add TileLayerRenderer.getPreferredZ_ plus tests

src/ol/dom/tilelayerrenderer_test.js

@@ -0,0 +1,73 @@
+goog.require('goog.dom');
+goog.require('goog.dom.TagName');
+goog.require('goog.testing.jsunit');
+goog.require('ol.Coordinate');
+goog.require('ol.Extent');
+goog.require('ol.Projection');
+goog.require('ol.TileGrid');
+goog.require('ol.TileLayer');
+goog.require('ol.TileStore');
+goog.require('ol.TileUrlFunction');
+goog.require('ol.dom.Map');
+goog.require('ol.dom.TileLayerRenderer');
+
+
+var tileLayerRenderer;
+
+
+function setUp() {
+  var map = new ol.dom.Map(
+      goog.dom.createElement(goog.dom.TagName.DIV));
+
+  var resolutions = [100, 80, 50, 10, 1, 0.1];
+  var extent = new ol.Extent(0, 0, 100000, 100000);
+  var origin = new ol.Coordinate(0, 0);
+  var tileGrid = new ol.TileGrid(resolutions, extent, origin);
+
+  var projection = ol.Projection.getFromCode('EPSG:3857');
+  var tileUrlFunction = ol.TileUrlFunction.createFromTemplate('{z}/{x}/{y}');
+  var tileStore = new ol.TileStore(projection, tileGrid, tileUrlFunction);
+
+  var tileLayer = new ol.TileLayer(tileStore);
+
+  tileLayerRenderer = new ol.dom.TileLayerRenderer(
+      map, tileLayer,
+      goog.dom.createElement(goog.dom.TagName.DIV));
+}
+
+
+function testGetPreferredZ() {
+
+  var z;
+
+  // gets the max resolution.
+  z = tileLayerRenderer.getPreferredZ_(100);
+  assertEquals(0, z);
+
+  // gets the min resolution.
+  z = tileLayerRenderer.getPreferredZ_(0.1);
+  assertEquals(5, z);
+
+  // gets the max when bigger.
+  z = tileLayerRenderer.getPreferredZ_(200);
+  assertEquals(0, z);
+
+  // gets the min when smaller.
+  z = tileLayerRenderer.getPreferredZ_(0.01);
+  assertEquals(5, z);
+
+  // gets the first when in the middle.
+  z = tileLayerRenderer.getPreferredZ_(90);
+  assertEquals(0, z);
+
+  // gets the closer when elsewhere.
+
+  z = tileLayerRenderer.getPreferredZ_(89);
+  assertEquals(1, z);
+
+  z = tileLayerRenderer.getPreferredZ_(49);
+  assertEquals(2, z);
+
+  z = tileLayerRenderer.getPreferredZ_(0.5);
+  assertEquals(5, z);
+}