Geo::OGR::Layer Class Reference

A collection of similar features. More...

Inheritance diagram for Geo::OGR::Layer:

Collaboration diagram for Geo::OGR::Layer:

Public Member Functions
public method	AlterFieldDefn (scalar name, hash params)
public list	Capabilities ()
public method	Clip (Geo::OGR::Layer method, Geo::OGR::Layer result, hashref options, subref callback, scalar callback_data)
public method	CommitTransaction ()
public method	CreateFeature (scalar feature)
public method	CreateField (hash params)
public method	DataSource ()
public method	DeleteFeature (scalar fid)
public method	DeleteField (scalar field)
public method	Erase (Geo::OGR::Layer method, Geo::OGR::Layer result, hashref options, subref callback, scalar callback_data)
public method	ForFeatures (scalar code, scalar in_place)
public method	ForGeometries (scalar code, scalar in_place)
public method	GeometryType ()
public Geo::OGR::DataSource	GetDataSource ()
public Geo::OGR::FeatureDefn	GetDefn ()
public list	GetExtent (scalar force=1)
public scalar	GetFIDColumn ()
public Geo::OGR::Feature	GetFeature (scalar fid)
public scalar	GetFeatureCount (scalar force=1)
public scalar	GetFeaturesRead ()
public hash	GetFieldDefn (scalar name)
public list	GetFieldNames ()
public scalar	GetName ()
public Geo::OGR::Feature	GetNextFeature ()
public hash reference	GetSchema ()
	Get the schema of this layer. More...
public Geo::OGR::Geometry	GetSpatialFilter ()
public method	GetStyleTable ()
public method	Identity (Geo::OGR::Layer method, Geo::OGR::Layer result, hashref options, subref callback, scalar callback_data)
public method	InsertFeature (scalar feature)
public method	Intersection (Geo::OGR::Layer method, Geo::OGR::Layer result, hashref options, subref callback, scalar callback_data)
public method	ReorderField ()
public method	ReorderFields ()
public method	ResetReading ()
public method	RollbackTransaction ()
public hash reference	Row (hash row)
public method	SetAttributeFilter (scalar filter_string)
public method	SetFeature (scalar feature)
public method	SetIgnoredFields (array fields)
public method	SetNextByIndex (scalar new_index)
public method	SetSpatialFilter (scalar filter)
public method	SetSpatialFilterRect (scalar minx, scalar miny, scalar maxx, scalar maxy)
public method	SetStyleTable ()
public Geo::OGR::Geometry	SpatialFilter (array filter)
public Geo::OSR::SpatialReference	SpatialReference (scalar name, Geo::OSR::SpatialReference sr)
public method	StartTransaction ()
public method	SymDifference (Geo::OGR::Layer method, Geo::OGR::Layer result, hashref options, subref callback, scalar callback_data)
public method	SyncToDisk ()
public scalar	TestCapability (scalar cap)
public list	Tuple (array tuple)
public method	Union (Geo::OGR::Layer method, Geo::OGR::Layer result, hashref options, subref callback, scalar callback_data)
public method	Update (Geo::OGR::Layer method, Geo::OGR::Layer result, hashref options, subref callback, scalar callback_data)
Public Member Functions inherited from Geo::GDAL::MajorObject
public scalar	Description (scalar description)
public method	Domains ()
public scalar	GetDescription ()
public hash reference	GetMetadata (scalar domain="")
public method	GetMetadataDomainList ()
public hash reference	Metadata (hashref metadata=undef, scalar domain= '')
public method	SetDescription (scalar NewDesc)
public method	SetMetadata (hashref metadata, scalar domain="")
Public Member Functions inherited from Geo::GDAL
public list	AccessTypes ()
public Geo::GDAL::Dataset	AutoCreateWarpedVRT (Geo::GDAL::Dataset src, Geo::OSR::SpatialReference src_srs=undef, Geo::OSR::SpatialReference dst_srs=undef, scalar ResampleAlg='NearestNeighbour', scalar maxerror=0.0)
public method	CPLBinaryToHex ()
public method	CPLHexToBinary ()
public list	Child (scalar node, scalar i)
public list	Children (scalar node)
