Mercurial > gemma
view pkg/imports/wkb.go @ 2455:54c9fe587fe6
Subdivide SQL function to prepare for improved error handling
The context of an error (e.g. the function in which it occured)
can be inferred by the database client. Not doing all in one
statement will render the context more meaningful.
author | Tom Gottfried <tom@intevation.de> |
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date | Fri, 01 Mar 2019 18:38:02 +0100 |
parents | f54ac71db1ac |
children | 63475c8e710e |
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// 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" ) type ( pointSlice []float64 lineSlice [][]float64 polygonSlice [][][]float64 ) const ( wkbNDR byte = 1 wkbPoint uint32 = 1 wkbLineString uint32 = 2 wkbPolygon uint32 = 3 ) 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, wkbNDR) binary.Write(buf, binary.LittleEndian, wkbLineString) 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 (p pointSlice) asWKB() []byte { size := 1 + 4 + 2*8 buf := bytes.NewBuffer(make([]byte, 0, size)) binary.Write(buf, binary.LittleEndian, wkbNDR) binary.Write(buf, binary.LittleEndian, wkbPoint) 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, wkbNDR) binary.Write(buf, binary.LittleEndian, wkbPolygon) 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 }