Adding a removeAllFeatures method to the vector layer. This bypasses a few unnecessary steps when removing all features but retains the same behavior as the removeFeatures method otherwise. Optimizing the clear method on elements renderers a bit by avoiding length calculation of the live collection and looking up the first child once per node removal. r=ahocevar (closes #2774)

git-svn-id: http://svn.openlayers.org/trunk/openlayers@10597 dc9f47b5-9b13-0410-9fdd-eb0c1a62fdaf

lib/OpenLayers/Layer/Vector.js

@@ -616,10 +616,13 @@ OpenLayers.Layer.Vector = OpenLayers.Class(OpenLayers.Layer, {
         if(!features || features.length === 0) {
             return;
         }
+        if (features === this.features) {
+            return this.removeAllFeatures(options);
+        }
         if (!(features instanceof Array)) {
             features = [features];
         }
-        if (features === this.features || features === this.selectedFeatures) {
+        if (features === this.selectedFeatures) {
             features = features.slice();
         }
 
@@ -681,6 +684,49 @@ OpenLayers.Layer.Vector = OpenLayers.Class(OpenLayers.Layer, {
         }
     },
     
+    /** 
+     * APIMethod: removeAllFeatures
+     * Remove all features from the layer.
+     *
+     * Parameters:
+     * options - {Object} Optional properties for changing behavior of the
+     *     removal.
+     *
+     * Valid options:
+     * silent - {Boolean} Supress event triggering.  Default is false.
+     */
+    removeAllFeatures: function(options) {
+        var notify = !options || !options.silent;
+        var features = this.features;
+        if (notify) {
+            this.events.triggerEvent(
+                "beforefeaturesremoved", {features: features}
+            );
+        }
+        var feature;
+        for (var i = features.length-1; i >= 0; i--) {
+            feature = features[i];
+            if (notify) {
+                this.events.triggerEvent("beforefeatureremoved", {
+                    feature: feature
+                });
+            }
+            feature.layer = null;
+            if (notify) {
+                this.events.triggerEvent("featureremoved", {
+                    feature: feature
+                });
+            }
+        }
+        this.renderer.clear();
+        this.features = [];
+        this.unrenderedFeatures = {};
+        this.selectedFeatures = [];
+        if (notify) {
+            this.events.triggerEvent("featuresremoved", {features: features});
+        }
+    },
+
     /**
      * APIMethod: destroyFeatures
      * Erase and destroy features on the layer.

lib/OpenLayers/Renderer/Elements.js

@@ -442,14 +442,17 @@ OpenLayers.Renderer.Elements = OpenLayers.Class(OpenLayers.Renderer, {
      * Remove all the elements from the root
      */    
     clear: function() {
-        if (this.vectorRoot) {
-            while (this.vectorRoot.childNodes.length > 0) {
-                this.vectorRoot.removeChild(this.vectorRoot.firstChild);
+        var child;
+        var root = this.vectorRoot;
+        if (root) {
+            while (child = root.firstChild) {
+                root.removeChild(child);
             }
         }
-        if (this.textRoot) {
-            while (this.textRoot.childNodes.length > 0) {
-                this.textRoot.removeChild(this.textRoot.firstChild);
+        root = this.textRoot;
+        if (root) {
+            while (child = root.firstChild) {
+                root.removeChild(child);
             }
         }
         if (this.indexer) {