org.geotools.coverage.io
Class AbstractGridCoverageReader

java.lang.Object
  org.geotools.coverage.io.AbstractGridCoverageReader

Direct Known Subclasses:

ExoreferencedGridCoverageReader

public abstract class AbstractGridCoverageReader

extends java.lang.Object

Base class for reading GridCoverage objects. Reading is a two steps process: The input file must be set first, then the actual reading is performed with the getGridCoverage(int). Example:

 AbstractGridCoverageReader reader = ...
 reader.setInput(new File("MyCoverage.dat"), true);
 GridCoverage coverage = reader.getGridCoverage(0);
 

Subclasses needs to implements at least the following methods:

• getCoordinateReferenceSystem(int)
• getEnvelope(int)

The default implementation should be able to create acceptable grid coverage using informations provided by the two above-mentioned methods. However, other methods may be overriden too in order to get finner control on the result.

Since:

2.2

Version:

$Id: AbstractGridCoverageReader.java 17672 2006-01-19 00:25:55Z desruisseaux $

Author:

Martin Desruisseaux

Field Summary

java.lang.String	formatName The format name (e.g.
protected javax.imageio.ImageReader	reader The ImageReader to use for decoding RenderedImages.

Constructor Summary

AbstractGridCoverageReader(java.lang.String formatName)
Constructs a for the specified format name.

Method Summary

abstract org.opengis.referencing.crs.CoordinateReferenceSystem	getCoordinateReferenceSystem(int index) Returns the coordinate reference system for the GridCoverage to be read.
abstract org.opengis.spatialschema.geometry.Envelope	getEnvelope(int index) Returns the envelope for the GridCoverage to be read.
org.opengis.coverage.grid.GridCoverage	getGridCoverage(int index) Read the grid coverage.
org.opengis.coverage.grid.GridRange	getGridRange(int index) Returns the grid range for the GridCoverage to be read.
protected java.util.Iterator	getImageReaders(java.lang.Object input) Returns an Iterator containing all currently registered ImageReaders that claim to be able to decode the image.
java.util.Locale	getLocale() Returns the currently set Locale, or if none has been set.
java.lang.String	getName(int index) Gets the GridCoverage name at the specified index.
int	getNumImages(boolean allowSearch) Returns the number of images available from the current input source.
org.opengis.coverage.SampleDimension[]	getSampleDimensions(int index) Returns the sample dimensions for each band of the GridCoverage to be read.
void	reset() Restores the AbstractGridCoverageReader to its initial state.
void	setInput(java.lang.Object input, boolean seekForwardOnly) Sets the input source to the given object.
void	setLocale(java.util.Locale locale) Sets the current Locale of this AbstractGridCoverageReader to the given value.

Methods inherited from class java.lang.Object

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

Field Detail

formatName

public final java.lang.String formatName

The format name (e.g. "PNG" or "GeoTIFF"). This format name should be understood by ImageIO.getImageReadersByFormatName(String), unless getImageReaders(java.lang.Object) is overriden.

reader

protected javax.imageio.ImageReader reader

The ImageReader to use for decoding RenderedImages. This reader is initially null and lazily created the first time setInput(java.lang.Object, boolean) is invoked. Once created, it is reused as much as possible. Invoking reset() dispose the reader and set it back to null.

Constructor Detail

AbstractGridCoverageReader

public AbstractGridCoverageReader(java.lang.String formatName)

Constructs a for the specified format name.

Method Detail

reset

public void reset()
           throws java.io.IOException

Restores the AbstractGridCoverageReader to its initial state.

Throws:

java.io.IOException - if an error occurs while disposing resources.

setInput

public void setInput(java.lang.Object input,
                     boolean seekForwardOnly)
              throws java.io.IOException

Sets the input source to the given object. The input is usually a File or an URL object. But some other types (e.g. ImageInputStream) may be accepted too.

If this method is invoked for the first time or after a call to reset(), then it will queries getImageReaders(java.lang.Object) for a list of ImageReaders and select the first one that accept the input.

Parameters:

input - The File or URL to be read.

seekForwardOnly - if true, grid coverages and metadata may only be read in ascending order from the input source.

Throws:

java.io.IOException - if an I/O operation failed.

java.lang.IllegalArgumentException - if input is not an instance of one of the classes declared by the ImageReader service provider.

getNumImages

public int getNumImages(boolean allowSearch)
                 throws java.io.IOException

Returns the number of images available from the current input source. Note that some image formats do not specify how many images are present in the stream. Thus determining the number of images will require the entire stream to be scanned and may require memory for buffering. The allowSearch parameter may be set to false to indicate that an exhaustive search is not desired.

