Various clean-up, finishing basic geometric methods

geoPHP.inc

@@ -114,8 +114,7 @@ class geoPHP
     }
     $wkb_writer = new GEOSWKBWriter();
     $wkb = $wkb_writer->writeHEX($geos);
-    $geometry = geoPHP::load($wkb,'wkb',TRUE);
-    //@@TODO: We no longer need to check this once we have Empty geometries
+    $geometry = geoPHP::load($wkb, 'wkb', TRUE);
     if ($geometry) {
       $geometry->setGeos($geos);
       return $geometry;

lib/adapters/WKB.class.php

@@ -123,9 +123,6 @@ function getMulti(&$mem, $type) {
     // Get the number of items expected in this multi out of the first 4 bytes
     $multi_length = unpack('L',fread($mem,4));
 
-    //@@TODO: create an EMPTY geometry instead of returning null
-    if (!$multi_length[1]) return NULL;
-
     $components = array();
     $i = 1;
     while ($i <= $multi_length[1]) {

lib/geometry/Collection.class.php

@@ -195,6 +195,81 @@ public function isEmpty() {
     }
   }
 
+  public function numPoints() {
+    $num = 0;
+    foreach ($this->components as $component) {
+      $num += $component->numPoints();
+    }
+    return $num;
+  }
+
+  public function getPoints() {
+    $points = array();
+    foreach ($this->components as $component) {
+      $points = array_merge($points, $component->getPoints());
+    }
+    return $points;
+  }
+
+  public function equals($geometry) {
+    if ($this->geos()) {
+      return $this->geos()->equals($geometry->geos());
+    }
+
+    // To test for equality we check to make sure that there is a matching point 
+    // in the other geometry for every point in this geometry. 
+    // This is slightly more strict than the standard, which
+    // uses Within(A,B) = true and Within(B,A) = true
+    // @@TODO: Eventually we could fix this by using some sort of simplification
+    // method that strips redundant vertices (that are all in a row)
+
+    $this_points = $this->getPoints();
+    $other_points = $geometry->getPoints();
+
+    // First do a check to make sure they have the same number of vertices
+    if (count($this_points) != count($other_points)) {
+      return FALSE;
+    }
+
+    foreach ($this_points as $point) {
+      $found_match = FALSE;
+      foreach ($other_points as $key => $test_point) {
+        if ($point->equals($test_point)) {
+          $found_match = TRUE;
+          unset($other_points[$key]);
+          break;
+        }
+      }
+      if (!$found_match) {
+        return FALSE;
+      }
+    }
+
+    // All points match, return TRUE
+    return TRUE;
+  }
+
+  public function isSimple() {
+    if ($this->geos()) {
+      return $this->geos()->isSimple();
+    }
+
+    // A collection is simple if all it's components are simple
+    foreach ($this->components as $component) {
+      if (!$component->isSimple()) return FALSE;
+    }
+
+    return TRUE;
+  }
+
+  public function explode() {
+    $parts = array();
+    foreach ($this->components as $component) {
+      $parts = array_merge($parts, $component->explode());
+    }
+    return $parts;
+  }
+
   // Not valid for this geometry type
   // --------------------------------
   public function x()                { return NULL; }
@@ -203,7 +278,6 @@ public function startPoint()       { return NULL; }
   public function endPoint()         { return NULL; }
   public function isRing()           { return NULL; }
   public function isClosed()         { return NULL; }
-  public function numPoints()        { return NULL; }
   public function pointN($n)         { return NULL; }
   public function exteriorRing()     { return NULL; }
   public function numInteriorRings() { return NULL; }

lib/geometry/Geometry.class.php

@@ -19,7 +19,7 @@ abstract public function y();
   abstract public function x();
   abstract public function numGeometries();
   abstract public function geometryN($n);
-  abstract public function startPoint(); 
+  abstract public function startPoint();
   abstract public function endPoint();
   abstract public function isRing();            // Mssing dependancy
   abstract public function isClosed();          // Missing dependancy
@@ -29,12 +29,16 @@ abstract public function exteriorRing();
   abstract public function numInteriorRings();
   abstract public function interiorRingN($n);
   abstract public function dimension();
+  abstract public function equals($geom);
   abstract public function isEmpty();
+  abstract public function isSimple();
 