public method	ComputeMedianCutPCT (Geo::GDAL::Band red, Geo::GDAL::Band green, Geo::GDAL::Band blue, scalar num_colors, scalar colors, subref progress, scalar progress_data)
public method	ComputeProximity (Geo::GDAL::Band src, Geo::GDAL::Band proximity, hashref options, subref progress, scalar progress_data)
public scalar	DataTypeIsComplex (scalar DataType)
public list	DataTypeValueRange (scalar DataType)
public list	DataTypes ()
public method	Debug ()
public scalar	DecToDMS (scalar angle, scalar axis, scalar precision=2)
public scalar	DecToPackedDMS (scalar dec)
public method	DitherRGB2PCT (scalar red, scalar green, scalar blue, scalar target, scalar colors, subref progress, scalar progress_data)
public method	EscapeString ()
public scalar	FindFile (scalar class, scalar basename)
public method	FinderClean ()
public method	GOA2GetAccessToken ()
public method	GOA2GetAuthorizationURL ()
public method	GOA2GetRefreshToken ()
public scalar	GetCacheMax ()
public scalar	GetCacheUsed ()
public scalar	GetConfigOption (scalar key, scalar default)
public scalar	GetDataTypeSize (scalar DataType)
public Geo::GDAL::Driver	GetDriver (scalar name)
public list	GetDriverNames ()
public method	GetJPEG2000StructureAsString ()
public Geo::GDAL::Driver	IdentifyDriver (scalar path, scalar siblings)
public list	NodeData (scalar node)
public scalar	NodeType (scalar type)
public list	NodeTypes ()
public Geo::GDAL::Dataset	Open (scalar name, scalar access= 'ReadOnly')
public Geo::GDAL::Dataset	OpenEx (scalar name, scalar open_flags=0, array reference allowed_drivers=undef, array reference open_options=undef, array reference sibling_files=undef)
public Geo::GDAL::Dataset	OpenShared (scalar name, scalar access= 'ReadOnly')
public scalar	PackCharacter (scalar DataType)
public scalar	PackedDMSToDec (scalar packed)
public array reference	ParseXMLString (scalar XML)
public method	Polygonize (Geo::GDAL::Band src, Geo::GDAL::Band mask, Geo::OGR::Layer out, scalar PixValField, hashref options, subref progress, scalar progress_data)
public method	PopFinderLocation ()
public method	PushFinderLocation (scalar path)
public list	RIOResamplingTypes ()
public method	RasterizeLayer (Geo::GDAL::Dataset ds, arrayref bands, Geo::OGR::Layer layer, scalar transformer, scalar arg, arrayref burn_values, hashref options, subref progress, scalar progress_data)
public method	ReprojectImage (scalar src_ds, scalar dst_ds, scalar src_wkt=undef, scalar dst_wkt=undef, scalar ResampleAlg='NearestNeighbour', scalar WarpMemoryLimit=0, scalar maxerror=0.0, subref progress, scalar progress_data)
public list	ResamplingTypes ()
public scalar	SerializeXMLTree (arrayref XMLTree)
public method	SetCacheMax (scalar Bytes)
public method	SetConfigOption (scalar key, scalar value)
public method	SieveFilter (Geo::GDAL::Band src, Geo::GDAL::Band mask, Geo::GDAL::Band dst, scalar threshold, scalar connectedness, hashref options, subref progress, scalar progress_data)
public scalar	VersionInfo (scalar request= 'VERSION_NUM')
Public Member Functions inherited from Geo::OGR
public list	ByteOrders ()
public scalar	GeometryTypeModify (scalar type, scalar modifier)
public scalar	GeometryTypeTest (scalar type, scalar test, scalar type2)
public list	GeometryTypes ()
public Geo::OGR::Driver	GetDriver (scalar name)
public list	GetDriverNames ()
public method	GetNonLinearGeometriesEnabledFlag ()
public Geo::OGR::DataSource	GetOpenDS (scalar number)
public scalar	GetOpenDSCount ()
public method	OLMD_FID64 ()
public Geo::OGR::DataSource	Open (scalar name, scalar update=0)
public Geo::OGR::DataSource	OpenShared (scalar name, scalar update=0)
public method	SetGenerate_DB2_V72_BYTE_ORDER (scalar Generate_DB2_V72_BYTE_ORDER)
public method	SetNonLinearGeometriesEnabledFlag ()

Detailed Description

A collection of similar features.

