wkb

Documentation

Overview

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

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

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

Index

• Variables
• func BufferedReader(bufferedReader io.Reader) []space.Geometry
• func BufferedWriter(bufferedWriter io.Writer, geoms []space.Geometry)
• func GeomFromWKBHexStr(wkbHex string) (space.Geometry, error)
• func GeomToWKBHexStr(geom space.Geometry) (wkbHex string, err error)
• func HexToBytes(hex string) []byte
• func Marshal(geom space.Geometry, bo ...byteOrder) ([]byte, error)
• func MustMarshal(geom space.Geometry, bo ...byteOrder) []byte
• func Unmarshal(data []byte) (space.Geometry, error)
• func Value(g space.Geometry) driver.Valuer
• type Decoder
  • func NewDecoder(r io.Reader) *Decoder
  • func (d *Decoder) Decode() (space.Geometry, error)
• type EWKBDecoder
  • func (d *EWKBDecoder) Decode() (space.Geometry, error)
• type EWKBEncoder
  • func (e *EWKBEncoder) Encode(geom space.Geometry) error
• type Encoder
  • func NewEncoder(w io.Writer) *Encoder
  • func (e *Encoder) Encode(geom space.Geometry) error
• 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.

var ErrAttempt = fmt.Errorf("Attempt to read past end of input")

ErrAttempt ...

var ErrUnknownWKBType = fmt.Errorf("Unknown WKB type ")

ErrUnknownWKBType ...

Functions

func BufferedReader

func BufferedReader(bufferedReader io.Reader) []space.Geometry

BufferedReader returns []Geometry from reader.

func BufferedWriter

func BufferedWriter(bufferedWriter io.Writer, geoms []space.Geometry)

BufferedWriter returns []Geometry from reader.

func GeomFromWKBHexStr

func GeomFromWKBHexStr(wkbHex string) (space.Geometry, error)

GeomFromWKBHexStr convert hex string to GEOSGeometry

func GeomToWKBHexStr

func GeomToWKBHexStr(geom space.Geometry) (wkbHex string, err error)

func HexToBytes

func HexToBytes(hex string) []byte

HexToBytes Converts a hexadecimal string to a byte array. The hexadecimal digit symbols are case-insensitive.

func Marshal

func Marshal(geom space.Geometry, bo ...byteOrder) ([]byte, error)

Marshal encodes the geometry with the given byte order.

func MustMarshal

func MustMarshal(geom space.Geometry, bo ...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) (space.Geometry, error)

Unmarshal will decode the type into a Geometry.

func Value

func Value(g space.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() (space.Geometry, error)

Decode will decode the next geometry off of the stream.

type EWKBDecoder

type EWKBDecoder struct {
	Srid uint32
	// contains filtered or unexported fields
}

EWKBDecoder Decoder can decoder EWKB geometry off of the stream.

func (*EWKBDecoder) Decode

func (d *EWKBDecoder) Decode() (space.Geometry, error)

Decode returns geometry,it will decode the next geometry off of the stream.

type EWKBEncoder

type EWKBEncoder struct {
	*Encoder
	Srid uint32
}

EWKBEncoder Decoder can decoder EWKB geometry off of the stream.

func (*EWKBEncoder) Encode

func (e *EWKBEncoder) Encode(geom space.Geometry) error

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

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 space.Geometry) error

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

type GeometryScanner

type GeometryScanner struct {
	Geometry space.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 space.Geometry type like a Point or LineString. In that case the value will be written to g and the Geometry attribute.

var p space.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 space.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 space geometry type pointer or, if nil, the scanner.Geometry attribute.