Package org.geotools.vectortiles.store

Class VectorTilesFeatureSource

Object

ContentFeatureSource

VectorTilesFeatureSource

All Implemented Interfaces:

FeatureSource<SimpleFeatureType,SimpleFeature>, SimpleFeatureSource

public class VectorTilesFeatureSource
extends ContentFeatureSource

Feature source for a single vector layer in a tiled vector dataset.

This class provides GeoTools feature access to a single vector layer from a tile archive. It handles the complexity of:

• Converting between GeoTools queries and tile-based queries
• Automatic zoom level selection based on query resolution hints
• Spatial filtering and bounding box optimization
• Coordinate reference system transformation
• Feature attribute filtering and property selection
• Pagination (offset/limit support)

Query Optimization:

• Zoom Level Selection: Automatically selects the best zoom level based on Hints.GEOMETRY_DISTANCE, Hints.GEOMETRY_SIMPLIFICATION, or Hints.GEOMETRY_GENERALIZATION hints
• Spatial Filtering: Extracts bounding boxes from query filters to minimize tile reads
• CRS Transformation: Efficiently transforms geometries using affine transformations where possible
• Pre-filtering: Applies filters at the vector tile level before converting to GeoTools features

Supported Operations:

• canFilter(Query) - Full filter support including spatial and attribute filters
• canReproject() - Automatic CRS transformation
• canRetype(Query) - Property selection and schema subsetting
• canOffset(Query) and canLimit(Query) - Pagination support
• canSort(Query) - Natural order only (tile order)

Feature Type Schema: The schema is automatically derived from the vector layer metadata (TileJSON), with field types mapped from TileJSON types (String, Number, Boolean) to Java types.

See Also:

• VectorTilesDataStore
• VectorTilesFeatureReader
• VectorTileStore

Field Summary

Fields

Modifier and Type	Field	Description
protected final VectorLayer	layerMetadata	TileJSON layer metadata

Fields inherited from class ContentFeatureSource

entry, hints, lock, query, queryCapabilities, schema, transaction

Constructor Summary

Constructors

Constructor	Description
VectorTilesFeatureSource(ContentEntry entry, VectorLayer layerMetadata)	Creates a new feature source for a vector layer.

Method Summary

Modifier and Type	Method	Description
protected void	addHints(Set<Hints.Key> hints)	Adds rendering hints supported by this feature source.
protected SimpleFeatureType	buildFeatureType()	Creates the feature type or schema for the feature source.
protected boolean	canFilter(Query query)	Determines if the datastore can natively perform a filtering.
protected boolean	canLimit(Query query)	Determines if the datastore can natively limit the number of features returned in a query.
protected boolean	canOffset(Query query)	Determines if the datastore can natively skip the first offset number of features returned in a query.
protected boolean	canReproject()	Determines if the datastore can natively perform reprojection.
protected boolean	canRetype(Query query)	Determines if the datastore can natively perform "retyping" which includes limiting the number of attributes returned and reordering of those attributes
protected boolean	canSort(Query query)	Determines if the datastore can natively perform sorting.
protected String	dedupGeometryName(Set<String> attributeNames)
protected int	determineZoomLevel(Query query)	Determines the optimal zoom level for a query based on resolution hints and layer constraints.
protected Class<?>	fieldTypeToBinding(String fieldType)
protected MathTransform	findMathTransform(Query query)
protected ReferencedEnvelope	getBoundsInternal()
protected ReferencedEnvelope	getBoundsInternal(Query query)	Calculates the bounds of a specified query.
protected int	getCountInternal(Query query)	Calculates the number of features of a specified query.
VectorTilesDataStore	getDataStore()	The datastore that this feature source originated from.
protected TileMatrixSet	getMatrixSet()	Returns the tile matrix set for this vector layer.
protected CoordinateReferenceSystem	getQueryCRS(Query query)
protected FeatureReader<SimpleFeatureType,SimpleFeature>	getReaderInternal(Query query)	Subclass method for returning a native reader from the datastore.
protected VectorTileStore	getTileStore()
protected SimpleFeatureType	retype(Query query)
protected CoordinateReferenceSystem	tileMatrixsetCRS()

Methods inherited from class ContentFeatureSource

accepts, addFeatureListener, buildQueryCapabilities, canEvent, canFilter, canLimit, canLock, canOffset, canRetype, canSort, canTransact, doLockInternal, doUnlockInternal, getAbsoluteSchema, getBounds, getBounds, getCount, getEntry, getFeatures, getFeatures, getFeatures, getInfo, getName, getQueryCapabilities, getReader, getReader, getReader, getSchema, getState, getSupportedHints, getTransaction, getView, getView, handleVisitor, isView, joinQuery, lockFeatures, lockFeatures, lockFeatures, processLock, removeFeatureListener, resolvePropertyNames, resolvePropertyNames, setFeatureLock, setTransaction, unLockFeatures, unLockFeatures, unLockFeatures

Methods inherited from class Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Details

layerMetadata

protected final VectorLayer layerMetadata

TileJSON layer metadata

Constructor Details

VectorTilesFeatureSource

public VectorTilesFeatureSource(ContentEntry entry,
 VectorLayer layerMetadata)

Creates a new feature source for a vector layer.

