Hmm... a bit counter intuitive, but I guess that would actually work.
So all layers would be "overlays" with respect to OpenLayers.
Regards, Kenneth Skovhede, GEOGRAF A/S
Christopher Schmidt skrev:
On Wed, Nov 19, 2008 at 08:04:39PM +0100, Kenneth Skovhede, GEOGRAF A/S wrote:
Very nice explanations!
The Wiki page explains the problem quite well.
I wish I had found that page a long time ago.
Just to carve it in stone, I would like my layer stack to look like this:
[Vector] -> OpenLayers vector layer
[Selection] -> Transparent PNG, rendered dynamically by MapGuide
[Dynamic Overlay] -> Main layer with bounds, etc. Also displays
thematics from MapGuide, eg Election districts.
[Base layer 1] -> Transparent PNG with things like lakes etc that are
not easily visible on an aerial
[Base layer 2] -> Transparent PNG with things building outlines, road
names etc.
[Base layer 3] -> Aerial JPG (opaque)
This enables the user to turn off building outlines without having to
reload the aerial.
It also enables the user to toggle different thematics on and off
without reloading the aerial or building outlines.
(It obviously costs more server calls to have the division).
As I see it, my "Vector" and "Selection" are clearly overlays, where as
the "Dynamic Overlay" is the main layer.
Currently I have to assign this as the "baseLayer" because it has all
the required info (units, bounds, etc.)
Since all of these layers are in the same projectino (since OpenLayers
has no way of doing anything else) I don't see that this is actually
required.
Instead, what I would recmomed you do is simply create an empty base
layer:
new OpenLayers.Layer("", {displayInLayerSwitcher:false,
isBaseLayer: true,
maxExtent:, maxResolution, etc.});
This layer would be the only base layer.
Then, all the other layers can be used in any way you want.
How does this not work for your situation?
Perhaps a real solution would be to follow the tracks of:
http://trac.openlayers.org/ticket/1096
But add a property named "isBottomLayer" instead to allow compatibility
with the existing code.
I don't understand what you mean, but I do not expect that any changes
will be made in this regard before 3.0.
Regards,
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