Geoinformatica: Geo::Vector Class Reference

scalar Geo::Vector::add	(	scalar	other,
		hash	params
	)

Add features from the other layer to this layer.

Parameters:

	other	A Geo::Vector object
	params	Named parameters, used for creating the new object, if one is created, and for iterating through the features of other.

Returns:: (If used in non-void context) A new Geo::Vector object, which contain features from both this and from the other.

void Geo::Vector::add_feature ( hash feature )

Adds a feature to the layer.

Parameters:

feature

As in make_feature.

scalar Geo::Vector::buffer ( hash params )

Create a new Geo::Vector object, whose features are buffer areas to the original.

Deprecated:

Parameters:

[in]

params

Named parameters: (see also the named parameters of Geo::Vector::new).

distance => float (default is 1.0). The width of the buffer.
quad_segs => int (default is 30). The number of segments used to approximate a 90 degree (quadrant) of curvature.
copy_attributes => true/false (default is false).
driver default is 'Memory'.
layer default is 'buffer'.

Returns:: The new Geo::Vector object.

Geo::Vector Geo::Vector::copy ( hash params )

Copy selected or all features from the layer into a new layer.

Parameters:

[in] params is a list of named parameters. They are forwarded to constructor (new) and init_iterate. If no value is given the defaults are taken from this layer.

Returns:: A Geo::Vector object.

Geo::OGR::FeatureDefn Geo::Vector::defn ( )

Create a FeatureDefn object, which is needed to create feature objects for this layer.

Returns:: a Geo::OGR::FeatureDefn object.

void Geo::Vector::delete_layer	(	scalar	driver,
		scalar	data_source,
		scalar	layer
	)

Attempts to delete a layer from a datasource.

Parameters:

`[in]`	driver
`[in]`	data_source
`[in]`	layer	Name of the layer that should be deleted.

Geo::Vector::driver ( )

The driver of the object.

Returns:: The name of the OGR driver as a string. Returns 'Memory' if the object is not an OGR layer.

Geo::Vector::dump ( hash parameters )

Print the contents of the layer.

hashref Geo::Vector::feature	(	scalar	fid,
		scalar	feature
	)

Get, add or update a feature.

Example of retrieving:

$feature = $vector->feature($i);

Example of updating:

$vector->feature($i, $feature);

Example of adding:

 $vector->feature($feature);

Parameters:

`[in]`	fid	The FID of the feature if updating
`[in]`	feature	Geo::OGR::Feature object to add or to update.

Returns:: an Geo::OGR::Feature object

Exceptions:

The

fid is higher than the feature count.

scalar Geo::Vector::feature_count ( )

Count the number of features in the layer.

Todo:: Add $force parameter.

Returns:: The number of features in the layer. The valued may be approximate.

listref Geo::Vector::features ( hash params )

Returns features satisfying the given requirement.

Parameters:

[in]

params

is a list named parameters

that_contain => an Geo::OGR::Geometry. The returned features are such that the geometry is within them. If the geometry is a multigeometry, then the features that have at least one of the geometries within.
that_are_within => an Geo::OGR::Geometry. The returned features are those that are within the geometry. If the geometry is a multigeometry, then the features are within at least one of the geometries.
that_intersect => Geo::OGR::Geometry object. The returned features are those that intersect with the geometry. If the geometry is a multigeometry, then the features intersect with at least one of the geometries.
filter
filter_rect
with_id => Reference to an array of feature indexes (fids).
from => If defined, the number of features that are skipped + 1.
limit => If defined, maximum number of features returned.

Returns:: A reference to an array of features.

scalar Geo::Vector::field_count ( hash params )

For a layer object returns the number of fields in the layer schema. For a feature set object requires a named parameter that specifies the feature.

Deprecated:

Each feature in a feature set object may have its own schema.

Returns:: For a layer object returns the number of fields in the layer schema. For a feature set object requires a named parameter that specifies the feature.

Geo::OGR::Geometry Geo::Vector::geometry	(	scalar	fid,
		scalar	geometry
	)

Get, set or add a geometry.

