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,
Robert Sanson
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