first import

sites/all/modules/geophp/geoPHP/lib/adapters/GeoHash.class.php

@@ -0,0 +1,166 @@
+<?php
+/**
+ * PHP Geometry GeoHash encoder/decoder.
+ *
+ * @author prinsmc
+ * @see http://en.wikipedia.org/wiki/Geohash
+ *
+ */
+class GeoHash extends GeoAdapter{
+  private $table = "0123456789bcdefghjkmnpqrstuvwxyz";
+
+  /**
+   * Convert the geohash to a Point. The point is 2-dimensional.
+   * @return Point the converted geohash
+   * @param string $hash a geohash
+   * @see GeoAdapter::read()
+   */
+  public function read($hash, $as_grid = FALSE) {
+    $ll = $this->decode($hash);
+    if (!$as_grid) {
+      return new Point($ll['medlon'], $ll['medlat']);
+    }
+    else {
+      return new Polygon(array(
+        new LineString(array(
+          new Point($ll['minlon'], $ll['maxlat']),
+          new Point($ll['maxlon'], $ll['maxlat']),
+          new Point($ll['maxlon'], $ll['minlat']),
+          new Point($ll['minlon'], $ll['minlat']),
+          new Point($ll['minlon'], $ll['maxlat']),
+        ))
+      ));
+    }
+  }
+
+  /**
+   * Convert the geometry to geohash.
+   * @return string the geohash or null when the $geometry is not a Point
+   * @param Point $geometry
+   * @see GeoAdapter::write()
+   */
+  public function write(Geometry $geometry, $precision = NULL){
+    if ($geometry->isEmpty()) return '';
+
+    if($geometry->geometryType() === 'Point'){
+      return $this->encodePoint($geometry, $precision);
+    }
+    else {
+      // The geohash is the hash grid ID that fits the envelope
+      $envelope = $geometry->envelope();
+      $geohashes = array();
+      $geohash = '';
+      foreach ($envelope->getPoints() as $point) {
+        $geohashes[] = $this->encodePoint($point, 0.0000001);
+      }
+      $i = 0;
+      while ($i < strlen($geohashes[0])) {
+        $char = $geohashes[0][$i];
+        foreach ($geohashes as $hash) {
+          if ($hash[$i] != $char) {
+            return $geohash;
+          }
+        }
+        $geohash .= $char;
+        $i++;
+      }
+      return $geohash;
+    }
+  }
+
+  /**
+   * @return string geohash
+   * @param Point $point
+   * @author algorithm based on code by Alexander Songe <a@songe.me>
+   * @see https://github.com/asonge/php-geohash/issues/1
+   */
+  private function encodePoint($point, $precision = NULL){
+    if ($precision === NULL) {
+      $lap = strlen($point->y())-strpos($point->y(),".");
+      $lop = strlen($point->x())-strpos($point->x(),".");
+      $precision = pow(10,-max($lap-1,$lop-1,0))/2;
+    }
+
+    $minlat =  -90;
+    $maxlat =   90;
+    $minlon = -180;
+    $maxlon =  180;
+    $latE   =   90;
+    $lonE   =  180;
+    $i = 0;
+    $error = 180;
+    $hash='';
+    while($error>=$precision) {
+      $chr = 0;
+      for($b=4;$b>=0;--$b) {
+        if((1&$b) == (1&$i)) {
+          // even char, even bit OR odd char, odd bit...a lon
+          $next = ($minlon+$maxlon)/2;
+          if($point->x()>$next) {
+            $chr |= pow(2,$b);
+            $minlon = $next;
+          } else {
+            $maxlon = $next;
+          }
+          $lonE /= 2;
+        } else {
+          // odd char, even bit OR even char, odd bit...a lat
+          $next = ($minlat+$maxlat)/2;
+          if($point->y()>$next) {
+            $chr |= pow(2,$b);
+            $minlat = $next;
+          } else {
+            $maxlat = $next;
+          }
+          $latE /= 2;
+        }
+      }
+      $hash .= $this->table[$chr];
+      $i++;
+      $error = min($latE,$lonE);
+    }
+    return $hash;
+  }
+
+  /**
+   * @param string $hash a geohash
+   * @author algorithm based on code by Alexander Songe <a@songe.me>
+   * @see https://github.com/asonge/php-geohash/issues/1
+   */
+  private function decode($hash){
+    $ll = array();
+    $minlat =  -90;
+    $maxlat =   90;
+    $minlon = -180;
+    $maxlon =  180;
+    $latE   =   90;
+    $lonE   =  180;
+    for($i=0,$c=strlen($hash);$i<$c;$i++) {
+      $v = strpos($this->table,$hash[$i]);
+      if(1&$i) {
+        if(16&$v)$minlat = ($minlat+$maxlat)/2; else $maxlat = ($minlat+$maxlat)/2;
+        if(8&$v) $minlon = ($minlon+$maxlon)/2; else $maxlon = ($minlon+$maxlon)/2;
+        if(4&$v) $minlat = ($minlat+$maxlat)/2; else $maxlat = ($minlat+$maxlat)/2;
+        if(2&$v) $minlon = ($minlon+$maxlon)/2; else $maxlon = ($minlon+$maxlon)/2;
+        if(1&$v) $minlat = ($minlat+$maxlat)/2; else $maxlat = ($minlat+$maxlat)/2;
+        $latE /= 8;
+        $lonE /= 4;
+      } else {
+        if(16&$v)$minlon = ($minlon+$maxlon)/2; else $maxlon = ($minlon+$maxlon)/2;
+        if(8&$v) $minlat = ($minlat+$maxlat)/2; else $maxlat = ($minlat+$maxlat)/2;
+        if(4&$v) $minlon = ($minlon+$maxlon)/2; else $maxlon = ($minlon+$maxlon)/2;
+        if(2&$v) $minlat = ($minlat+$maxlat)/2; else $maxlat = ($minlat+$maxlat)/2;
+        if(1&$v) $minlon = ($minlon+$maxlon)/2; else $maxlon = ($minlon+$maxlon)/2;
+        $latE /= 4;
+        $lonE /= 8;
+      }
+    }
+    $ll['minlat'] = $minlat;
+    $ll['minlon'] = $minlon;
+    $ll['maxlat'] = $maxlat;
+    $ll['maxlon'] = $maxlon;
+    $ll['medlat'] = round(($minlat+$maxlat)/2, max(1, -round(log10($latE)))-1);
+    $ll['medlon'] = round(($minlon+$maxlon)/2, max(1, -round(log10($lonE)))-1);
+    return $ll;
+  }
+}