feat: add geom from geos functions

README.md

@@ -41,7 +41,7 @@ geometries and use a geometric operation that is only available in `go-geos`.
 |                     | To `geom.T` | To `*geos.Geom` | To `orb.Geometry` |
 | ------------------- | ----------- | --------------- | ----------------- |
 | From `geom.T`       | n/a         | no              | yes               |
-| From `*geos.Geom`   | no          | n/a             | yes               |
+| From `*geos.Geom`   | yes         | n/a             | yes               |
 | From `orb.Geometry` | yes         | yes             | n/a               |
 
 ## License

geobabel_test.go

@@ -126,6 +126,7 @@ func TestAll(t *testing.T) {
 			require.True(t, tc.geos.IsValid())
 			require.Equal(t, "Valid Geometry", tc.geos.IsValidReason())
 
+			assert.Equal(t, tc.geom, geobabel.NewGeomTFromGEOSGeom(tc.geos))
 			assert.Equal(t, tc.geom, geobabel.NewGeomTFromOrbGeometry(tc.orb))
 
 			assert.True(t, tc.geos.Equals(geobabel.NewGEOSGeomFromOrbGeometry(geosContext, tc.orb)))

geomfromgeos.go

@@ -0,0 +1,137 @@
+package geobabel
+
+// FIXME add a geos.Geom.Flat method and use that instead
+// FIXME test non-XY layouts
+
+import (
+	"fmt"
+
+	"github.com/twpayne/go-geom"
+	"github.com/twpayne/go-geos"
+)
+
+func NewGeomTFromGEOSGeom(geosGeom *geos.Geom) geom.T {
+	switch geosGeom.TypeID() {
+	case geos.TypeIDPoint:
+		return NewGeomPointFromGEOSGeom(geosGeom)
+	case geos.TypeIDLineString:
+		return NewGeomLineStringFromGEOSGeom(geosGeom)
+	case geos.TypeIDLinearRing:
+		return NewGeomLinearRingFromGEOSGeom(geosGeom)
+	case geos.TypeIDPolygon:
+		return NewGeomPolygonFromGEOSGeom(geosGeom)
+	case geos.TypeIDMultiPoint:
+		return NewGeomMultiPointFromGEOSGeom(geosGeom)
+	case geos.TypeIDMultiLineString:
+		return NewGeomMultiLineStringFromGEOSGeom(geosGeom)
+	case geos.TypeIDMultiPolygon:
+		return NewGeomMultiPolygonFromGEOSGeom(geosGeom)
+	case geos.TypeIDGeometryCollection:
+		return NewGeomGeometryCollectionFromGEOSGeom(geosGeom)
+	default:
+		panic(fmt.Sprintf("%s: unsupported GEOS type", geosGeom.Type()))
+	}
+}
+
+func NewGeomPointFromGEOSGeom(geosGeom *geos.Geom) *geom.Point {
+	geosCoordSeq := geosGeom.CoordSeq()
+	geomLayout := GeomLayoutFromGEOSDimensions(geosCoordSeq.Dimensions())
+	return geom.NewPointFlat(geomLayout, geosCoordSeq.FlatCoords())
+}
+
+func NewGeomLineStringFromGEOSGeom(geosGeom *geos.Geom) *geom.LineString {
+	geosCoordSeq := geosGeom.CoordSeq()
+	geomLayout := GeomLayoutFromGEOSDimensions(geosCoordSeq.Dimensions())
+	return geom.NewLineStringFlat(geomLayout, geosCoordSeq.FlatCoords())
+}
+
+func NewGeomLinearRingFromGEOSGeom(geosGeom *geos.Geom) *geom.LinearRing {
+	geosCoordSeq := geosGeom.CoordSeq()
+	geomLayout := GeomLayoutFromGEOSDimensions(geosCoordSeq.Dimensions())
+	return geom.NewLinearRingFlat(geomLayout, geosCoordSeq.FlatCoords())
+}
+
+func NewGeomPolygonFromGEOSGeom(geosGeom *geos.Geom) *geom.Polygon {
+	geosExteriorRingCoordSeq := geosGeom.ExteriorRing().CoordSeq()
+	geomLayout := GeomLayoutFromGEOSDimensions(geosExteriorRingCoordSeq.Dimensions())
+	geomFlatCoords := geosExteriorRingCoordSeq.FlatCoords()
+	geomEnds := []int{len(geomFlatCoords)}
+	for i, n := 0, geosGeom.NumInteriorRings(); i < n; i++ {
+		geosInteriorRing := geosGeom.InteriorRing(i)
+		geomFlatCoords = append(geomFlatCoords, geosInteriorRing.CoordSeq().FlatCoords()...)
+		geomEnds = append(geomEnds, len(geomFlatCoords))
+	}
+	return geom.NewPolygonFlat(geomLayout, geomFlatCoords, geomEnds)
+}
+
+func NewGeomMultiPointFromGEOSGeom(geosGeom *geos.Geom) *geom.MultiPoint {
+	geosNumGeometries := geosGeom.NumGeometries()
+	geomLayout := geom.XY
+	var geomFlatCoords []float64
+	for i := 0; i < geosNumGeometries; i++ {
+		geosCoordSeq := geosGeom.Geometry(i).CoordSeq()
+		geomLayout = GeomLayoutFromGEOSDimensions(geosCoordSeq.Dimensions())
+		geomFlatCoords = append(geomFlatCoords, geosCoordSeq.FlatCoords()...)
+	}
+	return geom.NewMultiPointFlat(geomLayout, geomFlatCoords)
+}
+
+func NewGeomMultiLineStringFromGEOSGeom(geosGeom *geos.Geom) *geom.MultiLineString {
+	geosNumGeometries := geosGeom.NumGeometries()
+	geomLayout := geom.XY
+	var geomFlatCoords []float64
+	geomEnds := make([]int, 0, geosNumGeometries)
+	for i := 0; i < geosNumGeometries; i++ {
+		geosCoordSeq := geosGeom.Geometry(i).CoordSeq()
+		geomLayout = GeomLayoutFromGEOSDimensions(geosCoordSeq.Dimensions())
+		geomFlatCoords = append(geomFlatCoords, geosCoordSeq.FlatCoords()...)
+		geomEnds = append(geomEnds, len(geomFlatCoords))
+	}
+	return geom.NewMultiLineStringFlat(geomLayout, geomFlatCoords, geomEnds)
+}
+
+func NewGeomMultiPolygonFromGEOSGeom(geosGeom *geos.Geom) *geom.MultiPolygon {
+	geosNumGeometries := geosGeom.NumGeometries()
+	geomLayout := geom.XY
+	var geomFlatCoords []float64
+	geomEndss := make([][]int, 0, geosNumGeometries)
+	for i := 0; i < geosNumGeometries; i++ {
+		geosPolygon := geosGeom.Geometry(i)
+		geosExteriorRingCoordSeq := geosPolygon.ExteriorRing().CoordSeq()
+		geomLayout = GeomLayoutFromGEOSDimensions(geosExteriorRingCoordSeq.Dimensions())
+		geomFlatCoords = append(geomFlatCoords, geosExteriorRingCoordSeq.FlatCoords()...)
+		geomEnds := []int{len(geomFlatCoords)}
+		for i, n := 0, geosGeom.NumInteriorRings(); i < n; i++ {
+			geosInteriorRing := geosGeom.InteriorRing(i)
+			geomFlatCoords = append(geomFlatCoords, geosInteriorRing.CoordSeq().FlatCoords()...)
+			geomEnds = append(geomEnds, len(geomFlatCoords))
+		}
+		geomEndss = append(geomEndss, geomEnds)
+	}
+	return geom.NewMultiPolygonFlat(geomLayout, geomFlatCoords, geomEndss)
+}
+
+func NewGeomGeometryCollectionFromGEOSGeom(geosGeom *geos.Geom) *geom.GeometryCollection {
+	geosNumGeometries := geosGeom.NumGeometries()
+	geomGeomTs := make([]geom.T, 0, geosNumGeometries)
+	for i := 0; i < geosNumGeometries; i++ {
+		geosGeomT := NewGeomTFromGEOSGeom(geosGeom.Geometry(i))
+		geomGeomTs = append(geomGeomTs, geosGeomT)
+	}
+	return geom.NewGeometryCollection().MustPush(geomGeomTs...)
+}
+
+func GeomLayoutFromGEOSDimensions(geosDimensions int) geom.Layout {
+	switch {
+	case geosDimensions == 2:
+		return geom.XY
+	case geosDimensions == 3:
+		return geom.XYZ
+	case geosDimensions == 4:
+		return geom.XYZM
+	case geosDimensions > 4:
+		return geom.Layout(geosDimensions)
+	default:
+		panic(fmt.Sprintf("%d: unsupported GEOS dimensions", geosDimensions))
+	}
+}

