On Wed, Sep 10, 2008 at 11:32:27AM +0200, Guillaume Sueur wrote: > Hi, > > It seems that when layer's minResolution and maxResolution are set, the > map's resolution are overriden and goes then from maxResolution to > minResolution by x2 steps. > Is it a normal behaviour or am I missing something ?
This is normal behavior. OpenLayers has two different kind of layes: Base Layers, and Overlays. Base layer resolutions control the resolutions available to the map: when the base layer is switched, the available resolutions to zoom to change. Overlays don't really care about hteir 'list' of resolutions: this list is *only* used to determine whether a layer is in range or not. (In 2.7, unless you pass layer-related resolution options *explicitly*, a layer is always in range; this is a break from the past.) The map resolution options are used as a fallback to the layer resolution options. When creating a layer, the initResolutions function loops through all the resolution-relate properties, checking first if the layer has such a property, then checking if the map has such a property. In this way, it creates a 'complete' hash of all the resolution related options. It then acts as if the layer has passed all those resolution options in directly -- so, the map resolution parameters are just a fallback, which is overridden by the layer. So, it is completely expected behavior that a layer will take the feedback from the map, override it with its own settings, and call it done. An easy way to prevent misbehavior is to simply always pass a list of resolutions into your layer. Resolutions are the 'core' res properties in OpenLayers, and override naything else set on the map or layer. you don't *need* to go this far -- OpenLayers does a fair amount for you -- but if you do that, you can never go wrong. (This isn't the first time a resolution-related question has been asked which demosntrates a lack of understanding of this phenomen; This is just a general response to the more general qustions we get.) Regards, -- Christopher Schmidt MetaCarta _______________________________________________ Users mailing list [email protected] http://openlayers.org/mailman/listinfo/users
