Ticket #3485 (closed bug: fixed)
Zoom level mismatch with Layer.Bing and overlays
|Reported by:||nrenner||Owned by:||ahocever|
When adding an overlay to a map with Bing tiles as base layer, the two layers have different zoom levels. Tile request URLs for the overlay are calculated with the wrong zoom level and therefore the overlay doesn't align with the base map.
A live example can viewed at:
To reproduce, add the following lines to examples/bing-tiles.js (tested with 2.11 RC3 on Windows XP with Firefox 6.0.1):
var osm = new OpenLayers.Layer.OSM(); osm.isBaseLayer = false; osm.opacity = 0.5; map.addLayer(osm);
The OSM overlay gets initialized properly when debugging XYZ.getXYZ with a breakpoint at line 151:
this.map.getResolution() = 76.43702827453613 this.map.getZoom() = 11
By adding the condition "z == 10" to the breakpoint, you can see that a refresh after the Bing initialization goes wrong because the zoom and resolution don't match:
this.map.getResolution() = 76.43702827453613 this.map.getZoom() = 10
The reason seems to be, that within Bing.initLayer Layer.getZoomForResolution gets called, which determines the current zoom level based on the resolutions array. The Bing layer has a zoomOffset of 1, so in this case resolutions is only a subset of serverResolutions, thus the determined zoom level is relative to zoomOffset/maxResolution and doesn't fit to other layers with different settings.
I think this was introduced with changeset:12106; with RC1 Bing worked OK with overlays, which are broken since RC2.