Add RoundCoordinatesProjector

CHANGELOG.md

@@ -1,5 +1,11 @@
 # Changelog
 
+## [0.11.1](https://github.com/brick/geo/releases/tag/0.11.1) - 2024-08-19
+
+✨ **New features**
+
+- New projector: `RoundCoordinatesProjector`
+
 ## [0.11.0](https://github.com/brick/geo/releases/tag/0.11.0) - 2024-06-07
 
 💥 **Breaking changes**

README.md

@@ -448,6 +448,24 @@ The library supports reading and writing `Feature` and `FeatureCollection` objec
 
 GeoJSON aims to support WGS84 only, and as such all Geometries are imported using [SRID 4326](https://epsg.io/4326).
 
+## Reducing coordinate precision
+
+Before exporting geometries in a text format, you may need to reduce the precision of the coordinates to keep the output small, while retaining a sufficient precision.
+You can use the `RoundCoordinatesProjector` for this:
+
+```php
+use Brick\Geo\Point;
+use Brick\Geo\Projector\RoundCoordinatesProjector;
+
+$roundProjector = new RoundCoordinatesProjector(2);
+
+$point = Point::xy(1.2345678, 2.3456789);
+echo $point->asText(); // POINT (1.2345678 2.3456789)
+
+$roundedPoint = $roundProjector->project($point);
+echo $roundedPoint->asText(); // POINT (1.23 2.35)
+```
+
 ## Doctrine mappings
 
 You can use `brick/geo` types in your Doctrine entities using the [brick/geo-doctrine](https://github.com/brick/geo-doctrine) package.

src/Projector/RoundCoordinatesProjector.php

@@ -0,0 +1,35 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Brick\Geo\Projector;
+
+use Brick\Geo\CoordinateSystem;
+use Brick\Geo\Point;
+
+/**
+ * Rounds coordinates to a given precision.
+ * This projector is typically used to simplify the WKT representation of geometries.
+ */
+final class RoundCoordinatesProjector implements Projector
+{
+    public function __construct(
+        private readonly int $precision,
+    ) {
+    }
+
+    public function project(Point $point): Point
+    {
+        $coords = array_map(
+            fn (float $coord): float => round($coord, $this->precision),
+            $point->toArray(),
+        );
+
+        return new Point($point->coordinateSystem(), ...$coords);
+    }
+
+    public function getTargetCoordinateSystem(CoordinateSystem $sourceCoordinateSystem): CoordinateSystem
+    {
+        return $sourceCoordinateSystem;
+    }
+}

tests/Projector/RoundCoordinatesProjectorTest.php

@@ -0,0 +1,55 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Brick\Geo\Tests\Projector;
+
+use Brick\Geo\CoordinateSystem;
+use Brick\Geo\Point;
+use Brick\Geo\Projector\RoundCoordinatesProjector;
+use Brick\Geo\Tests\AbstractTestCase;
+use PHPUnit\Framework\Attributes\DataProvider;
+
+/**
+ * Unit tests for class RoundCoordinatesProjector.
+ */
+class RoundCoordinatesProjectorTest extends AbstractTestCase
+{
+    #[DataProvider('providerProject')]
+    public function testProject(float $x, float $y, int $srid, int $precision, float $expectedX, float $expectedY): void
+    {
+        $projector = new RoundCoordinatesProjector($precision);
+
+        $point = Point::xy($x, $y, $srid);
+        $projected = $projector->project($point);
+
+        $this->assertPointXYEquals($expectedX, $expectedY, $srid, $projected);
+    }
+
+    public static function providerProject(): array
+    {
+        return [
+            [1.234567, 2.345678, 1234, 0, 1, 2],
+            [1.234567, 2.345678, 2345, 1, 1.2, 2.3],
+            [1.234567, 2.345678, 3456, 2, 1.23, 2.35],
+            [1.234567, 2.345678, 4567, 3, 1.235, 2.346],
+        ];
+    }
+
+    #[DataProvider('providerGetTargetCoordinateSystem')]
+    public function testGetTargetCoordinateSystem(CoordinateSystem $sourceCoordinateSystem): void
+    {
+        $projector = new RoundCoordinatesProjector(2);
+        $targetCoordinateSystem = $projector->getTargetCoordinateSystem($sourceCoordinateSystem);
+
+        $this->assertSame($sourceCoordinateSystem, $targetCoordinateSystem);
+    }
+
+    public static function providerGetTargetCoordinateSystem(): array
+    {
+        return [
+            [CoordinateSystem::xy(4326)],
+            [CoordinateSystem::xyz(2154)],
+        ];
+    }
+}