Class JPEGDecoder

java.lang.Object

is.galia.codec.AbstractDecoder

is.galia.codec.AbstractImageIODecoder

is.galia.codec.jpeg.JPEGDecoder

All Implemented Interfaces:

Decoder, AutoCloseable

public final class JPEGDecoder
extends AbstractImageIODecoder
implements Decoder

Implementation wrapping the default JDK Image I/O JPEG ImageReader.

Field Summary

Fields inherited from class is.galia.codec.AbstractImageIODecoder

iioReader

Fields inherited from class is.galia.codec.AbstractDecoder

arena, imageFile, inputStream

Constructor Summary

Constructors

Constructor	Description
JPEGDecoder()

Method Summary

Modifier and Type	Method	Description
boolean	canSeek()
BufferedImage	decode(int imageIndex)	Expedient but not necessarily efficient method that reads a whole image (excluding subimages) in one shot.
BufferedImage	decode(int imageIndex, Region region, double[] scales, ReductionFactor reductionFactor, double[] diffScales, Set<DecoderHint> hints)	Override to handle images with incompatible ICC profiles, and also CMYK images, neither of which the Sun JPEGImageReader can do.
Format	detectFormat()	Called after a source has been set.
protected org.slf4j.Logger	getLogger()
int	getNumImages()	Overridden because the parent will include the thumbnail and other embedded images in the count, which we don't want.
int	getNumThumbnails(int imageIndex)	The default implementation returns 0.
protected String[]	getPreferredIIOImplementations()	N.B.: This method returns a list of strings rather than classes because some readers reside under the com.sun package, which is encapsulated.
Set<Format>	getSupportedFormats()
Size	getThumbnailSize(int imageIndex, int thumbIndex)	The default implementation throws an UnsupportedOperationException.
Metadata	readMetadata(int imageIndex)	Reads metadata pertaining to the image at the given index.
BufferedImage	readThumbnail(int imageIndex, int thumbIndex)	Reads a thumbnail image into memory.

Methods inherited from class is.galia.codec.AbstractImageIODecoder

close, decodeSequence, dispose, getNumResolutions, getSize, getTileSize, handle, initializeInputStream, readMonoResolution, readSmallestUsableSubimage

Methods inherited from class is.galia.codec.AbstractDecoder

setArena, setSource, setSource

Methods inherited from class java.lang.Object

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

Methods inherited from interface is.galia.codec.Decoder

close, decodeSequence, getNumResolutions, getSize, getTileSize, setArena, setSource, setSource

Constructor Details

JPEGDecoder

public JPEGDecoder()

Method Details

canSeek

public boolean canSeek()

Specified by:

canSeek in class AbstractImageIODecoder

detectFormat

public Format detectFormat()
                    throws IOException

Description copied from interface: Decoder

Called after a source has been set.

If reading from a Decoder.setSource(ImageInputStream) stream}, the stream position is reset to 0 before returning.

Unlike many of the other interface methods, implementations should not throw a SourceFormatException, and instead just return Format.UNKNOWN.

Specified by:

detectFormat in interface Decoder

Returns:

Format of the image to decode, if supported by the instance; otherwise Format.UNKNOWN. The implementation must create the instance from scratch and not obtain it from the format registry, which may be empty at the time this method is invoked.

Throws:

IOException - if there is some other error reading the image.

getLogger

protected org.slf4j.Logger getLogger()

Specified by:

getLogger in class AbstractImageIODecoder

getNumImages

public int getNumImages()
                 throws IOException

Overridden because the parent will include the thumbnail and other embedded images in the count, which we don't want.

Specified by:

getNumImages in interface Decoder

Overrides:

getNumImages in class AbstractImageIODecoder

Returns:

1, always.

Throws:

IOException - if there is some other error reading the number of images.

getNumThumbnails

public int getNumThumbnails(int imageIndex)
                     throws IOException

Description copied from interface: Decoder

The default implementation returns 0.