   // Abtract: Non-Standard
   // ---------------------
   abstract public function getBBox();
   abstract public function asArray();
+  abstract public function getPoints();
+  abstract public function explode();
 
 
   // Public: Standard -- Common to all geometries
@@ -127,7 +131,7 @@ public function asText() {
     return $this->out('wkt');
   }
 
-   public function asBinary() {
+  public function asBinary() {
     return $this->out('wkb');
   }
 
@@ -159,22 +163,20 @@ public function pointOnSurface() {
     }
   }
 
-  public function equals($geometry) {
-    if ($this->geos()) {
-      return $this->geos()->equals($geometry->geos());
-    }
-  }
-
   public function equalsExact($geometry) {
     if ($this->geos()) {
       return $this->geos()->equalsExact($geometry->geos());
     }
   }
 
-  public function relate($geometry) {
-    //@@TODO: Deal with second "pattern" parameter
+  public function relate($geometry, $pattern = NULL) {
     if ($this->geos()) {
-      return $this->geos()->relate($geometry->geos());
+      if ($pattern) {
+        return $this->geos()->relate($geometry->geos(), $pattern);
+      }
+      else {
+        return $this->geos()->relate($geometry->geos());
+      }
     }
   }
 
@@ -183,12 +185,6 @@ public function checkValidity() {
       return $this->geos()->checkValidity();
     }
   }
-
-  public function isSimple() {
-    if ($this->geos()) {
-      return $this->geos()->isSimple();
-    }
-  }
 
   public function buffer($distance) {
     if ($this->geos()) {
@@ -220,10 +216,19 @@ public function symDifference($geometry) {
     }
   }
 
+  // Can pass in a geometry or an array of geometries
   public function union($geometry) {
-    //@@TODO: also does union cascade
     if ($this->geos()) {
-      return geoPHP::geosToGeometry($this->geos()->union($geometry->geos()));
+      if (is_array($geometry)) {
+        $geom = $this->geos();
+        foreach ($geometry as $item) {
+          $geom = $geom->union($item->geos());
+        }
+        return geoPHP::geosToGeometry($geos);
+      }
+      else {
+        return geoPHP::geosToGeometry($this->geos()->union($geometry->geos()));
+      }
     }
   }
 

lib/geometry/LineString.class.php

@@ -37,13 +37,11 @@ public function endPoint() {
   }
 
   public function isClosed() {
-    //@@TODO: Need to complete equal() first;
-    #return ($this->startPoint->equal($this->endPoint()));
+    return ($this->startPoint()->equals($this->endPoint()));
   }
 
   public function isRing() {
-    //@@TODO: need to complete isSimple first
-    #return ($this->isClosed() && $this->isSimple());
+    return ($this->isClosed() && $this->isSimple());
   }
 
