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<?php |
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namespace MatthiasMullie\Geo; |
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/** |
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* Please report bugs on https://github.com/matthiasmullie/geo/issues |
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* |
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* @author Matthias Mullie <[email protected]> |
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* |
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* @copyright Copyright (c) 2013, Matthias Mullie. All rights reserved. |
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* @license MIT License |
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*/ |
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class Clusterer |
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{ |
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/** |
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* @var Bounds |
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*/ |
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protected $bounds; |
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/** |
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* Amount of coordinates in one cell needed to start clustering. |
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* |
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* @var int |
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*/ |
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protected $minLocations = 1; |
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/** |
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* @var int |
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*/ |
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protected $numberOfClusters = 50; |
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/** |
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* @var Cluster[][] |
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*/ |
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protected $clusters = array(); |
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/** |
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* @var Coordinate[][][] |
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*/ |
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protected $coordinates = array(); |
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/** |
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* @var int |
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*/ |
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protected $coefficientLat = 0; |
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/** |
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* @var int |
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*/ |
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protected $coefficientLng = 0; |
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/** |
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* @var bool |
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*/ |
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protected $spanBoundsLat = false; |
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/** |
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* @var bool |
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*/ |
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protected $spanBoundsLng = false; |
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/** |
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* @var bool |
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*/ |
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protected $saveCoordinates = false; |
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/** |
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* @param Bounds $bounds |
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*/ |
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public function __construct(Bounds $bounds) |
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{ |
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// determine if bounds span 360 to -360 degrees gap |
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$this->spanBoundsLng = $bounds->ne->longitude < $bounds->sw->longitude; |
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$this->spanBoundsLat = $bounds->ne->latitude < $bounds->sw->latitude; |
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$this->bounds = $this->fixBounds($bounds); |
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$this->createMatrix(); |
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} |
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/** |
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* Enables coordinate saving in clusters. |
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* |
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* Note that while it allows you to retrieve all Coordinate objects |
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* in a cluster, this does not scale. At some point, if you keep |
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* adding coordinates into clusters, you'll run out of memory |
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* because we're saving all those coordinates. |
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* If you don't need the exact information of coordinates in a |
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* cluster, leave this disabled. |
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* |
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* @param bool $save |
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* @throws Exception |
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*/ |
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public function setSaveCoordinates($save) |
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{ |
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if (count($this->clusters) || count($this->coordinates)) { |
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throw new Exception('Sorry, it is not possible to change coordinate saving policy after you have already added coordinates.'); |
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} |
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$this->saveCoordinates = $save; |
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} |
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/** |
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* Set the minimum amount of locations before clustering. |
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* |
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* @param int $limit |
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*/ |
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public function setMinClusterLocations($limit) |
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{ |
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$this->minLocations = $limit; |
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} |
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/** |
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* Set an approximate amount of clusters. |
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* Approximate in that it also depends on the viewport: |
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* less square = less clusters. |
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* |
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* @param int $number |
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*/ |
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public function setNumberOfClusters($number) |
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{ |
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$this->numberOfClusters = $number; |
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} |
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/** |
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* @param Coordinate $coordinate |
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*/ |
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public function addCoordinate(Coordinate $coordinate) |
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{ |
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list($latIndex, $lngIndex) = $this->findCell($coordinate); |
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$coordinateCount = isset($this->coordinates[$latIndex][$lngIndex]) ? count($this->coordinates[$latIndex][$lngIndex]) : 0; |
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// cluster already exists, add coordinate to it |
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if (isset($this->clusters[$latIndex][$lngIndex])) { |
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$this->clusters[$latIndex][$lngIndex]->addCoordinate($coordinate, $this->saveCoordinates); |
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// there's no cluster yet, but entry limit reached = cluster now |
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} elseif ($coordinateCount >= $this->minLocations - 1) { |
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// initialise cluster with given coordinate |
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$this->clusters[$latIndex][$lngIndex] = new Cluster(); |
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$this->clusters[$latIndex][$lngIndex]->addCoordinate($coordinate, $this->saveCoordinates); |
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if ($coordinateCount) { |
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// add existing coordinates |
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foreach ($this->coordinates[$latIndex][$lngIndex] as $coordinate) { |
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$this->clusters[$latIndex][$lngIndex]->addCoordinate($coordinate, $this->saveCoordinates); |
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} |
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// save cluster & clear array of individual coordinates (to free up |
