Geo::OGR::Layer Class Reference

Inheritance diagram for Geo::OGR::Layer:

List of all members.

Public Class Methods
list	Capabilities ()
Public Object Methods
scalar	TestCapability (scalar cap)
Geo::OGR::DataSource	DataSource ()
hash	GetField (scalar field_name)
	CreateField (hash parameters)
	CreateField (scalar field_definition, scalar approximation_ok)
	AlterField (scalar field_name, hash new_definition)
	AlterFieldDefn (scalar field, scalar definition, scalar flags)
	DeleteField (scalar field)
hashref	Schema (hash schema)
hashref	Row (hash row)
list	Tuple (list tuple)
Geo::OGR::Geometry	SpatialFilter (scalar filter)
Geo::OGR::Geometry	SpatialFilter (list filter)
	SetSpatialFilter (scalar filter)
	SetSpatialFilterRect (scalar minx, scalar miny, scalar maxx, scalar maxy)
Geo::OGR::Geometry	GetSpatialFilter ()
	SetAttributeFilter (scalar filter_string)
	ResetReading ()
Geo::OGR::Feature	GetNextFeature ()
	SetNextByIndex (scalar new_index)
scalar	GetFeaturesRead ()
	ForFeatures (scalar code, scalar in_place)
	ForGeometries (scalar code, scalar in_place)
scalar	GetName ()
Geo::OGR::Feature	GetFeature (scalar fid)
	SetFeature (scalar feature)
	CreateFeature (scalar feature)
	InsertFeature (scalar feature)
	DeleteFeature (scalar fid)
	SyncToDisk ()
Geo::OGR::FeatureDefn	GetLayerDefn ()
scalar	GetFeatureCount (scalar force=1)
list	GetExtent (scalar force=1)
	StartTransaction ()
	CommitTransaction ()
	RollbackTransaction ()
Geo::OSR::SpatialReference	GetSpatialRef ()
scalar	GetFIDColumn ()
scalar	GetGeometryColumn ()
scalar	GeometryType ()
	SetIgnoredFields (list fields)
Public Attributes
list	CAPABILITIES

---

Member Function Documentation

Geo::OGR::Layer::AlterField	(	scalar	field_name,
		hash	new_definition
	)

Parameters:

field_name	the name (or index) of the field to be altered
new_definition	one or more of Name, Type, and Width

Geo::OGR::Layer::AlterFieldDefn	(	scalar	field,
		scalar	definition,
		scalar	flags
	)

Deprecated:

use AlterField(scalar name, hash parameters) Alter the definition of an existing field on a layer.

Parameters:

field	index of the field whose definition is altered
definition	a Geo::OGR::FieldDefn object
flags	1 to alter the name, 2 to alter the type, 4 to alter the width, use combinations 3, 5, 6 or 7 to alter two or more properties

list Geo::OGR::Layer::Capabilities

(

)

Examples:

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

Returns:

a list of capabilities. The class method returns a list of all potential capabilities a layer may have. The object method returns a list of all capabilities the layer has.

Geo::OGR::Layer::CommitTransaction

(

)

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

Geo::OGR::Layer::CreateField

(

hash

parameters

)

Parameters:

parameters

named parameters: Name, Type, Justify, Width, Precision

Geo::OGR::Layer::CreateField	(	scalar	field_definition,
		scalar	approximation_ok
	)

Deprecated:

use CreateField(hash parameters)

Parameters:

field_definition	a Geo::OGR::FieldDefn object
approximation_ok	may the field be created in a slightly different form depending on the limitations of the format driver.

Geo::OGR::DataSource Geo::OGR::Layer::DataSource

(

)

Returns:

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

Geo::OGR::Layer::DeleteFeature

(

scalar

fid

)

Parameters:

fid	feature id

Geo::OGR::Layer::DeleteField

(

scalar

field

)

Delete an existing field from a layer.

Parameters:

field

name (or index) of the field which is deleted

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

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

scalar Geo::OGR::Layer::GeometryType

(

)

Returns:

the geometry type of the layer, one of @Geo::OGR::Geometry::GEOMETRY_TYPES

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)

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

(

scalar

fid

)

Parameters:

fid	feature id

Returns:

a new Geo::OGR::Feature object

scalar Geo::OGR::Layer::GetFeatureCount

(

scalar

force = 1

)

Parameters:

force

Returns:

integer

scalar Geo::OGR::Layer::GetFeaturesRead

(

)

Returns:

integer

scalar Geo::OGR::Layer::GetFIDColumn

(

)

Returns:

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

hash Geo::OGR::Layer::GetField

(

scalar

field_name

)

Parameters:

field_name

the name (or index) of the field

Returns:

the schema of the field in a hash (in list context) or in an anonymous hash

scalar Geo::OGR::Layer::GetGeometryColumn

(

)

Returns:

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

Geo::OGR::FeatureDefn Geo::OGR::Layer::GetLayerDefn

(

)

Deprecated:

use Geo::OGR::Layer::Schema, which returns a Perl structure

Returns:

a new Geo::OGR::FeatureDefn object

scalar Geo::OGR::Layer::GetName

(

)

Returns:

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.

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

(

)

Returns:

a new Geo::OGR::Geometry object

Geo::OSR::SpatialReference Geo::OGR::Layer::GetSpatialRef

(

)

Returns:

a new Geo::OSR::SpatialReference object

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)

Geo::OGR::Layer::ResetReading

(

)

Initialize the layer object for iterative reading.

Geo::OGR::Layer::RollbackTransaction

(

)

hashref 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

hashref Geo::OGR::Layer::Schema

(

hash

schema

)

Get and/or set the schema of the layer.

Parameters:

schema

The schema hash may contain the keys: Fields A reference to a list of field definitions (either Geo::OGR::FieldDefn objects or hashrefs from which they can be created). ApproxOK (optional) A flag specifying whether it is ok to change the requested field definition to accommodate limitations of the layer.

Returns:

a reference to a schema hash, which has keys:

• Name The name of this layer.
• GeometryType The type of the geometries in this layer (a string).
• Fields An array of references to hashes of field definitions.

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.

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

Geo::OGR::Layer::SetIgnoredFields

(

list

fields

)

Parameters:

fields

a list of field names

Geo::OGR::Layer::SetNextByIndex

(

scalar

new_index

)

Parameters:

new_index

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

Geo::OGR::Layer::SetSpatialFilter

(

scalar

filter

)

Parameters:

filter

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

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

Parameters:

minx
miny
maxx
maxy

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

(

scalar

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

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

(

list

filter

)

Parameters:

filter

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

Returns:

a new Geo::OGR::Geometry object

Geo::OGR::Layer::StartTransaction

(

)

Geo::OGR::Layer::SyncToDisk

(

)

scalar Geo::OGR::Layer::TestCapability

(

scalar

cap

)

Parameters:

cap	A capability string.

Returns:

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

list Geo::OGR::Layer::Tuple

(

list

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 order of the data in the tuple is: feature id, Geometry, fields in their order. 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

---

Member Data Documentation

list Geo::OGR::Layer::CAPABILITIES

Layer capabilities known to GDAL

---

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

• lib/Geo/OGR.pm