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Adding a zoomOffset property to XYZ and TMS layers. This allows you to have a map with a maximum resolution that differs from the maximum cache resolution (if you want to show a subset of OSM for example). r=ahocevar (closes #2616)

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git-svn-id: http://svn.openlayers.org/trunk/openlayers@10650 dc9f47b5-9b13-0410-9fdd-eb0c1a62fdaf
This commit is contained in:
Tim Schaub
2010-08-20 19:40:53 +00:00
parent 5750b5f6e0
commit 59953b8eb6
6 changed files with 192 additions and 2 deletions
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33
examples/xyz-offset.html Normal file
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@@ -0,0 +1,33 @@
<!DOCTYPE HTML>
<html>
<head>
<title>OpenLayers XYZ with Offset</title>
<link rel="stylesheet" href="../theme/default/style.css" type="text/css" />
<link rel="stylesheet" href="style.css" type="text/css" />
<script src="../lib/OpenLayers.js"></script>
<script src="xyz-offset.js"></script>
</head>
<body onload="init()">
<h1 id="title">XYZ Layer with Offset</h1>
<div id="shortdesc">Using a limited set of levels from an XYZ layer with zoomOffset.</div>
<div id="map" class="smallmap"></div>
<div id="docs">
<p>
The XYZ layer allows a zoomOffset to be set if you want to have
a maximum resolution for the map that differs from the maxiumum
resolution of the cached tiles. This example uses only 6 of the
levels in the cache, starting with the ninth level (index of 8)
in the cache. To do this, the layer is constructed with a
zoomOffset of 8. When the map zoom level is zero, the level
with index 8 will be requested from the cache.
</p>
<p>
See the <a href="xyz-offset.js" target="_blank">
xyz-offset.js source</a> to see how this is done.
</p>
</div>
</body>
</html>

37
examples/xyz-offset.js Normal file
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@@ -0,0 +1,37 @@
var map, layer;
// if tiles are not available, hide images
//OpenLayers.Util.onImageLoadError = function() {
// this.style.display = "none";
//}
// called on body load
function init() {
var extent = new OpenLayers.Bounds(
-13758743.4295939, 5591455.28887228, -13531302.3472101 , 5757360.4178881
);
map = new OpenLayers.Map({
div: "map",
maxExtent: new OpenLayers.Bounds(
-128 * 156543.0339, -128 * 156543.0339,
128 * 156543.0339, 128 * 156543.0339
),
restrictedExtent: extent,
maxResolution: 611.496226171875, // corresponds to level 8 in the cache
numZoomLevels: 6,
projection: new OpenLayers.Projection("EPSG:900913"),
units: "m",
layers: [
new OpenLayers.Layer.XYZ(
"ESRI",
"http://sampleserver1.arcgisonline.com/ArcGIS/rest/services/Portland/ESRI_LandBase_WebMercator/MapServer/tile/${z}/${y}/${x}",
{zoomOffset: 8} // since our map maxResolution differs from cache max resolution
)
]
});
map.zoomToExtent(extent);
}

16
lib/OpenLayers/Layer/TMS.js
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@@ -41,6 +41,20 @@ OpenLayers.Layer.TMS = OpenLayers.Class(OpenLayers.Layer.Grid, {
*/
serverResolutions: null,
/**
* APIProperty: zoomOffset
* {Number} If your cache has more zoom levels than you want to provide
* access to with this layer, supply a zoomOffset. This zoom offset
* is added to the current map zoom level to determine the level
* for a requested tile. For example, if you supply a zoomOffset
* of 3, when the map is at the zoom 0, tiles will be requested from
* level 3 of your cache. Default is 0 (assumes cache level and map
* zoom are equivalent). Using <zoomOffset> is an alternative to
* setting <serverResolutions> if you only want to expose a subset
* of the server resolutions.
*/
zoomOffset: 0,
/**
* Constructor: OpenLayers.Layer.TMS
*
@@ -107,7 +121,7 @@ OpenLayers.Layer.TMS = OpenLayers.Class(OpenLayers.Layer.Grid, {
var y = Math.round((bounds.bottom - this.tileOrigin.lat) / (res * this.tileSize.h));
var z = this.serverResolutions != null ?
OpenLayers.Util.indexOf(this.serverResolutions, res) :
this.map.getZoom();
this.map.getZoom() + this.zoomOffset;
var path = this.serviceVersion + "/" + this.layername + "/" + z + "/" + x + "/" + y + "." + this.type;
var url = this.url;
if (url instanceof Array) {