   public function numPoints() {
@@ -62,6 +60,68 @@ public function dimension() {
   public function area() {
     return 0;
   }
+
+  public function explode() {
+    $parts = array();
+    $points = $this->getPoints();
+
+    foreach ($points as $i => $point) {
+      if (isset($points[$i+1])) {
+        $parts[] = new LineString(array($point, $points[$i+1]));
+      }
+    }
+    return $parts;
+  }
+
+  public function isSimple() {
+    if ($this->geos()) {
+      return $this->geos()->isSimple();
+    }
+
+    $segments = $this->explode();
+
+    foreach ($segments as $i => $segment) {
+      foreach ($segments as $j => $check_segment) {
+        if ($i != $j) {
+          if ($segment->lineSegmentIntersect($check_segment)) {
+            return FALSE;
+          }
+        }
+      }
+    }
+    return TRUE;
+  }
+
+  // Utility function to check if any line sigments intersect
+  // Derived from http://stackoverflow.com/questions/563198/how-do-you-detect-where-two-line-segments-intersect
+  private function lineSegmentIntersect($segment) {  
+    $p0_x = $this->startPoint()->x();
+    $p0_y = $this->startPoint()->y();
+    $p1_x = $this->endPoint()->x();
+    $p1_y = $this->endPoint()->y();
+    $p2_x = $segment->startPoint()->x();
+    $p2_y = $segment->startPoint()->y();
+    $p3_x = $segment->endPoint()->x();
+    $p3_y = $segment->endPoint()->y();
+
+    $s1_x = $p1_x - $p0_x;     $s1_y = $p1_y - $p0_y;
+    $s2_x = $p3_x - $p2_x;     $s2_y = $p3_y - $p2_y;
+
+    $fps = (-$s2_x * $s1_y) + ($s1_x * $s2_y);
+    $fpt = (-$s2_x * $s1_y) + ($s1_x * $s2_y);
+
+    if ($fps == 0 || $fpt == 0) {
+      return FALSE;
+    }
+
+    $s = (-$s1_y * ($p0_x - $p2_x) + $s1_x * ($p0_y - $p2_y)) / $fps;
+    $t = ( $s2_x * ($p0_y - $p2_y) - $s2_y * ($p0_x - $p2_x)) / $fpt;
 
+    if ($s > 0 && $s < 1 && $t > 0 && $t < 1) {
+      // Collision detected
+      return TRUE;
+    }
+    return FALSE;
+  }
 }
 

lib/geometry/MultiPoint.class.php

@@ -5,5 +5,17 @@
 class MultiPoint extends Collection
 {
   protected $geom_type = 'MultiPoint';
+
+  public function numPoints() {
+    return $this->numGeometries();
+  }
+
+  public function isSimple() {
+    return TRUE;
+  }
+
+  // Not valid for this geometry type
+  // --------------------------------
+  public function explode() { return NULL; }
 }
 

lib/geometry/Point.class.php

@@ -113,6 +113,22 @@ public function dimension() {
   public function isEmpty() {
     return FALSE;
   }
+
+  public function numPoints() {
+    return 1;
+  }
+
+  public function getPoints() {
+    return array($this);
+  }
+
+  public function equals($geometry) {
+    return ($this->x() == $geometry->x() && $this->y() == $geometry->y());
+  }
+
+  public function isSimple() {
+    return TRUE;
+  }
 
   // Not valid for this geometry type
   public function numGeometries()    { return NULL; }
@@ -121,12 +137,11 @@ public function startPoint()       { return NULL; }
   public function endPoint()         { return NULL; }
   public function isRing()           { return NULL; }
   public function isClosed()         { return NULL; }
-  public function numPoints()        { return NULL; }
   public function pointN($n)         { return NULL; }
   public function exteriorRing()     { return NULL; }
   public function numInteriorRings() { return NULL; }
   public function interiorRingN($n)  { return NULL; }
   public function pointOnSurface()   { return NULL; }
-
+  public function explode()          { return NULL; }
 }
 

lib/geometry/Polygon.class.php

@@ -94,6 +94,25 @@ public function dimension() {
     return 2;
   }
 
+  public function isSimple() {
+    if ($this->geos()) {
+      return $this->geos()->isSimple();
+    }
+
+    $segments = $this->explode();
+
+    foreach ($segments as $i => $segment) {
+      foreach ($segments as $j => $check_segment) {
+        if ($i != $j) {
+          if ($segment->lineSegmentIntersect($check_segment)) {
+            return FALSE;
+          }
+        }
+      }
+    }
+    return TRUE;
+  }
+
   // Not valid for this geometry type
   // --------------------------------
   public function length() { return NULL; }