Making extent optional for projections

The projection validity extent is used to generate a sensible
set of default resolutions and a sensible default tile grid.
By making it optional, we can still generate defaults - with
zoom levels that are similar to the default web mercator zoom
levels (based on fitting the world on a single tile, even if the
projection is not available for the whole world).

src/objectliterals.jsdoc

@@ -68,7 +68,7 @@
  * Object literal with config options for the Proj4js projection.
  * @typedef {Object} ol.Proj4jsProjectionOptions
  * @property {string} code The SRS identifier code, e.g. 'EPSG:31256'.
- * @property {ol.Extent} extent The validity extent for the SRS.
+ * @property {ol.Extent|undefined} extent The validity extent for the SRS.
  * @property {boolean|undefined} global Whether the projection is valid for the
  *     whole globe. Default is false.
  */
@@ -78,7 +78,7 @@
  * @typedef {Object} ol.ProjectionOptions
  * @property {string} code The SRS identifier code, e.g. 'EPSG:4326'.
  * @property {ol.ProjectionUnits} units Units.
- * @property {ol.Extent} extent The validity extent for the SRS.
+ * @property {ol.Extent|undefined} extent The validity extent for the SRS.
  * @property {string|undefined} axisOrientation The axis orientation as
  *     specified in Proj4. The default is 'enu'.
  * @property {boolean|undefined} global Whether the projection is valid for the
@@ -89,6 +89,8 @@
  * Object literal with config options for the view.
  * @typedef {Object} ol.View2DOptions
  * @property {ol.Coordinate|undefined} center The view center in map projection.
+ * @property {ol.Extent|undefined} maxExtent The maximum extent for the view.
+ *     If configured, the view's center cannot be outside this extent.
  * @property {number|undefined} maxResolution The maximum resolution in map
  *     units per pixel.
  * @property {number|undefined} maxZoom The maximum zoom level for this view.

src/ol/proj/proj.js

@@ -74,7 +74,7 @@ ol.Projection = function(options) {
    * @private
    * @type {ol.Extent}
    */
-  this.extent_ = options.extent;
+  this.extent_ = goog.isDef(options.extent) ? options.extent : null;
 
   /**
    * @private

src/ol/tilegrid/tilegrid.js

@@ -4,6 +4,7 @@ goog.require('goog.array');
 goog.require('goog.asserts');
 goog.require('ol.Coordinate');
 goog.require('ol.Projection');
+goog.require('ol.ProjectionUnits');
 goog.require('ol.Size');
 goog.require('ol.TileCoord');
 goog.require('ol.TileRange');
@@ -410,21 +411,23 @@ ol.tilegrid.getForProjection = function(projection) {
 ol.tilegrid.createForProjection =
     function(projection, opt_maxZoom, opt_tileSize) {
   var projectionExtent = projection.getExtent();
-  var size = Math.max(
-      projectionExtent[1] - projectionExtent[0],
-      projectionExtent[3] - projectionExtent[2]);
+  var size = goog.isNull(projectionExtent) ?
+      360 * ol.METERS_PER_UNIT[ol.ProjectionUnits.DEGREES] /
+          ol.METERS_PER_UNIT[projection.getUnits()] :
+      Math.max(projectionExtent[1] - projectionExtent[0],
+          projectionExtent[3] - projectionExtent[2]);
   var maxZoom = goog.isDef(opt_maxZoom) ?
       opt_maxZoom : ol.DEFAULT_MAX_ZOOM;
   var tileSize = goog.isDef(opt_tileSize) ?
       opt_tileSize : [ol.DEFAULT_TILE_SIZE, ol.DEFAULT_TILE_SIZE];
   var resolutions = new Array(maxZoom + 1);
-  goog.asserts.assert(tileSize[0] == tileSize[1]);
-  size = size / tileSize[0];
+  size = size / Math.max(tileSize[0], tileSize[1]);
   for (var z = 0, zz = resolutions.length; z < zz; ++z) {
     resolutions[z] = size / Math.pow(2, z);
   }
   return new ol.tilegrid.TileGrid({
-    origin: ol.extent.getBottomLeft(projectionExtent),
+    origin: goog.isNull(projectionExtent) ? [0, 0] :
+        ol.extent.getBottomLeft(projectionExtent),
     resolutions: resolutions,
     tileSize: tileSize
   });

