The shared vertices structure now works with integer arrays only

Previously, a lookup object containing start indexes was also used.  This allowed us to remove arrays of vertices and properly update the start indexes for remaining coordinate values.  In order to provide callers with stable identifiers and to work with arrays of integers alone, we cannot support a remove method.  I think this is worth revisiting.  Even if the array length cannot be changed in WebGL, we don't need to also impose the restriction outside.  Instead, the WebGL renderer could be notified when array sizes change and update itself accordingly.  I think there is more value in providing geometries with stable identifiers.

This common structure is used to store vertices for all geometry types.  A slight optimization could be made by creating yet another structure to store point vertices - since these don't need to have a counts array (always 1).  Creating a new structure would mean saving memory at the expense of more lib code to transport.  The coordinate value lookups are not negatively impacted by using the same structure for points and higher order geometries.  Since the first change above goes against my instincts, I'm not making this second change (to add another structure for shared point vertices).

src/ol/geom/linestring.js

@@ -34,7 +34,7 @@ ol.geom.LineString = function(coordinates, opt_shared) {
   this.vertices = vertices;
 
   /**
-   * @type {string}
+   * @type {number}
    * @private
    */
   this.sharedId_ = vertices.add(coordinates);
@@ -142,7 +142,7 @@ ol.geom.LineString.prototype.getType = function() {
 
 /**
  * Get the identifier used to mark this line in the shared vertices structure.
- * @return {string} The identifier.
+ * @return {number} The identifier.
  */
 ol.geom.LineString.prototype.getSharedId = function() {
   return this.sharedId_;

src/ol/geom/point.js

@@ -32,7 +32,7 @@ ol.geom.Point = function(coordinates, opt_shared) {
   this.vertices = vertices;
 
   /**
-   * @type {string}
+   * @type {number}
    * @private
    */
   this.sharedId_ = vertices.add([coordinates]);
@@ -98,7 +98,7 @@ ol.geom.Point.prototype.getType = function() {
 
 /**
  * Get the identifier used to mark this point in the shared vertices structure.
- * @return {string} The identifier.
+ * @return {number} The identifier.
  */
 ol.geom.Point.prototype.getSharedId = function() {
   return this.sharedId_;

src/ol/geom/sharedvertices.js

@@ -20,19 +20,25 @@ ol.geom.SharedVerticesOptions;
  * @param {ol.geom.SharedVerticesOptions=} opt_options Shared vertices options.
  */
 ol.geom.SharedVertices = function(opt_options) {
-  var options = goog.isDef(opt_options) ? opt_options : {};
+  var options = opt_options ? opt_options : {};
-
-  /**
-   * @type {number}
-   * @private
-   */
-  this.counter_ = 0;
 
   /**
    * @type {Array.<number>}
    */
   this.coordinates = [];
 
+  /**
+   * @type {Array.<number>}
+   * @private
+   */
+  this.starts_ = [];
+
+  /**
+   * @type {Array.<number>}
+   * @private
+   */
+  this.counts_ = [];
+
   /**
    * Number of dimensions per vertex.  Default is 2.
    * @type {number}
@@ -49,25 +55,13 @@ ol.geom.SharedVertices = function(opt_options) {
   goog.asserts.assert(goog.isNull(this.offset_) ||
       this.offset_.length === this.dimension_);
 
-  /**
-   * @type {Object}
-   * @private
-   */
-  this.lookup_ = {};
-
-  /**
-   * @type {Array.<string>}
-   * @private
-   */
-  this.ids_ = [];
-
 };
 
 
 /**
  * Adds a vertex array to the shared coordinate array.
  * @param {ol.geom.VertexArray} vertices Array of vertices.
- * @return {string} Index used to reference the added vertex array.
+ * @return {number} Index used to reference the added vertex array.
  */
 ol.geom.SharedVertices.prototype.add = function(vertices) {
   var start = this.coordinates.length;
@@ -87,28 +81,23 @@ ol.geom.SharedVertices.prototype.add = function(vertices) {
       }
     }
   }
-  var id = this.getId_();
+  var length = this.starts_.push(start);
-  var idIndex = this.ids_.push(id) - 1;
+  this.counts_.push(count);
-  this.lookup_[id] = {
+  return length - 1;
-    idIndex: idIndex,
-    start: start,
-    count: count
-  };
-  return id;
 };
 
