[fusion-trac] #113: Can't zoom out beyond initial map view

[Fusion]

#113: Can't zoom out beyond initial map view
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 Reporter:  andrewd    |         Owner:  madair  
     Type:  defect     |        Status:  assigned
 Priority:  P2         |     Milestone:  1.1     
Component:  Core       |       Version:  SVN     
 Severity:  Critical   |    Resolution:          
 Keywords:             |   External_id:          
    State:  Analysing  |       Browser:  All     
       Os:  All        |  
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Changes (by madair):

  * status:  new => assigned
  * owner:  pagameba => madair
  * milestone:  2.0 => 1.1

Comment:

 looking into this further, I've found that:

 - in OL, layers (or the baseLayer in particular) MUST have a maxExtent
 property set, otherwise the geography calculations are messed up for any
 projection other than lon/lat; setting projection and units on the map
 object doesn't change this (but these should be set on the map anyway).
 The effect of this is that you can't pan the center of the viewport
 outside of the maxExtent.

 - in Fusion, we set the maxExtent to the bounds returned by LoadMap (which
 is the Studio 'initial view' setting with MapGuide, and the mapfile
 'extent' value with mapserver).  We can set an optional override of this
 value in the MapWidget extension if that is desired to allow panning
 outside the maxExtent

 - the issue of not zooming out beyond the initial view, was actually due
 to the maxScale value of 'Infinity'. (displayOutsideMaxExtent and
 alwaysInRange settings don't affect this).  In this case, the maxScale
 parameter is not supplied to the OL Layer constructor, and the maxScale
 gets calculated internally in OL based on the maxExtent and viewport size.
 This can be fixed by substituting a large maxScale value e.g. 1:billion
 and then the user can zoom out to that scale value, and/or optionally set
 a maxScale value in the MapWidget extension.

 If that analysis makes I'll go ahead and implement the changes.  Since it
 doesn't depend on alwaysInRange, this can be implemented in Fusion 1.1

-- 
Ticket URL: <http://trac.osgeo.org/fusion/ticket/113#comment:17>
Fusion <http://trac.osgeo.org/fusion>
Fusion is a web-mapping application development framework for MapServer and MapGuide OS.