gpkg

package
v0.0.4 Latest Latest
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 Go to latest Published: Oct 31, 2023 License: MIT Imports: 15 Imported by: 0

README

GPKG package

This package is still very much experimental. The API could use a lot of improvement. The idea is to try it out and see how well it works and fix up the API as issues arise.

Look in the example directory to see how it works.

Documentation

Index

Constants

View Source 
const (
	EnvelopeTypeNone    = EnvelopeType(0)
	EnvelopeTypeXY      = EnvelopeType(1)
	EnvelopeTypeXYZ     = EnvelopeType(2)
	EnvelopeTypeXYM     = EnvelopeType(3)
	EnvelopeTypeXYZM    = EnvelopeType(4)
	EnvelopeTypeInvalid = EnvelopeType(5)
)
View Source 
const (
	ErrEnvelopeEnvelopeTypeMismatch = errors.String("envelope and envelope type mismatch")
	ErrInvalidEnvelopeType          = errors.String("invalid envelope type")
	ErrInsufficentBytes             = errors.String("not enough bytes")
	ErrInvalidMagicNumber           = errors.String("invalid magic number")
	ErrNilStandardBinary            = errors.String("standard binary is nil")
	ErrNilHandler                   = errors.String("gpkg handler is nil")
)
View Source 
const (
	// SPATIALITE database driver name
	SPATIALITE = "spatialite"

	// ApplicationID is the required application id for the file
	ApplicationID = 0x47504B47 // "GPKG"

	// UserVersion is the version of the GPKG file format. We support
	// 1.2.1, so the the decimal representation is 10201 (1 digit for the major
	// two digit for the minor and bug-fix).
	UserVersion = 0x000027D9 // 10201

	// TableSpatialRefSysSQL is the normative sql for the required spatial ref
	// table. http://www.geopackage.org/spec/#gpkg_spatial_ref_sys_sql
	TableSpatialRefSysSQL = `` /* 245-byte string literal not displayed */

	// TableContentsSQL is the normative sql for the required contents table.
	// http://www.geopackage.org/spec/#gpkg_contents_sql
	TableContentsSQL = `` /* 427-byte string literal not displayed */

	// TableGeometryColumnsSQL is the normative sql for the geometry columns table that is
	// required if the contents table has at least one table with a data_type of features
	// http://www.geopackage.org/spec/#gpkg_geometry_columns_sql
	TableGeometryColumnsSQL = `` /* 654-byte string literal not displayed */

	// https://www.geopackage.org/spec/#gpkg_extensions_sql
	TableExtensionsSQL = `` /* 245-byte string literal not displayed */

)
View Source 
const (
	// ORNone is for basic SRS
	ORNone = "none"
	OREPSG = "epsg"
)

Organization names

View Source 
const (
	DataTypeFeatures   = "features"
	DataTypeAttributes = "attributes"
	DataTypeTitles     = "titles"
)
View Source 
const (
	No         = MaybeBool(0)
	Yes        = MaybeBool(1)
	Maybe      = MaybeBool(2)
	Prohibited = No
	Mandatory  = Yes
	Optional   = Maybe
)
View Source 
const (
	// Geometry is the Normative type for a geometry
	Geometry = GeometryType(0)
	// Point is the Normative type for a point geometry
	Point = GeometryType(1)
	// Linestring is the Normative type for a linestring geometry
	Linestring = GeometryType(2)
	// Polygon is the Normative type for a polygon geometry
	Polygon = GeometryType(3)
	// MultiPoint is the Normative type for a multipoint geometry
	MultiPoint = GeometryType(4)
	// MultiLinestring is the Normative type for a multilinestring geometry
	MultiLinestring = GeometryType(5)
	// MultiPolygon is the Normative type for a multipolygon geometry
	MultiPolygon = GeometryType(6)
	// GeometryCollection is the Normative type for a collection of geometries
	GeometryCollection = GeometryType(7)
)

