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<?php
/**
* Handles actions related to GIS POLYGON objects
*/
declare(strict_types=1);
namespace PhpMyAdmin\Gis;
use PhpMyAdmin\Image\ImageWrapper;
use TCPDF;
use function array_merge;
use function array_slice;
use function count;
use function explode;
use function hexdec;
use function json_encode;
use function max;
use function mb_substr;
use function min;
use function round;
use function sqrt;
use function str_contains;
use function trim;
/**
* Handles actions related to GIS POLYGON objects
*/
class GisPolygon extends GisGeometry
{
/** @var self */
private static $instance;
/**
* A private constructor; prevents direct creation of object.
*/
private function __construct()
{
}
/**
* Returns the singleton.
*
* @return GisPolygon the singleton
*/
public static function singleton()
{
if (! isset(self::$instance)) {
self::$instance = new GisPolygon();
}
return self::$instance;
}
/**
* Scales each row.
*
* @param string $spatial spatial data of a row
*
* @return array an array containing the min, max values for x and y coordinates
*/
public function scaleRow($spatial)
{
// Trim to remove leading 'POLYGON((' and trailing '))'
$polygon = mb_substr($spatial, 9, -2);
// If the polygon doesn't have an inner ring, use polygon itself
if (! str_contains($polygon, '),(')) {
$ring = $polygon;
} else {
// Separate outer ring and use it to determine min-max
$parts = explode('),(', $polygon);
$ring = $parts[0];
}
return $this->setMinMax($ring, []);
}
/**
* Adds to the PNG image object, the data related to a row in the GIS dataset.
*
* @param string $spatial GIS POLYGON object
* @param string|null $label Label for the GIS POLYGON object
* @param string $fill_color Color for the GIS POLYGON object
* @param array $scale_data Array containing data related to scaling
*/
public function prepareRowAsPng(
$spatial,
?string $label,
$fill_color,
array $scale_data,
ImageWrapper $image
): ImageWrapper {
// allocate colors
$black = $image->colorAllocate(0, 0, 0);
$red = (int) hexdec(mb_substr($fill_color, 1, 2));
$green = (int) hexdec(mb_substr($fill_color, 3, 2));
$blue = (int) hexdec(mb_substr($fill_color, 4, 2));
$color = $image->colorAllocate($red, $green, $blue);
$label = trim($label ?? '');
// Trim to remove leading 'POLYGON((' and trailing '))'
$polygon = mb_substr($spatial, 9, -2);
// If the polygon doesn't have an inner polygon
if (! str_contains($polygon, '),(')) {
$points_arr = $this->extractPoints($polygon, $scale_data, true);
} else {
// Separate outer and inner polygons
$parts = explode('),(', $polygon);
$outer = $parts[0];
$inner = array_slice($parts, 1);
$points_arr = $this->extractPoints($outer, $scale_data, true);
foreach ($inner as $inner_poly) {
$points_arr = array_merge(
$points_arr,
$this->extractPoints($inner_poly, $scale_data, true)
);
}
}
// draw polygon
$image->filledPolygon($points_arr, $color);
// print label if applicable
if ($label !== '') {
$image->string(
1,
(int) round($points_arr[2]),
(int) round($points_arr[3]),
$label,
$black
);
}
return $image;
}
/**
* Adds to the TCPDF instance, the data related to a row in the GIS dataset.
