[OpenLayers-Users] OpenStreetMap - trying to limit zoom levels

[bradleyspencer]

I have done this by having an array of zoom max/mins and then I control my
own layer list in a form. It’s a long winded way but it works for me.

Have a look at http://demo.cubewerx.com.au/osdm/interopdemo.html

I set up an event that monitors the zooming and activates/deactivates these
controls

map.events.register('zoomend', null, function(evt)
            {
                        var macroCheckBox =
document.getElementById('macro');
                        zmlevel= map.getZoom();
                        // run through the layer controls array setting
Checkbox to deactive
                        for (j=0; j<numLayers; j++)
                        {
                                    var layId= 'layer'+j;
                                    var layerCheckbox =
document.getElementById(layId)

                                    // if the layer is viewable at this
layer set the checkbox to reflect
                                    if (zmlevel < Minzm[j] || zmlevel >
Maxzm[j])
                                    {           layerCheckbox.disabled =
true;
                                                layerCheckbox.checked=false;
                                                layerVisibility(layId);
                                    }
                                    else
                                    {           layerCheckbox.disabled =
false;
                                                if (macroCheckBox.checked)
                                                {
                                                            layerCheckbox.ch
ecked= true;
                                                            layerVisibility(
layId);
                                                }

                                    }
                        }
                        Event.stop(evt);
    });

You will need to build your own layerVisibility() function that will just
run through the checkboxes and activate/deactivate the visibility of the
layer accordingly.

Hope this helps


Cheers,

Brad Spencer


-----Original Message-----
From: users-bounces at openlayers.org [mailto:users-bounces at openlayers.org]On
Behalf Of Linda Rawson
Sent: Friday, 14 December 2007 4:57 AM
To: The Bun
Cc: users at openlayers.org
Subject: Re: [OpenLayers-Users] OpenStreetMap - trying to limit zoom levels

I think you have to customize PanZoomBar.

Linda



On Dec 13, 2007 10:30 AM, The Bun < rosario.carbone at ipl.com
<mailto:rosario.carbone at ipl.com> > wrote:

Hi

I am using OSM and connecting successfully to their mapnik server.
Everything works OK, this is my code:

               map = new OpenLayers.Map ("map", {
                       controls:[
                               new OpenLayers.Control.Permalink(),
                               new OpenLayers.Control.MouseDefaults (),
                               new OpenLayers.Control.LayerSwitcher(),
                               new OpenLayers.Control.MousePosition(),
                               new OpenLayers.Control.PanZoomBar()],
                       maxExtent: new
OpenLayers.Bounds(-20037508.34,-20037508.34,20037508.34,20037508.34),
                       numZoomLevels:17,
                 maxResolution:156543,
                 units:'meters',
                 projection: "EPSG:41001"} );

       layerMapnik = new OpenLayers.Layer.TMS(
               "Mapnik (updated weekly)",
               " http://tile.openstreetmap.org/mapnik/
<http://tile.openstreetmap.org/mapnik/> ",
               {type:'png', getURL: get_osm_url, displayOutsideMaxExtent:
true },
{'buffer':1} );

etc. etc.

What I am not understanding is how to limit the zoom levels to just from
zoom 9 to zoom 16 I tried different ways: An array of scales, an array of
resolutions, changing the maxResolution, change the numZoomLevels etc etc
always failed, is there someone in the list who can help with this issue?

Kind Regards
Rosario Carbone
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