Add a proper OpenLayers plugin for Swiss<->WGS84 transformations

2 files changed, 184 insertions, 59 deletions

diff --git a/web/js/OpenLayers.Projection.CH1903.js b/web/js/OpenLayers.Projection.CH1903.js
new file mode 100644
index 000000000..f050441e6
--- /dev/null
+++ b/web/js/OpenLayers.Projection.CH1903.js
@@ -0,0 +1,173 @@
+/**
+ * OpenLayers Swiss (CH1903) grid projection transformations
+ * 
+ * Provides transform functions for WGS84<->CH1903 projections.
+ *
+ * Maths courtesy of the Swiss Federal Office of Topography:
+ * http://www.swisstopo.admin.ch/internet/swisstopo/en/home/products/software/products/skripts.html
+ */
+
+
+OpenLayers.Projection.CH1903 = {
+
+    // Convert SEX DMS angle to DEC
+    SEXtoDEC: function(angle) {
+
+        // Extract DMS
+        var deg = parseInt(angle, 10);
+        var min = parseInt((angle - deg) * 100, 10);
+        var sec = (((angle - deg) * 100) - min) * 100;
+
+        // Result in degrees sex (dd.mmss)
+        return deg + ((sec / 60 + min) / 60);
+
+    },
+
+    // Convert DEC angle to SEX DMS
+    DECtoSEX: function(angle) {
+
+        // Extract DMS
+        var deg = parseInt(angle, 10);
+        var min = parseInt((angle - deg) * 60, 10);
+        var sec =  (((angle - deg) * 60) - min) * 60;   
+
+        // Result in degrees sex (dd.mmss)
+        return deg + (min / 100) + (sec / 10000);
+
+    },
+
+    // Convert Degrees angle to seconds
+    DEGtoSEC: function(angle) {
+
+        // Extract DMS
+        var deg = parseInt( angle );
+        var min = parseInt( (angle - deg) * 100 );
+        var sec = (((angle - deg) * 100) - min) * 100;
+
+        // Result in degrees sex (dd.mmss)
+        return sec + (min * 60) + (deg * 3600);
+
+    },
+
+    // Convert WGS lat/long (° dec) to CH y
+    WGStoCHy: function(lat, lng) {
+
+        // Converts degrees dec to sex
+        lat = OpenLayers.Projection.CH1903.DECtoSEX(lat);
+        lng = OpenLayers.Projection.CH1903.DECtoSEX(lng);
+
+        // Converts degrees to seconds (sex)
+        lat = OpenLayers.Projection.CH1903.DEGtoSEC(lat);
+        lng = OpenLayers.Projection.CH1903.DEGtoSEC(lng);
+
+        // Axiliary values (% Bern)
+        var lat_aux = (lat - 169028.66) / 10000;
+        var lng_aux = (lng - 26782.5) / 10000;
+
+        // Process Y
+        y = 600072.37;
+        y = y + (211455.93 * lng_aux);
+        y = y - (10938.51 * lng_aux * lat_aux);
+        y = y - (0.36 * lng_aux * Math.pow(lat_aux, 2));
+        y = y - (44.54 * Math.pow(lng_aux, 3));
+
+        return y;
+    },
+
+    // Convert WGS lat/long (° dec) to CH x
+    WGStoCHx: function(lat, lng) {
+
+        // Converts degrees dec to sex
+        lat = OpenLayers.Projection.CH1903.DECtoSEX(lat);
+        lng = OpenLayers.Projection.CH1903.DECtoSEX(lng);
+
+        // Converts degrees to seconds (sex)
+        lat = OpenLayers.Projection.CH1903.DEGtoSEC(lat);
+        lng = OpenLayers.Projection.CH1903.DEGtoSEC(lng);
+
+        // Axiliary values (% Bern)
+        var lat_aux = (lat - 169028.66)/10000;
+        var lng_aux = (lng - 26782.5)/10000;
+
+        // Process X
+        x = 200147.07;
+        x = x + (308807.95 * lat_aux);
+        x = x + (3745.25 * Math.pow(lng_aux, 2));
+        x = x + (76.63 * Math.pow(lat_aux, 2));
+        x = x - (194.56 * Math.pow(lng_aux, 2) * lat_aux);
+        x = x + (119.79 * Math.pow(lat_aux, 3));
+
+        return x;
+      
+    },
+
+    // Convert CH y/x to WGS lat
+    chToWGSlat: function(y, x) {
+
+        // Converts militar to civil and  to unit = 1000km
+        // Axiliary values (% Bern)
+        var y_aux = (y - 600000) / 1000000;
+        var x_aux = (x - 200000) / 1000000;
+
+        // Process lat
+        var lat = 16.9023892;
+        lat = lat + (3.238272 * x_aux);
+        lat = lat - (0.270978 * Math.pow(y_aux, 2));
+        lat = lat - (0.002528 * Math.pow(x_aux, 2));
+        lat = lat - (0.0447 * Math.pow(y_aux, 2) * x_aux);
+        lat = lat - (0.0140 * Math.pow(x_aux, 3));
+
+        // Unit 10000" to 1 " and converts seconds to degrees (dec)
+        lat = lat * 100 / 36;
+
+        return lat;
+
+    },
+
+    // Convert CH y/x to WGS long
+    chToWGSlng: function(y, x) {
+
+        // Converts militar to civil and  to unit = 1000km
+        // Axiliary values (% Bern)
+        var y_aux = (y - 600000) / 1000000;
+        var x_aux = (x - 200000) / 1000000;
+
+        // Process long
+        var lng = 2.6779094;
+        lng = lng + (4.728982 * y_aux);
+        lng = lng + (0.791484 * y_aux * x_aux);
+        lng = lng + (0.1306 * y_aux * Math.pow(x_aux, 2));
+        lng = lng - (0.0436 * Math.pow(y_aux, 3));
+
+        // Unit 10000" to 1 " and converts seconds to degrees (dec)
+        lng = lng * 100 / 36;
+
+        return lng;
+
+    },
+
+    // Function to convert a WGS84 coordinate to a Swiss coordinate.
+    projectForwardSwiss: function(point) {
+        var newPoint = {};
+        newPoint.x = OpenLayers.Projection.CH1903.WGStoCHx(point.x, point.y);
+        newPoint.y = OpenLayers.Projection.CH1903.WGStoCHy(point.x, point.y);
+        return newPoint;
+    },
+
+    // Function to convert a Swiss coordinate to a WGS84 coordinate. 
+    projectInverseSwiss: function(point) {
+        var newPoint = {};
+        newPoint.x = OpenLayers.Projection.CH1903.chToWGSlng(point.y, point.x);
+        newPoint.y = OpenLayers.Projection.CH1903.chToWGSlat(point.y, point.x);
+        return newPoint;
+    }
+};
+
+/**
+ * Note: One transform declared
+ * Transforms from EPSG:4326 to EPSG:21781
+ */
+ OpenLayers.Projection.addTransform("EPSG:4326", "EPSG:21781",
+    OpenLayers.Projection.CH1903.projectForwardSwiss);
+ OpenLayers.Projection.addTransform("EPSG:21781", "EPSG:4326",
+    OpenLayers.Projection.CH1903.projectInverseSwiss);
\ No newline at end of file
diff --git a/web/js/map-wmts-zurich.js b/web/js/map-wmts-zurich.js
index 441df91eb..231b87786 100644
--- a/web/js/map-wmts-zurich.js
+++ b/web/js/map-wmts-zurich.js
@@ -65,59 +65,6 @@ function init_zurich_map(after) {
       'xml');
 }
 
