polyline: Added encode/decodeFloats() functions

src/ol/parser/polyline.js

@@ -72,6 +72,49 @@ ol.parser.polyline.decodeFlatCoordinates = function(encoded, opt_dimension) {
 };
 
 
+/**
+ * Encode a list of floating point numbers and return an encoded string
+ *
+ * Attention: This function will modify the passed array!
+ *
+ * @param {Array.<number>} numbers A list of floating point numbers.
+ * @param {number=} opt_factor The factor by which the numbers will be
+ * multiplied. The remaining decimal places will get rounded away.
+ * @return {string} The encoded string.
+ */
+ol.parser.polyline.encodeFloats = function(numbers, opt_factor) {
+  var factor = opt_factor || 1e5;
+
+  var numbersLength = numbers.length;
+  for (var i = 0; i < numbersLength; ++i) {
+    numbers[i] =  Math.round(numbers[i] * factor);
+  }
+
+  return ol.parser.polyline.encodeSignedIntegers(numbers);
+};
+
+
+/**
+ * Decode a list of floating point numbers from an encoded string
+ *
+ * @param {string} encoded An encoded string.
+ * @param {number=} opt_factor The factor by which the result will be divided.
+ * @return {Array.<number>} A list of floating point numbers.
+ */
+ol.parser.polyline.decodeFloats = function(encoded, opt_factor) {
+  var factor = opt_factor || 1e5;
+
+  var numbers = ol.parser.polyline.decodeSignedIntegers(encoded);
+
+  var numbersLength = numbers.length;
+  for (var i = 0; i < numbersLength; ++i) {
+    numbers[i] /= factor;
+  }
+
+  return numbers;
+};
+
+
 /**
  * Encode a list of signed integers and return an encoded string
  *

test/spec/ol/parser/polyline.test.js

@@ -27,6 +27,31 @@ describe('ol.parser.polyline', function() {
   });
 
 
+  var floats = [0.00, 0.15, -0.01, -0.16, 0.16, 0.01];
+  var smallFloats = [0.00000, 0.00015, -0.00001, -0.00016, 0.00016, 0.00001];
+  var encodedFloats = '?]@^_@A';
+
+  describe('encodeFloats', function() {
+    it('returns expected value', function() {
+      var encodeFloats = ol.parser.polyline.encodeFloats;
+
+      expect(encodeFloats(smallFloats.slice())).toEqual(encodedFloats);
+      expect(encodeFloats(smallFloats.slice(), 1e5)).toEqual(encodedFloats);
+      expect(encodeFloats(floats.slice(), 1e2)).toEqual(encodedFloats);
+    });
+  });
+
+  describe('decodeFloats', function() {
+    it('returns expected value', function() {
+      var decodeFloats = ol.parser.polyline.decodeFloats;
+
+      expect(decodeFloats(encodedFloats)).toEqual(smallFloats);
+      expect(decodeFloats(encodedFloats, 1e5)).toEqual(smallFloats);
+      expect(decodeFloats(encodedFloats, 1e2)).toEqual(floats);
+    });
+  });
+
+
   var signedIntegers = [0, 15, -1, -16, 16, 1];
   var encodedSignedIntegers = '?]@^_@A';