*
* @param string $spatial GIS POLYGON object
* @param string|null $label Label for the GIS POLYGON object
* @param string $fill_color Color for the GIS POLYGON object
* @param array $scale_data Array containing data related to scaling
* @param TCPDF $pdf TCPDF instance
*
* @return TCPDF the modified TCPDF instance
*/
public function prepareRowAsPdf($spatial, ?string $label, $fill_color, array $scale_data, $pdf)
{
// allocate colors
$red = hexdec(mb_substr($fill_color, 1, 2));
$green = hexdec(mb_substr($fill_color, 3, 2));
$blue = hexdec(mb_substr($fill_color, 4, 2));
$color = [
$red,
$green,
$blue,
];
$label = trim($label ?? '');
// Trim to remove leading 'POLYGON((' and trailing '))'
$polygon = mb_substr($spatial, 9, -2);
// If the polygon doesn't have an inner polygon
if (! str_contains($polygon, '),(')) {
$points_arr = $this->extractPoints($polygon, $scale_data, true);
} else {
// Separate outer and inner polygons
$parts = explode('),(', $polygon);
$outer = $parts[0];
$inner = array_slice($parts, 1);
$points_arr = $this->extractPoints($outer, $scale_data, true);
foreach ($inner as $inner_poly) {
$points_arr = array_merge(
$points_arr,
$this->extractPoints($inner_poly, $scale_data, true)
);
}
}
// draw polygon
$pdf->Polygon($points_arr, 'F*', [], $color, true);
// print label if applicable
if ($label !== '') {
$pdf->setXY($points_arr[2], $points_arr[3]);
$pdf->setFontSize(5);
$pdf->Cell(0, 0, $label);
}
return $pdf;
}
/**
* Prepares and returns the code related to a row in the GIS dataset as SVG.
*
* @param string $spatial GIS POLYGON object
* @param string $label Label for the GIS POLYGON object
* @param string $fill_color Color for the GIS POLYGON object
* @param array $scale_data Array containing data related to scaling
*
* @return string the code related to a row in the GIS dataset
*/
public function prepareRowAsSvg($spatial, $label, $fill_color, array $scale_data)
{
$polygon_options = [
'name' => $label,
'id' => $label . $this->getRandomId(),
'class' => 'polygon vector',
'stroke' => 'black',
'stroke-width' => 0.5,
'fill' => $fill_color,
'fill-rule' => 'evenodd',
'fill-opacity' => 0.8,
];
// Trim to remove leading 'POLYGON((' and trailing '))'
$polygon = mb_substr($spatial, 9, -2);
$row = '<path d="';
// If the polygon doesn't have an inner polygon
if (! str_contains($polygon, '),(')) {
$row .= $this->drawPath($polygon, $scale_data);
} else {
// Separate outer and inner polygons
$parts = explode('),(', $polygon);
$outer = $parts[0];
$inner = array_slice($parts, 1);
$row .= $this->drawPath($outer, $scale_data);
foreach ($inner as $inner_poly) {
$row .= $this->drawPath($inner_poly, $scale_data);
}
}
$row .= '"';
foreach ($polygon_options as $option => $val) {
$row .= ' ' . $option . '="' . trim((string) $val) . '"';
}
$row .= '/>';
return $row;
}
/**
* Prepares JavaScript related to a row in the GIS dataset
* to visualize it with OpenLayers.
*
* @param string $spatial GIS POLYGON object
* @param int $srid Spatial reference ID
* @param string $label Label for the GIS POLYGON object
* @param array $fill_color Color for the GIS POLYGON object
* @param array $scale_data Array containing data related to scaling
*
* @return string JavaScript related to a row in the GIS dataset
*/
public function prepareRowAsOl($spatial, int $srid, $label, $fill_color, array $scale_data)
{
$fill_color[] = 0.8;
$fill_style = ['color' => $fill_color];
$stroke_style = [
'color' => [0,0,0],
'width' => 0.5,
];
$row = 'var style = new ol.style.Style({'
. 'fill: new ol.style.Fill(' . json_encode($fill_style) . '),'
. 'stroke: new ol.style.Stroke(' . json_encode($stroke_style) . ')';
if (trim($label) !== '') {
$text_style = ['text' => trim($label)];
$row .= ',text: new ol.style.Text(' . json_encode($text_style) . ')';
}
$row .= '});';
if ($srid === 0) {
$srid = 4326;
}
$row .= $this->getBoundsForOl($srid, $scale_data);
// Trim to remove leading 'POLYGON((' and trailing '))'
$polygon = mb_substr($spatial, 9, -2);
// Separate outer and inner polygons
$parts = explode('),(', $polygon);
return $row . $this->getPolygonForOpenLayers($parts, $srid)
. 'var feature = new ol.Feature({geometry: polygon});'
. 'feature.setStyle(style);'
. 'vectorLayer.addFeature(feature);';
}
/**
* Draws a ring of the polygon using SVG path element.
