Changeset 870

Timestamp:

09/17/06 17:26:28 (2 years ago)

Author:

nick

Message:

Support doing Helmert Transforms as required, using the MySociety? Helmert transform library, if installed. References #89

Location:

trunk

Files:

• lib/OpenGuides/Utils.pm (modified) (2 diffs)
• t/28_wgs84_coords.t (modified) (3 diffs)

trunk/lib/OpenGuides/Utils.pm

@@ -236 +236 @@
        or croak "No longitude supplied to get_wgs84_coords";
     croak "geo_handler not defined!" unless $config->geo_handler;
+
     if ($config->force_wgs84) {
         # Only as a rough approximation, good enough for large scale guides
         return ($longitude, $latitude);
-    } elsif ($config->geo_handler == 1) {
+    }
+
+    # If we don't have a lat and long, return undef right away
+    unless($args{longitude} || $args{latitude}) {
+        return undef;
+    }
+
+    # Try to load a provider of Helmert Transforms
+    my $helmert;
+    # First up, try the MySociety Geo::HelmertTransform
+    unless($helmert) {
+        eval {
+            require Geo::HelmertTransform;
+            $helmert = sub($$$) {
+                my ($datum,$oldlat,$oldlong) = @_;
+                my $datum_helper = Geo::HelmertTransform::datum($datum);
+                my $wgs84_helper = Geo::HelmertTransform::datum('WGS84');
+                unless($datum_helper) {
+                    croak("No convertion helper for datum '$datum'");
+                    return undef;
+                }
+
+                my ($lat,$long,$h) = 
+                    Geo::HelmertTransform::convert_datum($datum_helper,$wgs84_helper,$oldlat,$oldlong,0);
+                return ($long,$lat);
+            };
+        };
+    }
+    # Next, try .....
+    unless($helmert) {
+        eval {
+        };
+    }
+    # Give up, return undef
+    unless($helmert) {
+       return undef; 
+    }
+    
+
+    if ($config->geo_handler == 1) {
         # Do conversion here
-        return undef;
+        return &$helmert('Airy1830',$latitude,$longitude);
     } elsif ($config->geo_handler == 2) {
         # Do conversion here
-        return undef;
+        return &$helmert('Airy1830Modified',$latitude,$longitude);
     } elsif ($config->geo_handler == 3) {
         if ($config->ellipsoid eq "WGS-84") {
@@ -250 +290 @@
         } else {
             # Do conversion here
-            return undef;
+            return &$helmert($config->ellipsoid,$latitude,$longitude);
         }
     } else {

trunk/t/28_wgs84_coords.t

@@ -5 +5 @@
 use Test::More;
 
-plan tests => 2;
+plan tests => 4;
 
 # Clear out the database from any previous runs.
@@ -18 +18 @@
 my $guide = OpenGuides->new( config => $config );
 
-my ($longitude, $latitude) = (0, 0);
+my ($longitude, $latitude) = (10, 12);
 
 my ($wgs_long, $wgs_lat) = OpenGuides::Utils->get_wgs84_coords(
@@ -29 +29 @@
 is( $wgs_lat, $latitude,
     "get_wgs84_coords returns the original latitude when force_wgs84 is on");
+
+
+# Now claim to be in the UK
+eval{ require Geo::HelmertTransform; };
+my $have_helmert = $@ ? 0 : 1;
+SKIP : {
+    skip "Geo::HelmertTransform not installed - can't do transforms", 2
+        unless $have_helmert;
+
+    $config->force_wgs84(0);
+    $config->geo_handler(1);
+
+    # Set our location to be somewhere known
+       ($longitude,$latitude)  = (-1.258200,51.754349);
+    my ($wgs84_lon,$wgs84_lat) = (-1.259687,51.754813);
+
+    ($wgs_long, $wgs_lat) = OpenGuides::Utils->get_wgs84_coords(
+                                                     longitude => $longitude,
+                                                     latitude => $latitude,
+                                                     config => $config);
+
+    # Round to 5 dp
+    my $fivedp = 1 * 1000 * 100;
+    $wgs_long = int($wgs_long * $fivedp)/$fivedp;
+    $wgs_lat  = int($wgs_lat  * $fivedp)/$fivedp;
+    $wgs84_lon = int($wgs84_lon * $fivedp)/$fivedp;
+    $wgs84_lat = int($wgs84_lat * $fivedp)/$fivedp;
+
+    is( $wgs_long, $wgs84_lon,
+        "get_wgs84_coords does Airy1830 -> WGS84 convertion properly");
+    is( $wgs_lat, $wgs84_lat,
+        "get_wgs84_coords does Airy1830 -> WGS84 convertion properly");
+}