galileo.bmp

Class GeoavailabilityGrid

java.lang.Object

galileo.bmp.GeoavailabilityGrid

public class GeoavailabilityGrid
extends java.lang.Object

Implements a bitmap-based spatial index that can be used to determine whether or not data is stored within specified spatial regions.

Author:

malensek

Field Summary

Fields

Modifier and Type	Field and Description
Bitmap	bmp

Constructor Summary

Constructors

Constructor and Description
GeoavailabilityGrid(java.lang.String baseGeohash, int precision)

Method Summary

Modifier and Type	Method and Description
boolean	addPoint(Coordinates coords) Adds a new point to this GeoavailabilityGrid.
Point<java.lang.Integer>	coordinatesToXY(Coordinates coords) Converts a coordinate pair (defined with latitude, longitude in decimal degrees) to an x, y location in the grid.
boolean	equals(java.lang.Object obj)
SpatialRange	getBaseRange() Retrieves the base SpatialRange that this GeoavailabilityGrid is responsible for; the base range defines the geographic scope of this GeoavailabilityGrid instance.
protected Bitmap	getBitmap() Retrieves the underlying Bitmap instance backing this GeoavailabilityGrid.
int	getHeight() Retrieves the height of this GeoavailabilityGrid, in grid cells.
int	getWidth() Retrieves the width of this GeoavailabilityGrid, in grid cells.
int	hashCode()
SpatialRange	indexToSpatialRange(int index) Converts a bitmap index location to a corresponding SpatialRange that the indexed grid point spans.
Point<java.lang.Integer>	indexToXY(int index) Converts a bitmap index to X, Y coordinates in the grid.
boolean	intersects(GeoavailabilityQuery query) Reports whether or not the supplied GeoavailabilityQuery instance intersects with the bits set in this geoavailability grid.
int[]	query(GeoavailabilityQuery query) Queries the geoavailability grid, which involves performing a logical AND operation and reporting the resulting Bitmap.
int	XYtoIndex(int x, int y) Converts X, Y coordinates to a particular index within the underlying bitmap implementation.
SpatialRange	XYtoSpatialRange(int x, int y) Converts an X, Y grid point to the corresponding SpatialRange that the grid point spans.

Methods inherited from class java.lang.Object

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

Field Detail

bmp

public Bitmap bmp

Constructor Detail

GeoavailabilityGrid

public GeoavailabilityGrid(java.lang.String baseGeohash,
                           int precision)

Method Detail

addPoint

public boolean addPoint(Coordinates coords)

Adds a new point to this GeoavailabilityGrid.

Parameters:

coords - The location (coordinates in lat, lon) to add.

Returns:

true if the point could be added to grid, false otherwise (for example, if the point falls outside the purview of the grid)

coordinatesToXY

public Point<java.lang.Integer> coordinatesToXY(Coordinates coords)

Converts a coordinate pair (defined with latitude, longitude in decimal degrees) to an x, y location in the grid.

Parameters:

coords - the Coordinates to convert.

Returns:

Corresponding x, y location in the grid.

XYtoIndex

public int XYtoIndex(int x,
                     int y)

Converts X, Y coordinates to a particular index within the underlying bitmap implementation. Essentially this converts a 2D index to a 1D index.

Parameters:

x - The x coordinate to convert

y - The y coorddinate to convert

Returns:

A single integer representing the bitmap location of the X, Y coordinates.

indexToXY

public Point<java.lang.Integer> indexToXY(int index)

Converts a bitmap index to X, Y coordinates in the grid.

XYtoSpatialRange

public SpatialRange XYtoSpatialRange(int x,
                                     int y)

Converts an X, Y grid point to the corresponding SpatialRange that the grid point spans.

indexToSpatialRange

public SpatialRange indexToSpatialRange(int index)

Converts a bitmap index location to a corresponding SpatialRange that the indexed grid point spans.

intersects

public boolean intersects(GeoavailabilityQuery query)
                   throws BitmapException

Reports whether or not the supplied GeoavailabilityQuery instance intersects with the bits set in this geoavailability grid. This operation can be much faster than performing a full inspection of what bits are actually set.

Parameters:

query - The query geometry to test for intersection.

Returns:

true if the supplied GeoavailabilityQuery intersects with the data in the geoavailability grid.

Throws:

BitmapException

query

public int[] query(GeoavailabilityQuery query)
            throws BitmapException

Queries the geoavailability grid, which involves performing a logical AND operation and reporting the resulting Bitmap.

Parameters:

query - The query geometry to evaluate against the geoavailability grid.

Returns:

An array of bitmap indices that matched the query.

Throws:

BitmapException

getBitmap

protected Bitmap getBitmap()

Retrieves the underlying Bitmap instance backing this GeoavailabilityGrid.

getWidth

public int getWidth()

Retrieves the width of this GeoavailabilityGrid, in grid cells.

getHeight

public int getHeight()

Retrieves the height of this GeoavailabilityGrid, in grid cells.

getBaseRange

public SpatialRange getBaseRange()

Retrieves the base SpatialRange that this GeoavailabilityGrid is responsible for; the base range defines the geographic scope of this GeoavailabilityGrid instance.

Returns:

SpatialRange representing this GeoavailabilityGrid's scope.

hashCode

public int hashCode()

Overrides:

hashCode in class java.lang.Object

equals

public boolean equals(java.lang.Object obj)

Overrides:

equals in class java.lang.Object