Refactor tile functions

* Add support for minZoom in XYZ tile grids and tile sources
* Factor out common tile coordinate transforms

src/ol/source/bingmapssource.js

@@ -3,11 +3,9 @@ goog.provide('ol.source.BingMaps');
 goog.require('goog.Uri');
 goog.require('goog.array');
 goog.require('goog.asserts');
-goog.require('goog.math');
 goog.require('goog.net.Jsonp');
 goog.require('ol.Attribution');
 goog.require('ol.Size');
-goog.require('ol.TileCoord');
 goog.require('ol.TileRange');
 goog.require('ol.TileUrlFunction');
 goog.require('ol.extent');
@@ -72,30 +70,17 @@ ol.source.BingMaps.prototype.handleImageryMetadataResponse =
   goog.asserts.assert(resourceSet.resources.length == 1);
   var resource = resourceSet.resources[0];
 
-  var zoomMin = resource.zoomMin;
-  var zoomMax = resource.zoomMax;
   var tileSize = new ol.Size(resource.imageWidth, resource.imageHeight);
   var tileGrid = new ol.tilegrid.XYZ({
-    maxZoom: zoomMax,
+    minZoom: resource.zoomMin,
+    maxZoom: resource.zoomMax,
     tileSize: tileSize
   });
   this.tileGrid = tileGrid;
 
   var culture = this.culture_;
   this.tileUrlFunction = ol.TileUrlFunction.withTileCoordTransform(
-      function(tileCoord) {
-        if (tileCoord.z < zoomMin || zoomMax < tileCoord.z) {
-          return null;
-        }
-        var n = 1 << tileCoord.z;
-        var y = -tileCoord.y - 1;
-        if (y < 0 || n <= y) {
-          return null;
-        } else {
-          var x = goog.math.modulo(tileCoord.x, n);
-          return new ol.TileCoord(tileCoord.z, x, y);
-        }
-      },
+      tileGrid.createTileCoordTransform(),
       ol.TileUrlFunction.createFromTileUrlFunctions(
           goog.array.map(
               resource.imageUrlSubdomains,

src/ol/source/tilejsonsource.js

@@ -1,6 +1,5 @@
 // FIXME add some error checking
 // FIXME check order of async callbacks
-// FIXME use minzoom when supported
 
 /**
  * @see http://mapbox.com/developers/api/
@@ -10,10 +9,8 @@ goog.provide('ol.source.TileJSON');
 goog.provide('ol.tilejson');
 
 goog.require('goog.asserts');
-goog.require('goog.math');
 goog.require('goog.net.jsloader');
 goog.require('ol.Attribution');
-goog.require('ol.TileCoord');
 goog.require('ol.TileRange');
 goog.require('ol.TileUrlFunction');
 goog.require('ol.extent');
@@ -77,17 +74,14 @@ ol.source.TileJSON.prototype.handleTileJSONResponse = function() {
 
   var epsg4326Projection = ol.projection.get('EPSG:4326');
 
-  var epsg4326Extent, extent;
+  var extent;
   if (goog.isDef(tileJSON.bounds)) {
     var bounds = tileJSON.bounds;
-    epsg4326Extent = [bounds[0], bounds[2], bounds[1], bounds[3]];
+    var epsg4326Extent = [bounds[0], bounds[2], bounds[1], bounds[3]];
     var transform = ol.projection.getTransformFromProjections(
         epsg4326Projection, this.getProjection());
     extent = ol.extent.transform(epsg4326Extent, transform);
     this.setExtent(extent);
-  } else {
-    epsg4326Extent = null;
-    extent = null;
   }
 
   var scheme = goog.isDef(tileJSON.scheme) || 'xyz';
@@ -95,38 +89,22 @@ ol.source.TileJSON.prototype.handleTileJSONResponse = function() {
     goog.asserts.assert(tileJSON.scheme == 'xyz');
   }
   var minZoom = tileJSON.minzoom || 0;
-  goog.asserts.assert(minZoom === 0); // FIXME
   var maxZoom = tileJSON.maxzoom || 22;
   var tileGrid = new ol.tilegrid.XYZ({
-    maxZoom: maxZoom
+    maxZoom: maxZoom,
+    minZoom: minZoom
   });
   this.tileGrid = tileGrid;
 
