[OpenLayers-Dev] [OpenLayers-Trac] [OpenLayers] #1195: allow
for maintaining layer visibility when switching base layers
Pierre GIRAUD
bluecarto at gmail.com
Thu Dec 13 04:01:02 EST 2007
This is clear for me now and it makes sense. Isn't something we would
reconsider for 3.0 and write it another way. Will the map still
require a base layer to work ?
On Dec 12, 2007 6:08 PM, OpenLayers <trac at openlayers.org> wrote:
> #1195: allow for maintaining layer visibility when switching base layers
> ----------------------+-----------------------------------------------------
> Reporter: tschaub | Owner:
> Type: feature | Status: new
> Priority: minor | Milestone:
> Component: general | Version: 2.5
> Resolution: | Keywords:
> ----------------------+-----------------------------------------------------
> Comment (by tschaub):
>
> Currently, isBaseLayer means two things:
>
> 1) can be used by the map to determine projection/extent related
> properties, and
> 2) can not be displayed at the same time as other layers with isBaseLayer
> true.
>
> The first meaning makes some sense, though in reality any layer could be
> used for this purpose. The second meaning is a bit arbitrary. Just
> because I want a layer to be used to determine projection/extent related
> properties doesn't necessarily mean I also never want to display the layer
> at the same time as another layer that has the same property.
>
> Take, for example, a map with many WMS layers - all of them with some
> transparent areas. A user may want to reorder these layers, keeping all
> of them visible. This same user may want to remove some of these layers
> and add new ones. These two requirements mean that the base layer will be
> changing. On solution is to use a "dummy layer" as a base layer. I think
> this is dumb. I like the fact that the map determines it's
> projection/extent related properties based on some real layer.
>
> This patch allows an application to have a single layer with isBaseLayer
> set to true. This layer is the map.baseLayer. When the user reorders
> layers, the map.baseLayer is changed, but the visiblity of the old layer
> is not turned off.
>
> --
> Ticket URL: <http://trac.openlayers.org/ticket/1195#comment:2>
>
> OpenLayers <http://openlayers.org/>
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