Merge pull request #22 from chrispahm/add-concave-hull

🐛 add missing concave hull functions

GEOS_EMCC_FLAGS.mk

@@ -68,6 +68,9 @@ GEOS_EMCC_FLAGS += -s EXPORTED_FUNCTIONS="[\
   '_GEOSBufferWithStyle_r',\
   '_GEOSSingleSidedBuffer_r',\
   '_GEOSOffsetCurve_r',\
+  '_GEOSConcaveHull_r',\
+  '_GEOSConcaveHullByLength_r',\
+  '_GEOSConcaveHullOfPolygons_r',\
   '_GEOSConvexHull_r',\
   '_GEOSMinimumRotatedRectangle_r',\
   '_GEOSMaximumInscribedCircle_r',\

test/tests/GEOSConcaveHull.spec.mjs

@@ -0,0 +1,43 @@
+// Import tape and geos
+import test from 'tape'
+import initGeosJs from '../../build/package/geos.esm.js'
+
+// Initialize geos asynchronously
+initGeosJs().then(geos => {
+  // Create a test case for GEOSConvexHull
+  test('GEOSConcaveHull', t => {
+    // Create a reader and a writer for WKT conversion
+    const reader = geos.GEOSWKTReader_create()
+    const writer = geos.GEOSWKTWriter_create()
+    // Set the writer output precision to 0
+    geos.GEOSWKTWriter_setRoundingPrecision(writer, 0)
+
+    // Create a WKT string for a polygon with a hole
+    const wkt = 'POLYGON ((0 0, 10 0, 10 10, 0 10, 0 0), (2 2, 8 2, 8 8, 2 8, 2 2))'
+
+    // Convert the WKT string to a GEOS geometry pointer
+    const geomPtr = geos.GEOSWKTReader_read(reader, wkt)
+
+    // Call the GEOSConvexHull function with the geometry pointer as the argument
+    // The function returns another geometry pointer for the convex hull
+    const hullPtr = geos.GEOSConcaveHull(geomPtr)
+
+    // Convert the convex hull pointer to a WKT string
+    const hullWkt = geos.GEOSWKTWriter_write(writer, hullPtr)
+
+    // Assert that the concave hull WKT string is equal to the expected value
+    t.equal(hullWkt, 'POLYGON ((2 8, 0 10, 8 8, 10 10, 10 0, 8 2, 0 0, 2 2, 2 8))')
+
+    // Free the memory allocated for the pointers
+    geos.GEOSGeom_destroy(geomPtr)
+    geos.GEOSGeom_destroy(hullPtr)
+    geos.GEOSFree(hullWkt)
+
+    // Destroy the reader and writer objects
+    geos.GEOSWKTReader_destroy(reader)
+    geos.GEOSWKTWriter_destroy(writer)
+
+    // End the test case
+    t.end()
+  })
+})