Specified by:

getNumThumbnails in interface Decoder

Overrides:

getNumThumbnails in class AbstractImageIODecoder

Returns:

Number of thumbnail images available for the image at the given index. (See class documentation.)

Throws:

IOException - if there is some other error reading the number of thumbnails.

getPreferredIIOImplementations

protected String[] getPreferredIIOImplementations()

Description copied from class: AbstractImageIODecoder

N.B.: This method returns a list of strings rather than classes because some readers reside under the com.sun package, which is encapsulated.

Specified by:

getPreferredIIOImplementations in class AbstractImageIODecoder

Returns:

Preferred reader implementation classes, in order of highest to lowest priority, or an empty array if there is no preference.

getSupportedFormats

public Set<Format> getSupportedFormats()

Specified by:

getSupportedFormats in interface Decoder

Specified by:

getSupportedFormats in class AbstractImageIODecoder

Returns:

All formats supported by the implementation. The instances must be created from scratch and not obtained from the format registry, which may be empty at the time this method is invoked.

getThumbnailSize

public Size getThumbnailSize(int imageIndex,
 int thumbIndex)
                      throws IOException

Description copied from interface: Decoder

The default implementation throws an UnsupportedOperationException.

Specified by:

getThumbnailSize in interface Decoder

Overrides:

getThumbnailSize in class AbstractImageIODecoder

Parameters:

imageIndex - See the class documentation..

thumbIndex - Value between 0 and Decoder.getNumThumbnails(int) - 1.

Returns:

Size of the thumbnail at the given coordinates.

Throws:

IOException - if there is an error reading the size.

decode

public BufferedImage decode(int imageIndex)
                     throws IOException

Expedient but not necessarily efficient method that reads a whole image (excluding subimages) in one shot.

Specified by:

decode in interface Decoder

Overrides:

decode in class AbstractImageIODecoder

Throws:

IOException

decode

public BufferedImage decode(int imageIndex,
 Region region,
 double[] scales,
 ReductionFactor reductionFactor,
 double[] diffScales,
 Set<DecoderHint> hints)
                     throws IOException

Override to handle images with incompatible ICC profiles, and also CMYK images, neither of which the Sun JPEGImageReader can do.

Specified by:

decode in interface Decoder

Overrides:

decode in class AbstractImageIODecoder

Parameters:

imageIndex - Image index.

region - May be null.

scales - May be null.

reductionFactor - The ReductionFactor.factor property will be modified to reflect the reduction factor of the returned image.

diffScales - Two-element array that will be populated with the X and Y axis differential scales used during reading (if the decoder supports this).

hints - Will be populated by information returned from the reader.

Returns:

Image best matching the given arguments.

Throws:

IOException - if there is some other error reading the image.

readMetadata

public Metadata readMetadata(int imageIndex)
                      throws IOException

Description copied from interface: Decoder

Reads metadata pertaining to the image at the given index.

Specified by:

readMetadata in interface Decoder

Specified by:

readMetadata in class AbstractImageIODecoder

Returns:

Metadata for the image at the given index. If there is none, an EmptyMetadata can be returned.

Throws:

IOException - if there is some other error reading the metadata.

readThumbnail

public BufferedImage readThumbnail(int imageIndex,
 int thumbIndex)
                            throws IOException

Description copied from interface: Decoder

Reads a thumbnail image into memory.

Implementations are encouraged to return an instance whose Raster is backed by a DataBufferByte. See the documentation of Decoder.decode(int, Region, double[], ReductionFactor, double[], Set) for more information.

The default implementation throws an UnsupportedOperationException.

Specified by:

readThumbnail in interface Decoder

Overrides:

readThumbnail in class AbstractImageIODecoder

Parameters:

imageIndex - See the class documentation.

thumbIndex - Value between 0 and Decoder.getNumThumbnails(int) - 1.

Throws:

IOException - if there is some other error reading the image.