A layer object is typically obtained with a data source object. A layer has a data model (a schema), which is maintained in a definition object, and a set of features, which contain data according to the data model. The schema is typically set when the layer is created or opened, but it may be altered somewhat with methods Geo::OGR::Layer::CreateField, Geo::OGR::Layer::AlterFieldDefn, and Geo::OGR::Layer::DeleteField. Features and/or their data can be read, inserted and deleted. Reading can be filtered. Layers can be compared to each other with methods Clip, Erase, Identity, Intersection, SymDifference, Union, and Update.

Definition at line 10570 of file all.pm.

Member Function Documentation

public method Geo::OGR::Layer::AlterFieldDefn	(	scalar	name,
		hash	params
	)

Parameters

field	the name of the field to be altered.
params	as in Geo::OGR::FieldDefn::new. Width and Precision should be both or neither.

Note

Only non-spatial fields can be altered.

Also the deprecated form AlterFieldDefn($field, Geo::OGR::FieldDefn $Defn, $Flags) works.

Code:

public list Geo::OGR::Layer::Capabilities

(

)

Both a class and an object method.

Returns

a list of capabilities. The object method returns a list of the capabilities the layer has. The class method returns a list of all potential capabilities a layer may have. These are currently: AlterFieldDefn, CreateField, CreateGeomField, CurveGeometries, DeleteFeature, DeleteField, FastFeatureCount, FastGetExtent, FastSetNextByIndex, FastSpatialFilter, IgnoreFields, RandomRead, RandomWrite, ReorderFields, SequentialWrite, StringsAsUTF8, and Transactions.

Examples:

@cap = Geo::OGR::Layer::Capabilities(); # the class method
@cap = $layer->Capabilities(); # the object method

Code:

public method Geo::OGR::Layer::Clip	(	Geo::OGR::Layer	method,
		Geo::OGR::Layer	result,
		hashref	options,
		subref	callback,
		scalar	callback_data
	)

Clip off areas that are not covered by the method layer. The schema of the result layer can be set before calling this method, or is initialized to to contain all fields from this and method layer.

Parameters

method	method layer.
result	result layer.
options	a reference to an options hash.
callback	[optional] a reference to a subroutine, which will be called with parameters (number progress, string msg, callback_data)
callback_data	[optional]

Code:

public method Geo::OGR::Layer::CommitTransaction

(

)

Code:

public method Geo::OGR::Layer::CreateFeature

(

scalar

feature

)

Deprecated:

use Geo::OGR::Layer::InsertFeature which accepts Perl data and checks for geometry type and attribute data

Note

The feature should have the same schema as the layer.

Inserts a feature into the layer. The given feature's id may change.

Parameters

feature

a Geo::OGR::Feature object

Code:

public method Geo::OGR::Layer::CreateField

(

hash

params

)

Create a field.

Parameters

params

as in Geo::OGR::FieldDefn::new or Geo::OGR::GeomFieldDefn::new, plus ApproxOK (whose default is true).

Code:

public method Geo::OGR::Layer::DataSource

(

)

Code:

public method Geo::OGR::Layer::DeleteFeature

(

scalar

fid

)

Parameters

fid	feature id

Code:

public method Geo::OGR::Layer::DeleteField

(

scalar

field

)

Delete an existing field from a layer.

Parameters

field

name (or index) of the field which is deleted

Note

Only non-spatial fields can be deleted.