14
lib/OpenLayers/Layer/XYZ.js
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@@ -31,6 +31,18 @@ OpenLayers.Layer.XYZ = OpenLayers.Class(OpenLayers.Layer.Grid, {
*/
sphericalMercator: false,
/**
* APIProperty: zoomOffset
* {Number} If your cache has more zoom levels than you want to provide
* access to with this layer, supply a zoomOffset. This zoom offset
* is added to the current map zoom level to determine the level
* for a requested tile. For example, if you supply a zoomOffset
* of 3, when the map is at the zoom 0, tiles will be requested from
* level 3 of your cache. Default is 0 (assumes cache level and map
* zoom are equivalent).
*/
zoomOffset: 0,
/**
* Constructor: OpenLayers.Layer.XYZ
*
@@ -101,7 +113,7 @@ OpenLayers.Layer.XYZ = OpenLayers.Class(OpenLayers.Layer.Grid, {
/ (res * this.tileSize.w));
var y = Math.round((this.maxExtent.top - bounds.top)
/ (res * this.tileSize.h));
var z = this.map.getZoom();
var z = this.map.getZoom() + this.zoomOffset;
var url = this.url;
var s = '' + x + y + z;

53
tests/Layer/TMS.html
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@@ -166,6 +166,59 @@
map.destroy();
}
function test_zoomOffset(t) {
t.plan(2);
var offset, zoom;
// test offset of 2
offset = 2;
zoom = 3;
var map = new OpenLayers.Map({
div: "map",
maxResolution: OpenLayers.Map.prototype.maxResolution / Math.pow(2, offset)
});
var layer = new OpenLayers.Layer.TMS("TMS", "", {
layername: "basic",
type: "png",
zoomOffset: offset
});
map.addLayer(layer);
map.setCenter(new OpenLayers.LonLat(0, 0), zoom);
var tileurl = layer.getURL(new OpenLayers.Bounds(3.515625,45,4.21875,45.703125));
level = parseInt(tileurl.split("/")[2]);
t.eq(parseInt(tileurl.split("/")[2]), zoom + offset, "correct level for offset 2");
map.destroy();
// test offset of -1
offset = -1;
zoom = 3;
var map = new OpenLayers.Map({
div: "map",
maxResolution: OpenLayers.Map.prototype.maxResolution / Math.pow(2, offset)
});
var layer = new OpenLayers.Layer.TMS("TMS", "", {
layername: "basic",
type: "png",
zoomOffset: offset
});
map.addLayer(layer);
map.setCenter(new OpenLayers.LonLat(0, 0), zoom);
var tileurl = layer.getURL(new OpenLayers.Bounds(3.515625,45,4.21875,45.703125));
level = parseInt(tileurl.split("/")[2]);
t.eq(parseInt(tileurl.split("/")[2]), zoom + offset, "correct level for offset -1");
map.destroy();
}
function test_Layer_TMS_setMap(t) {
t.plan(3);

41
tests/Layer/XYZ.html
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@@ -148,6 +148,47 @@
map.destroy();
}
function test_zoomOffset(t) {
t.plan(2);
var offset;
// test offset of 2
offset = 2;
var map = new OpenLayers.Map({
div: "map",
maxResolution: OpenLayers.Map.prototype.maxResolution / Math.pow(2, offset)
});
var layer = new OpenLayers.Layer.XYZ(name, url, {zoomOffset: offset});
map.addLayer(layer);
map.setCenter(new OpenLayers.LonLat(0,0), 7);
var tileurl = layer.getURL(new OpenLayers.Bounds(3.515625,45,4.21875,45.703125));
t.eq(tileurl, "http://labs.metacarta.com/wms-c/Basic.py/1.0.0/basic/9/261/63.png", "correct URL for offset of 2");
map.destroy();
// test offset of -1
offset = -1;
var map = new OpenLayers.Map({
div: "map",
maxResolution: OpenLayers.Map.prototype.maxResolution / Math.pow(2, offset)
});
var layer = new OpenLayers.Layer.XYZ(name, url, {zoomOffset: offset});
map.addLayer(layer);
map.setCenter(new OpenLayers.LonLat(0,0), 10);
var tileurl = layer.getURL(new OpenLayers.Bounds(3.515625,45,4.21875,45.703125));
t.eq(tileurl, "http://labs.metacarta.com/wms-c/Basic.py/1.0.0/basic/9/261/63.png", "correct URL for offset of -1");
map.destroy();
}
function test_Layer_XYZ_destroy (t) {
t.plan( 3 );