org.geotoolkit.image.io
Class TextImageReader

Object
  ImageReader
      SpatialImageReader
          StreamImageReader
              TextImageReader

All Implemented Interfaces:

WarningProducer, Disposable, Localized

Direct Known Subclasses:

AsciiGridReader, TextMatrixImageReader, TextRecordImageReader

public abstract class TextImageReader
extends StreamImageReader

Base class for image readers that expect a BufferedReader input source. "Text images" are usually ASCII files where pixels values are actually the geophysical values. This base class provides the following conveniences:

• Get a BufferedReader from the input types, which may be a any type documented in the super-class plus Reader.
• Get a LineFormat for parsing a whole line as a record. Subclasses can override this method for parsing text files having non-numeric columns (angles, dates, etc.).
• Get the character encoding and the locale (for parsing numbers) from the fields declared in the Service Provider. Alternatively, subclasses can also get more control by overriding the getCharset(InputStream) method.

Since:

3.08 (derived from 1.2)

Version:

3.08

Author:

Martin Desruisseaux (IRD, Geomatys)

See Also:

TextImageWriter

Module:

coverage/geotk-coverageio (download)

View source code for this class

Nested Class Summary

protected static class

TextImageReader.Spi Service provider interface (SPI) for TextImageReaders.

Field Summary

Fields inherited from class StreamImageReader

closeOnReset

Fields inherited from class ImageReader

availableLocales, ignoreMetadata, input, locale, minIndex, originatingProvider, progressListeners, seekForwardOnly, updateListeners, warningListeners, warningLocales

Fields inherited from interface WarningProducer

LOGGER

Constructor Summary

protected

TextImageReader(TextImageReader.Spi provider) Constructs a new image reader.

Method Summary

protected void	close() Closes the reader created by getReader().
protected Charset	getCharset(InputStream input) Returns the character set to use for decoding the string from the input stream.
protected LineFormat	getLineFormat(int imageIndex) Returns the line format to use for parsing every lines in the input stream.
protected double	getPadValue(int imageIndex) Returns the pad value for missing data, or Double.NaN if none.
protected String	getPositionString(String message) Returns a string representation of the current stream position.
protected BufferedReader	getReader() Returns the input as an buffered reader.
protected boolean	isComment(String line) Returns true if the specified line is a comment.

Methods inherited from class StreamImageReader

finalize, getChannel, getInputStream, getStreamLength, setInput

Methods inherited from class SpatialImageReader

checkBandIndex, checkImageIndex, collapseNoDataValues, createMetadata, dispose, flipVertically, getDefaultReadParam, getDestination, getDimension, getGridEnvelope, getImageMetadata, getImageType, getImageTypes, getNumBands, getNumImages, getRawDataType, getRawImageType, getStreamMetadata, hasColors, warningOccurred

Methods inherited from class ImageReader

abort, abortRequested, addIIOReadProgressListener, addIIOReadUpdateListener, addIIOReadWarningListener, canReadRaster, checkReadParamBandSettings, clearAbortRequest, computeRegions, getAspectRatio, getAvailableLocales, getDestination, getFormatName, getHeight, getImageMetadata, getInput, getLocale, getMinIndex, getNumThumbnails, getOriginatingProvider, getSourceRegion, getStreamMetadata, getThumbnailHeight, getThumbnailWidth, getTileGridXOffset, getTileGridYOffset, getTileHeight, getTileWidth, getWidth, hasThumbnails, isIgnoringMetadata, isImageTiled, isRandomAccessEasy, isSeekForwardOnly, processImageComplete, processImageProgress, processImageStarted, processImageUpdate, processPassComplete, processPassStarted, processReadAborted, processSequenceComplete, processSequenceStarted, processThumbnailComplete, processThumbnailPassComplete, processThumbnailPassStarted, processThumbnailProgress, processThumbnailStarted, processThumbnailUpdate, processWarningOccurred, processWarningOccurred, read, read, readAll, readAll, readAsRenderedImage, readerSupportsThumbnails, readRaster, readThumbnail, readTile, readTileRaster, removeAllIIOReadProgressListeners, removeAllIIOReadUpdateListeners, removeAllIIOReadWarningListeners, removeIIOReadProgressListener, removeIIOReadUpdateListener, removeIIOReadWarningListener, reset, setInput, setInput, setLocale

Methods inherited from class Object

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

Methods inherited from interface Localized

getLocale

Constructor Detail

TextImageReader

protected TextImageReader(TextImageReader.Spi provider)

Constructs a new image reader.