 
 /**
- * @param {string} id The vertex array identifier (returned by add).
+ * @param {number} id The vertex array identifier (returned by add).
  * @param {number} index The vertex index.
  * @param {number} dim The coordinate dimension.
  * @return {number} The coordinate value.
  */
 ol.geom.SharedVertices.prototype.get = function(id, index, dim) {
+  goog.asserts.assert(id < this.starts_.length);
   goog.asserts.assert(dim <= this.dimension_);
-  goog.asserts.assert(this.lookup_.hasOwnProperty(id));
+  goog.asserts.assert(index < this.counts_[id]);
-  goog.asserts.assert(index < this.lookup_[id].count);
+  var start = this.starts_[id];
-  var start = this.lookup_[id].start;
   var value = this.coordinates[start + (index * this.dimension_) + dim];
   if (this.offset_) {
     value += this.offset_[dim];
@@ -118,22 +107,23 @@ ol.geom.SharedVertices.prototype.get = function(id, index, dim) {
 
 
 /**
- * @param {string} id The vertex array identifier (returned by add).
+ * @param {number} id The vertex array identifier (returned by add).
  * @return {number} The number of vertices in the referenced array.
  */
 ol.geom.SharedVertices.prototype.getCount = function(id) {
-  goog.asserts.assert(this.lookup_.hasOwnProperty(id));
+  goog.asserts.assert(id < this.counts_.length);
-  return this.lookup_[id].count;
+  return this.counts_[id];
 };
 
 
 /**
- * Gets an identifier that is unique for this instance.
+ * Get the array of counts.  The index returned by the add method can be used
- * @return {string} Identifier.
+ * to look up the number of vertices.
- * @private
+ *
+ * @return {Array.<number>} The counts array.
  */
-ol.geom.SharedVertices.prototype.getId_ = function() {
+ol.geom.SharedVertices.prototype.getCounts = function() {
-  return String(++this.counter_);
+  return this.counts_;
 };
 
 
@@ -154,42 +144,20 @@ ol.geom.SharedVertices.prototype.getOffset = function() {
 
 
 /**
- * @param {string} id The vertex array identifier (returned by add).
+ * @param {number} id The vertex array identifier (returned by add).
  * @return {number} The start index in the shared vertices array.
  */
 ol.geom.SharedVertices.prototype.getStart = function(id) {
-  goog.asserts.assert(this.lookup_.hasOwnProperty(id));
+  goog.asserts.assert(id < this.starts_.length);
-  return this.lookup_[id].start;
+  return this.starts_[id];
 };
 
 
 /**
- * @param {number} id The vertex array identifier (returned by add).
+ * Get the array of start indexes.
- * @return {ol.geom.VertexArray} The removed vertex array.
+ * @return {Array.<number>} The starts array.
  */
-ol.geom.SharedVertices.prototype.remove = function(id) {
+ol.geom.SharedVertices.prototype.getStarts = function() {
-  goog.asserts.assert(this.lookup_.hasOwnProperty(id));
+  return this.starts_;
-  var info = this.lookup_[id];
-  var dimension = this.dimension_;
-  var length = info.count * dimension;
-  var removed = this.coordinates.splice(info.start, length);
-  var offset = this.offset_;
-  var array = new Array(info.count);
-  var vertex;
-  for (var i = 0; i < info.count; ++i) {
-    vertex = new Array(dimension);
-    for (var j = 0; j < dimension; ++j) {
-      vertex[j] = removed[(i * dimension) + j] + (offset ? offset[j] : 0);
-    }
-    array[i] = vertex;
-  }
-  delete this.lookup_[id];
-  this.ids_.splice(info.idIndex, 1);
-  var afterInfo;
-  for (var k = info.idIndex, kk = this.ids_.length; k < kk; ++k) {
-    afterInfo = this.lookup_[this.ids_[k]];
-    afterInfo.idIndex -= 1;
-    afterInfo.start -= length;
-  }
-  return array;
 };
+

test/spec/ol/filter/geometryfilter.test.js

@@ -34,7 +34,7 @@ describe('ol.filter.Geometry', function() {
 
     it('works for multi-linestring', function() {
       var filter = new ol.filter.Geometry(
-            ol.filter.GeometryType.MULTILINESTRING);
+          ol.filter.GeometryType.MULTILINESTRING);
       expect(filter.getType()).toBe(ol.filter.GeometryType.MULTILINESTRING);
     });
 

test/spec/ol/geom/sharedvertices.test.js

@@ -43,8 +43,24 @@ describe('ol.geom.SharedVertices', function() {
     it('returns an identifier for coordinate access', function() {
       var vertices = new ol.geom.SharedVertices();
       var id = vertices.add([[1, 2], [3, 4]]);
-      expect(typeof id).toBe('string');
+      expect(typeof id).toBe('number');
     });
+
+    it('returns the index of the added vertices', function() {
+      var vertices = new ol.geom.SharedVertices();
+
+      var first = vertices.add([[1, 2]]);
+      var second = vertices.add([[3, 4], [5, 6]]);
+      var third = vertices.add([[7, 8], [9, 10], [11, 12]]);
+
+      expect(vertices.coordinates).toEqual(
+          [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12]);
+
+      expect(first).toBe(0);
+      expect(second).toBe(1);
+      expect(third).toBe(2);
+    });
+
   });
 
   describe('#get()', function() {
@@ -98,6 +114,17 @@ describe('ol.geom.SharedVertices', function() {
     });
   });
 
