Adding a getMinZoom API method.

This can be used by zoom slider controls, e.g. the GeoExt.ZoomSlider. Note that adjustZoom now also respects the map's fractionalZoom setting.

lib/OpenLayers/Control/PanZoomBar.js

@@ -194,10 +194,7 @@ OpenLayers.Control.PanZoomBar = OpenLayers.Class(OpenLayers.Control.PanZoom, {
     _addZoomBar:function(centered) {
         var imgLocation = OpenLayers.Util.getImageLocation("slider.png");
         var id = this.id + "_" + this.map.id;
-        var minZoom = 0;
+        var minZoom = this.map.getMinZoom();
-        if (this.map.baseLayer && this.map.baseLayer.wrapDateLine) {
-            minZoom = this.map.adjustZoom(0);
-        }
         var zoomsToEnd = this.map.getNumZoomLevels() - 1 - this.map.getZoom();
         var slider = OpenLayers.Util.createAlphaImageDiv(id,
                        centered.add(-1, zoomsToEnd * this.zoomStopHeight), 

lib/OpenLayers/Map.js

@@ -1786,18 +1786,42 @@ OpenLayers.Map = OpenLayers.Class({
      * <baseLayer>'s maxExtent.
      */
     adjustZoom: function(zoom) {
-        var resolution, resolutions = this.baseLayer.resolutions,
+        if (this.baseLayer && this.baseLayer.wrapDateLine) {
-            maxResolution = this.getMaxExtent().getWidth() / this.size.w;
+            var resolution, resolutions = this.baseLayer.resolutions,
-        if (this.getResolutionForZoom(zoom) > maxResolution) {
+                maxResolution = this.getMaxExtent().getWidth() / this.size.w;
-            for (var i=zoom|0, ii=resolutions.length; i<ii; ++i) {
+            if (this.getResolutionForZoom(zoom) > maxResolution) {
-                if (resolutions[i] <= maxResolution) {
+                if (this.fractionalZoom) {
-                    zoom = i;
+                    zoom = this.getZoomForResolution(maxResolution);
-                    break;
+                } else {
-                }
+                    for (var i=zoom|0, ii=resolutions.length; i<ii; ++i) {
+                        if (resolutions[i] <= maxResolution) {
+                            zoom = i;
+                            break;
+                        }
+                    }
+                } 
             }
         }
         return zoom;
     },
+    
+    /**
+     * APIMethod: getMinZoom
+     * Returns the minimum zoom level for the current map view. If the base
+     * layer is configured with <wrapDateLine> set to true, this will be the
+     * first zoom level that shows no more than one world width in the current
+     * map viewport. Components that rely on this value (e.g. zoom sliders)
+     * should also listen to the map's "updatesize" event and call this method
+     * in the "updatesize" listener.
+     *
+     * Returns:
+     * {Number} Minimum zoom level that shows a map not wider than its
+     * <baseLayer>'s maxExtent. This is an Integer value, unless the map is
+     * configured with <fractionalZoom> set to true.
+     */
+    getMinZoom: function() {
+        return this.adjustZoom(0);
+    },
 
     /**
      * Method: moveTo
@@ -1820,13 +1844,11 @@ OpenLayers.Map = OpenLayers.Class({
                 zoom = Math.round(zoom);
             }
         }
-        if (this.baseLayer.wrapDateLine) {
+        var requestedZoom = zoom;
-            var requestedZoom = zoom;
+        zoom = this.adjustZoom(zoom);
-            zoom = this.adjustZoom(zoom);
+        if (zoom !== requestedZoom) {
-            if (zoom !== requestedZoom) {
+            // zoom was adjusted, so keep old lonlat to avoid panning
-                // zoom was adjusted, so keep old lonlat to avoid panning
+            lonlat = this.getCenter();
-                lonlat = this.getCenter();
-            }
         }
         // dragging is false by default
         var dragging = options.dragging || this.dragging;