Code:

public method Geo::OGR::Layer::Erase	(	Geo::OGR::Layer	method,
		Geo::OGR::Layer	result,
		hashref	options,
		subref	callback,
		scalar	callback_data
	)

The result layer contains features whose geometries represent areas that are in the input layer but not in the method layer. The features in the result layer have attributes from the input layer. The schema of the result layer can be set by the user or, if it is empty, is initialized to contain all fields in the input layer.

Parameters

method	method layer.
result	result layer.
options	a reference to an options hash.
callback	[optional] a reference to a subroutine, which will be called with parameters (number progress, string msg, callback_data)
callback_data	[optional]

Code:

public method Geo::OGR::Layer::ForFeatures	(	scalar	code,
		scalar	in_place
	)

Note

experimental, the syntax may change

Call code for all features. This is a simple wrapper for ResetReading and while(GetNextFeature).

Example usage:

$layer->ForFeatures(sub {my $f = shift; $self->DeleteFeature($f->FID)}); # empties the layer

Parameters

code	a reference to a subroutine, which is called with each feature as an argument
in_place	if set to true, the feature is stored back to the layer

Code:

public method Geo::OGR::Layer::ForGeometries	(	scalar	code,
		scalar	in_place
	)

Note

experimental, the syntax may change

Call code for all geometries. This is a simple wrapper for ResetReading and while(GetNextFeature).

Example usage:

my $area = 0;
$layer->ForGeometries(sub {my $g = shift; $area += $g->Area}); # computes the total area

Parameters

code	a reference to a subroutine, which is called with each geometry as an argument
in_place	if set to true, the geometry is stored back to the layer

Code:

public method Geo::OGR::Layer::GeometryType

(

)

Code:

public Geo::OGR::DataSource Geo::OGR::Layer::GetDataSource

(

)

Returns

the data source object to which this layer object belongs to.

Code:

public Geo::OGR::FeatureDefn Geo::OGR::Layer::GetDefn

(

)

A.k.a GetLayerDefn.

Returns

a Geo::OGR::FeatureDefn object.

Code:

public list Geo::OGR::Layer::GetExtent

(

scalar

force = 1

)

Parameters

force

compute the extent even if it is expensive

Note

In scalar context returns a reference to an anonymous array containing the extent.

The order of values is different from those returned by Geo::OGR::Geometry::GetEnvelope.

Returns

the extent ($minx, $miny, $maxx, $maxy)

Parameters

force

Returns

the extent = ($minx, $miny, $maxx, $maxy) as a listref

Code:

public Geo::OGR::Feature Geo::OGR::Layer::GetFeature

(

scalar

fid

)

Parameters

fid	feature id

Returns

a new Geo::OGR::Feature object that represents the feature in the layer.

Code:

public scalar Geo::OGR::Layer::GetFeatureCount

(

scalar

force = 1

)

Parameters

force

Returns

integer

Code:

public scalar Geo::OGR::Layer::GetFeaturesRead

(

)

Returns

integer

Code:

public scalar Geo::OGR::Layer::GetFIDColumn

(

)

Returns

the name of the underlying database column being used as the FID column, or "" if not supported.

Code:

public hash Geo::OGR::Layer::GetFieldDefn

(

scalar

name

)

Get the definition of a field.

Parameters

name	the name of the field.

Returns

the field definition object, either Geo::OGR::FieldDefn or Geo::OGR::GeomFieldDefn.

Code:

public list Geo::OGR::Layer::GetFieldNames

(

)

Returns

a list of the names of the fields in this layer. The non-geometry field names are first in the list and then the geometry fields.

Code:

public scalar Geo::OGR::Layer::GetName

(

)

Returns

the name of the layer.

Code:

public Geo::OGR::Feature Geo::OGR::Layer::GetNextFeature

(

)

Returns

iteratively Geo::OGR::Feature objects from the layer. The iteration obeys the spatial and the attribute filter.

Code:

public hash reference Geo::OGR::Layer::GetSchema

(

)

Get the schema of this layer.

