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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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package javax.imageio.spi;

import java.awt.image.RenderedImage;
import java.io.IOException;
import javax.imageio.ImageTypeSpecifier;
import javax.imageio.ImageWriter;
import javax.imageio.stream.ImageOutputStream;


The service provider interface (SPI) for ImageWriters.
For more information on service provider classes, see the class comment
for the IIORegistry class.

 Each ImageWriterSpi provides several types of information
about the ImageWriter class with which it is associated.

 The name of the vendor who defined the SPI class and a
brief description of the class are available via the
getVendorName, getDescription,
and getVersion methods.
These methods may be internationalized to provide locale-specific
output.  These methods are intended mainly to provide short,
human-writable information that might be used to organize a pop-up
menu or other list.

 Lists of format names, file suffixes, and MIME types associated
with the service may be obtained by means of the
getFormatNames, getFileSuffixes, and
getMIMEType methods.  These methods may be used to
identify candidate ImageWriters for writing a
particular file or stream based on manual format selection, file
naming, or MIME associations.

 A more reliable way to determine which ImageWriters
are likely to be able to parse a particular data stream is provided
by the canEncodeImage method.  This methods allows the
service provider to inspect the actual image contents.

 Finally, an instance of the ImageWriter class
associated with this service provider may be obtained by calling
the createWriterInstance method.  Any heavyweight
initialization, such as the loading of native libraries or creation
of large tables, should be deferred at least until the first
invocation of this method.

See Also:
/**
 * The service provider interface (SPI) for <code>ImageWriter</code>s.
 * For more information on service provider classes, see the class comment
 * for the <code>IIORegistry</code> class.
 *
 * <p> Each <code>ImageWriterSpi</code> provides several types of information
 * about the <code>ImageWriter</code> class with which it is associated.
 *
 * <p> The name of the vendor who defined the SPI class and a
 * brief description of the class are available via the
 * <code>getVendorName</code>, <code>getDescription</code>,
 * and <code>getVersion</code> methods.
 * These methods may be internationalized to provide locale-specific
 * output.  These methods are intended mainly to provide short,
 * human-writable information that might be used to organize a pop-up
 * menu or other list.
 *
 * <p> Lists of format names, file suffixes, and MIME types associated
 * with the service may be obtained by means of the
 * <code>getFormatNames</code>, <code>getFileSuffixes</code>, and
 * <code>getMIMEType</code> methods.  These methods may be used to
 * identify candidate <code>ImageWriter</code>s for writing a
 * particular file or stream based on manual format selection, file
 * naming, or MIME associations.
 *
 * <p> A more reliable way to determine which <code>ImageWriter</code>s
 * are likely to be able to parse a particular data stream is provided
 * by the <code>canEncodeImage</code> method.  This methods allows the
 * service provider to inspect the actual image contents.
 *
 * <p> Finally, an instance of the <code>ImageWriter</code> class
 * associated with this service provider may be obtained by calling
 * the <code>createWriterInstance</code> method.  Any heavyweight
 * initialization, such as the loading of native libraries or creation
 * of large tables, should be deferred at least until the first
 * invocation of this method.
 *
 * @see IIORegistry
 * @see javax.imageio.ImageTypeSpecifier
 * @see javax.imageio.ImageWriter
 *
 */
public abstract class ImageWriterSpi extends ImageReaderWriterSpi {

    
A single-element array, initially containing
ImageInputStream.class, to be returned from
getInputTypes.

/**
     * A single-element array, initially containing
     * <code>ImageInputStream.class</code>, to be returned from
     * <code>getInputTypes</code>.
     */
    public static final Class[] STANDARD_OUTPUT_TYPE =
        { ImageOutputStream.class };

    
An array of Class objects to be returned from
getOutputTypes, initially null.

/**
     * An array of <code>Class</code> objects to be returned from
     * <code>getOutputTypes</code>, initially <code>null</code>.
     */
    protected Class[] outputTypes = null;

    
An array of strings to be returned from
getImageReaderSpiNames, initially
null.

/**
     * An array of strings to be returned from
     * <code>getImageReaderSpiNames</code>, initially
     * <code>null</code>.
     */
    protected String[] readerSpiNames = null;

    
The Class of the writer, initially
null.

/**
     * The <code>Class</code> of the writer, initially
     * <code>null</code>.
     */
    private Class writerClass = null;

    
Constructs a blank ImageWriterSpi.  It is up to
the subclass to initialize instance variables and/or override
method implementations in order to provide working versions of
all methods.