src/ol/view2d.js

@@ -4,10 +4,12 @@ goog.provide('ol.View2D');
 goog.provide('ol.View2DProperty');
 
 goog.require('goog.asserts');
+goog.require('goog.math');
 goog.require('ol.Constraints');
 goog.require('ol.IView2D');
 goog.require('ol.IView3D');
 goog.require('ol.Projection');
+goog.require('ol.ProjectionUnits');
 goog.require('ol.ResolutionConstraint');
 goog.require('ol.RotationConstraint');
 goog.require('ol.RotationConstraintType');
@@ -57,18 +59,12 @@ ol.View2D = function(opt_options) {
       options.center : null;
   values[ol.View2DProperty.PROJECTION] = ol.proj.createProjection(
       options.projection, 'EPSG:3857');
-  if (goog.isDef(options.resolution)) {
-    values[ol.View2DProperty.RESOLUTION] = options.resolution;
-  } else if (goog.isDef(options.zoom)) {
-    var projectionExtent = values[ol.View2DProperty.PROJECTION].getExtent();
-    var size = Math.max(
-        projectionExtent[1] - projectionExtent[0],
-        projectionExtent[3] - projectionExtent[2]);
-    values[ol.View2DProperty.RESOLUTION] =
-        size / (ol.DEFAULT_TILE_SIZE * Math.pow(2, options.zoom));
-  }
-  values[ol.View2DProperty.ROTATION] = options.rotation;
-  this.setValues(values);
+
+  /**
+   * @private
+   * @type {ol.Extent}
+   */
+  this.maxExtent_ = goog.isDef(options.maxExtent) ? options.maxExtent : null;
 
   var parts = ol.View2D.createResolutionConstraint_(options);
 
@@ -94,6 +90,14 @@ ol.View2D = function(opt_options) {
   this.constraints_ = new ol.Constraints(resolutionConstraint,
       rotationConstraint);
 
+  if (goog.isDef(options.resolution)) {
+    values[ol.View2DProperty.RESOLUTION] = options.resolution;
+  } else if (goog.isDef(options.zoom)) {
+    values[ol.View2DProperty.RESOLUTION] = resolutionConstraint(
+        this.maxResolution_, options.zoom);
+  }
+  values[ol.View2DProperty.ROTATION] = options.rotation;
+  this.setValues(values);
 };
 goog.inherits(ol.View2D, ol.View);
 
@@ -355,7 +359,10 @@ ol.View2D.prototype.isDef = function() {
  * @param {ol.Coordinate|undefined} center Center.
  */
 ol.View2D.prototype.setCenter = function(center) {
-  this.set(ol.View2DProperty.CENTER, center);
+  this.set(ol.View2DProperty.CENTER, goog.isNull(this.maxExtent_) ? center : [
+    goog.math.clamp(center[0], this.maxExtent_[0], this.maxExtent_[1]),
+    goog.math.clamp(center[1], this.maxExtent_[2], this.maxExtent_[3])
+  ]);
 };
 goog.exportProperty(
     ol.View2D.prototype,
@@ -421,11 +428,16 @@ ol.View2D.createResolutionConstraint_ = function(options) {
   } else {
     maxResolution = options.maxResolution;
     if (!goog.isDef(maxResolution)) {
-      var projectionExtent = ol.proj.createProjection(
-          options.projection, 'EPSG:3857').getExtent();
-      maxResolution = Math.max(
-          projectionExtent[1] - projectionExtent[0],
-          projectionExtent[3] - projectionExtent[2]) / ol.DEFAULT_TILE_SIZE;
+      var projection = options.projection;
+      var projectionExtent = ol.proj.createProjection(projection, 'EPSG:3857')
+          .getExtent();
+      var size = goog.isNull(projectionExtent) ?
+          // use an extent that can fit the whole world if need be
+          360 * ol.METERS_PER_UNIT[ol.ProjectionUnits.DEGREES] /
+              ol.METERS_PER_UNIT[projection.getUnits()] :
+          Math.max(projectionExtent[1] - projectionExtent[0],
+              projectionExtent[3] - projectionExtent[2]);
+      maxResolution = size / ol.DEFAULT_TILE_SIZE;
     }
     var maxZoom = options.maxZoom;
     if (!goog.isDef(maxZoom)) {