Parameters:

	$fid	(optional) The feature id, whose geometry to set or get.
	$geometry	(optional) The geometry, which to set or add.

Returns:: A geometry object.

scalar Geo::Vector::geometry_type ( hash params )

For a layer object returns the geometry type of the layer. For a feature set object requires a named parameter that specifies the feature.

Parameters:

[in]

params

Named parameters:

flatten => true/false. Default is false.
feature => integer. Index of the feature whose geometry type is queried.

Returns:: For a layer object returns the geometry type of the layer. For a feature set object returns specified features geometry type.

list Geo::Vector::geometry_types ( )

Returns a list of valid geometry types.

Returns:: a list of valid geometry types (as strings).

Geo::Vector::get_next ( )

Geo::Vector::init_iterate ( hash options )

Reset reading features from the object iteratively.

Parameters:

options

Named parameters, all are optional.

selected_features => reference to a list of features, which to iterate through.
filter => a spatial filter
filter_rect => reference to an array defining a spatial rectangle filter (min_x, min_y, max_x, max_y)

Todo:: filter for feature collections

ref hash Geo::Vector::layers	(	scalar	driver,
		scalar	data_source
	)

Lists the layers that are available in a data source.

Returns:: A hashref to a (layer_name => geometry_type) hash.

Geo::OGR::Feature Geo::Vector::make_feature ( hash feature )

Creates a Geo::OGR::Feature object from attribute data and a Geo::OGC::Geometry object.

Parameters:

[in] feature a hash whose keys are field names or 'geometry' and values are field values, or, for geometry, well-known text or an object which responds to AsText method by returning well-known text.

Returns:: Geo::OGR::Feature object.

Note:: If the parameter is already a Geo::OGR::Feature object nothing is done to the feature.

retval Geo::Vector::MAX ( )

retval Geo::Vector::MIN ( )

Geo::Vector Geo::Vector::new ( hash params )

Create a new Geo::Vector object.

A Geo::Vector object is either a wrapped Geo::OGR::Layer or a collection of Geo::OGR::Feature objects. Without any parameters an empty OGR memory layer without any attributes is created. A feature collection object does not have a unique schema.

Parameters:

params

Named parameters, all are optional: (see also the named parameters of the Geo::Vector::layer method)

driver => string Name of the OGR driver for creating or opening a data source. If not given, an attempt is made to open the data source using the data source parameter.
create_options => reference to a hash of data source creation options. May be empty. Forwarded to Geo::OGR::CreateDataSource. Required to create other than memory data sources.
data_source => string OGR data source to create or open. Opening a data source is first attempted unless create_options is given. If open fails, creation is attempted.
open => string The layer to open.
update => boolean Set true if open in update mode.
layer => string [deprecated] Same as open.
create => string The layer to create.
layer_options forwarded to Geo::OGR::DataSource::CreateLayer.
SQL => string SQL-string, forwarded to Geo::OGR::DataSource::ExecuteSQL. An alternative to open and create.
geometry_type => string The geometry type for the new layer. Default is 'Unknown'.
schema, as in method Geo::Vector::schema.
encoding => string, the encoding of the attribute values of the features.
srs => either a string which defines a spatial reference system (e.g. 'EPSG:XXXX') or a Geo::OSR::SpatialReference object. The srs for the new layer. Default is 'EPSG:4326'.
features => a reference to a list of features to be inserted into the collection. May be empty. If given, the resulting object is a feature collection object, and not an OGR layer.
geometries => a reference to a list of geometries to be inserted as new features into the collection. Creates features without attributes for the geometries. May be empty. If given, the resulting object is a feature collection object, and not an OGR layer. Do not mix with features.

Returns:: A new Geo::Vector object

Geo::Vector Geo::Vector::new ( scalar data_source )

Create a new Geo::Vector object for the first layer in a given OGR data souce.

An example of creating a Geo::Vector object for a ESRI shapefile:

$v = Geo::Vector->new("borders.shp");

Parameters:

data_source

An OGR data source string

Returns:: A new Geo::Vector object

Geo::Vector::next_feature ( )

Return a feature iteratively or undef if no more features.

void Geo::Vector::overlay_graph ( Gtk2::Gdk::Pixmap pixmap )

Creates from the objects graph an overlay graph (incl. vertices and edges) as a pixmap.

