[OpenLayers-Dev] allOverlays question

[bartvde at osgis.nl]

Hi Eric,

my map definition has the following set:

var map = new OpenLayers.Map({
  fractionalZoom: true,
  maxResolution: GeoServices.MapMaxResolution,
  projection: GeoServices.MapProjection,
  units: GeoServices.MapUnits,
  allOverlays: true,
  maxExtent: GeoServices.MapMaxExtent
});

However, since my layers come from a Web Map Context (WMC) document, it
always has numZoomLevels set in the Extension:

      <Extension>
        <ol:maxExtent xmlns:ol="http://openlayers.org/context"
minx="0.000000000" miny="300000.0000" maxx="300000.0000"
maxy="625000.0000"/>
        <ol:transparent
xmlns:ol="http://openlayers.org/context">TRUE</ol:transparent>
        <ol:numZoomLevels
xmlns:ol="http://openlayers.org/context">18</ol:numZoomLevels>
        <ol:units xmlns:ol="http://openlayers.org/context">m</ol:units>
        <ol:isBaseLayer
xmlns:ol="http://openlayers.org/context">false</ol:isBaseLayer>
        <ol:displayInLayerSwitcher
xmlns:ol="http://openlayers.org/context">true</ol:displayInLayerSwitcher>
        <ol:singleTile
xmlns:ol="http://openlayers.org/context">true</ol:singleTile>
      </Extension>

So I guess this won't work for me?

Best regards,
Bart

> On Tue, Apr 13, 2010 at 10:00 AM,  <bartvde at osgis.nl> wrote:
>> Hi list,
>>
>> I am tracking down an issue in my application. I am using allOverlays
>> true
>> on the Map object. When I start up my application, a layer with no scale
>> info set is as the lowest in the stack and hence acts as the "base"
>> layer.
>>
>> However, I have a control which raises this layer (a marker layer) to
>> the
>> top, and then another (WMS) layer acts as the "base" layer. This layer
>> is
>> however scale-dependent, which means the map is not zoomable anymore
>> after
>> 1:500.000.
>>
>> Is there a way around this, or is this a side-effect of allOverlays? Do
>> I
>> need to resort back to my dummy base layer?
>
> Hi Bart
>
> Do you have resolutions or resolution information set in the map?
>
> I think my patch for <http://trac.openlayers.org/ticket/2427> would
> help you. With my patch if your layer options include maxResolution
> (or minResolution) and doesn't include numZoomLevels (which is the
> default), then no attempt to calculate resolutions based on the
> maxResolution value will be done, and the resolution data from the map
> will be used.
>
> Tell me if you need further information.
>
> PS: I have a complete description of my patch, but I'm holding it
> until 2.9 is released.
>
> --
> Eric Lemoine
>
> Camptocamp France SAS
> Savoie Technolac, BP 352
> 73377 Le Bourget du Lac, Cedex
>
> Tel : 00 33 4 79 44 44 96
> Mail : eric.lemoine at camptocamp.com
> http://www.camptocamp.com
>