I resolved the previous problem but ran into another: when an XYZ layer has "isBaseMap: false", has maxExtent set, and has a non-default tileOrigin, the getXYZ method in Layers/XYZ.js incorrectly calculates the x, y, and z coordinates based on the layer's maxExtent bounds rather than on its tileOrigin property. I fixed this problem by replacing "this.maxExtent.left" with "this.tileOrigin.lon" and replacing "this.maxExtent.top" with "-this.tileOrigin.lat" in the getXYZ method of Layers/XYZ.js.
I hope this helps somebody and that OpenLayers can be patched to fix the bug. I am using 2.12. -Dave On Sun, Apr 21, 2013 at 11:46 AM, David Fuhry <dfu...@gmail.com> wrote: > Hi Rohan or others, > > Wondering if you ever found a resolution for this problem. What I'm > experiencing is when using an XYZ layer with isBaseMap: false, setting > maxScale to anything other than NaN or null, or setting minResolution to > anything other than null, or 'auto', results in the layer never displaying. > Obviously I want to set maxScale or minResolution to a numeric value, but > the layer simply never displays when I do, no matter what the numeric value. > > Thanks, > > Dave > > > Rohan Parkes rohan.parkes at pelicancorp.com > Fri Jun 24 00:05:27 EDT 2011 > > I have a layer based on a 3rd-party map provider that uses an XYZ layer > type > that is optimised to show Australia and New Zealand. If I just let the > layer > run with sphericalMercator set to true, and don't set anything else, > everything's fine. However, I want to be able to limit the number of layers > available based on criteria like zoom level (e.g. the map should have zoom > levels between 20km and 1 km). I have been able to do this with other layer > types like ArcGIS93Rest by having a resolutions array in advance, and > truncating it according to the calculated zoom level and then passing it to > the map object. > > I can't get the same idea to work if I use an XYZ layer. It won't work > properly if I pass in any array of resolutions, even if it's the same array > of Spherical Mercator resolutions that it generates itself. > > Based on the information in > http://trac.osgeo.org/openlayers/wiki/SettingZoomLevels I've tried setting > the minZoomLevel/maxZoomLevel, minResolution/maxResolution. These seem to > have no effect, or they create bizarre results. The only setting that seems > to constrain the levels is numZoomLevels, but this doesn't give me any > control over which range of levels it selects - if I set it to 10, it > defaults to the outermost 10. > > (I have the same issue with the OSM layer type, which I would like to have > as a fallback if the main map provider fails - again I can't seem to > specify > the exact zoom levels I want.) > > One issue - I'm not passing the array into the map constructor via the > options parameter during initialisation. Due to the way the code has been > written, it creates an empty map object, then sets various parameters. I > don't know it that's a factor. > > One other thing that seems a bit odd - even if I can successfully set the > levels with a resolutions array, I still have to specify the number of zoom > levels in the map object. I thought it would figure this out itself from > the > size of the array. > > Rohan Parkes > > Melbourne >
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