Mercurial > gemma
view pkg/imports/wkb.go @ 4324:36d384326407
BottleneckDialogue: Prototype for delete of surveys implemented
author | Thomas Junk <thomas.junk@intevation.de> |
---|---|
date | Wed, 04 Sep 2019 14:39:51 +0200 |
parents | 5da02dcc51f6 |
children | 046a07a33b19 |
line wrap: on
line source
// This is Free Software under GNU Affero General Public License v >= 3.0 // without warranty, see README.md and license for details. // // SPDX-License-Identifier: AGPL-3.0-or-later // License-Filename: LICENSES/AGPL-3.0.txt // // Copyright (C) 2018 by via donau // – Österreichische Wasserstraßen-Gesellschaft mbH // Software engineering by Intevation GmbH // // Author(s): // * Sascha L. Teichmann <sascha.teichmann@intevation.de> package imports import ( "bytes" "encoding/binary" "fmt" "math" shp "github.com/jonas-p/go-shp" "gemma.intevation.de/gemma/pkg/wkb" ) type ( pointSlice []float64 lineSlice [][]float64 polygonSlice [][][]float64 ) func (l lineSlice) asWKB() []byte { size := 1 + 4 + 4 + len(l)*(2*8) buf := bytes.NewBuffer(make([]byte, 0, size)) binary.Write(buf, binary.LittleEndian, wkb.NDR) binary.Write(buf, binary.LittleEndian, wkb.LineString) binary.Write(buf, binary.LittleEndian, uint32(len(l))) for _, c := range l { var lat, lon float64 if len(c) > 0 { lat = c[0] } if len(c) > 1 { lon = c[1] } binary.Write(buf, binary.LittleEndian, math.Float64bits(lat)) binary.Write(buf, binary.LittleEndian, math.Float64bits(lon)) } return buf.Bytes() } func (ls lineSlice) LinearRingGeom() wkb.LinearRingGeom { lr := make(wkb.LinearRingGeom, len(ls)) for i, v := range ls { lr[i].X = v[0] lr[i].Y = v[1] } return lr } func (p pointSlice) asWKB() []byte { size := 1 + 4 + 2*8 buf := bytes.NewBuffer(make([]byte, 0, size)) binary.Write(buf, binary.LittleEndian, wkb.NDR) binary.Write(buf, binary.LittleEndian, wkb.Point) var lat, lon float64 if len(p) > 0 { lat = p[0] } if len(p) > 1 { lon = p[1] } binary.Write(buf, binary.LittleEndian, math.Float64bits(lat)) binary.Write(buf, binary.LittleEndian, math.Float64bits(lon)) return buf.Bytes() } func (p polygonSlice) asWKB() []byte { if p == nil { return nil } // pre-calculate size to avoid reallocations. size := 1 + 4 + 4 for _, ring := range p { size += 4 + len(ring)*2*8 } buf := bytes.NewBuffer(make([]byte, 0, size)) binary.Write(buf, binary.LittleEndian, wkb.NDR) binary.Write(buf, binary.LittleEndian, wkb.Polygon) binary.Write(buf, binary.LittleEndian, uint32(len(p))) for _, ring := range p { binary.Write(buf, binary.LittleEndian, uint32(len(ring))) for _, v := range ring { var lat, lon float64 if len(v) > 0 { lat = v[0] } if len(v) > 1 { lon = v[1] } binary.Write(buf, binary.LittleEndian, math.Float64bits(lat)) binary.Write(buf, binary.LittleEndian, math.Float64bits(lon)) } } return buf.Bytes() } func shapeToPolygon(s shp.Shape) (polygonSlice, error) { switch p := s.(type) { case *shp.Polygon: return toPolygon(p.NumParts, p.Parts, p.Points), nil case *shp.PolygonZ: return toPolygon(p.NumParts, p.Parts, p.Points), nil case *shp.PolygonM: return toPolygon(p.NumParts, p.Parts, p.Points), nil } return nil, fmt.Errorf("unsupported shape type %T", s) } func toPolygon(numParts int32, parts []int32, points []shp.Point) polygonSlice { out := make(polygonSlice, numParts) var pos int32 for i := range out { var howMany int32 if i+1 >= len(parts) { howMany = int32(len(points)) - pos } else { howMany = parts[i+1] - parts[i] } line := make([][]float64, howMany) vertices := make([]float64, 2*howMany) for j := int32(0); j < howMany; j, pos = j+1, pos+1 { p := &points[pos] vertex := vertices[j*2 : j*2+2] vertex[0], vertex[1] = p.X, p.Y line[j] = vertex } out[i] = line } return out } func (ps polygonSlice) MultiPolygonGeom() wkb.MultiPolygonGeom { var mp wkb.MultiPolygonGeom var curr wkb.PolygonGeom for _, r := range ps { lr := lineSlice(r).LinearRingGeom() // A counter clockwise ring starts a new polygon. if lr.CCW() { if len(curr) > 0 { mp = append(mp, curr) curr = wkb.PolygonGeom{} } } curr = append(curr, lr) } if len(curr) > 0 { mp = append(mp, curr) } return mp }