topic Maximum extent in ArcGIS JavaScript Maps SDK Questions

Maximum extent

EricPfirman — Thu, 12 Jul 2012 17:24:47 GMT

I have 2 layers.
The bottom layer is the "World_Street_Map" tiled map service.
The top layer is a dynamic layer covers a portion of New York State.
I set the initial extent to the extent of the dynamic layer.

If I zoom all the way out with the ZoomSlider or with "navToolbar.zoomToFullExtent()" it zooms to the entire world. How can I constrain the map so the maximum extent is equal to the extent of the dynamic layer?

  var extentMap;
  extentMap = new esri.geometry.Extent({xmin:-8478000, ymin:5014590, xmax:-8099500, ymax:5245000, spatialReference:{wkid:102100}});
        map = new esri.Map("mapDiv", { extent: extentMap, nav:true});

Re: Maximum extent

SiqiLi — Sun, 12 Dec 2021 05:14:02 GMT

You need to define an array of LODs (Levels of Detail) to specify the zoom levels. Each LOD corresponds to a map at a given scale or resolution. Then, apply the array of LODs in the map constructor as an option. For example:

 function init() {
      var lods = [
 {"level" : 13, "resolution" : 19.1092570712683, "scale" : 72223.819286},
 {"level" : 14, "resolution" : 9.55462853563415, "scale" : 36111.909643},
 {"level" : 15, "resolution" : 4.77731426794937, "scale" : 18055.954822},
 {"level" : 16, "resolution" : 2.38865713397468, "scale" : 9027.977411},
 {"level" : 17, "resolution" : 1.19432856685505, "scale" : 4513.988705},
 {"level" : 18, "resolution" : 0.597164283559817, "scale" : 2256.994353},
 {"level" : 19, "resolution" : 0.298582141647617, "scale" : 1128.497176}
 ];
        var initExtent = new esri.geometry.Extent({"xmin":-1.3074977201954123E7,"ymin":4015620.159117397,"xmax":-1.3073987658308368E7,"ymax":4016419.790346289,"spatialReference":{"wkid":102100}});
        map = new esri.Map("map",{extent:initExtent, lods:lods});
        var basemap = new esri.layers.ArcGISTiledMapServiceLayer("http://server.arcgisonline.com/ArcGIS/rest/services/World_Street_Map/MapServer");
        map.addLayer(basemap); 
        var dynamicLyr = new esri.layers.ArcGISDynamicMapServiceLayer("http://sampleserver6.arcgisonline.com/arcgis/rest/services/PoolPermits/MapServer");  
        map.addLayer(dynamicLyr);

        dojo.connect(map, 'onLoad', function(theMap) {
        dojo.connect(dijit.byId('map'), 'resize', map,map.resize);
        });
      }

FYI: You can look into the REST endpoint of the World_Street_Map service and pick the LODs you need. If you decide to use another tiled map service, make sure you look into that service's REST endpoint and pick up the correct LODs.

Re: Maximum extent

StephenLead — Fri, 13 Jul 2012 09:21:43 GMT

Note that this only restricts you to the same zoom level as the maximum extent of the layer - you'll still be able to pan to another location.

If that's a problem (ie, you want to prevent the user from navigating away from the study area) you could write a function which examines the map extent after panning or zooming (see the onExtentChange event) and nudges it back to the desired extent.

Steve

Re: Maximum extent

LaurensZwakhals — Wed, 20 Feb 2013 09:27:51 GMT

Note that this only restricts you to the same zoom level as the maximum extent of the layer - you'll still be able to pan to another location.

If that's a problem (ie, you want to prevent the user from navigating away from the study area) you could write a function which examines the map extent after panning or zooming (see the onExtentChange event) and nudges it back to the desired extent.

Steve

Indeed, I'd like to prevent the user from navigating away from the study area. I'm not really a crack in writing functions using JavaScript. How should such a function look like?

Re: Maximum extent

StephenLead — Wed, 20 Feb 2013 20:28:57 GMT

To get started, I'd suggest you install Firefox and Firebug and spend some time playing around with the developer tools. Learn how to put a breakpoint into code and inspect what's happening.

Then add a listener for the onExtentChange event so you can see what happens when your map's extent changes.

Inside this function, put some logic which ensures that the user hasn't moved outside your study area - if they have, move the map back again.

Re: Maximum extent

HaroldBostic — Thu, 14 Mar 2013 13:39:39 GMT

Hello, they have the solution to your question here

http://forums.arcgis.com/threads/27971-Constrain-Map-Extent?highlight=constrain