go.mod

@@ -14,3 +14,5 @@ require (
 	github.com/pmezard/go-difflib v1.0.0 // indirect
 	gopkg.in/yaml.v3 v3.0.1 // indirect
 )
+
+replace github.com/twpayne/go-geos => ../go-geos

go.sum

@@ -20,8 +20,6 @@ github.com/stretchr/testify v1.8.1 h1:w7B6lhMri9wdJUVmEZPGGhZzrYTPvgJArz7wNPgYKs
 github.com/stretchr/testify v1.8.1/go.mod h1:w2LPCIKwWwSfY2zedu0+kehJoqGctiVI29o6fzry7u4=
 github.com/twpayne/go-geom v1.5.0 h1:seB5SE58wtTDOljFXFnyz2UmKI2SU86tRb2l4yFWH6c=
 github.com/twpayne/go-geom v1.5.0/go.mod h1:Kz4sX4LtdesDQgkhsMERazLlH/NiCg90s6FPaNr0KNI=
-github.com/twpayne/go-geos v0.9.0 h1:Dcgmnqyj6EeaGlq6WH3yZ2uKGQ3e/VxdnxBhWu5mXe0=
-github.com/twpayne/go-geos v0.9.0/go.mod h1:ghmhzeDJuLrFJFvOXUbn+sjPukdKYh11fxaGVq3e7Hk=
 github.com/yuin/goldmark v1.1.27/go.mod h1:3hX8gzYuyVAZsxl0MRgGTJEmQBFcNTphYh9decYSb74=
 github.com/yuin/goldmark v1.2.1/go.mod h1:3hX8gzYuyVAZsxl0MRgGTJEmQBFcNTphYh9decYSb74=
 golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=