Variables

View Source 
var KnownSRS = map[int32]SpatialReferenceSystem{
	-1: {
		Name:                   "any",
		ID:                     -1,
		Organization:           ORNone,
		OrganizationCoordsysID: -1,
		Definition:             "",
		Description:            "any",
	},
	0: {
		Name:                   "any",
		ID:                     0,
		Organization:           ORNone,
		OrganizationCoordsysID: 0,
		Definition:             "",
		Description:            "any",
	},
	4326: {
		Name:                   "WGS 84",
		ID:                     4326,
		Organization:           OREPSG,
		OrganizationCoordsysID: 4326,
		Definition: `
		GEOGCS["WGS 84",
		DATUM["WGS_1984",
			SPHEROID["WGS 84",6378137,298.257223563,
				AUTHORITY["EPSG","7030"]],
			AUTHORITY["EPSG","6326"]],
		PRIMEM["Greenwich",0,
			AUTHORITY["EPSG","8901"]],
		UNIT["degree",0.0174532925199433,
			AUTHORITY["EPSG","9122"]],
		AUTHORITY["EPSG","4326"]]
		`,
		Description: "World Geodetic System: WGS 84",
	},
	3857: {
		Name:                   "WebMercator",
		ID:                     3857,
		Organization:           OREPSG,
		OrganizationCoordsysID: 3857,
		Definition: `
		PROJCS["WGS 84 / Pseudo-Mercator",
    GEOGCS["WGS 84",
        DATUM["WGS_1984",
            SPHEROID["WGS 84",6378137,298.257223563,
                AUTHORITY["EPSG","7030"]],
            AUTHORITY["EPSG","6326"]],
        PRIMEM["Greenwich",0,
            AUTHORITY["EPSG","8901"]],
        UNIT["degree",0.0174532925199433,
            AUTHORITY["EPSG","9122"]],
        AUTHORITY["EPSG","4326"]],
    PROJECTION["Mercator_1SP"],
    PARAMETER["central_meridian",0],
    PARAMETER["scale_factor",1],
    PARAMETER["false_easting",0],
    PARAMETER["false_northing",0],
    UNIT["metre",1,
        AUTHORITY["EPSG","9001"]],
    AXIS["X",EAST],
    AXIS["Y",NORTH],
    EXTENSION["PROJ4","+proj=merc +a=6378137 +b=6378137 +lat_ts=0.0 +lon_0=0.0 +x_0=0.0 +y_0=0 +k=1.0 +units=m +nadgrids=@null +wktext  +no_defs"],
    AUTHORITY["EPSG","3857"]]
		`,
		Description: "WGS83 / Web Mercator",
	},
}
View Source 
var Magic = [2]byte{0x47, 0x50}

Magic is the magic number encode in the header. It should be 0x4750

Functions

func EncodeHeaderFlags 

func EncodeHeaderFlags(byteOrder binary.ByteOrder, envelope EnvelopeType, extendGeom bool, emptyGeom bool) headerFlags

Types

type BinaryHeader 

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

BinaryHeader is the gpkg header that accompainies every feature.

func DecodeBinaryHeader 

func DecodeBinaryHeader(data []byte) (*BinaryHeader, error)

DecodeBinaryHeader decodes the data into the BinaryHeader

func NewBinaryHeader 

func NewBinaryHeader(byteOrder binary.ByteOrder, srsid int32, envelope []float64, et EnvelopeType, extendGeom bool, emptyGeom bool) (*BinaryHeader, error)

NewBinaryHeader returns a new binary header

func (*BinaryHeader) Encode 

func (h *BinaryHeader) Encode() ([]byte, error)

func (*BinaryHeader) EncodeTo 

func (h *BinaryHeader) EncodeTo(data *bytes.Buffer) error

func (*BinaryHeader) Endian 

func (h *BinaryHeader) Endian() binary.ByteOrder

func (*BinaryHeader) Envelope 

func (h *BinaryHeader) Envelope() []float64

Envelope is the bounding box of the feature, used for searching. If the EnvelopeType is EvelopeTypeNone, then there isn't a envelope encoded and a search without an index will need to be preformed. This is to save space.

func (*BinaryHeader) EnvelopeType 

func (h *BinaryHeader) EnvelopeType() EnvelopeType

EnvelopeType is the type of the envelope that is provided.