/**
     * Constructs a blank <code>ImageWriterSpi</code>.  It is up to
     * the subclass to initialize instance variables and/or override
     * method implementations in order to provide working versions of
     * all methods.
     */
    protected ImageWriterSpi() {
    }

    
Constructs an ImageWriterSpi with a given
set of values.

Params:
  • vendorName – the vendor name, as a non-null
String.
  • version – a version identifier, as a non-null
String.
  • names – a non-null array of
Strings indicating the format names.  At least one
entry must be present.
  • suffixes – an array of Strings indicating the
common file suffixes.  If no suffixes are defined,
null should be supplied.  An array of length 0
will be normalized to null.
  • MIMETypes – an array of Strings indicating
the format's MIME types.  If no suffixes are defined,
null should be supplied.  An array of length 0
will be normalized to null.
  • writerClassName – the fully-qualified name of the
associated ImageWriterSpi class, as a
non-null String.
  • outputTypes – an array of Class objects of
length at least 1 indicating the legal output types.
  • readerSpiNames – an array Strings of length
at least 1 naming the classes of all associated
ImageReaders, or null.  An array of
length 0 is normalized to null.
  • supportsStandardStreamMetadataFormat – a
boolean that indicates whether a stream metadata
object can use trees described by the standard metadata format.
  • nativeStreamMetadataFormatName – a
String, or null, to be returned from
getNativeStreamMetadataFormatName.
  • nativeStreamMetadataFormatClassName – a
String, or null, to be used to instantiate
a metadata format object to be returned from
getNativeStreamMetadataFormat.
  • extraStreamMetadataFormatNames – an array of
Strings, or null, to be returned from
getExtraStreamMetadataFormatNames.  An array of length
0 is normalized to null.
  • extraStreamMetadataFormatClassNames – an array of
Strings, or null, to be used to instantiate
a metadata format object to be returned from
getStreamMetadataFormat.  An array of length
0 is normalized to null.
  • supportsStandardImageMetadataFormat – a
boolean that indicates whether an image metadata
object can use trees described by the standard metadata format.
  • nativeImageMetadataFormatName – a
String, or null, to be returned from
getNativeImageMetadataFormatName.
  • nativeImageMetadataFormatClassName – a
String, or null, to be used to instantiate
a metadata format object to be returned from
getNativeImageMetadataFormat.
  • extraImageMetadataFormatNames – an array of
Strings to be returned from
getExtraImageMetadataFormatNames.  An array of length 0
is normalized to null.
  • extraImageMetadataFormatClassNames – an array of
Strings, or null, to be used to instantiate
a metadata format object to be returned from
getImageMetadataFormat.  An array of length
0 is normalized to null.
Throws:
/**
     * Constructs an <code>ImageWriterSpi</code> with a given
     * set of values.
     *
     * @param vendorName the vendor name, as a non-<code>null</code>
     * <code>String</code>.
     * @param version a version identifier, as a non-<code>null</code>
     * <code>String</code>.
     * @param names a non-<code>null</code> array of
     * <code>String</code>s indicating the format names.  At least one
     * entry must be present.
     * @param suffixes an array of <code>String</code>s indicating the
     * common file suffixes.  If no suffixes are defined,
     * <code>null</code> should be supplied.  An array of length 0
     * will be normalized to <code>null</code>.
     * @param MIMETypes an array of <code>String</code>s indicating
     * the format's MIME types.  If no suffixes are defined,
     * <code>null</code> should be supplied.  An array of length 0
     * will be normalized to <code>null</code>.
     * @param writerClassName the fully-qualified name of the
     * associated <code>ImageWriterSpi</code> class, as a
     * non-<code>null</code> <code>String</code>.
     * @param outputTypes an array of <code>Class</code> objects of
     * length at least 1 indicating the legal output types.
     * @param readerSpiNames an array <code>String</code>s of length
     * at least 1 naming the classes of all associated
     * <code>ImageReader</code>s, or <code>null</code>.  An array of
     * length 0 is normalized to <code>null</code>.
     * @param supportsStandardStreamMetadataFormat a
