package wkb

import "github.com/paulmach/orb/encoding/wkb"

Package wkb is for decoding ESRI's Well Known Binary (WKB) format sepcification at https://en.wikipedia.org/wiki/Well-known_text_representation_of_geometry#Well-known_binary

Index ¶

• Variables
• func Marshal(geom orb.Geometry, byteOrder ...binary.ByteOrder) ([]byte, error)
• func MustMarshal(geom orb.Geometry, byteOrder ...binary.ByteOrder) []byte
• func Unmarshal(data []byte) (orb.Geometry, error)
• func Value(g orb.Geometry) driver.Valuer
• type Decoder
• func NewDecoder(r io.Reader) *Decoder
• func (d *Decoder) Decode() (orb.Geometry, error)
• type Encoder
• func NewEncoder(w io.Writer) *Encoder
• func (e *Encoder) Encode(geom orb.Geometry) error
• func (e *Encoder) SetByteOrder(bo binary.ByteOrder)
• type GeometryScanner
• func Scanner(g interface{}) *GeometryScanner
• func (s *GeometryScanner) Scan(d interface{}) error

Variables ¶

var (
	// ErrUnsupportedDataType is returned by Scan methods when asked to scan
	// non []byte data from the database. This should never happen
	// if the driver is acting appropriately.
	ErrUnsupportedDataType = errors.New("wkb: scan value must be []byte")

	// ErrNotWKB is returned when unmarshalling WKB and the data is not valid.
	ErrNotWKB = errors.New("wkb: invalid data")

	// ErrIncorrectGeometry is returned when unmarshalling WKB data into the wrong type.
	// For example, unmarshaling linestring data into a point.
	ErrIncorrectGeometry = errors.New("wkb: incorrect geometry")

	// ErrUnsupportedGeometry is returned when geometry type is not supported by this lib.
	ErrUnsupportedGeometry = errors.New("wkb: unsupported geometry")
)

var DefaultByteOrder binary.ByteOrder = binary.LittleEndian

DefaultByteOrder is the order used for marshalling or encoding is none is specified.

Functions ¶

func Marshal ¶

func Marshal(geom orb.Geometry, byteOrder ...binary.ByteOrder) ([]byte, error)

Marshal encodes the geometry with the given byte order.

func MustMarshal ¶

func MustMarshal(geom orb.Geometry, byteOrder ...binary.ByteOrder) []byte

MustMarshal will encode the geometry and panic on error. Currently there is no reason to error during geometry marshalling.

func Unmarshal ¶

func Unmarshal(data []byte) (orb.Geometry, error)

Unmarshal will decode the type into a Geometry.

func Value ¶

func Value(g orb.Geometry) driver.Valuer

Value will create a driver.Valuer that will WKB the geometry into the database query.

Types ¶

type Decoder ¶

type Decoder struct {
	// contains filtered or unexported fields
}

Decoder can decoder WKB geometry off of the stream.

func NewDecoder ¶

func NewDecoder(r io.Reader) *Decoder

NewDecoder will create a new WKB decoder.

func (*Decoder) Decode ¶

func (d *Decoder) Decode() (orb.Geometry, error)

Decode will decode the next geometry off of the stream.

type Encoder ¶

type Encoder struct {
	// contains filtered or unexported fields
}

An Encoder will encode a geometry as WKB to the writer given at creation time.

func NewEncoder ¶

func NewEncoder(w io.Writer) *Encoder

NewEncoder creates a new Encoder for the given writer.

func (*Encoder) Encode ¶

func (e *Encoder) Encode(geom orb.Geometry) error

Encode will write the geometry encoded as WKB to the given writer.

func (*Encoder) SetByteOrder ¶

func (e *Encoder) SetByteOrder(bo binary.ByteOrder)

SetByteOrder will override the default byte order set when the encoder was created.

type GeometryScanner ¶

type GeometryScanner struct {
	Geometry orb.Geometry
	Valid    bool // Valid is true if the geometry is not NULL
	// contains filtered or unexported fields
}

GeometryScanner is a thing that can scan in sql query results. It can be used as a scan destination:

var s wkb.GeometryScanner
err := db.QueryRow("SELECT latlon FROM foo WHERE id=?", id).Scan(&s)
...
if s.Valid {
  // use s.Geometry
} else {
  // NULL value
}

func Scanner ¶

func Scanner(g interface{}) *GeometryScanner

Scanner will return a GeometryScanner that can scan sql query results. The geometryScanner.Geometry attribute will be set to the value. If g is non-nil, it MUST be a pointer to an orb.Geometry type like a Point or LineString. In that case the value will be written to g and the Geometry attribute.

var p orb.Point
err := db.QueryRow("SELECT latlon FROM foo WHERE id=?", id).Scan(wkb.Scanner(&p))
...
// use p

If the value may be null check Valid first:

var point orb.Point
s := wkb.Scanner(&point)
err := db.QueryRow("SELECT latlon FROM foo WHERE id=?", id).Scan(&s)
...
if s.Valid {
  // use p
} else {
  // NULL value
}

Scanning directly from MySQL columns is supported. By default MySQL returns geometry data as WKB but prefixed with a 4 byte SRID. To support this, if the data is not valid WKB, the code will strip the first 4 bytes and try again. This works for most use cases.

func (*GeometryScanner) Scan ¶

func (s *GeometryScanner) Scan(d interface{}) error

Scan will scan the input []byte data into a geometry. This could be into the orb geometry type pointer or, if nil, the scanner.Geometry attribute.

Source Files ¶

collection.go line_string.go point.go polygon.go scanner.go wkb.go