Added support for different projections for main map and overview map. Patch by bartvde. Modifications to the original patch:

* caclulation of resolution factor no longer depends on proj4js,
 * created a member variable for the resolution factor and moved the calculation of the resolution factor to createMap(),
 * created acceptance test (tests/manual/overviewmap-projection.html).
r=me (closes #1620)

git-svn-id: http://svn.openlayers.org/trunk/openlayers@7864 dc9f47b5-9b13-0410-9fdd-eb0c1a62fdaf

lib/OpenLayers/Control/OverviewMap.js

@@ -103,6 +103,12 @@ OpenLayers.Control.OverviewMap = OpenLayers.Class(OpenLayers.Control, {
      */
     handlers: null,
 
+    /**
+     * Property: resolutionFactor
+     * {Object}
+     */
+    resolutionFactor: 1,
+
     /**
      * Constructor: OpenLayers.Control.OverviewMap
      * Create a new overview map
@@ -402,6 +408,13 @@ OpenLayers.Control.OverviewMap = OpenLayers.Class(OpenLayers.Control, {
                                 Math.max(mapExtent.bottom, maxExtent.bottom),
                                 Math.min(mapExtent.right, maxExtent.right),
                                 Math.min(mapExtent.top, maxExtent.top));        
+
+        if (this.ovmap.getProjection() != this.map.getProjection()) {
+            testExtent = testExtent.transform(
+                this.map.getProjectionObject(),
+                this.ovmap.getProjectionObject() );
+        }
+
         var resRatio = this.ovmap.getResolution() / this.map.getResolution();
         return ((resRatio > this.minRatio) &&
                 (resRatio <= this.maxRatio) &&
@@ -423,8 +436,16 @@ OpenLayers.Control.OverviewMap = OpenLayers.Class(OpenLayers.Control, {
             // zoom out overview map
             targetRes = this.maxRatio * mapRes;
         }
-        this.ovmap.setCenter(this.map.center,
-                            this.ovmap.getZoomForResolution(targetRes));
+        var center;
+        if (this.ovmap.getProjection() != this.map.getProjection()) {
+            center = this.map.center.clone();
+            center.transform(this.map.getProjectionObject(),
+                this.ovmap.getProjectionObject() );
+        } else {
+            center = this.map.center;
+        }
+        this.ovmap.setCenter(center, this.ovmap.getZoomForResolution(
+            targetRes * this.resolutionFactor));
         this.updateRectToMap();
     },
     
@@ -486,6 +507,15 @@ OpenLayers.Control.OverviewMap = OpenLayers.Class(OpenLayers.Control, {
             }
         });
 
+        if (this.ovmap.getProjection() != this.map.getProjection()) {
+            var sourceUnits = this.map.getProjectionObject().getUnits() ||
+                this.map.units || this.map.baseLayer.units;
+            var targetUnits = this.ovmap.getProjectionObject().getUnits() ||
+                this.ovmap.units || this.ovmap.baseLayer.units;
+            this.resolutionFactor = sourceUnits && targetUnits ?
+                OpenLayers.INCHES_PER_UNIT[sourceUnits] /
+                OpenLayers.INCHES_PER_UNIT[targetUnits] : 1;
+        }
     },
         
