removing the restrictedMinZoom property, and allow for restricting zoom levels with maxResolution and numZoomLevels. Thanks tschaub for the doc, test and examples improvements. r=tschaub (see #3338)

git-svn-id: http://svn.openlayers.org/trunk/openlayers@12106 dc9f47b5-9b13-0410-9fdd-eb0c1a62fdaf

lib/OpenLayers/Layer.js

@@ -275,18 +275,6 @@ OpenLayers.Layer = OpenLayers.Class({
      */
     numZoomLevels: null,
     
-    /**
-     * Property: restrictedMinZoom
-     * {Integer} Restriction of the minimum zoom level. This is used for layers
-     *     that only use a subset of the resolutions in the <resolutions>
-     *     array. This is independent of <numResolutions>, which always starts
-     *     counting at zoom level 0. If restrictedMinZoom is e.g. set to 2,
-     *     the first two zoom levels (0 and 1) will not be used by this layer.
-     *     If the layer is a base layer, zooming to the map's maxExtent means
-     *     setting the map's zoom to 2.
-     */
-    restrictedMinZoom: 0,
-   
     /**
      * APIProperty: minScale
      * {Float}
@@ -474,8 +462,12 @@ OpenLayers.Layer = OpenLayers.Class({
     * 
     * Parameters:
     * newOptions - {Object}
+    * reinitialize - {Boolean} If set to true, and if resolution options of the
+    *     current baseLayer were changed, the map will be recentered to make
+    *     sure that it is displayed with a valid resolution, and a
+    *     changebaselayer event will be triggered.
     */
-    addOptions: function (newOptions) {
+    addOptions: function (newOptions, reinitialize) {
 
         if (this.options == null) {
             this.options = {};
@@ -502,6 +494,8 @@ OpenLayers.Layer = OpenLayers.Class({
         // properties of the "properties" array defined below is set
         // in the new options
         if(this.map) {
+            // store current resolution so we can try to restore it later
+            var resolution = this.map.getResolution();
             var properties = this.RESOLUTION_PROPERTIES.concat(
                 ["projection", "units", "minExtent", "maxExtent"]
             );
@@ -510,6 +504,20 @@ OpenLayers.Layer = OpenLayers.Class({
                    OpenLayers.Util.indexOf(properties, o) >= 0) {
 
                     this.initResolutions();
+                    if (reinitialize && this.map.baseLayer === this) {
+                        // update map position, and restore previous resolution
+                        this.map.setCenter(this.map.getCenter(),
+                            this.map.getZoomForResolution(resolution),
+                            false, true
+                        );
+                        // trigger a changebaselayer event to make sure that
+                        // all controls (especially
+                        // OpenLayers.Control.PanZoomBar) get notified of the
+                        // new options
+                        this.map.events.triggerEvent("changebaselayer", {
+                            layer: this
+                        });
+                    }
                     break;
                 }
             }
@@ -763,8 +771,7 @@ OpenLayers.Layer = OpenLayers.Class({
         } else {
             if (this.map) {
                 var resolution = this.map.getResolution();
-                inRange = ( this.map.getZoom() >= this.restrictedMinZoom &&
-                            (resolution >= this.minResolution) &&
+                inRange = ( (resolution >= this.minResolution) &&
                             (resolution <= this.maxResolution) );
             }
         }
@@ -1197,7 +1204,7 @@ OpenLayers.Layer = OpenLayers.Class({
             }
             zoom = Math.max(0, i-1);
         }
-        return Math.max(this.restrictedMinZoom, zoom);
+        return zoom;
     },
     
     /**