Parameters:

allowSearch - If , the true number of images will be returned even if a search is required. If , the reader may return -1 without performing the search.

Returns:

The number of images, or -1 if is and a search would be required.

Throws:

java.lang.IllegalStateException - If the input source has not been set, or if the input has been specified with set to .

java.io.IOException - If an error occurs reading the information from the input source.

getName

public java.lang.String getName(int index)
                         throws java.io.IOException

Gets the GridCoverage name at the specified index. The default implementation returns the input path, or the "Untitled" string if input is not a File or an URL object.

Parameters:

index - The index of the image to be queried.

Returns:

The name for the GridCoverage at the specified index.

Throws:

java.lang.IllegalStateException - if the input source has not been set.

java.lang.IndexOutOfBoundsException - if the supplied index is out of bounds.

java.io.IOException - if an error occurs reading the width information from the input source.

getCoordinateReferenceSystem

public abstract org.opengis.referencing.crs.CoordinateReferenceSystem getCoordinateReferenceSystem(int index)
                                                                                            throws java.io.IOException

Returns the coordinate reference system for the GridCoverage to be read.

Parameters:

index - The index of the image to be queried.

Returns:

The coordinate reference system for the GridCoverage at the specified index.

Throws:

java.lang.IllegalStateException - if the input source has not been set.

java.lang.IndexOutOfBoundsException - if the supplied index is out of bounds.

java.io.IOException - if an error occurs reading the width information from the input source.

getEnvelope

public abstract org.opengis.spatialschema.geometry.Envelope getEnvelope(int index)
                                                                 throws java.io.IOException

Returns the envelope for the GridCoverage to be read. The envelope must have the same number of dimensions than the coordinate reference system.

Parameters:

index - The index of the image to be queried.

Returns:

The envelope for the GridCoverage at the specified index.

Throws:

java.lang.IllegalStateException - if the input source has not been set.

java.lang.IndexOutOfBoundsException - if the supplied index is out of bounds.

java.io.IOException - if an error occurs reading the width information from the input source.

getGridRange

public org.opengis.coverage.grid.GridRange getGridRange(int index)
                                                 throws java.io.IOException

Returns the grid range for the GridCoverage to be read. The grid range must have the same number of dimensions than the envelope. The default implementation construct a GridRange object using information provided by ImageReader.getWidth(int) and ImageReader.getHeight(int).

Parameters:

index - The index of the image to be queried.

Returns:

The grid range for the GridCoverage at the specified index.

Throws:

java.lang.IllegalStateException - if the input source has not been set.

java.lang.IndexOutOfBoundsException - if the supplied index is out of bounds.

java.io.IOException - if an error occurs reading the width information from the input source.

getSampleDimensions

public org.opengis.coverage.SampleDimension[] getSampleDimensions(int index)
                                                           throws java.io.IOException

Returns the sample dimensions for each band of the GridCoverage to be read. If sample dimensions are not known, then this method returns . The default implementation always returns .

Parameters:

index - The index of the image to be queried.

Returns:

The category lists for the GridCoverage at the specified index. This array's length must be equals to the number of bands in GridCoverage.

Throws:

java.lang.IllegalStateException - if the input source has not been set.

java.lang.IndexOutOfBoundsException - if the supplied index is out of bounds.

java.io.IOException - if an error occurs reading the width information from the input source.

getGridCoverage

public org.opengis.coverage.grid.GridCoverage getGridCoverage(int index)
                                                       throws java.io.IOException

Read the grid coverage. The default implementation gets the default ImageReadParam and checks if it is an instance of RawBinaryImageReadParam. If it is, this method then invokes RawBinaryImageReadParam#setStreamImageSize with informations provided by getGridRange(int). Finally, a grid coverage is constructed using informations provided by getName(int), getCoordinateReferenceSystem(int) and getEnvelope(int).

Parameters:

index - The index of the image to be queried.

Returns:

The GridCoverage at the specified index.

Throws:

java.lang.IllegalStateException - if the input source has not been set.

java.lang.IndexOutOfBoundsException - if the supplied index is out of bounds.

java.io.IOException - if an error occurs reading the width information from the input source.

getImageReaders

protected java.util.Iterator getImageReaders(java.lang.Object input)

Returns an Iterator containing all currently registered ImageReaders that claim to be able to decode the image. The default implementation returns ImageIO.getImageReadersByFormatName(formatName).

Parameters:

input - The input source.

setLocale

public void setLocale(java.util.Locale locale)

Sets the current Locale of this AbstractGridCoverageReader to the given value. A value of null removes any previous setting, and indicates that the reader should localize as it sees fit.

getLocale

public java.util.Locale getLocale()

Returns the currently set Locale, or if none has been set.