+  describe('#getCounts()', function() {
+    it('returns the counts array', function() {
+      var vertices = new ol.geom.SharedVertices();
+      var first = vertices.add([[2, 3], [3, 4], [4, 5]]);
+      var second = vertices.add([[5, 6], [6, 6]]);
+      var third = vertices.add([[7, 8]]);
+
+      expect(vertices.getCounts()).toEqual([3, 2, 1]);
+    });
+  });
+
   describe('#getDimension()', function() {
     it('returns 2 by default', function() {
       var vertices = new ol.geom.SharedVertices();
@@ -123,57 +150,43 @@ describe('ol.geom.SharedVertices', function() {
   });
 
   describe('#getStart()', function() {
-    it('returns the start of the identified vertex array', function() {
+    it('returns the start index of an identified vertex array', function() {
       var vertices = new ol.geom.SharedVertices();
-      var first = vertices.add([[1, 2]]);
+      var first = vertices.add([[2, 3], [4, 5], [6, 7]]);
-      var second = vertices.add([[3, 4], [5, 6]]);
+      var second = vertices.add([[8, 9], [10, 11]]);
-      var third = vertices.add([[7, 8], [9, 10], [11, 12]]);
+      var third = vertices.add([[12, 13]]);
 
       expect(vertices.coordinates).toEqual(
-          [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12]);
+          [2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13]);
+      //   0  1  2  3  4  5  6  7   8   9  10  11
+
       expect(vertices.getStart(first)).toBe(0);
-      expect(vertices.getStart(second)).toBe(2);
+      expect(vertices.getStart(second)).toBe(6);
-      expect(vertices.getStart(third)).toBe(6);
+      expect(vertices.getStart(third)).toBe(10);
     });
   });
 
-  describe('#remove()', function() {
+  describe('#getStarts()', function() {
-    it('removes a vertex array', function() {
+    it('returns the counts array', function() {
+      var vertices = new ol.geom.SharedVertices();
+      var first = vertices.add([[2, 3], [3, 4], [4, 5]]);
+      var second = vertices.add([[5, 6], [6, 6]]);
+      var third = vertices.add([[7, 8]]);
+
+      expect(vertices.getStarts()).toEqual([0, 6, 10]);
+    });
+  });
+
+  describe('#coordinates', function() {
+    it('is a flat array of all coordinate values', function() {
       var vertices = new ol.geom.SharedVertices();
       var first = vertices.add([[1, 2], [3, 4]]);
       var second = vertices.add([[5, 6]]);
       var third = vertices.add([[7, 8], [9, 10], [11, 12]]);
-
+      expect(vertices.coordinates).toEqual(
-      expect(vertices.remove(second)).toEqual([[5, 6]]);
+          [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12]);
-      expect(vertices.coordinates).toEqual([1, 2, 3, 4, 7, 8, 9, 10, 11, 12]);
-
-      expect(vertices.remove(first)).toEqual([[1, 2], [3, 4]]);
-      expect(vertices.coordinates).toEqual([7, 8, 9, 10, 11, 12]);
-
-      expect(vertices.remove(third)).toEqual([[7, 8], [9, 10], [11, 12]]);
-      expect(vertices.coordinates).toEqual([]);
     });
 
-    it('adjusts returned vertices by offset', function() {
-
-      var vertices = new ol.geom.SharedVertices({offset: [10, 20]});
-      var first = vertices.add([[1, 2]]);
-      var second = vertices.add([[3, 4]]);
-      var third = vertices.add([[5, 6]]);
-
-      expect(vertices.remove(second)).toEqual([[3, 4]]);
-      expect(vertices.coordinates).toEqual([-9, -18, -5, -14]);
-
-      expect(vertices.remove(third)).toEqual([[5, 6]]);
-      expect(vertices.coordinates).toEqual([-9, -18]);
-
-      expect(vertices.remove(first)).toEqual([[1, 2]]);
-      expect(vertices.coordinates).toEqual([]);
-    });
-
-  });
-
-  describe('#coordinates', function() {
     it('is not reassigned', function() {
       var vertices = new ol.geom.SharedVertices();
       var first = vertices.add([[1, 2], [3, 4]]);
@@ -181,12 +194,6 @@ describe('ol.geom.SharedVertices', function() {
 
       var second = vertices.add([[5, 6]]);
       expect(vertices.coordinates).toBe(coordinates);
-
-      vertices.remove(first);
-      expect(vertices.coordinates).toBe(coordinates);
-
-      vertices.remove(second);
-      expect(vertices.coordinates).toBe(coordinates);
     });
   });