   this.tileUrlFunction = ol.TileUrlFunction.withTileCoordTransform(
-      function(tileCoord) {
-        if (tileCoord.z < minZoom || maxZoom < tileCoord.z) {
-          return null;
-        }
-        var n = 1 << tileCoord.z;
-        var y = -tileCoord.y - 1;
-        if (y < 0 || n <= y) {
-          return null;
-        }
-        var x = goog.math.modulo(tileCoord.x, n);
-        if (!goog.isNull(extent)) {
-          var tileExtent = tileGrid.getTileCoordExtent(
-              new ol.TileCoord(tileCoord.z, x, tileCoord.y));
-          if (!ol.extent.intersects(tileExtent, extent)) {
-            return null;
-          }
-        }
-        return new ol.TileCoord(tileCoord.z, x, y);
-      },
+      tileGrid.createTileCoordTransform({
+        extent: extent
+      }),
       ol.TileUrlFunction.createFromTemplates(tileJSON.tiles));
 
   if (goog.isDef(tileJSON.attribution)) {
-    var attributionExtent = goog.isNull(extent) ?
-        epsg4326Projection.getExtent() : extent;
+    var attributionExtent = goog.isDef(extent) ?
+        extent : epsg4326Projection.getExtent();
     /** @type {Object.<string, Array.<ol.TileRange>>} */
     var tileRanges = {};
     var z, zKey;

src/ol/source/xyzsource.js

@@ -1,15 +1,10 @@
-// FIXME add minZoom support
-
 goog.provide('ol.source.XYZ');
 goog.provide('ol.source.XYZOptions');
 
-goog.require('goog.math');
 goog.require('ol.Attribution');
 goog.require('ol.Projection');
-goog.require('ol.TileCoord');
 goog.require('ol.TileUrlFunction');
 goog.require('ol.TileUrlFunctionType');
-goog.require('ol.extent');
 goog.require('ol.projection');
 goog.require('ol.source.ImageTileSource');
 goog.require('ol.tilegrid.XYZ');
@@ -21,6 +16,7 @@ goog.require('ol.tilegrid.XYZ');
  *            extent: (ol.Extent|undefined),
  *            logo: (string|undefined),
  *            maxZoom: number,
+ *            minZoom: (number|undefined),
  *            projection: (ol.Projection|undefined),
  *            tileUrlFunction: (ol.TileUrlFunctionType|undefined),
  *            url: (string|undefined),
@@ -54,55 +50,16 @@ ol.source.XYZ = function(options) {
   }
 
   var tileGrid = new ol.tilegrid.XYZ({
-    maxZoom: options.maxZoom
+    maxZoom: options.maxZoom,
+    minZoom: options.minZoom
   });
 
-  // FIXME factor out common code
-  if (goog.isDef(options.extent)) {
+  var tileCoordTransform = tileGrid.createTileCoordTransform({
+    extent: options.extent
+  });
 
-    var extent = options.extent;
-    var tmpExtent = ol.extent.createEmptyExtent();
-    var tmpTileCoord = new ol.TileCoord(0, 0, 0);
-    tileUrlFunction = ol.TileUrlFunction.withTileCoordTransform(
-        function(tileCoord) {
-          if (options.maxZoom < tileCoord.z) {
-            return null;
-          }
-          var n = 1 << tileCoord.z;
-          var y = -tileCoord.y - 1;
-          if (y < 0 || n <= y) {
-            return null;
-          }
-          var x = goog.math.modulo(tileCoord.x, n);
-          tmpTileCoord.z = tileCoord.z;
-          tmpTileCoord.x = x;
-          tmpTileCoord.y = tileCoord.y;
-          var tileExtent = tileGrid.getTileCoordExtent(tmpTileCoord, tmpExtent);
-          if (!ol.extent.intersects(tileExtent, extent)) {
-            return null;
-          }
-          return new ol.TileCoord(tileCoord.z, x, y);
-        },
-        tileUrlFunction);
-
-  } else {
-
-    tileUrlFunction = ol.TileUrlFunction.withTileCoordTransform(
-        function(tileCoord) {
-          if (options.maxZoom < tileCoord.z) {
-            return null;
-          }
-          var n = 1 << tileCoord.z;
-          var y = -tileCoord.y - 1;
-          if (y < 0 || n <= y) {
-            return null;
-          } else {
-            var x = goog.math.modulo(tileCoord.x, n);
-            return new ol.TileCoord(tileCoord.z, x, y);
-          }
-        },
-        tileUrlFunction);
-  }
+  tileUrlFunction = ol.TileUrlFunction.withTileCoordTransform(
+      tileCoordTransform, tileUrlFunction);
 
   goog.base(this, {
     attributions: options.attributions,