Support line and polygon label points for ol.render.Feature

src/ol/render/feature.js

@@ -1,8 +1,12 @@
 goog.provide('ol.render.Feature');
 
 goog.require('ol');
+goog.require('ol.array');
 goog.require('ol.extent');
 goog.require('ol.geom.GeometryType');
+goog.require('ol.geom.flat.center');
+goog.require('ol.geom.flat.interiorpoint');
+goog.require('ol.geom.flat.interpolate');
 goog.require('ol.geom.flat.transform');
 goog.require('ol.transform');
 
@@ -45,6 +49,18 @@ ol.render.Feature = function(type, flatCoordinates, ends, properties, id) {
    */
   this.flatCoordinates_ = flatCoordinates;
 
+  /**
+   * @private
+   * @type {Array.<number>}
+   */
+  this.flatInteriorPoints_ = null;
+
+  /**
+   * @private
+   * @type {Array.<number>}
+   */
+  this.flatMidpoints_ = null;
+
   /**
    * @private
    * @type {Array.<number>|Array.<Array.<number>>}
@@ -102,6 +118,66 @@ ol.render.Feature.prototype.getExtent = function() {
   return this.extent_;
 };
 
+
+/**
+ * @return {Array.<number>} Flat interior points.
+ */
+ol.render.Feature.prototype.getFlatInteriorPoint = function() {
+  if (!this.flatInteriorPoints_) {
+    var flatCenter = ol.extent.getCenter(this.getExtent());
+    this.flatInteriorPoints_ = ol.geom.flat.interiorpoint.linearRings(
+        this.flatCoordinates_, 0, this.ends_, 2, flatCenter, 0);
+  }
+  return this.flatInteriorPoints_;
+};
+
+
+/**
+ * @return {Array.<number>} Flat interior points.
+ */
+ol.render.Feature.prototype.getFlatInteriorPoints = function() {
+  if (!this.flatInteriorPoints_) {
+    var flatCenters = ol.geom.flat.center.linearRingss(
+        this.flatCoordinates_, 0, this.ends_, 2);
+    this.flatInteriorPoints_ = ol.geom.flat.interiorpoint.linearRingss(
+        this.flatCoordinates_, 0, this.ends_, 2, flatCenters);
+  }
+  return this.flatInteriorPoints_;
+};
+
+
+/**
+ * @return {Array.<number>} Flat midpoint.
+ */
+ol.render.Feature.prototype.getFlatMidpoint = function() {
+  if (!this.flatMidpoints_) {
+    this.flatMidpoints_ = ol.geom.flat.interpolate.lineString(
+        this.flatCoordinates_, 0, this.flatCoordinates_.length, 2, 0.5);
+  }
+  return this.flatMidpoints_;
+};
+
+
+/**
+ * @return {Array.<number>} Flat midpoints.
+ */
+ol.render.Feature.prototype.getFlatMidpoints = function() {
+  if (!this.flatMidpoints_) {
+    this.flatMidpoints_ = [];
+    var flatCoordinates = this.flatCoordinates_;
+    var offset = 0;
+    var ends = this.ends_;
+    for (var i = 0, ii = ends.length; i < ii; ++i) {
+      var end = ends[i];
+      var midpoint = ol.geom.flat.interpolate.lineString(
+          flatCoordinates, offset, end, 2, 0.5);
+      ol.array.extend(this.flatMidpoints_, midpoint);
+      offset = end;
+    }
+  }
+  return this.flatMidpoints_;
+};
+
 /**
  * Get the feature identifier.  This is a stable identifier for the feature and
  * is set when reading data from a remote source.

test/spec/ol/render/feature.test.js

@@ -1,5 +1,7 @@
-
-
+goog.require('ol.geom.LineString');
+goog.require('ol.geom.MultiLineString');
+goog.require('ol.geom.MultiPolygon');
+goog.require('ol.geom.Polygon');
 goog.require('ol.render.Feature');
 
 
@@ -51,6 +53,51 @@ describe('ol.render.Feature', function() {
     });
   });
 
+  describe('#getFlatInteriorPoint()', function() {
+    it('returns correct point and caches it', function() {
+      var polygon = new ol.geom.Polygon([[[0, 0], [0, 10], [10, 10], [10, 0], [0, 0]]]);
+      var feature = new ol.render.Feature('Polygon', polygon.getOrientedFlatCoordinates(),
+          polygon.getEnds());
+      expect(feature.getFlatInteriorPoint()).to.eql([5, 5, 10]);
+      expect(feature.getFlatInteriorPoint()).to.be(feature.flatInteriorPoints_);
+    });
+  });
+
+  describe('#getFlatInteriorPoints()', function() {
+    it('returns correct points and caches them', function() {
+      var polygon = new ol.geom.MultiPolygon([
+        [[[0, 0], [0, 10], [10, 10], [10, 0], [0, 0]]],
+        [[[10, 0], [10, 10], [20, 10], [20, 0], [10, 0]]]
+      ]);
+      var feature = new ol.render.Feature('MultiPolygon', polygon.getOrientedFlatCoordinates(),
+          polygon.getEndss());
+      expect(feature.getFlatInteriorPoints()).to.eql([5, 5, 10, 15, 5, 10]);
+      expect(feature.getFlatInteriorPoints()).to.be(feature.flatInteriorPoints_);
+    });
+  });
+
+  describe('#getFlatMidpoint()', function() {
+    it('returns correct point', function() {
+      var line = new ol.geom.LineString([[0, 0], [0, 10], [10, 10], [10, 0], [0, 0]]);
+      var feature = new ol.render.Feature('LineString', line.getFlatCoordinates());
+      expect(feature.getFlatMidpoint()).to.eql([10, 10]);
+      expect(feature.getFlatMidpoint()).to.eql(feature.flatMidpoints_);
+    });
+  });
+
+  describe('#getFlatMidpoints()', function() {
+    it('returns correct points and caches them', function() {
+      var line = new ol.geom.MultiLineString([
+        [[0, 0], [0, 10], [10, 10], [10, 0], [0, 0]],
+        [[10, 0], [10, 10], [20, 10], [20, 0], [10, 0]]
+      ]);
+      var feature = new ol.render.Feature('MultiLineString', line.getFlatCoordinates(),
+          line.getEnds());
+      expect(feature.getFlatMidpoints()).to.eql([10, 10, 20, 10]);
+      expect(feature.getFlatMidpoints()).to.be(feature.flatMidpoints_);
+    });
+  });
+
   describe('#getGeometry()', function() {
     it('returns itself as geometry', function() {
       expect(renderFeature.getGeometry()).to.equal(renderFeature);