Adding support for fractional zoom to the pan zoom bar. Setting map.fractionalZoom to true allows you to access a continuous range of resolutions with the pan zoom bar. r=crschmidt,me (closes #1288)

git-svn-id: http://svn.openlayers.org/trunk/openlayers@6331 dc9f47b5-9b13-0410-9fdd-eb0c1a62fdaf

examples/fractional-zoom.html

@@ -13,7 +13,10 @@
         var map;
 
         function init() {
-            map = new OpenLayers.Map('map');
+            map = new OpenLayers.Map('map', 
+                 {controls: [new OpenLayers.Control.Navigation(), 
+                             new OpenLayers.Control.PanZoomBar()], 
+                  numZoomLevels: 10 });
             var wms = new OpenLayers.Layer.WMS(
                 "OpenLayers WMS",
                 "http://labs.metacarta.com/wms/vmap0",
@@ -22,7 +25,6 @@
             map.addLayers([wms]);
 
             map.events.register("moveend", null, displayZoom);
-            map.addControl( new OpenLayers.Control.LayerSwitcher() );
 
             map.zoomToMaxExtent();
             
@@ -36,6 +38,7 @@
         
         function update(input) {
             map.fractionalZoom = input.checked;
+            map.zoomTo(Math.round(map.zoom));
         }
     </script>
   </head>

lib/OpenLayers/Control/PanZoomBar.js

@@ -241,8 +241,14 @@ OpenLayers.Control.PanZoomBar = OpenLayers.Class(OpenLayers.Control.PanZoom, {
         }
         var y = evt.xy.y;
         var top = OpenLayers.Util.pagePosition(evt.object)[1];
-        var levels = Math.floor((y - top)/this.zoomStopHeight);
+        var levels = (y - top)/this.zoomStopHeight;
-        this.map.zoomTo((this.map.getNumZoomLevels() -1) -  levels);
+        var zoom = (this.map.getNumZoomLevels() - 1) - levels; 
+        if(this.map.fractionalZoom) {
+           zoom = Math.min(Math.max(zoom, 0), this.map.getNumZoomLevels() - 1);
+        } else {
+            zoom = Math.floor(zoom);
+        }    
+        this.map.zoomTo(zoom);
         OpenLayers.Event.stop(evt);
     },
     
@@ -314,7 +320,15 @@ OpenLayers.Control.PanZoomBar = OpenLayers.Class(OpenLayers.Control.PanZoom, {
                 scope: this
             });
             var deltaY = this.zoomStart.y - evt.xy.y;
-            this.map.zoomTo(this.map.zoom + Math.round(deltaY/this.zoomStopHeight));
+            var zoomLevel = this.map.zoom;
+            if (this.map.fractionalZoom) {
+                zoomLevel += deltaY/this.zoomStopHeight;
+                zoomLevel = Math.min(Math.max(zoomLevel, 0), 
+                                     this.map.getNumZoomLevels() - 1);
+            } else {
+                zoomLevel += Math.round(deltaY/this.zoomStopHeight);
+            }
+            this.map.zoomTo(zoomLevel);
             this.moveZoomBar();
             this.mouseDragStart = null;
             OpenLayers.Event.stop(evt);