Dedicated module for transforms cache

src/ol/proj/transforms.js

@@ -0,0 +1,80 @@
+goog.provide('ol.proj.transforms');
+
+goog.require('ol');
+goog.require('ol.obj');
+
+
+/**
+ * @private
+ * @type {Object.<string, Object.<string, ol.TransformFunction>>}
+ */
+ol.proj.transforms.cache_ = {};
+
+
+/**
+ * Clear the transform cache.
+ */
+ol.proj.transforms.clear = function() {
+  ol.proj.transforms.cache_ = {};
+};
+
+
+/**
+ * Registers a conversion function to convert coordinates from the source
+ * projection to the destination projection.
+ *
+ * @param {ol.proj.Projection} source Source.
+ * @param {ol.proj.Projection} destination Destination.
+ * @param {ol.TransformFunction} transformFn Transform.
+ */
+ol.proj.transforms.add = function(source, destination, transformFn) {
+  var sourceCode = source.getCode();
+  var destinationCode = destination.getCode();
+  var transforms = ol.proj.transforms.cache_;
+  if (!(sourceCode in transforms)) {
+    transforms[sourceCode] = {};
+  }
+  transforms[sourceCode][destinationCode] = transformFn;
+};
+
+
+/**
+ * Unregisters the conversion function to convert coordinates from the source
+ * projection to the destination projection.  This method is used to clean up
+ * cached transforms during testing.
+ *
+ * @param {ol.proj.Projection} source Source projection.
+ * @param {ol.proj.Projection} destination Destination projection.
+ * @return {ol.TransformFunction} transformFn The unregistered transform.
+ */
+ol.proj.transforms.remove = function(source, destination) {
+  var sourceCode = source.getCode();
+  var destinationCode = destination.getCode();
+  var transforms = ol.proj.transforms.cache_;
+  ol.DEBUG && console.assert(sourceCode in transforms,
+      'sourceCode should be in transforms');
+  ol.DEBUG && console.assert(destinationCode in transforms[sourceCode],
+      'destinationCode should be in transforms of sourceCode');
+  var transform = transforms[sourceCode][destinationCode];
+  delete transforms[sourceCode][destinationCode];
+  if (ol.obj.isEmpty(transforms[sourceCode])) {
+    delete transforms[sourceCode];
+  }
+  return transform;
+};
+
+
+/**
+ * Get a transform given a source code and a destination code.
+ * @param {string} sourceCode The code for the source projection.
+ * @param {string} destinationCode The code for the destination projection.
+ * @return {?ol.TransformFunction} The transform function (if found).
+ */
+ol.proj.transforms.get = function(sourceCode, destinationCode) {
+  var transform = null;
+  var transforms = ol.proj.transforms.cache_;
+  if (sourceCode in transforms && destinationCode in transforms[sourceCode]) {
+    transform = transforms[sourceCode][destinationCode];
+  }
+  return transform;
+};