[mapguide-internals] Tile maps...

Paul Spencer pspencer at dmsolutions.ca
Mon Sep 17 12:59:39 EDT 2007 

OpenLayers has a concept of 'baseLayer', of which there can only be  
one 'on' at any time (since it is opaque).  I could see the MapGroup  
allowing the definition of more than one 'baseLayer' and indicating  
which is the default one.  The legend would then allow toggling  
between them using the visibility checkboxes - which would likely  
have to change to radio buttons to make sense.

We will need to think through how the menu thing will work - will  
loading a map from a resource id remove all existing layers or 'add'  
it to the legend as another baseLayer?

Paul
On 15-Sep-07, at 12:14 AM, Jason Birch wrote:

> Hi Paul,
>
> How would this work if I were to, say, have three user-toggleable  
> basemap possibilities per "theme", similar to Google Maps?  Is this  
> something that would be better-handled with custom JS?  Perhaps it  
> would be better to manage the basemaps separately, or at least  
> provide that option, rather than bundling them with particular  
> themes...
>
> And seeing how this XML works... is there still going to be the  
> ability to point to a folder to populate the Theme dropdown, or  
> will they all have to be defined manually?
>
> Jason
>
> ________________________________
>
> From: mapguide-internals-bounces at lists.osgeo.org on behalf of Paul  
> Spencer
> Sent: Fri 2007-09-14 5:28 PM
> To: MapGuide Internals Mail List
> Subject: Re: [mapguide-internals] Tile maps...
>
>
>
> One thing that should be possible in Fusion is to create an
> application definition that refers to two separate map definitions.
> This would be done in the map set as follows:
>
> <MapSet>
>    <MapGroup id="NamaimoEngineeringMap">
>      <Map>
>        <Name>NanaimoBaseMap</Name>
>        <Type>MapGuide</Type>
>        <SingleTile>false</SingleTile>
>        <Extension>
>          <ResourceId>Libary://path/to/tiled.MapDefinition</ResourceId>
>        </Extension>
>      </Map>
>      <Map>
>        <Name>EngineeringTheme</Name>
>        <Type>MapGuide</Type>
>        <SingleTile>true</SingleTile>
>        <Extension>
>          <ResourceId>Libary://path/to/EngineeringTheme.MapDefinition</
> ResourceId>
>        </Extension>
>      </Map>
>    </MapGroup>
> </MapSet>
>
> This would result in two OpenLayers layers being created, a tiled one
> that would be the baseMap (in OpenLayers terms) and an overlay that
> would be drawn using GETDYNAMICOVERLAYIMAGE and thus be transparent
> to the tiled layers underneath.
>
> By possible, I mean it is theoretically possible to support this but
> I suspect that we will not have time to investigate this for the
> first integration.
>
> Note that the intention is also to support other OpenLayers layer
> types in the MapGroup as overlays so you can also overlay WMS
> directly in the client (for instance) or use another tile source for
> the baseMap and use MapGuide as the overlay.
>
> Cheers
>
> Paul
>
> On 14-Sep-07, at 7:35 PM, Trevor Wekel wrote:
>
>> Hi Jason,
>>
>> A possible enhancement would be to define two map definitions for a
>> "map".  The first definition would define the overlay/dynamic
>> layers and
>> the second definition would be used only for the tiles.  I think they
>> are separate layers in the new client framework so it may be
>> possible to
>> implement.
>>
>> There would be some other implementation details like selection and
>> query that would have to be worked out.  You may need to hit two
>> maps to
>> find the selected/queried object.  This could be a little tricky  
>> but I
>> don't think it would be impossible.  I suspect all the maps would  
>> also
>> have to use the same coordinate system.
>>
>> Version 1.2.0 of the GETTILEIMAGE operation takes the resource id
>> of the
>> map definition, the base map layer group name, the tile row and  
>> column
>> and the scale index.  Authentication can be specified using
>> sessionid or
>> username/password.
>>
>> A further enhancement to the "two layer" / "two map" approach  
>> would be
>> to code up two different URLs for the overlay/dynamic and tiled
>> layers.
>> This would allow us offload the base tiles to a completely separate
>> server and web extensions.
>>
>> Thanks,
>> Trevor
>>
>> -----Original Message-----
>> From: mapguide-internals-bounces at lists.osgeo.org
>> [mailto:mapguide-internals-bounces at lists.osgeo.org] On Behalf Of  
>> Jason
>> Birch
>> Sent: Friday, September 14, 2007 4:38 PM
>> To: MapGuide Internals Mail List
>> Subject: [mapguide-internals] Tile maps...
>>
>> Hi all,
>>
>> I've been thinking (not a good sign) about how tile maps are
>> implemented
>> in MapGuide.  I'm seeing some real limitations on how useful this is
>> going to be for me because of the association of tile sets with
>> specific
>> maps.
>>
>> With the new Fusion framework, I intend to have several dozen maps
>> (themes), each using one of three tile set definitions.  With the
>> current inclusion of tile groups in map definitions, this means that
>> I'll have to have separate copies of these tile groups for each  
>> one of
>> my maps.
>>
>> I would really like to see some way of abstracting tile groups from
>> map
>> definitions.  Either through a new resource type that defines the  
>> tile
>> group, or by allowing tiled maps to be referenced from regular maps,
>> rather than redefined in each one.
>>
>> Thoughts?
>>
>> Jason
>> _______________________________________________
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>
> +-----------------------------------------------------------------+
> |Paul Spencer                          pspencer at dmsolutions.ca    |
> +-----------------------------------------------------------------+
> |Chief Technology Officer                                         |
> |DM Solutions Group Inc                http://www.dmsolutions.ca/ |
> +-----------------------------------------------------------------+
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+-----------------------------------------------------------------+
|Paul Spencer                          pspencer at dmsolutions.ca    |
+-----------------------------------------------------------------+
|Chief Technology Officer                                         |
|DM Solutions Group Inc                http://www.dmsolutions.ca/ |
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