     * <code>boolean</code> that indicates whether a stream metadata
     * object can use trees described by the standard metadata format.
     * @param nativeStreamMetadataFormatName a
     * <code>String</code>, or <code>null</code>, to be returned from
     * <code>getNativeStreamMetadataFormatName</code>.
     * @param nativeStreamMetadataFormatClassName a
     * <code>String</code>, or <code>null</code>, to be used to instantiate
     * a metadata format object to be returned from
     * <code>getNativeStreamMetadataFormat</code>.
     * @param extraStreamMetadataFormatNames an array of
     * <code>String</code>s, or <code>null</code>, to be returned from
     * <code>getExtraStreamMetadataFormatNames</code>.  An array of length
     * 0 is normalized to <code>null</code>.
     * @param extraStreamMetadataFormatClassNames an array of
     * <code>String</code>s, or <code>null</code>, to be used to instantiate
     * a metadata format object to be returned from
     * <code>getStreamMetadataFormat</code>.  An array of length
     * 0 is normalized to <code>null</code>.
     * @param supportsStandardImageMetadataFormat a
     * <code>boolean</code> that indicates whether an image metadata
     * object can use trees described by the standard metadata format.
     * @param nativeImageMetadataFormatName a
     * <code>String</code>, or <code>null</code>, to be returned from
     * <code>getNativeImageMetadataFormatName</code>.
     * @param nativeImageMetadataFormatClassName a
     * <code>String</code>, or <code>null</code>, to be used to instantiate
     * a metadata format object to be returned from
     * <code>getNativeImageMetadataFormat</code>.
     * @param extraImageMetadataFormatNames an array of
     * <code>String</code>s to be returned from
     * <code>getExtraImageMetadataFormatNames</code>.  An array of length 0
     * is normalized to <code>null</code>.
     * @param extraImageMetadataFormatClassNames an array of
     * <code>String</code>s, or <code>null</code>, to be used to instantiate
     * a metadata format object to be returned from
     * <code>getImageMetadataFormat</code>.  An array of length
     * 0 is normalized to <code>null</code>.
     *
     * @exception IllegalArgumentException if <code>vendorName</code>
     * is <code>null</code>.
     * @exception IllegalArgumentException if <code>version</code>
     * is <code>null</code>.
     * @exception IllegalArgumentException if <code>names</code>
     * is <code>null</code> or has length 0.
     * @exception IllegalArgumentException if <code>writerClassName</code>
     * is <code>null</code>.
     * @exception IllegalArgumentException if <code>outputTypes</code>
     * is <code>null</code> or has length 0.
     */
    public ImageWriterSpi(String vendorName,
                          String version,
                          String[] names,
                          String[] suffixes,
                          String[] MIMETypes,
                          String writerClassName,
                          Class[] outputTypes,
                          String[] readerSpiNames,
                          boolean supportsStandardStreamMetadataFormat,
                          String nativeStreamMetadataFormatName,
                          String nativeStreamMetadataFormatClassName,
                          String[] extraStreamMetadataFormatNames,
                          String[] extraStreamMetadataFormatClassNames,
                          boolean supportsStandardImageMetadataFormat,
                          String nativeImageMetadataFormatName,
                          String nativeImageMetadataFormatClassName,
                          String[] extraImageMetadataFormatNames,
                          String[] extraImageMetadataFormatClassNames) {
        super(vendorName, version,
              names, suffixes, MIMETypes, writerClassName,
              supportsStandardStreamMetadataFormat,
              nativeStreamMetadataFormatName,
              nativeStreamMetadataFormatClassName,
              extraStreamMetadataFormatNames,
              extraStreamMetadataFormatClassNames,
              supportsStandardImageMetadataFormat,
              nativeImageMetadataFormatName,
              nativeImageMetadataFormatClassName,
              extraImageMetadataFormatNames,
              extraImageMetadataFormatClassNames);

