Maximum extent

Question

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});

HaroldBostic · Answer

Hello, they have the solution to your question here

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

StephenLead · Answer

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.

LaurensZwakhals · Answer

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?