*
* @param string $polygon The ring
* @param array $scale_data Array containing data related to scaling
*
* @return string the code to draw the ring
*/
private function drawPath($polygon, array $scale_data)
{
$points_arr = $this->extractPoints($polygon, $scale_data);
$row = ' M ' . $points_arr[0][0] . ', ' . $points_arr[0][1];
$other_points = array_slice($points_arr, 1, count($points_arr) - 2);
foreach ($other_points as $point) {
$row .= ' L ' . $point[0] . ', ' . $point[1];
}
$row .= ' Z ';
return $row;
}
/**
* Generate the WKT with the set of parameters passed by the GIS editor.
*
* @param array $gis_data GIS data
* @param int $index Index into the parameter object
* @param string|null $empty Value for empty points
*
* @return string WKT with the set of parameters passed by the GIS editor
*/
public function generateWkt(array $gis_data, $index, $empty = '')
{
$no_of_lines = $gis_data[$index]['POLYGON']['no_of_lines'] ?? 1;
if ($no_of_lines < 1) {
$no_of_lines = 1;
}
$wkt = 'POLYGON(';
for ($i = 0; $i < $no_of_lines; $i++) {
$no_of_points = $gis_data[$index]['POLYGON'][$i]['no_of_points'] ?? 4;
if ($no_of_points < 4) {
$no_of_points = 4;
}
$wkt .= '(';
for ($j = 0; $j < $no_of_points; $j++) {
$wkt .= (isset($gis_data[$index]['POLYGON'][$i][$j]['x'])
&& trim((string) $gis_data[$index]['POLYGON'][$i][$j]['x']) != ''
? $gis_data[$index]['POLYGON'][$i][$j]['x'] : $empty)
. ' ' . (isset($gis_data[$index]['POLYGON'][$i][$j]['y'])
&& trim((string) $gis_data[$index]['POLYGON'][$i][$j]['y']) != ''
? $gis_data[$index]['POLYGON'][$i][$j]['y'] : $empty) . ',';
}
$wkt = mb_substr($wkt, 0, -1);
$wkt .= '),';
}
$wkt = mb_substr($wkt, 0, -1);
return $wkt . ')';
}
/**
* Calculates the area of a closed simple polygon.
*
* @param array $ring array of points forming the ring
*
* @return float the area of a closed simple polygon
*
* @static
*/
public static function area(array $ring)
{
$no_of_points = count($ring);
// If the last point is same as the first point ignore it
$last = count($ring) - 1;
if (($ring[0]['x'] == $ring[$last]['x']) && ($ring[0]['y'] == $ring[$last]['y'])) {
$no_of_points--;
}
// _n-1
// A = _1_ \ (X(i) * Y(i+1)) - (Y(i) * X(i+1))
// 2 /__
// i=0
$area = 0;
for ($i = 0; $i < $no_of_points; $i++) {
$j = ($i + 1) % $no_of_points;
$area += $ring[$i]['x'] * $ring[$j]['y'];
$area -= $ring[$i]['y'] * $ring[$j]['x'];
}
$area /= 2.0;
return $area;
}
/**
* Determines whether a set of points represents an outer ring.
* If points are in clockwise orientation then, they form an outer ring.
*
* @param array $ring array of points forming the ring
*
* @static
*/
public static function isOuterRing(array $ring): bool
{
// If area is negative then it's in clockwise orientation,
// i.e. it's an outer ring
return self::area($ring) < 0;
}
/**
* Determines whether a given point is inside a given polygon.
