add numZoomLevels and maxResolution properties to the TileLayer

src/ol/layer/TileLayer.js

@@ -50,6 +50,18 @@ ol.layer.TileLayer = function() {
      */
     this.tileOriginCorner_ = 'bl';
 
+    /**
+     * @private
+     * @type {number|undefined}
+     */
+    this.maxResolution_ = undefined;
+
+    /**
+     * @private
+     * @type {number|undefined}
+     */
+    this.numZoomLevels_ = undefined;
+
     /**
      * @protected
      * @type {Array.<number>}
@@ -121,6 +133,20 @@ ol.layer.TileLayer.prototype.getTileOrigin = function() {
     return null;
 };
 
+/**
+ * Get layer resolutions. Return null if the layer has no resolutions.
+ * @return {Array.<number>}
+ */
+ol.layer.TileLayer.prototype.getResolutions = function() {
+    if (goog.isNull(this.resolutions_) && goog.isDef(this.maxResolution_)) {
+        this.resolutions_ = [];
+        for (var i = 0; i < this.numZoomLevels_; i++) {
+            this.resolutions_[i] = this.maxResolution_ / Math.pow(2, i);
+        }
+    }
+    return this.resolutions_;
+};
+
 /**
  * Set layer projection.
  * @param {ol.Projection} projection
@@ -165,6 +191,22 @@ ol.layer.TileLayer.prototype.setTileOriginCorner = function(tileOriginCorner) {
     this.tileOriginCorner_ = tileOriginCorner;
 };
 
+/**
+ * Set maximum resolution.
+ * @param {number} maxResolution
+ */
+ol.layer.TileLayer.prototype.setMaxResolution = function(maxResolution) {
+    this.maxResolution_ = maxResolution;
+};
+
+/**
+ * Set the number of zoom levels.
+ * @param {number} numZoomLevels
+ */
+ol.layer.TileLayer.prototype.setNumZoomLevels = function(numZoomLevels) {
+    this.numZoomLevels_ = numZoomLevels;
+};
+
 /**
  * Set resolutions for the layer.
  * @param {Array.<number>} resolutions

src/ol/layer/XYZ.js

@@ -24,16 +24,7 @@ ol.layer.XYZ = function(url) {
 
     goog.base(this);
 
-    this.setResolutions([
+    this.setMaxResolution(156543.03390625);
-        156543.03390625, 78271.516953125, 39135.7584765625,
-        19567.87923828125, 9783.939619140625, 4891.9698095703125,
-        2445.9849047851562, 1222.9924523925781, 611.4962261962891,
-        305.74811309814453, 152.87405654907226, 76.43702827453613,
-        38.218514137268066, 19.109257068634033, 9.554628534317017,
-        4.777314267158508, 2.388657133579254, 1.194328566789627,
-        0.5971642833948135, 0.29858214169740677, 0.14929107084870338,
-        0.07464553542435169
-    ]);
 };
 
 goog.inherits(ol.layer.XYZ, ol.layer.TileLayer);
@@ -45,8 +36,9 @@ goog.inherits(ol.layer.XYZ, ol.layer.TileLayer);
  */
 ol.layer.XYZ.prototype.getData = function(bounds, resolution) {
     var me = this,
-        zoom = me.zoomForResolution(resolution);
+        zoomAndRes = me.getZoomAndRes(resolution),
-    resolution = me.resolutions_[zoom];
+        zoom = zoomAndRes[0];
+    resolution = zoomAndRes[1];
 
     // define some values used for the actual tiling
     var boundsMinX = bounds.getMinX(),
@@ -88,7 +80,7 @@ ol.layer.XYZ.prototype.getData = function(bounds, resolution) {
                                        tileRight, tileTop, this.projection_);
             url = me.url_.replace('{x}', offsetX + x + '')
                          .replace('{y}', offsetY + y + '')
-                         .replace('{z}', zoom);
+                         .replace('{z}', zoom + '');
             tile = new ol.Tile(url, tileBounds);
             tiles[y][x] = tile;
         }
@@ -98,13 +90,15 @@ ol.layer.XYZ.prototype.getData = function(bounds, resolution) {
 };
 
