org.gridfour.gvrs

Interface ITilePositionIndex

public interface ITilePositionIndex

Method Summary

Modifier and Type	Method and Description
int	getCountOfPopulatedTiles() Gets the count of the number of tiles that are currently populated.
long	getFilePosition(int tileIndex) Gets the file position for the specified tile.
int	getStorageSize() Gets the amount of storage space required to store the tile index, in bytes.
boolean	isFilePositionSet(int tileIndex) Indicates whether a file position is set for the specified tile index.
void	readTilePositions(BufferedRandomAccessFile braf) Reads the tile position data from the specified file.
void	setFilePosition(int tileIndex, long offset) Store the specified offset at the position given by the tile row and column.
void	writeTilePositions(BufferedRandomAccessFile braf) Writes the tile position data from the specified file.

Method Detail

getFilePosition

long getFilePosition(int tileIndex)

Gets the file position for the specified tile.

Parameters:

tileIndex - a positive integer

Returns:

if found, a value greater than zero; otherwise, zero.

getStorageSize

int getStorageSize()

Gets the amount of storage space required to store the tile index, in bytes.

Returns:

a positive value, in bytes.

isFilePositionSet

boolean isFilePositionSet(int tileIndex)

Indicates whether a file position is set for the specified tile index.

Parameters:

tileIndex - a positive integer

Returns:

true if a valid file position is stored for a tile; otherwise, false

readTilePositions

void readTilePositions(BufferedRandomAccessFile braf)
                throws IOException

Reads the tile position data from the specified file.

Parameters:

braf - a valid file reference

Throws:

IOException - in the event of an unhandled I/O exception.

setFilePosition

void setFilePosition(int tileIndex,
                     long offset)

Store the specified offset at the position given by the tile row and column. If necessary, the index is resized to accommodate the specified coordinates.

File positions must be positive values and a multiple of eight.

Parameters:

tileIndex - the index of the tile to be stored.

offset - the file position, in bytes.

writeTilePositions

void writeTilePositions(BufferedRandomAccessFile braf)
                 throws IOException

Writes the tile position data from the specified file.

Parameters:

braf - a valid file reference

Throws:

IOException - in the event of an unhandled I/O exception.

getCountOfPopulatedTiles

int getCountOfPopulatedTiles()

Gets the count of the number of tiles that are currently populated. This count does not include tiles that may have been written to, but are still being retained in the tile cache and so have not yet been committed to the output file.

Returns:

a positive integer.