Parameters:

[in,out] pixmap Gtk2::Gdk::Pixmap

Geo::Raster Geo::Vector::rasterize ( hash params )

Creates a new Geo::Raster from this Geo::Vector object.

The new Geo::Raster has the size and extent of the Geo::Raster $this and draws the layer on it. The raster is boolean integer raster unless value_field is given. If value_field is floating point value, the returned raster is a floating point raster. render_as hash is optional, but if given should be one of 'Native', 'Points', 'Lines', or 'Polygons'. $fid (optional) is the number of the feature to render.

Parameters:

[in]

params

is a list of named parameters:

like (optional). A Geo::Raster object, from which the resulting Geo::Raster object's size and extent are copied.
M (optional). Height of the resulting Geo::Raster object. Has to be given if hash like is not given. If like is given, then M will not be used.
N (optional). Width of the resulting Geo::Raster object. Has to be given if hash like is not given. If like is given, then N will not be used.
world (optional). The world (bounding box) of the resulting raster layer. Useless to give if parameter like is given, because then it's world will be used.
render_as (optional). Rendering mode, which should be 'Native', 'Points', 'Lines' or 'Polygons'.
feature (optional). Number of the feature to render.
value_field (optional). Value fields name.

Returns:: A new Geo::Raster, which has the size and extent of the given as

Todo:: make this work for schema free layers parameters and values

list Geo::Vector::render_as_modes ( )

Returns a list of valid render as modes.

Returns:: a list of valid render as modes (as strings).

hashref Geo::Vector::schema	(	scalar	feature,
		hashref	schema
	)

Get or set the schema of a feature in a feature collection.

Parameters:

`[in]`	feature	the index of the feature, whose schema to get or set.
`[in]`	schema	(optional) a reference to a hash specifying the schema.

Returns:: the schema.

hashref Geo::Vector::schema ( hashref schema )

Get or set the schema of the layer.

Schema is a hash whose keyes are GeometryType, FID, and Fields. Fields is a reference to a list of field schemas. A field schema is a hash whose keys are Name, Type, Justify, Width, and Precision. This is similar to schemas in Geo::OGR.

Parameters:

[in] schema (optional) a reference to a hash specifying the schema.

Returns:: the schema.

Geo::OSR::SpatialReference Geo::Vector::srs ( hash params )

Get or set (set is not yet implemented) the spatial reference system of the layer.

SRS (Spatial reference system) is a geographic coordinate system code number in the EPSG database (European Petroleum Survey Group, http://www.epsg.org/). Default value is 4326, which is for WGS84.

Parameters:

[in]

params

(optional) Named parameters:

format => string. Name of the wanted return format, like 'Wkt'. Wkt is for Well-known text and is defined by the The OpenGIS Consortium specification for the exchange (and easy persistance) of geometry data in ASCII format.

Returns:: Returns the current spatial reference system of the layer as a Geo::OSR::SpatialReference or wkt string.

list Geo::Vector::value_range ( scalar field_name )

Returns a list of the value range of the field.

Parameters:

[in] field_name The name of the field, whose min and max values are looked up.

Returns:: An array that has as it's first value the ranges minimum and as second the maximum -- array(min, max).

list Geo::Vector::value_range ( hash params )

Returns a list of the value range of the field.

Parameters:

[in]

params

Named parameters:

field_name => string. The attribute whose min and max values are looked up.
filter => reference to a Geo::OGR::Geometry (optional). Used by Geo::OGR::SetSpatialFilter() if the layer is an OGR layer.
filter_rect => reference to an array defining the rect (min_x, min_y, max_x, max_y) (optional). Used by the Geo::OGR::SetSpatialFilterRect() if the layer is an OGR layer.

Returns:: An array that has as it's first value the ranges minimum and as second the maximum -- array(min, max).

scalar Geo::Vector::within	(	scalar	other,
		hash	params
	)

Return the features from this layer that are within the features of other.