Parameters:

entry - the content entry for this feature type

layerMetadata - the TileJSON metadata for this vector layer

Method Details

canRetype

protected boolean canRetype(Query query)

Description copied from class: ContentFeatureSource

Determines if the datastore can natively perform "retyping" which includes limiting the number of attributes returned and reordering of those attributes

If the subclass can handle retyping natively it should override this method to return true. In this case it must do the retyping or throw an exception.

Not overriding this method or returning false will cause the feature reader created by the subclass to be wrapped in a retyping feature reader when the query specifies a retype.

Overrides:

canRetype in class ContentFeatureSource

Returns:

true

See Also:

• ContentFeatureSource.canRetype()

canReproject

protected boolean canReproject()

Description copied from class: ContentFeatureSource

Determines if the datastore can natively perform reprojection.

If the subclass can handle reprojection natively then it should override this method to return true . In this case it must do the reprojection or throw an exception.

Not overriding this method or returning false will case the feature reader created by the subclass to be wrapped in a reprojecting decorator when the query specifies a coordinate system reproject (using crs and crsReproject)

To handle reprojection an implementation should:

• Query.getCoordinateSystem() - optional override - if provided this is used instead of the native CRS provided by the data format (as a workaround for clients).
• <@link Query.getCoordinateSystemReproject() - if this value is provided it is used to set up a transform from the origional CRS (native or from query).

Overrides:

canReproject in class ContentFeatureSource

Returns:

true

See Also:

• ContentFeatureSource.canReproject()
• reprojectFunction(Query)

canFilter

protected boolean canFilter(Query query)

Description copied from class: ContentFeatureSource

Determines if the datastore can natively perform a filtering.

If the subclass can handle filtering natively it should override this method to return true. In this case it must do the filtering or throw an exception. This includes the case of partial native filtering where the datastore can only handle part of the filter natively. In these cases it is up to the subclass to apply a decorator to the reader it returns which will handle any part of the filter can was not applied natively. See FilteringFeatureReader.

Not overriding this method or returning false will cause the feature reader created by the subclass to be wrapped in a filtering feature reader when the query specifies a filter. See FilteringFeatureReader.

Overrides:

canFilter in class ContentFeatureSource

Returns:

true

See Also:

• ContentFeatureSource.canFilter()
• preFilter(Query)
• postFilter(Query)

canOffset

protected boolean canOffset(Query query)

Description copied from class: ContentFeatureSource

Determines if the datastore can natively skip the first offset number of features returned in a query.

If the subclass can handle a map feature cap natively then it should override this method to return true . In this case it must do the cap or throw an exception.

Not overriding this method or returning false will case the feature reader created by the subclass to be accessed offset times before being returned to the caller.

Overrides:

canOffset in class ContentFeatureSource

Returns:

true

See Also:

• ContentFeatureSource.canOffset()

canLimit

protected boolean canLimit(Query query)

Description copied from class: ContentFeatureSource

Determines if the datastore can natively limit the number of features returned in a query.

If the subclass can handle a map feature cap natively then it should override this method to return true . In this case it must do the cap or throw an exception.

Not overriding this method or returning false will case the feature reader created by the subclass to be wrapped in a max feature capping decorator when the query specifies a max feature cap.

Overrides:

canLimit in class ContentFeatureSource

Returns:

true

See Also:

• ContentFeatureSource.canLimit()

canSort

protected boolean canSort(Query query)

Description copied from class: ContentFeatureSource

Determines if the datastore can natively perform sorting.

If the subclass can handle retyping natively it should override this method to return true. In this case it must do the retyping or throw an exception.

Not overriding this method or returning false will cause an exception to be thrown when the query specifies sorting.

Overrides:

canSort in class ContentFeatureSource

Returns:

true for natural order, false otherwise

See Also:

• ContentFeatureSource.canSort()

getDataStore

public VectorTilesDataStore getDataStore()

Description copied from class: ContentFeatureSource

The datastore that this feature source originated from.

Subclasses may wish to extend this method in order to type narrow its return type.

Specified by:

getDataStore in interface FeatureSource<SimpleFeatureType,SimpleFeature>

Overrides:

getDataStore in class ContentFeatureSource

Returns:

the data source providing this FeatureSource

getTileStore

protected VectorTileStore getTileStore()

getMatrixSet

protected TileMatrixSet getMatrixSet()

Returns the tile matrix set for this vector layer.

Returns:

the tile matrix set defining the tiling scheme

addHints

protected void addHints(Set<Hints.Key> hints)

Adds rendering hints supported by this feature source.

