github.com/cockroachdb/cockroach@v20.2.0-alpha.1+incompatible/pkg/geo/bbox.go (about)

     1  // Copyright 2020 The Cockroach Authors.
     2  //
     3  // Use of this software is governed by the Business Source License
     4  // included in the file licenses/BSL.txt.
     5  //
     6  // As of the Change Date specified in that file, in accordance with
     7  // the Business Source License, use of this software will be governed
     8  // by the Apache License, Version 2.0, included in the file
     9  // licenses/APL.txt.
    10  
    11  package geo
    12  
    13  import (
    14  	"github.com/cockroachdb/cockroach/pkg/geo/geopb"
    15  	"github.com/cockroachdb/errors"
    16  	"github.com/twpayne/go-geom"
    17  )
    18  
    19  // BoundingBoxFromGeom returns a bounding box from a given geom.T.
    20  func BoundingBoxFromGeom(g geom.T) (*geopb.BoundingBox, error) {
    21  	bbox := geopb.NewBoundingBox()
    22  	if g.Empty() {
    23  		return nil, nil
    24  	}
    25  	switch g := g.(type) {
    26  	case *geom.Point:
    27  		bbox.Update(g.X(), g.Y())
    28  	case *geom.LineString:
    29  		for _, coord := range g.Coords() {
    30  			bbox.Update(coord.X(), coord.Y())
    31  		}
    32  	case *geom.Polygon:
    33  		for _, coord := range g.LinearRing(0).Coords() {
    34  			bbox.Update(coord.X(), coord.Y())
    35  		}
    36  	case *geom.MultiPoint:
    37  		for i := 0; i < g.NumPoints(); i++ {
    38  			if g.Point(i).Empty() {
    39  				continue
    40  			}
    41  			point := g.Point(i)
    42  			bbox.Update(point.X(), point.Y())
    43  		}
    44  	case *geom.MultiLineString:
    45  		for i := 0; i < g.NumLineStrings(); i++ {
    46  			lineString := g.LineString(i)
    47  			for _, coord := range lineString.Coords() {
    48  				bbox.Update(coord.X(), coord.Y())
    49  			}
    50  		}
    51  	case *geom.MultiPolygon:
    52  		for i := 0; i < g.NumPolygons(); i++ {
    53  			polygon := g.Polygon(i)
    54  			for _, coord := range polygon.LinearRing(0).Coords() {
    55  				bbox.Update(coord.X(), coord.Y())
    56  			}
    57  		}
    58  	case *geom.GeometryCollection:
    59  		for i := 0; i < g.NumGeoms(); i++ {
    60  			shapeBBox, err := BoundingBoxFromGeom(g.Geom(i))
    61  			if err != nil {
    62  				return nil, err
    63  			}
    64  			if shapeBBox == nil {
    65  				continue
    66  			}
    67  			bbox.Update(shapeBBox.MinX, shapeBBox.MinY)
    68  			bbox.Update(shapeBBox.MaxX, shapeBBox.MaxY)
    69  		}
    70  	default:
    71  		return nil, errors.Newf("unknown geom type: %T", g)
    72  	}
    73  	return bbox, nil
    74  }