-// These next two functions come from the Swiss Federal Office of Topography
-// http://www.swisstopo.admin.ch/internet/swisstopo/en/home/products/software/products/skripts.html
-
-// Convert CH y/x to WGS lat
-function chToWGSlat(y, x) {
-
-    // Converts militar to civil and  to unit = 1000km
-    // Axiliary values (% Bern)
-    var y_aux = (y - 600000) / 1000000;
-    var x_aux = (x - 200000) / 1000000;
-
-    // Process lat
-    var lat = 16.9023892;
-    lat = lat + (3.238272 * x_aux);
-    lat = lat - (0.270978 * Math.pow(y_aux, 2));
-    lat = lat - (0.002528 * Math.pow(x_aux, 2));
-    lat = lat - (0.0447 * Math.pow(y_aux, 2) * x_aux);
-    lat = lat - (0.0140 * Math.pow(x_aux, 3));
-
-    // Unit 10000" to 1 " and converts seconds to degrees (dec)
-    lat = lat * 100 / 36;
-
-    return lat;
-  
-}
-
-// Convert CH y/x to WGS long
-function chToWGSlng(y, x) {
-
-    // Converts militar to civil and  to unit = 1000km
-    // Axiliary values (% Bern)
-    var y_aux = (y - 600000) / 1000000;
-    var x_aux = (x - 200000) / 1000000;
-
-    // Process long
-    var lng = 2.6779094;
-    lng = lng + (4.728982 * y_aux);
-    lng = lng + (0.791484 * y_aux * x_aux);
-    lng = lng + (0.1306 * y_aux * Math.pow(x_aux, 2));
-    lng = lng - (0.0436 * Math.pow(y_aux, 3));
-
-    // Unit 10000" to 1 " and converts seconds to degrees (dec)
-    lng = lng * 100 / 36;
-
-    return lng;
-  
-}
-
-// Function to convert a Swiss coordinate to a WGS84 coordinate. 
-function getOLLatLonFromSwiss(y, x) {
-    return new OpenLayers.LonLat(chToWGSlng(y, x), chToWGSlat(y, x));
-}
-
 /* 
  * set_map_config() is called on dom ready in map-OpenLayers.js
  * to setup the way the map should operate.
@@ -164,13 +111,18 @@ OpenLayers.Strategy.ZurichBBOX = OpenLayers.Class(OpenLayers.Strategy.BBOX, {
         if (this.layer.map === null) {
             return null;
         }
+
         var swissBounds = this.layer.map.getExtent();
-        var topLeft = getOLLatLonFromSwiss(swissBounds.left,swissBounds.top);
-        var bottomRight = getOLLatLonFromSwiss(swissBounds.right,swissBounds.bottom);
-        var bounds = new OpenLayers.Bounds();
-        bounds.extend(topLeft);
-        bounds.extend(bottomRight);
-        return bounds;
+
+        // Transform bound corners into WGS84 - note x/y arrangement of
+        // values from the current bounding box, it seems wrong but is not.
+        var topLeft = OpenLayers.Projection.CH1903.projectInverseSwiss(
+                {y: swissBounds.left, x: swissBounds.top}
+            );
+        var bottomRight = OpenLayers.Projection.CH1903.projectInverseSwiss(
+                {y: swissBounds.right, x: swissBounds.bottom}
+            );  
+        return new OpenLayers.Bounds(topLeft.x, bottomRight.y, bottomRight.x, topLeft.y);
     },
 
     CLASS_NAME: "OpenLayers.Strategy.ZurichBBOX"