Supported hints include:

• Hints.FEATURE_DETACHED - Features can be safely modified
• Hints.JTS_GEOMETRY_FACTORY - Custom geometry factory
• Hints.JTS_COORDINATE_SEQUENCE_FACTORY - Custom coordinate sequence factory
• Hints.GEOMETRY_GENERALIZATION - Topology-preserving simplification distance
• Hints.GEOMETRY_SIMPLIFICATION - Non-topology-preserving simplification distance
• Hints.GEOMETRY_DISTANCE - Target resolution for zoom level selection
• Hints.GEOMETRY_CLIP - Tile clip mask for rendering (this is an "output" hint, added to each returned Property.getUserData() map. See VectorTilesFeatureReader)

Overrides:

addHints in class ContentFeatureSource

Parameters:

hints - the set to add supported hints to

buildFeatureType

protected SimpleFeatureType buildFeatureType()
                                      throws IOException

Description copied from class: ContentFeatureSource

Creates the feature type or schema for the feature source.

Implementations should use SimpleFeatureTypeBuilder to build the feature type. Also, the builder should be injected with the feature factory which has been set on the DataStore (see ContentDataStore.getFeatureFactory(). Example:

   SimpleFeatureTypeBuilder b = new SimpleFeatureTypeBuilder();
   b.setFeatureTypeFactory( getDataStore().getFeatureTypeFactory() );

   //build the feature type
   ...
 

Specified by:

buildFeatureType in class ContentFeatureSource

Throws:

IOException

getCountInternal

protected int getCountInternal(Query query)
                        throws IOException

Description copied from class: ContentFeatureSource

Calculates the number of features of a specified query. Subclasses must implement this method. If the computation is not fast, it's possible to return -1.

Specified by:

getCountInternal in class ContentFeatureSource

Returns:

-1, too complex to calculate, tiles have different number of features at different zoom levels

Throws:

IOException

getBoundsInternal

protected ReferencedEnvelope getBoundsInternal(Query query)
                                        throws IOException

Description copied from class: ContentFeatureSource

Calculates the bounds of a specified query. Subclasses must implement this method. If the computation is not fast, subclasses can return null.

Specified by:

getBoundsInternal in class ContentFeatureSource

Throws:

IOException

getBoundsInternal

protected ReferencedEnvelope getBoundsInternal()

getReaderInternal

protected FeatureReader<SimpleFeatureType,SimpleFeature> getReaderInternal(Query query)
                                                                    throws IOException

Description copied from class: ContentFeatureSource

Subclass method for returning a native reader from the datastore.

It is important to note that if the native reader intends to handle any of the following natively:

• reprojection
• filtering
• max feature limiting
• sorting
• locking
• transactions

Then it *must* set the corresponding flags to true:

• ContentFeatureSource.canReproject() - handles Query.getCoordinateSystemReproject() internally. Example would be PostGIS using Proj to handle reproejction internally
• ContentFeatureSource.canFilter(Query) - handles internally.</li> <li>{@link #canLimit(Query)} - handles {@link Query#getMaxFeatures()} and {@link Query#getStartIndex()} internally.</li> <li>{@link #canSort(Query)} - handles {@link Query#getSortBy()} natively.</li> <li>{@link #canRetype(Query)} - handles {@link Query#getProperties()} natively. Example would be only parsing the properties the user asks for from an XML file</li> <li>{@link #canLock()} - handles read-locks natively</li> <li>{@link #canTransact()} - handles transactions natively</li> </ul> </p>

Specified by:

getReaderInternal in class ContentFeatureSource

Throws:

IOException

findMathTransform

protected MathTransform findMathTransform(Query query)

getQueryCRS

protected CoordinateReferenceSystem getQueryCRS(Query query)

retype

protected SimpleFeatureType retype(Query query)

tileMatrixsetCRS

protected CoordinateReferenceSystem tileMatrixsetCRS()
                                              throws IOException

Throws:

IOException

determineZoomLevel

protected int determineZoomLevel(Query query)

Determines the optimal zoom level for a query based on resolution hints and layer constraints.

This method selects the best zoom level by considering:

• Query resolution hints (Hints.GEOMETRY_DISTANCE, Hints.GEOMETRY_SIMPLIFICATION, Hints.GEOMETRY_GENERALIZATION)
• Layer-specific min/max zoom levels from VectorLayer.minZoom() and VectorLayer.maxZoom()
• Tile matrix set available zoom levels
• Query strategy (SPEED vs QUALITY)

For SPEED strategy (when simplification hints are present), starts from the minimum zoom level to favor performance. For QUALITY strategy (no simplification hints), starts from the layer's minimum zoom level to favor detail.

Parameters:

query - the query containing resolution hints

Returns:

the selected zoom level

fieldTypeToBinding

protected Class<?> fieldTypeToBinding(String fieldType)

dedupGeometryName

protected String dedupGeometryName(Set<String> attributeNames)