No new argument for Layer::redraw.

Instead, make _resolution a private property (resolution) which is set to null to make redraw call moveTo with zoomChanged set to true.

lib/OpenLayers/Layer.js

@@ -266,6 +266,14 @@ OpenLayers.Layer = OpenLayers.Class({
      */
     minResolution: null,
     
+    /**
+     * Property: resolution
+     * {Float} Current resolution that the layer is drawn in. Used by
+     * subclasses to determine whether the zoom has changed when calling
+     * <moveTo>.
+     */
+    resolution: null,
+
     /**
      * APIProperty: numZoomLevels
      * {Integer}
@@ -541,9 +549,7 @@ OpenLayers.Layer = OpenLayers.Class({
      * Returns:
      * {Boolean} The layer was redrawn.
      */
-    redraw: function(zoomChanged) {
+    redraw: function() {
-        // zoomChanged forces a zoom change in the layer's moveTo
-        // call. This isn't documented because not part of the API.
         var redrawn = false;
         if (this.map) {
 
@@ -554,9 +560,8 @@ OpenLayers.Layer = OpenLayers.Class({
             var extent = this.getExtent();
 
             if (extent && this.inRange && this.visibility) {
-                zoomChanged = zoomChanged ||
+                zoomChanged = this.resolution == null ||
-                              this._resolution === undefined ||
+                              this.resolution !== this.map.getResolution();
-                              this._resolution !== this.map.getResolution();
                 this.moveTo(extent, zoomChanged, false);
                 this.events.triggerEvent("moveend",
                     {"zoomChanged": zoomChanged});
@@ -581,7 +586,7 @@ OpenLayers.Layer = OpenLayers.Class({
             display = display && this.inRange;
         }
         this.display(display);
-        this._resolution = this.map.getResolution();
+        this.resolution = this.map.getResolution();
     },
 
     /**
@@ -638,7 +643,7 @@ OpenLayers.Layer = OpenLayers.Class({
             // deal with gutters
             this.setTileSize();
 
-            delete this._resolution;
+            this.resolution = null;
         }
     },
     

lib/OpenLayers/Layer/HTTPRequest.js

@@ -120,7 +120,8 @@ OpenLayers.Layer.HTTPRequest = OpenLayers.Class(OpenLayers.Layer, {
      */
     mergeNewParams:function(newParams) {
         this.params = OpenLayers.Util.extend(this.params, newParams);
-        var ret = OpenLayers.Layer.prototype.redraw.call(this, true);
+        this.resolution = null;
+        var ret = this.redraw();
         if(this.map != null) {
             this.map.events.triggerEvent("changelayer", {
                 layer: this,
@@ -142,10 +143,9 @@ OpenLayers.Layer.HTTPRequest = OpenLayers.Class(OpenLayers.Layer, {
      */
     redraw: function(force) { 
         if (force) {
-            return this.mergeNewParams({"_olSalt": Math.random()});
+            this.params["_olSalt"] = Math.random();
-        } else {
-            return OpenLayers.Layer.prototype.redraw.call(this);
         }
+        return OpenLayers.Layer.prototype.redraw.call(this);
     },
     
     /**

tests/Layer.html

@@ -710,7 +710,8 @@
                 "[a] redraw calls moveTo with zoomChanged false");
 
         log = {};
-        l1.redraw(true);
+        l1.resolution = null;
+        l1.redraw();
         t.eq(log.moveTo.zoomChanged, true,
              "[b] redraw calls moveTo with zoomChanged true");
 

tests/Layer/HTTPRequest.html

@@ -95,8 +95,8 @@
         t.eq( layer.params.chickpeas, "image/png", "mergeNewParams() makes clean copy of hash");
 
         var redraw = OpenLayers.Layer.prototype.redraw;
-        OpenLayers.Layer.prototype.redraw = function(forceZoomChanged) {
+        OpenLayers.Layer.prototype.redraw = function() {
-            t.eq(forceZoomChanged, true, 'mergeNewParams() sends true to Layer.redraw');
+            t.eq(this.resolution, null, 'mergeNewParams sets layer resolution to null, causing redraw to call moveTo with zoomChanged set to true');
         };
         layer.mergeNewParams();
         OpenLayers.Layer.prototype.redraw = redraw;