 /**
- * Get the zoom level (z) for the given resolution.
+ * Get the zoom level (z) and layer resolution for the given resolution.
  * @param {number} resolution
+ * @return {Array.<number>}
  */
-ol.layer.XYZ.prototype.zoomForResolution = function(resolution) {
+ol.layer.XYZ.prototype.getZoomAndRes = function(resolution) {
     var delta = Number.POSITIVE_INFINITY,
         currentDelta,
-        resolutions = this.resolutions_;
+        resolutions = this.getResolutions(),
+        zoom;
     for (var i=resolutions.length-1; i>=0; --i) {
         currentDelta = Math.abs(resolutions[i] - resolution);
         if (currentDelta > delta) {
@@ -112,5 +106,6 @@ ol.layer.XYZ.prototype.zoomForResolution = function(resolution) {
         }
         delta = currentDelta;
     }
-    return i + 1;
+    zoom = i + 1;
+    return [zoom, resolutions[zoom]];
 };

test/spec/api/map.test.js

@@ -145,7 +145,7 @@ describe("ol.map", function() {
     
     it("provides feedback when you mess up", function() {
         var map;
-        if (ol.DEBUG) {
+        if (goog.DEBUG) {
             // misspelling
             expect(function() {
                 map = ol.map({

test/spec/ol/layer/TileLayer.test.js

@@ -16,7 +16,7 @@ describe('ol.layer.TileLayer', function() {
             layer = new ol.layer.TileLayer();
         });
 
-        describe('with tileOriginX and tileOriginY set', function() {
+        describe('with tileOriginX and tileOriginY', function() {
 
             beforeEach(function() {
                 layer.setTileOrigin(1, 2);
@@ -29,7 +29,7 @@ describe('ol.layer.TileLayer', function() {
 
         });
 
-        describe('with extent set', function() {
+        describe('with extent', function() {
 
             beforeEach(function() {
                 layer.setExtent(new ol.Bounds(-180, -90, 180, 90));
@@ -42,7 +42,7 @@ describe('ol.layer.TileLayer', function() {
 
         });
 
-        describe('with extent and tileOriginCorner set', function() {
+        describe('with tileOriginCorner and extent', function() {
 
             beforeEach(function() {
                 layer.setExtent(new ol.Bounds(-180, -90, 180, 90));
@@ -56,6 +56,81 @@ describe('ol.layer.TileLayer', function() {
 
         });
 
+        describe('with tileOriginCorner, without extent', function() {
+
+            beforeEach(function() {
+                layer.setTileOriginCorner('tr');
+            });
+
+            it('throws an error or return null', function() {
+                var origin;
+                if (goog.DEBUG) {
+                    expect(function() {
+                        origin = layer.getTileOrigin();
+                    }).toThrow();
+                } else {
+                    expect(function() {
+                        origin = layer.getTileOrigin();
+                    }).not.toThrow();
+                    expect(origin).toBeNull();
+                }
+            });
+
+        });
+
+        describe('with bad tileOriginCorner', function() {
+
+            beforeEach(function() {
+                layer.setTileOriginCorner('foo');
+            });
+
+            it('returns the expected origin', function() {
+                if (goog.DEBUG) {
+                    expect(function() {
+                        var origin = layer.getTileOrigin();
+                    }).toThrow();
+                } else {
+                    expect(function() {
+                        var origin = layer.getTileOrigin();
+                    }).not.toThrow();
+                }
+            });
+
+        });
     });
 
+    describe('get resolutions', function() {
+        var layer;
+
+        beforeEach(function() {
+            layer = new ol.layer.TileLayer();
+        });
+
+        describe('with resolutions set', function() {
+
+            beforeEach(function() {
+                layer.setResolutions([1, 0.5, 0.25]);
+            });
+
+            it('returns the expected resolutions', function() {
+                var resolutions = layer.getResolutions();
+                expect(resolutions).toEqual([1, 0.5, 0.25]);
+            });
+
+        });
+
+        describe('with maxResolution and numZoomLevels set', function() {
+
+            beforeEach(function() {
+                layer.setMaxResolution(1);
+                layer.setNumZoomLevels(3);
+            });
+
+            it('returns the expected resolutions', function() {
+                var resolutions = layer.getResolutions();
+                expect(resolutions).toEqual([1, 0.5, 0.25]);
+            });
+
+        });
+    });
 });