Note

The schema of a layer cannot be set with this method. If you have a Geo::OGR::FeatureDefn object before creating the layer, use its schema in the Geo::OGR::CreateLayer method.

Returns

the schema of this layer, as in Geo::OGR::FeatureDefn::Schema.

Code:

public Geo::OGR::Geometry Geo::OGR::Layer::GetSpatialFilter

(

)

Returns

a new Geo::OGR::Geometry object

Code:

public method Geo::OGR::Layer::GetStyleTable

(

)

Code:

public method Geo::OGR::Layer::Identity	(	Geo::OGR::Layer	method,
		Geo::OGR::Layer	result,
		hashref	options,
		subref	callback,
		scalar	callback_data
	)

The result layer contains features whose geometries represent areas that are in the input layer. The features in the result layer have attributes from both input and method layers. The schema of the result layer can be set by the user or, if it is empty, is initialized to contain all fields in input and method layers.

Parameters

method	method layer.
result	result layer.
options	a reference to an options hash.
callback	[optional] a reference to a subroutine, which will be called with parameters (number progress, string msg, callback_data)
callback_data	[optional]

Code:

public method Geo::OGR::Layer::InsertFeature

(

scalar

feature

)

Creates a new feature which has the schema of the layer and initializes it with data from the argument. Then inserts the feature into the layer (using CreateFeature). Uses Geo::OGR::Feature::Row or Geo::OGR::Feature::Tuple.

Parameters

feature

a Geo::OGR::Feature object or reference to feature data in a hash (as in Geo::OGR::Feature::Row) or in an array (as in Geo::OGR::Feature::Tuple)

Code:

public method Geo::OGR::Layer::Intersection	(	Geo::OGR::Layer	method,
		Geo::OGR::Layer	result,
		hashref	options,
		subref	callback,
		scalar	callback_data
	)

The result layer contains features whose geometries represent areas that are common between features in the input layer and in the method layer. The schema of the result layer can be set before calling this method, or is initialized to contain all fields from this and method layer.

Parameters

method	method layer.
result	result layer.
options	a reference to an options hash.
callback	[optional] a reference to a subroutine, which will be called with parameters (number progress, string msg, callback_data)
callback_data	[optional]

Code:

public method Geo::OGR::Layer::ReorderField

(

)

Code:

public method Geo::OGR::Layer::ReorderFields

(

)

Code:

public method Geo::OGR::Layer::ResetReading

(

)

Initialize the layer object for iterative reading.

Code:

public method Geo::OGR::Layer::RollbackTransaction

(

)

Code:

public hash reference Geo::OGR::Layer::Row

(

hash

row

)

Get and/or set the data of a feature that has the supplied feature id (the next feature obtained with GetNextFeature is used if feature id is not given). Calls Geo::OGR::Feature::Row.

Parameters

row	[optional] feature data

Returns

a reference to feature data in a hash

Code:

public method Geo::OGR::Layer::SetAttributeFilter

(

scalar

filter_string

)

Set or clear the attribute filter.

Parameters

filter_string

a SQL WHERE clause or undef to clear the filter.

Code:

public method Geo::OGR::Layer::SetFeature

(

scalar

feature

)

Note

The feature should have the same schema as the layer.

Replaces a feature in the layer based on the given feature's id. Requires RandomWrite capability.

Parameters

feature

a Geo::OGR::Feature object

Code:

public method Geo::OGR::Layer::SetIgnoredFields

(

array

fields

)

Parameters

fields

a list of field names

Code:

public method Geo::OGR::Layer::SetNextByIndex

(

scalar

new_index

)

Parameters

new_index

the index to which set the read cursor in the current iteration

Code:

public method Geo::OGR::Layer::SetSpatialFilter

(

scalar

filter

)

Parameters

filter

[optional] a Geo::OGR::Geometry object. If not given, removes the filter if there is one.