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// memory, in case we're dealing with lots of coordinates) |
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unset($this->coordinates[$latIndex][$lngIndex]); |
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} |
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// entry limit for clustering not yet reached, save coordinate |
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} else { |
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$this->coordinates[$latIndex][$lngIndex][] = $coordinate; |
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} |
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} |
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/** |
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* @return Coordinate[] |
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*/ |
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public function getCoordinates() |
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{ |
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// flatten matrix of coordinates |
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$coordinates = $this->coordinates ? call_user_func_array('array_merge', $this->coordinates) : array(); |
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return $coordinates ? call_user_func_array('array_merge', $coordinates) : array(); |
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} |
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/** |
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* @return Cluster[] |
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*/ |
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public function getClusters() |
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{ |
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// flatten matrix of clusters |
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return $this->clusters ? call_user_func_array('array_merge', $this->clusters) : array(); |
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} |
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/** |
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* Based on given bounds, determine matrix size/structure. |
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*/ |
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protected function createMatrix() |
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{ |
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$totalLat = $this->bounds->ne->latitude - $this->bounds->sw->latitude; |
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$totalLng = $this->bounds->ne->longitude - $this->bounds->sw->longitude; |
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$approxMiddle = round(sqrt($this->numberOfClusters)); |
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// the smaller one wins |
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$func = $totalLat > $totalLng ? 'floor' : 'ceil'; |
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$numLat = $func($totalLat / ($totalLat + $totalLng) * $approxMiddle * 2); |
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$numLng = $approxMiddle * 2 - $numLat; |
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// this will be used later to calculate exactly which sector a |
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// coordinate falls into (see findCell) |
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$this->coefficientLat = 1 / ($totalLat) * $numLat; |
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$this->coefficientLng = 1 / ($totalLng) * $numLng; |
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} |
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/** |
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* Find the lat & lng indices of the matrix cell |
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* the given coordinate fits into. |
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* |
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* @param Coordinate $coordinate |
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* @return array |
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*/ |
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protected function findCell(Coordinate $coordinate) |
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{ |
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$coordinate = $this->fixCoordinates($coordinate); |
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return array( |
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floor(($coordinate->latitude - $this->bounds->sw->latitude) * $this->coefficientLat), |
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floor(($coordinate->longitude - $this->bounds->sw->longitude) * $this->coefficientLng), |
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); |
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} |
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/** |
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* "Fix" coordinates - when leaping from east 360 to west -359, increase |
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* the west coordinated by 360 to make calculating easier. |
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* |
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* @param Coordinate $coordinate |
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* @return Coordinate |
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*/ |
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protected function fixCoordinates(Coordinate $coordinate) |
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{ |
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// create a new copy of this object, don't just change existing one |
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$coordinate = clone $coordinate; |
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if ($this->spanBoundsLat && $coordinate->latitude < $this->bounds->sw->latitude) { |
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$coordinate->latitude += 180; |
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} |
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if ($this->spanBoundsLng && $coordinate->longitude < $this->bounds->sw->longitude) { |
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$coordinate->longitude += 360; |
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} |
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return $coordinate; |
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} |
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/** |
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* North and east coordinates can actually be lower than south & west. |
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* This will happen when the left side of a map is displaying east and |
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* the right side is displaying west. At the center of the map, we'll |
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* suddenly have coordinates jumping from 360 to -359. |
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* To make calculating things easier, we'll just increase the west |
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* (= negative) coordinates by 360, and consider those to now be east |
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* (and east as west). Now, coordinates will go from 360 to 361. |
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* |
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* @param Bounds $bounds |
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* @return Bounds |
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*/ |
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protected function fixBounds(Bounds $bounds) |
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{ |
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// create a new copy of this object, don't just change existing one |
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$bounds = clone $bounds; |
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View Code Duplication |
if ($this->spanBoundsLat) { |
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// workaround for crossover bounds being rounded too aggressively |
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if ($bounds->sw->latitude == 0) { |
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$bounds->sw->latitude += 180; |
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} |
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$neLat = max(180 + $bounds->ne->latitude, 180 + $bounds->sw->latitude); |
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$bounds->sw->latitude = $bounds->ne->latitude; |
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$bounds->ne->latitude = $neLat; |
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} |
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View Code Duplication |
if ($this->spanBoundsLng) { |
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// workaround for crossover bounds being rounded too aggressively |
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if ($bounds->sw->longitude == 0) { |
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$bounds->sw->longitude += 360; |
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} |
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$neLng = max(360 + $bounds->ne->longitude, 360 + $bounds->sw->longitude); |
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$bounds->sw->longitude = $bounds->ne->longitude; |
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$bounds->ne->longitude = $neLng; |
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} |
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return $bounds; |
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} |
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} |
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This check looks for assignments to scalar types that may be of the wrong type.
To ensure the code behaves as expected, it may be a good idea to add an explicit type cast.