when the initial viewport of the XamMap covers a small enough area (i.e. the zoom level is high), the XamMap does not display any map data at all. The issue is present also in the new 13.1 release.
If I e.g. use a custom MapTileSource that downloads OpenStreetMap data from MapQuest, I find that the XamMap may try to fill the initial view with tiles at zoom level 20, while MapQuest OSM only supports zoom levels 0-19. Obviously the requested tiles can't be found. I think that the XamMap should try to download tiles at a lower zoom level to at least fill the view with map data at a lower resolution, but this is not the case. As it is now, I have to manually zoom out (to trigger download of tiles at a valid zoom level) and then zoom in again to get the lower-resolution data.
Is there a simple way around this issue ? Is there e.g. a way to tell the XamMap what zoom levels are supported by the tile source, to make it at least request valid tiles only ?Is it e.g. possible to 'trick' the XamMap to download tiles at lower resolution than the ones requested by the MapTileSource.GetTileLayers method ?
Thank you for posting!
I have been looking into your description and what I could suggest you here is setting the zoom level after the map has loaded at the initial zoom level. This will allow the tiles to be rendered and then the zoom level could be changed. Would you mind providing a sample project where this issue is presented so I could investigate it further for you?
the attached sample shows the issue. It sets the initial viewport (after the map has loaded) to a region that corresponds to an OpenStreetMap zoom level of 19. Since the default OpenStreetMap server (and MapTileSource) does not support higher zoom levels than 18, no map data is initially rendered. You have to zoom out a bit to start rendering map data.
If you enable the (commented) MapQuest OSM tile source, the view shows map data initially, since the MapQuest OSM service supports zoom levels up to 19. However, choosing an initial viewport that corresponds to zoom levels above 19 will also make the initial view empty using the MapQuest tile source as well.
Thank you for the provided sample and the details. I have logged this behavior in our tracking system, with an issue ID of 141030. I have linked the development issue to your case CAS-114786-R7F9C4 so that you are automatically updated when a Service Release containing your fix is available for download or our developers come up with a solution for this.