Use in-place transforms where possible

src/ol/control/mousepositioncontrol.js

@@ -178,8 +178,9 @@ ol.control.MousePosition.prototype.updateHTML_ = function(pixel) {
     var map = this.getMap();
     var coordinate = map.getCoordinateFromPixel(pixel);
     if (!goog.isNull(coordinate)) {
-      var output = this.transform_([coordinate.x, coordinate.y]);
+      var vertex = [coordinate.x, coordinate.y];
-      coordinate = new ol.Coordinate(output[0], output[1]);
+      vertex = this.transform_(vertex, vertex);
+      coordinate = new ol.Coordinate(vertex[0], vertex[1]);
       if (goog.isDef(this.coordinateFormat_)) {
         html = this.coordinateFormat_(coordinate);
       } else {

src/ol/geolocation.js

@@ -79,9 +79,10 @@ ol.Geolocation.prototype.handleProjectionChanged_ = function() {
     this.transformFn_ = ol.projection.getTransform(
         ol.projection.getFromCode('EPSG:4326'), projection);
     if (!goog.isNull(this.position_)) {
-      var output = this.transformFn_([this.position_.x, this.position_.y]);
+      var vertex = [this.position_.x, this.position_.y];
+      vertex = this.transformFn_(vertex, vertex, 2);
       this.set(ol.GeolocationProperty.POSITION,
-          new ol.Coordinate(output[0], output[1]));
+          new ol.Coordinate(vertex[0], vertex[1]));
     }
   }
 };
@@ -109,9 +110,10 @@ ol.Geolocation.prototype.positionChange_ = function(position) {
   this.set(ol.GeolocationProperty.HEADING, goog.isNull(coords.heading) ?
       undefined : goog.math.toRadians(coords.heading));
   this.position_ = new ol.Coordinate(coords.longitude, coords.latitude);
-  var output = this.transformFn_([coords.longitude, coords.latitude]);
+  var vertex = [coords.longitude, coords.latitude];
+  vertex = this.transformFn_(vertex, vertex, 2);
   this.set(ol.GeolocationProperty.POSITION,
-      new ol.Coordinate(output[0], output[1]));
+      new ol.Coordinate(vertex[0], vertex[1]));
   this.set(ol.GeolocationProperty.SPEED,
       goog.isNull(coords.speed) ? undefined : coords.speed);
 };

src/ol/projection.js

@@ -458,6 +458,14 @@ ol.projection.getTransformFromCodes = function(sourceCode, destinationCode) {
  * @return {Array.<number>} Input coordinate array (same array as input).
  */
 ol.projection.identityTransform = function(input, opt_output, opt_dimension) {
+  if (goog.isDef(opt_output) && input !== opt_output) {
+    // TODO: consider making this a warning instead
+    goog.asserts.assert(false, 'This should not be used internally.');
+    for (var i = 0, ii = input.length; i < ii; ++i) {
+      opt_output[i] = input[i];
+    }
+    input = opt_output;
+  }
   return input;
 };
 
@@ -470,7 +478,16 @@ ol.projection.identityTransform = function(input, opt_output, opt_dimension) {
  *     values).
  */
 ol.projection.cloneTransform = function(input, opt_output, opt_dimension) {
-  return input.slice();
+  var output;
+  if (goog.isDef(opt_output)) {
+    for (var i = 0, ii = input.length; i < ii; ++i) {
+      opt_output[i] = input[i];
+    }
+    output = opt_output;
+  } else {
+    output = input.slice();
+  }
+  return output;
 };