Deprecated:

Todo:: Add some optimizations.

Returns:: A new Geo::Vector object

list Geo::Vector::world ( hash params )

Get the bounding box (xmin, ymin, xmax, ymax) of the layer or one of its features.

The method uses Geo::OGR::Geometry::GetEnvelope() or Geo::OGR::Layer::GetExtent().

Example of getting a bounding box:

@bb = $vector->world(feature=><feature_index>);

Parameters:

[in]

params

is a list of named parameters:

feature => feature_index (optional).

Returns:: Returns the bounding box (minX, minY, maxX, maxY) as an array. If a single feature is defined with it's index as parameter, then the method returns that feature's bounding box, else the whole layer's bounding box.

Geo::Vector Class Reference

Public Class Methods

Public Object Methods

Public Functions

Classes

Detailed Description

Member Function Documentation


Public Class Methods
list	geometry_types ()
	Returns a list of valid geometry types.
list	render_as_modes ()
	Returns a list of valid render as modes.
ref hash	layers (scalar driver, scalar data_source)
	Lists the layers that are available in a data source.
void	delete_layer (scalar driver, scalar data_source, scalar layer)
	Attempts to delete a layer from a datasource.
Geo::Vector	new (scalar data_source)
	Create a new Geo::Vector object for the first layer in a given OGR data souce.
Geo::Vector	new (hash params)
	Create a new Geo::Vector object.
Public Object Methods
	driver ()
	The driver of the object.
	dump (hash parameters)
	Print the contents of the layer.
	init_iterate (hash options)
	Reset reading features from the object iteratively.
	next_feature ()
	Return a feature iteratively or undef if no more features.
	get_next ()
scalar	buffer (hash params)
	Create a new Geo::Vector object, whose features are buffer areas to the original.
scalar	within (scalar other, hash params)
	Return the features from this layer that are within the features of other.
scalar	add (scalar other, hash params)
	Add features from the other layer to this layer.
scalar	feature_count ()
	Count the number of features in the layer.
Geo::OSR::SpatialReference	srs (hash params)
	Get or set (set is not yet implemented) the spatial reference system of the layer.
scalar	field_count (hash params)
	For a layer object returns the number of fields in the layer schema. For a feature set object requires a named parameter that specifies the feature.
scalar	geometry_type (hash params)
	For a layer object returns the geometry type of the layer. For a feature set object requires a named parameter that specifies the feature.
hashref	schema (hashref schema)
	Get or set the schema of the layer.
hashref	schema (scalar feature, hashref schema)
	Get or set the schema of a feature in a feature collection.
Geo::OGR::FeatureDefn	defn ()
	Create a FeatureDefn object, which is needed to create feature objects for this layer.
list	value_range (hash params)
	Returns a list of the value range of the field.
list	value_range (scalar field_name)
	Returns a list of the value range of the field.
hashref	feature (scalar fid, scalar feature)
	Get, add or update a feature.
Geo::OGR::Geometry	geometry (scalar fid, scalar geometry)
	Get, set or add a geometry.
Geo::OGR::Feature	make_feature (hash feature)
	Creates a Geo::OGR::Feature object from attribute data and a Geo::OGC::Geometry object.
void	add_feature (hash feature)
	Adds a feature to the layer.
listref	features (hash params)
	Returns features satisfying the given requirement.
list	world (hash params)
	Get the bounding box (xmin, ymin, xmax, ymax) of the layer or one of its features.
Geo::Vector	copy (hash params)
	Copy selected or all features from the layer into a new layer.
Geo::Raster	rasterize (hash params)
	Creates a new Geo::Raster from this Geo::Vector object.
void	overlay_graph (Gtk2::Gdk::Pixmap pixmap)
	Creates from the objects graph an overlay graph (incl. vertices and edges) as a pixmap.
Public Functions
retval	MIN ()
retval	MAX ()
Classes
class	Feature
class	Layer
class	Layer
class	Layer
class	Layer
class	Layer
class	Layer
class	Layer
class	Layer
class	Layer
class	Layer