     /**
@@ -493,14 +523,16 @@ OpenLayers.Control.OverviewMap = OpenLayers.Class(OpenLayers.Control, {
      * Updates the extent rectangle position and size to match the map extent
      */
     updateRectToMap: function() {
-        // The base layer for overview map needs to be in the same projection
-        // as the base layer for the main map.  This should be made more robust.
-        if(this.map.getUnits() != 'degrees') {
-            if(this.ovmap.getProjection() && (this.map.getProjection() != this.ovmap.getProjection())) {
-                OpenLayers.Console.userError(OpenLayers.i18n("sameProjection"));
-            }
+        // If the projections differ we need to reproject
+        var bounds;
+        if (this.ovmap.getProjection() != this.map.getProjection()) {
+            bounds = this.map.getExtent().transform(
+                this.map.getProjectionObject(), 
+                this.ovmap.getProjectionObject() );
+        } else {
+            bounds = this.map.getExtent();
         }
-        var pxBounds = this.getRectBoundsFromMapBounds(this.map.getExtent());
+        var pxBounds = this.getRectBoundsFromMapBounds(bounds);
         if (pxBounds) {
             this.setRectPxBounds(pxBounds);
         }
@@ -512,6 +544,11 @@ OpenLayers.Control.OverviewMap = OpenLayers.Class(OpenLayers.Control, {
      */
     updateMapToRect: function() {
         var lonLatBounds = this.getMapBoundsFromRectBounds(this.rectPxBounds);
+        if (this.ovmap.getProjection() != this.map.getProjection()) {
+            lonLatBounds = lonLatBounds.transform(
+                this.ovmap.getProjectionObject(),
+                this.map.getProjectionObject() );
+        }
         this.map.panTo(lonLatBounds.getCenterLonLat());
     },
 

tests/manual/overviewmap-projection.html

@@ -0,0 +1,70 @@
+<html xmlns="http://www.w3.org/1999/xhtml">
+  <head>
+    <link rel="stylesheet" href="../../theme/default/style.css" type="text/css" />
+    <link rel="stylesheet" href="../../examples/style.css" type="text/css" />
+    <style type="text/css">
+        .olControlAttribution { bottom: 0px!important }
+        #map {
+            height: 512px;
+        }
+    </style>
+
+    <script src='http://maps.google.com/maps?file=api&amp;v=2&amp;key=ABQIAAAAjpkAC9ePGem0lIq5XcMiuhR_wWLPFku8Ix9i2SXYRVK3e45q1BQUd_beF8dtzKET_EteAjPdGDwqpQ'></script>
+
+    <script src="../../lib/OpenLayers.js"></script>
+    <script type="text/javascript">
+
+        // make map available for easy debugging
+        var map;
+
+        function init(){
+            var options = {
+                projection: new OpenLayers.Projection("EPSG:900913"),
+                displayProjection: new OpenLayers.Projection("EPSG:4326"),
+                units: "m",
+                maxResolution: 156543.0339,
+                maxExtent: new OpenLayers.Bounds(-20037508, -20037508,
+                                                 20037508, 20037508.34)
+            };
+            map = new OpenLayers.Map('map', options);
+
+            // create Google Mercator layers
+            var gmap = new OpenLayers.Layer.Google(
+                "Google Streets",
+                {'sphericalMercator': true}
+            );
+            map.addLayers([gmap]);
+            map.addControl(new OpenLayers.Control.LayerSwitcher());
+            map.addControl(new OpenLayers.Control.Permalink());
+            map.addControl(new OpenLayers.Control.MousePosition());
+            var ovmap = new OpenLayers.Control.OverviewMap({
+                maxRatio: 16,
+                layers: [new OpenLayers.Layer.WMS("OpenLayers WMS", 
+                    "http://labs.metacarta.com/wms/vmap0",
+                    {layers: 'basic'})]
+            });
+            map.addControl(ovmap);
+            ovmap.maximizeControl();
+            if (!map.getCenter()) {map.zoomToMaxExtent()};
+        }
+    </script>
+  </head>
+  <body onload="init()">
+    <h1 id="title">OpenLayers Overview Map Projection Test</h1>
+
+    <div id="tags">
+    </div>
+    <p id="shortdesc">
+        Acceptance test for different projections in map and overview map.
+        The map uses EPSG:900913, the overview map EPSG:4326. Zoom the map and
+        drag both the map and the overview map to see it in action.
+    </p>
+    <div id="map" class="smallmap"></div>
+
+    <div id="docs">
+    </div>
+  </body>
+</html>
+
+
+