*
* @param array $point x, y coordinates of the point
* @param array $polygon array of points forming the ring
*
* @static
*/
public static function isPointInsidePolygon(array $point, array $polygon): bool
{
// If first point is repeated at the end remove it
$last = count($polygon) - 1;
if (($polygon[0]['x'] == $polygon[$last]['x']) && ($polygon[0]['y'] == $polygon[$last]['y'])) {
$polygon = array_slice($polygon, 0, $last);
}
$no_of_points = count($polygon);
$counter = 0;
// Use ray casting algorithm
$p1 = $polygon[0];
for ($i = 1; $i <= $no_of_points; $i++) {
$p2 = $polygon[$i % $no_of_points];
if ($point['y'] <= min([$p1['y'], $p2['y']])) {
$p1 = $p2;
continue;
}
if ($point['y'] > max([$p1['y'], $p2['y']])) {
$p1 = $p2;
continue;
}
if ($point['x'] > max([$p1['x'], $p2['x']])) {
$p1 = $p2;
continue;
}
if ($p1['y'] != $p2['y']) {
$xinters = ($point['y'] - $p1['y'])
* ($p2['x'] - $p1['x'])
/ ($p2['y'] - $p1['y']) + $p1['x'];
if ($p1['x'] == $p2['x'] || $point['x'] <= $xinters) {
$counter++;
}
}
$p1 = $p2;
}
return $counter % 2 != 0;
}
/**
* Returns a point that is guaranteed to be on the surface of the ring.
* (for simple closed rings)
*
* @param array $ring array of points forming the ring
*
* @return array|false a point on the surface of the ring
*/
public static function getPointOnSurface(array $ring)
{
$x0 = null;
$x1 = null;
$y0 = null;
$y1 = null;
// Find two consecutive distinct points.
for ($i = 0, $nb = count($ring) - 1; $i < $nb; $i++) {
if ($ring[$i]['y'] != $ring[$i + 1]['y']) {
$x0 = $ring[$i]['x'];
$x1 = $ring[$i + 1]['x'];
$y0 = $ring[$i]['y'];
$y1 = $ring[$i + 1]['y'];
break;
}
}
if (! isset($x0)) {
return false;
}
// Find the mid point
$x2 = ($x0 + $x1) / 2;
$y2 = ($y0 + $y1) / 2;
// Always keep $epsilon < 1 to go with the reduction logic down here
$epsilon = 0.1;
$denominator = sqrt(($y1 - $y0) ** 2 + ($x0 - $x1) ** 2);
$pointA = [];
$pointB = [];
while (true) {
// Get the points on either sides of the line
// with a distance of epsilon to the mid point
$pointA['x'] = $x2 + ($epsilon * ($y1 - $y0)) / $denominator;
$pointA['y'] = $y2 + ($pointA['x'] - $x2) * ($x0 - $x1) / ($y1 - $y0);
$pointB['x'] = $x2 + ($epsilon * ($y1 - $y0)) / (0 - $denominator);
$pointB['y'] = $y2 + ($pointB['x'] - $x2) * ($x0 - $x1) / ($y1 - $y0);
// One of the points should be inside the polygon,
// unless epsilon chosen is too large
if (self::isPointInsidePolygon($pointA, $ring)) {
return $pointA;
}
if (self::isPointInsidePolygon($pointB, $ring)) {
return $pointB;
}
//If both are outside the polygon reduce the epsilon and
//recalculate the points(reduce exponentially for faster convergence)
$epsilon **= 2;
if ($epsilon == 0) {
return false;
}
}
}
/**
* Generate parameters for the GIS data editor from the value of the GIS column.
*
* @param string $value Value of the GIS column
* @param int $index Index of the geometry
*
* @return array params for the GIS data editor from the value of the GIS column
*/
public function generateParams($value, $index = -1)
{
$params = [];
if ($index == -1) {
$index = 0;
$data = GisGeometry::generateParams($value);
$params['srid'] = $data['srid'];
$wkt = $data['wkt'];
} else {
$params[$index]['gis_type'] = 'POLYGON';
$wkt = $value;
}
// Trim to remove leading 'POLYGON((' and trailing '))'
$polygon = mb_substr($wkt, 9, -2);
// Separate each linestring
$linerings = explode('),(', $polygon);
$params[$index]['POLYGON']['no_of_lines'] = count($linerings);
$j = 0;
foreach ($linerings as $linering) {
$points_arr = $this->extractPoints($linering, null);
$no_of_points = count($points_arr);
$params[$index]['POLYGON'][$j]['no_of_points'] = $no_of_points;
for ($i = 0; $i < $no_of_points; $i++) {
$params[$index]['POLYGON'][$j][$i]['x'] = $points_arr[$i][0];
$params[$index]['POLYGON'][$j][$i]['y'] = $points_arr[$i][1];
}
$j++;
}
return $params;
}
}
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