Parameters:

provider - The ImageReaderSpi that is constructing this object, or null.

Method Detail

getCharset

protected Charset getCharset(InputStream input)
                      throws IOException

Returns the character set to use for decoding the string from the input stream. The default implementation returns the character set specified to the TextImageReader.Spi object given to this TextImageReader constructor. Subclasses can override this method if they want to detect the character encoding in some other way.

Parameters:

input - The input stream.

Returns:

The character encoding, or null for the platform default encoding.

Throws:

IOException - If reading from the input stream failed.

See Also:

TextImageReader.Spi.charset

getLineFormat

protected LineFormat getLineFormat(int imageIndex)
                            throws IOException

Returns the line format to use for parsing every lines in the input stream. The default implementation creates a new LineFormat instance using the locale specified by TextImageReader.Spi.locale. Subclasses should override this method if they want more control on the parser to be created.

Parameters:

imageIndex - the index of the image to be queried.

Returns:

The object to use for parsing lines of text.

Throws:

IOException - If reading from the input stream failed.

See Also:

TextImageReader.Spi.locale

getPadValue

protected double getPadValue(int imageIndex)
                      throws IOException

Returns the pad value for missing data, or Double.NaN if none. The pad value will applies to all columns except the one for x and y values, if any.

The default implementation returns the pad value specified to the TextImageReader.Spi object given to this TextImageReader constructor. Subclasses can override this method if they want to detect the pad value in some other way.

Parameters:

imageIndex - the index of the image to be queried.

Returns:

The pad value, or Double.NaN if none.

Throws:

IOException - If reading from the input stream failed.

See Also:

TextImageReader.Spi.padValue

getReader

protected BufferedReader getReader()
                            throws IllegalStateException,
                                   IOException

Returns the input as an buffered reader. If the input is already a buffered reader, it is returned unchanged. Otherwise this method creates a new line number reader from various input types including File, URL, URLConnection, Reader, InputStream and ImageInputStream.

This method creates a new reader only when first invoked. All subsequent calls will returns the same instance. Consequently, the returned reader should never be closed by the caller. It may be closed automatically when setInput(...), reset() or dispose() methods are invoked.

Returns:

ImageReader.getInput() as a BufferedReader.

Throws:

IllegalStateException - if the input is not set.

IOException - If the input stream can't be created for an other reason.

See Also:

ImageReader.getInput(), StreamImageReader.getInputStream()

isComment

protected boolean isComment(String line)

Returns true if the specified line is a comment. This method is invoked automatically during a read operation. The default implementation returns true if the line is empty or if the first non-whitespace character is '#', and false otherwise. Override this method if comment lines should be determined in a different way.

Parameters:

line - A line to be parsed.

Returns:

true if the line is a comment and should be ignored, or false if it should be parsed.

getPositionString

protected String getPositionString(String message)

Returns a string representation of the current stream position. For example this method may returns something like "Line 14 in file HUV18204.asc". This method returns null if the stream position is unknown.

Parameters:

message - An optional message to append to the stream position, or null if none.

Returns:

A string representation of current stream position.

close

protected void close()
              throws IOException

Closes the reader created by getReader(). This method does nothing if the reader is the input instance given by the user rather than a reader created by this class from a File or URL input.

Overrides:

close in class StreamImageReader

Throws:

IOException - If an error occurred while closing the reader.

See Also:

StreamImageReader.closeOnReset