Thanks so much Eric. I have solved the problem by patching XYZ.js with setMap
and calculateGridLayout functions from Zoomify.js
Robert
>>> Eric Lemoine <eric.lemo...@camptocamp.com> 10/06/2010 7:00 p.m. >>>
On Tue, Jun 8, 2010 at 5:29 AM, Robert Sanson <sans...@asurequality.com> wrote:
> Hi developers
>
> I have been struggling with trying to get tiles requested from an ArcGIS
> tile cache to line up correctly with other data (requested via Layer.WMS
> etc). I have tried both Layer.XYZ and Layer.ArcGISCache (from T Schaub's
> sandbox).
>
> It seems Layer.XYZ and Layer.ArcGISCache are requesting the correct tiles,
> as calculated down from the specified layer tileOrigin or from the specified
> map maxExtent left and top values. However, the code that calculates where
> to put each tile is trying to work up from the maxExtent left and bottom
> values.
>
> The north-south displacement of the tiles changes depending on the zoom
> level. I have managed to find a lower left coordinate pair that I can
> specify in the map's maxExtent left and bottom that coincide exactly with
> the tile corners for most of the zoom levels but not for all zoom levels.
>
> I would like to see the positioning worked down from the layer tileOrigin,
> using tileSize and resolution, rather than up from the lower left of the map
> maxExtent bounds.
>
> Is it possible to modify the OL code so that the map maxExtent and
> restrictedExtent apply as map only properties, and allow one to specify the
> tileOrigin for each tile cache layer plus a property that indicates whether
> the tileOrigin is top left or bottom left? ArcGIS Server caches are all
> worked down from the top left.
>
> In the meantime, I have tried to add a "zoomend" event listener that traps
> when the zoomend event has occurred on the map, and set a new maxExtent in
> order to try and force OL to re-work out the tile placements, but to no
> avail.
>
> Here is my code:
>
> var mapoptions = {
> maxExtent: new OpenLayers.Bounds(-4020900, 4554869.11353823,
> 2568710.79993, 19998100),
> restrictedExtent: new
> OpenLayers.Bounds(980902.6296,4672753.201,2606505.881,6298356.452),
> resolutions: new Array(3175.0063500127003, //0
> 793.75158750317507, //1
> 264.58386250105838, //2
> 198.43789687579377, //3
> 132.29193125052919, //4
> 66.145965625264594, //5
> 26.458386250105836, //6
> 19.843789687579378, //7
> 13.229193125052918, //8
> 9.260435187537043, //9
> 6.6145965625264589, //10
> 5.2916772500211673, //11
> 3.9687579375158752, //12
> 2.6458386250105836, //13
> 1.9843789687579376, //14
> 1.3229193125052918),//15
> tileSize: new OpenLayers.Size(256,256),
> units: 'm',
> projection: new OpenLayers.Projection('EPSG:2193'),
> fractionalZoom: false
> };
> var map = new OpenLayers.Map( 'map',mapoptions );
> var topoagc = new OpenLayers.Layer.ArcGISCache({
> name: "agscache",
> url:
> "http://ws-esrimt/MapCache/mapservice_topography_vector_prod/Layers/_alllayers/";,
> tileOrigin: new
> OpenLayers.LonLat(-4020900,19998100)
> });
> map.addLayers([topoagc]);
>
> map.events.register('zoomend', null, function() {
> var zm = map.getZoom();
> var curcenter = new OpenLayers.LonLat(map.getCenter());
> //alert(zm);
> if (zm == 9) {
> alert("scale = 1:35000");
> map.maxExtent.bottom = 4553175.77681822;
> }
> else {
> map.maxExtent.bottom = 4554869.11353823;
> }
> map.setCenter(curcenter);
> });
>
> Any help appreciated.
>
> Many thanks,
Hi Robert, I don't feel very confident with tileOrigin and stuff, but
I think you might be interested to look at Layer/Zoomifiy.js. Zoomify
overrides calculateGridLayout to use left-top instead of left-bottom
as the tile origin. It may be that Grid assumes left-bottom, whatever
the value of tileOrigin in the layer. As I said, I'm not too sure
about all this but take my words with caution.
Good luck,
--
Eric Lemoine
Camptocamp France SAS
Savoie Technolac, BP 352
73377 Le Bourget du Lac, Cedex
Tel : 00 33 4 79 44 44 96
Mail : eric.lemo...@camptocamp.com
http://www.camptocamp.com
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