw=new GLatLng(this.ne.lat(),this.sw.lng());this.se=new GLatLng(this.sw.lat(),this.ne.lng());}
MapWindow.prototype.blockout=function(gBounds){if(!gBounds.intersects(this.bounds))return;var coveringLayer=new MapWindow(gBounds);if(gBounds.contains(this.ne)){this.ne=coveringLayer.sw;}
if(gBounds.contains(this.nw)){this.nw=coveringLayer.se;}
if(gBounds.contains(this.se)){this.se=coveringLayer.nw;}
if(gBounds.contains(this.sw)){this.sw=coveringLayer.ne;}}
MapWindow.prototype.isCovered=function(){if(this.nw.lng()<this.se.lng()||this.nw.lat()>this.se.lat())return false;if(this.sw.lng()<this.ne.lng()||this.sw.lat()<this.ne.lat())return false;return true;}
function orderByZoomLevel(mapUpdateA,mapUpdateB){return mapUpdateB.zoomLevel-mapUpdateA.zoomLevel;}
function MapScreen(){};