        if (outputTypes == null) {
            throw new IllegalArgumentException
                ("outputTypes == null!");
        }
        if (outputTypes.length == 0) {
            throw new IllegalArgumentException
                ("outputTypes.length == 0!");
        }

        this.outputTypes = (outputTypes == STANDARD_OUTPUT_TYPE) ?
            new Class<?>[] { ImageOutputStream.class } :
            outputTypes.clone();

        // If length == 0, leave it null
        if (readerSpiNames != null && readerSpiNames.length > 0) {
            this.readerSpiNames = (String[])readerSpiNames.clone();
        }
    }

    
Returns true if the format that this writer
outputs preserves pixel data bit-accurately.  The default
implementation returns true.

Returns:true if the format preserves full pixel
accuracy.
/**
     * Returns <code>true</code> if the format that this writer
     * outputs preserves pixel data bit-accurately.  The default
     * implementation returns <code>true</code>.
     *
     * @return <code>true</code> if the format preserves full pixel
     * accuracy.
     */
    public boolean isFormatLossless() {
        return true;
    }

    
Returns an array of Class objects indicating what
types of objects may be used as arguments to the writer's
setOutput method.

 For most writers, which only output to an
ImageOutputStream, a single-element array
containing ImageOutputStream.class should be
returned.

Returns:a non-null array of
Classobjects of length at least 1.
/**
     * Returns an array of <code>Class</code> objects indicating what
     * types of objects may be used as arguments to the writer's
     * <code>setOutput</code> method.
     *
     * <p> For most writers, which only output to an
     * <code>ImageOutputStream</code>, a single-element array
     * containing <code>ImageOutputStream.class</code> should be
     * returned.
     *
     * @return a non-<code>null</code> array of
     * <code>Class</code>objects of length at least 1.
     */
    public Class[] getOutputTypes() {
        return (Class[])outputTypes.clone();
    }

    
Returns true if the ImageWriter
implementation associated with this service provider is able to
encode an image with the given layout.  The layout
(i.e., the image's SampleModel and
ColorModel) is described by an
ImageTypeSpecifier object.

 A return value of true is not an absolute
guarantee of successful encoding; the encoding process may still
produce errors due to factors such as I/O errors, inconsistent
or malformed data structures, etc.  The intent is that a
reasonable inspection of the basic structure of the image be
performed in order to determine if it is within the scope of
the encoding format.  For example, a service provider for a
format that can only encode greyscale would return
false if handed an RGB BufferedImage.
Similarly, a service provider for a format that can encode
8-bit RGB imagery might refuse to encode an image with an
associated alpha channel.

 Different ImageWriters, and thus service
providers, may choose to be more or less strict.  For example,
they might accept an image with premultiplied alpha even though
it will have to be divided out of each pixel, at some loss of
precision, in order to be stored.

Params:
  • type – an ImageTypeSpecifier specifying the
layout of the image to be written.
Throws:
Returns:true if this writer is likely to be able
to encode images with the given layout.
/**
     * Returns <code>true</code> if the <code>ImageWriter</code>
     * implementation associated with this service provider is able to
     * encode an image with the given layout.  The layout
     * (<i>i.e.</i>, the image's <code>SampleModel</code> and
     * <code>ColorModel</code>) is described by an
     * <code>ImageTypeSpecifier</code> object.
     *
     * <p> A return value of <code>true</code> is not an absolute
     * guarantee of successful encoding; the encoding process may still
     * produce errors due to factors such as I/O errors, inconsistent
     * or malformed data structures, etc.  The intent is that a
     * reasonable inspection of the basic structure of the image be
     * performed in order to determine if it is within the scope of
     * the encoding format.  For example, a service provider for a
     * format that can only encode greyscale would return
     * <code>false</code> if handed an RGB <code>BufferedImage</code>.
     * Similarly, a service provider for a format that can encode
     * 8-bit RGB imagery might refuse to encode an image with an
     * associated alpha channel.
     *
     * <p> Different <code>ImageWriter</code>s, and thus service
     * providers, may choose to be more or less strict.  For example,
     * they might accept an image with premultiplied alpha even though
     * it will have to be divided out of each pixel, at some loss of
     * precision, in order to be stored.
     *
     * @param type an <code>ImageTypeSpecifier</code> specifying the
     * layout of the image to be written.
     *
     * @return <code>true</code> if this writer is likely to be able
     * to encode images with the given layout.
     *
     * @exception IllegalArgumentException if <code>type</code>
     * is <code>null</code>.
     */
    public abstract boolean canEncodeImage(ImageTypeSpecifier type);

    
Returns true if the ImageWriter
implementation associated with this service provider is able to
encode the given RenderedImage instance.  Note
that this includes instances of
java.awt.image.BufferedImage.

 See the discussion for
canEncodeImage(ImageTypeSpecifier) for information
on the semantics of this method.

