added fromWMSLayer convenience function to Protocol.WFS. Thanks tschaub

for the improved patch. r=tschaub (closes #1937)


git-svn-id: http://svn.openlayers.org/trunk/openlayers@8993 dc9f47b5-9b13-0410-9fdd-eb0c1a62fdaf

lib/OpenLayers/Protocol/WFS.js

@@ -20,6 +20,44 @@ OpenLayers.Protocol.WFS = function(options) {
     return new cls(options);
 };
 
+/**
+ * Function: OpenLayers.Protocol.WFS.fromWMSLayer
+ * Convenience function to create a WFS protocol from a WMS layer.  This makes
+ *     the assumption that a WFS requests can be issued at the same URL as
+ *     WMS requests and that a WFS featureType exists with the same name as the
+ *     WMS layer.
+ *     
+ * This function is designed to auto-configure <url>, <featureType>,
+ *     <featurePrefix> and <srsName> for WFS <version> 1.1.0. Note that
+ *     srsName matching with the WMS layer will not work with WFS 1.0.0..
+ * 
+ * Parameters:
+ * layer - {<OpenLayers.Layer.WMS>} WMS layer that has a matching WFS
+ *     FeatureType at the same server url with the same typename.
+ * options - {Object} Default properties to be set on the protocol.
+ *
+ */
+OpenLayers.Protocol.WFS.fromWMSLayer = function(layer, options) {
+    var typeName, featurePrefix;
+    var param = layer.params["LAYERS"];
+    var parts = (param instanceof Array ? param[0] : param).split(":");
+    if(parts.length > 1) {
+        featurePrefix = parts[0];
+    }
+    typeName = parts.pop();
+    var protocolOptions = {
+        url: layer.url,
+        featureType: typeName,
+        featurePrefix: featurePrefix,
+        srsName: layer.projection && layer.projection.getCode() ||
+                 layer.map && layer.map.getProjectionObject().getCode(),
+        version: "1.1.0"
+    };
+    return new OpenLayers.Protocol.WFS(OpenLayers.Util.applyDefaults(
+        options, protocolOptions
+    ));
+};
+
 /**
  * Constant: OpenLayers.Protocol.WFS.DEFAULTS
  */