func (*BinaryHeader) IsGeometryEmpty 

func (h *BinaryHeader) IsGeometryEmpty() bool

IsGeometryEmpty tells us if the geometry should be considered empty.

func (*BinaryHeader) IsStandardGeometry 

func (h *BinaryHeader) IsStandardGeometry() bool

IsStandardGeometry is the geometry a core/extended geometry type, or a user defined geometry type.

func (*BinaryHeader) Magic 

func (h *BinaryHeader) Magic() [2]byte

Magic is the magic number encode in the header. It should be 0x4750

func (*BinaryHeader) SRSID 

func (h *BinaryHeader) SRSID() int32

SRSID is the SRS id of the feature.

func (*BinaryHeader) Size 

func (h *BinaryHeader) Size() int

Size is the size of the header in bytes.

func (*BinaryHeader) Version 

func (h *BinaryHeader) Version() uint8

Version is the version number encode in the header.

type EnvelopeType 

type EnvelopeType uint8

func (EnvelopeType) NumberOfElements 

func (et EnvelopeType) NumberOfElements() int

NumberOfElements that the particular Evnelope Type will have.

func (EnvelopeType) String 

func (et EnvelopeType) String() string

type GeometryType 

type GeometryType uint8

GeometryType describes the type of geometry to find for a table

func TypeForGeometry 

func TypeForGeometry(g geom.Geometry) GeometryType

func (GeometryType) Empty 

func (gt GeometryType) Empty() (geom.Geometry, error)

func (GeometryType) String 

func (gt GeometryType) String() string

type Handle 

type Handle struct {
	*sql.DB
}

Handle is the handle to the DB

func New 

func New(filename string) (*Handle, error)

New will create a new gpkg file and return a new db handle

func Open 

func Open(filename string) (*Handle, error)

Open will open or create the sqlite file, and return a new db handle to it.

func (*Handle) AddGeometryTable 

func (h *Handle) AddGeometryTable(table TableDescription) error

AddGeometryTable will add the given features table to the metadata tables This should be called after creating the table.

func (*Handle) CalculateGeometryExtent 

func (h *Handle) CalculateGeometryExtent(tablename string) (*geom.Extent, error)

CalculateGeometryExtent will grab all the geometries from the given table, use it to calculate the extent of all geometries in that table.

func (*Handle) UpdateGeometryExtent 

func (h *Handle) UpdateGeometryExtent(tablename string, extent *geom.Extent) error

UpdateGeometryExtent will modify the extent for the given table by adding the passed in extent to the extent of the table. Growing the extent as necessary.

func (*Handle) UpdateSRS 

func (h *Handle) UpdateSRS(srss ...SpatialReferenceSystem) error

UpdateSRS will insert or update the srs table with the given srs

type MaybeBool 

type MaybeBool int8

func (MaybeBool) False 

func (mbe MaybeBool) False() bool

func (MaybeBool) True 

func (mbe MaybeBool) True() bool

type SpatialReferenceSystem 

type SpatialReferenceSystem struct {
	Name                   string
	ID                     int
	Organization           string
	OrganizationCoordsysID int
	Definition             string
	Description            string
}

SpatialReferenceSystem describes the SRS

type StandardBinary 

type StandardBinary struct {
	Header   *BinaryHeader
	SRSID    int32
	Geometry geom.Geometry
}

StandardBinary is the binary encoding pluse some meta data should be stored as a blob

func DecodeGeometry 

func DecodeGeometry(bytes []byte) (*StandardBinary, error)

func NewBinary 

func NewBinary(srs int32, geo geom.Geometry) (*StandardBinary, error)

func (StandardBinary) Encode 

func (sb StandardBinary) Encode() ([]byte, error)

func (*StandardBinary) Extent 

func (sb *StandardBinary) Extent() *geom.Extent

func (*StandardBinary) Scan 

func (sb *StandardBinary) Scan(value interface{}) error

func (*StandardBinary) Value 

func (sb *StandardBinary) Value() (driver.Value, error)

type TableDescription 

type TableDescription struct {
	Name          string
	ShortName     string
	Description   string
	GeometryField string
	GeometryType  GeometryType
	SRS           int32
	Z             MaybeBool
	M             MaybeBool
}

TableDescription describes a content table

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