Add a getTileBounds method to gridded layers. Thanks to crschmidt for the tests on this one. Committed with a few minor ndoc changes (closes 482).

git-svn-id: http://svn.openlayers.org/trunk/openlayers@4088 dc9f47b5-9b13-0410-9fdd-eb0c1a62fdaf

lib/OpenLayers/Layer/Grid.js

@@ -229,13 +229,16 @@ OpenLayers.Layer.Grid = OpenLayers.Class(OpenLayers.Layer.HTTPRequest, {
     },
 
     /**
-     * Method: getTilesBounds
+     * APIMethod: getTileBounds
-     * Get the bounds of the grid
+     * Returns The tile bounds for a layer given a pixel location.
      *
-     * Return:
+     * Parameters:
+     * viewPortPx - {<OpenLayers.Pixel>} The location in the viewport.
+     *
+     * Returns:
      * {<OpenLayers.Bounds>} A Bounds object representing the bounds of all the
      *     currently loaded tiles (including those partially or not at all seen 
-     * onscreen)
+     *     onscreen).
      */
     getTilesBounds: function() {    
         var bounds = null; 
@@ -673,5 +676,31 @@ OpenLayers.Layer.Grid = OpenLayers.Class(OpenLayers.Layer.HTTPRequest, {
       }
     },
     
+    /**
+     * APIMethod: getTileBounds
+     * Returns The tile bounds for a layer given a pixel location
+     *
+     * Parameters: 
+     * viewPortPx - {OpenLayers.Pixel} The location in the viewport
+     */
+    getTileBounds: function(viewPortPx) {
+        var maxExtent = this.map.getMaxExtent();
+        var resolution = this.getResolution();
+        var tileMapWidth = resolution * this.tileSize.w;
+        var tileMapHeight = resolution * this.tileSize.h;
+        var mapPoint = this.getLonLatFromViewPortPx(viewPortPx);
+        var tileLeft = maxExtent.left + (tileMapWidth *
+                                         Math.floor((mapPoint.lon -
+                                                     maxExtent.left) /
+                                                    tileMapWidth));
+        var tileBottom = maxExtent.bottom + (tileMapHeight *
+                                             Math.floor((mapPoint.lat -
+                                                         maxExtent.bottom) /
+                                                        tileMapHeight));
+        return new OpenLayers.Bounds(tileLeft, tileBottom,
+                                     tileLeft + tileMapWidth,
+                                     tileBottom + tileMapHeight);
+    },
+    
     CLASS_NAME: "OpenLayers.Layer.Grid"
 });

lib/OpenLayers/Layer/KaMap.js

@@ -226,5 +226,27 @@ OpenLayers.Layer.KaMap = OpenLayers.Class(OpenLayers.Layer.Grid, {
         return obj;
     },    
     
+    /**
+     * APIMethod: getTileBounds
+     * Returns The tile bounds for a layer given a pixel location.
+     *
+     * Parameters:
+     * viewPortPx - {<OpenLayers.Pixel>} The location in the viewport.
+     *
+     * Returns:
+     * {<OpenLayers.Bounds>} Bounds of the tile at the given pixel location.
+     */
+    getTileBounds: function(viewPortPx) {
+        var resolution = this.getResolution();
+        var tileMapWidth = resolution * this.tileSize.w;
+        var tileMapHeight = resolution * this.tileSize.h;
+        var mapPoint = this.getLonLatFromViewPortPx(viewPortPx);
+        var tileLeft = tileMapWidth * Math.floor(mapPoint.lon / tileMapWidth);
+        var tileBottom = tileMapHeight * Math.floor(mapPoint.lat / tileMapHeight);
+        return new OpenLayers.Bounds(tileLeft, tileBottom,
+                                     tileLeft + tileMapWidth,
+                                     tileBottom + tileMapHeight);
+    },
+
     CLASS_NAME: "OpenLayers.Layer.KaMap"
 });

tests/Layer/test_Grid.html

@@ -528,6 +528,24 @@
         height = layer.tileSize.h;
         t.ok(width == parseInt(width) && height == parseInt(height), "calculated tileSize width/height are integer values");
     }
+    function test_12_Layer_Grid_getTileBounds(t) {
+        t.plan(2);
+        var map = new OpenLayers.Map("map2");
+        var url = "http://octo.metacarta.com/cgi-bin/mapserv";
+        layer = new OpenLayers.Layer.WMS(name, url, params);
+        
+        var newParams = { layers: 'sooper', 
+                          chickpeas: 'image/png'};
+
+        map.addLayer(layer);
+        map.zoomToMaxExtent();
+        map.zoomIn();
+        var bounds = layer.getTileBounds(new OpenLayers.Pixel(200,200));
+        t.eq(bounds.toBBOX(), "-180,-90,0,90", "get tile bounds returns correct bounds"); 
+        map.pan(200,0);
+        var bounds = layer.getTileBounds(new OpenLayers.Pixel(200,200));
+        t.eq(bounds.toBBOX(), "0,-90,180,90", "get tile bounds returns correct bounds after pan"); 
+    }
 
     function test_99_Layer_Grid_destroy (t) {
 
@@ -563,5 +581,6 @@
 </head>
 <body>
 <div id="map" style="width:499px;height:549px;display:none"></div>
+<div id="map2" style="width:500px;height:550px;display:none"></div>
 </body>
 </html>

tests/Layer/test_KaMap.html

@@ -189,6 +189,24 @@
         t.ok( layer.tileSize != null, "tileSize has been set");
         t.ok( (layer.tileSize.h == 50) && (layer.tileSize.w == 500), "tileSize has been set correctly");
     }
+    function test_12_Layer_KaMap_getTileBounds(t) {
+        t.plan(2);
+        var map = new OpenLayers.Map("map");
+        var url = "http://octo.metacarta.com/cgi-bin/mapserv";
+        layer = new OpenLayers.Layer.KaMap(name, url, params);
+        
+        var newParams = { layers: 'sooper', 
+                          chickpeas: 'image/png'};
+
+        map.addLayer(layer);
+        map.zoomToMaxExtent();
+        map.zoomIn();
+        var bounds = layer.getTileBounds(new OpenLayers.Pixel(200,200));
+        t.eq(bounds.toBBOX(), "-180,0,0,180", "get tile bounds returns correct bounds"); 
+        map.pan(200,0);
+        var bounds = layer.getTileBounds(new OpenLayers.Pixel(200,200));
+        t.eq(bounds.toBBOX(), "0,0,180,180", "get tile bounds returns correct bounds after pan"); 
+    }
 
     function test_99_Layer_KaMap_destroy (t) {