Calculating maxResolution instead of having it in defaults.

lib/OpenLayers/Layer.js

@@ -255,8 +255,8 @@ OpenLayers.Layer = OpenLayers.Class({
      * APIProperty: maxResolution
      * {Float} Default max is 360 deg / 256 px, which corresponds to
      *     zoom level 0 on gmaps.  Specify a different value in the layer 
-     *     options if you are not using a geographic projection and 
+     *     options if you are not using the default <OpenLayers.Map.tileSize>
-     *     displaying the whole world.
+     *     and displaying the whole world.
      */
     maxResolution: null,
 
@@ -638,12 +638,6 @@ OpenLayers.Layer = OpenLayers.Class({
                          this.units || this.map.units;
             
             this.initResolutions();
-            if (!this.resolutions) {
-                throw(
-                    "Could not calculate resolutions for layer " + this.name +
-                    ". Configure maxResolution or resolutions or scales."
-                );
-            }
             
             if (!this.isBaseLayer) {
                 this.inRange = this.calculateInRange();
@@ -896,6 +890,16 @@ OpenLayers.Layer = OpenLayers.Class({
                 props.resolutions = this.resolutionsFromScales(props.scales);
             }
             if(props.resolutions == null) {
+                var maxExtent = this.maxExtent;
+                if (!props.maxResolution && maxExtent) {
+                    // maxResolution for default grid sets assumes that at zoom
+                    // level zero, the whole world fits on one tile.
+                    var tileSize = this.tileSize || this.map.getTileSize();
+                    props.maxResolution = Math.max(
+                        maxExtent.getWidth() / tileSize.w,
+                        maxExtent.getHeight() / tileSize.h
+                    );
+                }
                 props.resolutions = this.calculateResolutions(props);
             }
         }

lib/OpenLayers/Map.js

@@ -274,8 +274,8 @@ OpenLayers.Map = OpenLayers.Class({
 
     /**
      * APIProperty: maxResolution
-     * {Float} Specify if you are not using a geographic projection or Web
+     * {Float} Required if you are not displaying the whole world on a tile
-     *     Mercator and displaying the whole world.
+     * with the size specified in <tileSize>.
      */
     maxResolution: null,
 

lib/OpenLayers/Projection.js

@@ -167,26 +167,22 @@ OpenLayers.Projection.transforms = {};
  * {Object} Defaults for the SRS codes known to OpenLayers (currently
  * EPSG:4326, CRS:84, urn:ogc:def:crs:EPSG:6.6:4326, EPSG:900913, EPSG:3857,
  * EPSG:102113 and EPSG:102100). Keys are the SRS code, values are units,
- * maxExtent (the validity extent for the SRS), maxResolution (the maximum
+ * maxExtent (the validity extent for the SRS) and yx (true if this SRS is
- * resolution commonly used in grid sets for this SRS) and yx (true if this
+ * known to have a reverse axis order).
- * SRS is known to have a reverse axis order).
  */
 OpenLayers.Projection.defaults = {
     "EPSG:4326": {
         units: "degrees",
         maxExtent: [-180, -90, 180, 90],
-        maxResolution: 1.40625,
         yx: true
     },
     "CRS:84": {
         units: "degrees",
-        maxExtent: [-180, -90, 180, 90],
+        maxExtent: [-180, -90, 180, 90]
-        maxResolution: 1.40625
     },
     "EPSG:900913": {
         units: "m",
-        maxExtent: [-20037508.34, -20037508.34, 20037508.34, 20037508.34],
+        maxExtent: [-20037508.34, -20037508.34, 20037508.34, 20037508.34]
-        maxResolution: 156543.03390625
     }
 };
 

tests/Layer/WMS.html

@@ -388,6 +388,7 @@
         var map = new OpenLayers.Map({
             div: "map",
             maxExtent: new OpenLayers.Bounds(-185, -95, 185, 95),
+            maxResolution: 1.40625,
             layers: [dummy, unconstrained, constrained],
             center: new OpenLayers.LonLat(0, 0),
             zoom: 1

tests/Layer/WMTS.html

@@ -136,7 +136,8 @@
                     layer: "world",
                     style: "blue_marble",
                     matrixSet: "arcgis_online",
-                    tileSize: new OpenLayers.Size(512, 512),            
+                    tileSize: new OpenLayers.Size(512, 512),  
+                    maxResolution: 1.40625,          
                     requestEncoding: "REST"            
                 });
                 map.addLayer(layer1);
@@ -156,7 +157,8 @@
                     layer: "world",
                     style: "blue_marble",
                     matrixSet: "arcgis_online",
-                    tileSize: new OpenLayers.Size(512, 512),            
+                    tileSize: new OpenLayers.Size(512, 512),       
+                    maxResolution: 1.40625,     
                     requestEncoding: "REST"            
                 });                                
                 map.addLayer(layer1);

tests/Layer/XYZ.html

@@ -195,7 +195,7 @@
         
         var map = new OpenLayers.Map({
             div: "map",
-            maxResolution: OpenLayers.Projection.defaults["EPSG:4326"].maxResolution / Math.pow(2, offset)
+            maxResolution: 1.40625 / Math.pow(2, offset)
         });
         var layer = new OpenLayers.Layer.XYZ(name, url, {zoomOffset: offset});
         map.addLayer(layer);
@@ -211,7 +211,7 @@
         
         var map = new OpenLayers.Map({
             div: "map",
-            maxResolution: OpenLayers.Projection.defaults["EPSG:4326"].maxResolution / Math.pow(2, offset)
+            maxResolution: 1.40625 / Math.pow(2, offset)
         });
         var layer = new OpenLayers.Layer.XYZ(name, url, {zoomOffset: offset});
         map.addLayer(layer);