Make the resolution constraint configurable through map options

src/ol/mapoptions.js

@@ -1,3 +1,5 @@
+// FIXME rotation constraint is not configurable at the moment
+
 goog.provide('ol.MapOptions');
 goog.provide('ol.MapOptionsLiteral');
 goog.provide('ol.MapOptionsType');
@@ -171,9 +173,27 @@ ol.MapOptions.create = function(mapOptionsLiteral) {
  * @return {ol.Constraints} Map constraints.
  */
 ol.MapOptions.createConstraints_ = function(mapOptionsLiteral) {
-  // FIXME this should be configurable
+  var resolutionConstraint;
-  var resolutionConstraint = ol.ResolutionConstraint.createSnapToPower(
+  if (goog.isDef(mapOptionsLiteral.resolutions)) {
-      Math.exp(Math.log(2) / 4), ol.Projection.EPSG_3857_HALF_SIZE / 128);
+    resolutionConstraint = ol.ResolutionConstraint.createSnapToResolutions(
+        mapOptionsLiteral.resolutions);
+  } else {
+    var maxResolution, numZoomLevels, zoomFactor;
+    if (goog.isDef(mapOptionsLiteral.maxResolution) &&
+        goog.isDef(mapOptionsLiteral.numZoomLevels) &&
+        goog.isDef(mapOptionsLiteral.zoomFactor)) {
+      maxResolution = mapOptionsLiteral.maxResolution;
+      numZoomLevels = mapOptionsLiteral.numZoomLevels;
+      zoomFactor = mapOptionsLiteral.zoomFactor;
+    } else {
+      maxResolution = ol.Projection.EPSG_3857_HALF_SIZE / 128;
+      numZoomLevels = 29;
+      zoomFactor = Math.exp(Math.log(2) / 4);
+    }
+    resolutionConstraint = ol.ResolutionConstraint.createSnapToPower(
+        zoomFactor, maxResolution, numZoomLevels - 1);
+  }
+  // FIXME rotation constraint is not configurable at the moment
   var rotationConstraint = ol.RotationConstraint.none;
   return new ol.Constraints(resolutionConstraint, rotationConstraint);
 };

test/ol.html

@@ -76,6 +76,7 @@
   <script type="text/javascript" src="spec/ol/object.test.js"></script>
   <script type="text/javascript" src="spec/ol/tilecoord.test.js"></script>
   <script type="text/javascript" src="spec/ol/tilegrid.test.js"></script>
+  <script type="text/javascript" src="spec/ol/mapoptions.test.js"></script>
   <script type="text/javascript" src="spec/ol/projection.test.js"></script>
   <script type="text/javascript" src="spec/ol/rectangle.test.js"></script>
   <script type="text/javascript" src="spec/ol/tilerange.test.js"></script>

test/spec/ol/mapoptions.test.js

@@ -0,0 +1,54 @@
+goog.require('ol.MapOptions');
+
+describe('ol.MapOptions', function() {
+
+  describe('create constraints', function() {
+
+    describe('create resolution constraint', function() {
+
+      describe('with no options', function() {
+        it('gives a correct resolution constraint function', function() {
+          var options = {};
+          var fn = ol.MapOptions.createConstraints_(options).resolution;
+          expect(fn(156543.03392804097, 0))
+              .toRoughlyEqual(156543.03392804097, 1e-9);
+          expect(fn(78271.51696402048, 0))
+              .toRoughlyEqual(78271.51696402048, 1e-10);
+        });
+      });
+
+      describe('with maxResolution, numZoomLevels, and zoomFactor options',
+          function() {
+        it('gives a correct resolution constraint function', function() {
+          var options = {
+            maxResolution: 81,
+            numZoomLevels: 4,
+            zoomFactor: 3
+          };
+          var fn = ol.MapOptions.createConstraints_(options).resolution;
+          expect(fn(82, 0)).toEqual(81);
+          expect(fn(81, 0)).toEqual(81);
+          expect(fn(27, 0)).toEqual(27);
+          expect(fn(9, 0)).toEqual(9);
+          expect(fn(3, 0)).toEqual(3);
+          expect(fn(2, 0)).toEqual(3);
+        });
+      });
+
+      describe('with resolutions', function() {
+        it('gives a correct resolution constraint function', function() {
+          var options = {
+            resolutions: [97, 76, 65, 54, 0.45]
+          };
+          var fn = ol.MapOptions.createConstraints_(options).resolution;
+          expect(fn(97, 0), 97);
+          expect(fn(76, 0), 76);
+          expect(fn(65, 0), 65);
+          expect(fn(54, 0), 54);
+          expect(fn(0.45, 0), 0.45);
+        });
+      });
+
+    });
+  });
+});