[feature] add contains point functionality

contains.go

@@ -0,0 +1,47 @@
+package geom
+
+// https://wrfranklin.org/Research/Short_Notes/pnpoly.html
+func pnPoly(coords []Coord, pt Coord) bool {
+	var in bool
+	n := len(coords)
+	for i, j := 0, n-1; i < n; j, i = i, i+1 {
+		if (coords[i][1] > pt[1]) != (coords[j][1] > pt[1]) && (pt[0] < (coords[j][0]-coords[i][0])*(pt[1]-coords[i][1])/(coords[j][1]-coords[i][1])+coords[i][0]) {
+			in = !in
+		}
+	}
+	return in
+}
+
+// ContainsPoint reports whether a geometry T contains the given point.
+func ContainsPoint(geo T, point *Point) bool {
+	if geo.Bounds().OverlapsPoint(point.Layout(), point.Coords()) {
+		zero := NewPoint(point.Layout()).Coords()
+		switch g := geo.(type) {
+		case *Point:
+			return g == point
+		case *LinearRing:
+			pnPoly(g.Coords(), point.Coords())
+		case *Polygon:
+			var coords []Coord
+			for r := 0; r < g.NumLinearRings(); r++ {
+				ring := g.LinearRing(r)
+				c := ring.Coords()
+				coords = append(append(append(coords, zero), c...), zero)
+			}
+			return pnPoly(coords, point.Coords())
+		case *MultiPolygon:
+			for pl := 0; pl < g.NumPolygons(); pl++ {
+				if ContainsPoint(g.Polygon(pl), point) {
+					return true
+				}
+			}
+		case *GeometryCollection:
+			for i := 0; i < g.NumGeoms(); i++ {
+				if ContainsPoint(g.Geom(i), point) {
+					return true
+				}
+			}
+		}
+	}
+	return false
+}

contains_test.go

@@ -0,0 +1,60 @@
+package geom
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+var testGeo = []struct {
+	geom T
+	pts  []*Point
+	in   []bool
+}{
+	{
+		NewPolygon(XY).MustSetCoords([][]Coord{
+			{
+				{24.950899, 60.169158},
+				{24.953492, 60.169158},
+				{24.953510, 60.170104},
+				{24.950958, 60.169990},
+				{24.950899, 60.169158},
+			},
+		}),
+		[]*Point{
+			NewPoint(XY).MustSetCoords(Coord{24.952242, 60.1696017}),
+			NewPoint(XY).MustSetCoords(Coord{24.976567, 60.1612500}),
+		},
+		[]bool{
+			true,
+			false,
+		},
+	},
+	{
+		NewPolygon(XY).MustSetCoords([][]Coord{
+			{
+				{40.7711, -73.9345},
+				{40.7710, -73.9342},
+				{40.7704, -73.9344},
+				{40.7702, -73.9345},
+				{40.7711, -73.9345},
+			},
+		}),
+		[]*Point{
+			NewPoint(XY).MustSetCoords(Coord{40.7705, -73.9394}),
+			NewPoint(XY).MustSetCoords(Coord{40.7707, -73.9344}),
+		},
+		[]bool{
+			false,
+			true,
+		},
+	},
+}
+
+func TestContain(t *testing.T) {
+	for i, test := range testGeo {
+		for j, pt := range test.pts {
+			assert.Equal(t, test.in[j], ContainsPoint(test.geom, pt), "not match in geom[%d] and pt[%d]", i, j)
+		}
+	}
+}

go.mod

@@ -7,6 +7,7 @@ require (
 	github.com/alecthomas/assert/v2 v2.4.0
 	github.com/lib/pq v1.10.9
 	github.com/ory/dockertest/v3 v3.9.1
+	github.com/stretchr/testify v1.8.1
 	github.com/twpayne/go-kml/v3 v3.1.0
 )
 
@@ -17,6 +18,7 @@ require (
 	github.com/alecthomas/repr v0.3.0 // indirect
 	github.com/cenkalti/backoff/v4 v4.1.3 // indirect
 	github.com/containerd/continuity v0.3.0 // indirect
+	github.com/davecgh/go-spew v1.1.1 // indirect
 	github.com/docker/cli v20.10.17+incompatible // indirect
 	github.com/docker/docker v24.0.7+incompatible // indirect
 	github.com/docker/go-connections v0.4.0 // indirect
@@ -31,8 +33,8 @@ require (
 	github.com/opencontainers/image-spec v1.0.2 // indirect
 	github.com/opencontainers/runc v1.1.12 // indirect
 	github.com/pkg/errors v0.9.1 // indirect
+	github.com/pmezard/go-difflib v1.0.0 // indirect
 	github.com/sirupsen/logrus v1.9.0 // indirect
-	github.com/stretchr/testify v1.8.1 // indirect
 	github.com/xeipuuv/gojsonpointer v0.0.0-20190905194746-02993c407bfb // indirect
 	github.com/xeipuuv/gojsonreference v0.0.0-20180127040603-bd5ef7bd5415 // indirect
 	github.com/xeipuuv/gojsonschema v1.2.0 // indirect