Code:

public method Geo::OGR::Layer::SetSpatialFilterRect	(	scalar	minx,
		scalar	miny,
		scalar	maxx,
		scalar	maxy
	)

Parameters

minx
miny
maxx
maxy	Code:

public method Geo::OGR::Layer::SetStyleTable

(

)

Code:

public Geo::OGR::Geometry Geo::OGR::Layer::SpatialFilter

(

array

filter

)

Parameters

filter

[optional] a Geo::OGR::Geometry object or a string. An undefined value removes the filter if there is one.

Returns

a new Geo::OGR::Geometry object

Parameters

filter

[optional] a rectangle ($minx, $miny, $maxx, $maxy).

Returns

a new Geo::OGR::Geometry object

Code:

public Geo::OSR::SpatialReference Geo::OGR::Layer::SpatialReference	(	scalar	name,
		Geo::OSR::SpatialReference	sr
	)

Note

A.k.a GetSpatialRef. Get or set the projection of a spatial field of this layer. Gets or sets the projection of the first field if no field name is given.

Parameters

name	[optional] a name of a spatial field in this layer.
sr	[optional] a Geo::OSR::SpatialReference object, which replaces the existing projection.

Returns

a Geo::OSR::SpatialReference object, which represents the projection in the given spatial field.

Code:

public method Geo::OGR::Layer::StartTransaction

(

)

Code:

public method Geo::OGR::Layer::SymDifference	(	Geo::OGR::Layer	method,
		Geo::OGR::Layer	result,
		hashref	options,
		subref	callback,
		scalar	callback_data
	)

The result layer contains features whose geometries represent areas that are in either in the input layer or in the method layer but not in both. The features in the result layer have attributes from both input and method layers. For features which represent areas that are only in the input or in the method layer the respective attributes have undefined values. The schema of the result layer can be set by the user or, if it is empty, is initialized to contain all fields in the input and method layers.

Parameters

method	method layer.
result	result layer.
options	a reference to an options hash.
callback	[optional] a reference to a subroutine, which will be called with parameters (number progress, string msg, callback_data)
callback_data	[optional]

Code:

public method Geo::OGR::Layer::SyncToDisk

(

)

Code:

public scalar Geo::OGR::Layer::TestCapability

(

scalar

cap

)

Parameters

cap	A capability string.

Returns

a boolean value indicating whether the layer has the specified capability.

Code:

public list Geo::OGR::Layer::Tuple

(

array

tuple

)

Get and/set the data of a feature that has the supplied feature id (the next feature obtained with GetNextFeature is used if feature id is not given). The expected data in the tuple is: ([feature id,] non-spatial fields, spatial fields). Calls Geo::OGR::Feature::Tuple.

Parameters

tuple

[optional] feature data

Note

The schema of the tuple needs to be the same as that of the layer.

Returns

a reference to feature data in an array

Code:

public method Geo::OGR::Layer::Union	(	Geo::OGR::Layer	method,
		Geo::OGR::Layer	result,
		hashref	options,
		subref	callback,
		scalar	callback_data
	)

The result layer contains features whose geometries represent areas that are in either in the input layer or in the method layer. The schema of the result layer can be set before calling this method, or is initialized to contain all fields from this and method layer.

Parameters

method	method layer.
result	result layer.
options	a reference to an options hash.
callback	[optional] a reference to a subroutine, which will be called with parameters (number progress, string msg, callback_data)
callback_data	[optional]

Code:

public method Geo::OGR::Layer::Update	(	Geo::OGR::Layer	method,
		Geo::OGR::Layer	result,
		hashref	options,
		subref	callback,
		scalar	callback_data
	)

The result layer contains features whose geometries represent areas that are either in the input layer or in the method layer. The features in the result layer have areas of the features of the method layer or those ares of the features of the input layer that are not covered by the method layer. The features of the result layer get their attributes from the input layer. The schema of the result layer can be set by the user or, if it is empty, is initialized to contain all fields in the input layer.

Parameters

method	method layer.
result	result layer.
options	a reference to an options hash.
callback	[optional] a reference to a subroutine, which will be called with parameters (number progress, string msg, callback_data)
callback_data	[optional]

Code:

---

The documentation for this class was generated from the following file:

• all.pm