Params:
  • im – an instance of RenderedImage to be encoded.
Throws:
Returns:true if this writer is likely to be able
to encode this image.
/**
     * Returns <code>true</code> if the <code>ImageWriter</code>
     * implementation associated with this service provider is able to
     * encode the given <code>RenderedImage</code> instance.  Note
     * that this includes instances of
     * <code>java.awt.image.BufferedImage</code>.
     *
     * <p> See the discussion for
     * <code>canEncodeImage(ImageTypeSpecifier)</code> for information
     * on the semantics of this method.
     *
     * @param im an instance of <code>RenderedImage</code> to be encoded.
     *
     * @return <code>true</code> if this writer is likely to be able
     * to encode this image.
     *
     * @exception IllegalArgumentException if <code>im</code>
     * is <code>null</code>.
     */
    public boolean canEncodeImage(RenderedImage im) {
        return canEncodeImage(ImageTypeSpecifier.createFromRenderedImage(im));
    }

    
Returns an instance of the ImageWriter
implementation associated with this service provider.
The returned object will initially be in an initial state as if
its reset method had been called.

 The default implementation simply returns
createWriterInstance(null).

Throws:
  • IOException – if an error occurs during loading,
or initialization of the writer class, or during instantiation
or initialization of the writer object.
Returns:an ImageWriter instance.
/**
     * Returns an instance of the <code>ImageWriter</code>
     * implementation associated with this service provider.
     * The returned object will initially be in an initial state as if
     * its <code>reset</code> method had been called.
     *
     * <p> The default implementation simply returns
     * <code>createWriterInstance(null)</code>.
     *
     * @return an <code>ImageWriter</code> instance.
     *
     * @exception IOException if an error occurs during loading,
     * or initialization of the writer class, or during instantiation
     * or initialization of the writer object.
     */
    public ImageWriter createWriterInstance() throws IOException {
        return createWriterInstance(null);
    }

    
Returns an instance of the ImageWriter
implementation associated with this service provider.
The returned object will initially be in an initial state
as if its reset method had been called.

 An Object may be supplied to the plug-in at
construction time.  The nature of the object is entirely
plug-in specific.

 Typically, a plug-in will implement this method using code
such as return new MyImageWriter(this).

Params:
  • extension – a plug-in specific extension object, which may
be null.
Throws:
  • IOException – if the attempt to instantiate
the writer fails.
  • IllegalArgumentException – if the
ImageWriter's constructor throws an
IllegalArgumentException to indicate that the
extension object is unsuitable.
Returns:an ImageWriter instance.
/**
     * Returns an instance of the <code>ImageWriter</code>
     * implementation associated with this service provider.
     * The returned object will initially be in an initial state
     * as if its <code>reset</code> method had been called.
     *
     * <p> An <code>Object</code> may be supplied to the plug-in at
     * construction time.  The nature of the object is entirely
     * plug-in specific.
     *
     * <p> Typically, a plug-in will implement this method using code
     * such as <code>return new MyImageWriter(this)</code>.
     *
     * @param extension a plug-in specific extension object, which may
     * be <code>null</code>.
     *
     * @return an <code>ImageWriter</code> instance.
     *
     * @exception IOException if the attempt to instantiate
     * the writer fails.
     * @exception IllegalArgumentException if the
     * <code>ImageWriter</code>'s constructor throws an
     * <code>IllegalArgumentException</code> to indicate that the
     * extension object is unsuitable.
     */
    public abstract ImageWriter createWriterInstance(Object extension)
        throws IOException;

    
Returns true if the ImageWriter object
passed in is an instance of the ImageWriter
associated with this service provider.

Params:
  • writer – an ImageWriter instance.
Throws:
Returns:true if writer is recognized
/**
     * Returns <code>true</code> if the <code>ImageWriter</code> object
     * passed in is an instance of the <code>ImageWriter</code>
     * associated with this service provider.
     *
     * @param writer an <code>ImageWriter</code> instance.
     *
     * @return <code>true</code> if <code>writer</code> is recognized
     *
     * @exception IllegalArgumentException if <code>writer</code> is
     * <code>null</code>.
     */
    public boolean isOwnWriter(ImageWriter writer) {
        if (writer == null) {
            throw new IllegalArgumentException("writer == null!");
        }
        String name = writer.getClass().getName();
        return name.equals(pluginClassName);
    }

    
Returns an array of Strings containing all the
fully qualified names of all the ImageReaderSpi
classes that can understand the internal metadata
representation used by the ImageWriter associated
with this service provider, or null if there are
no such ImageReaders specified.  If a
non-null value is returned, it must have non-zero
length.

 The first item in the array must be the name of the service
provider for the "preferred" reader, as it will be used to
instantiate the ImageReader returned by
ImageIO.getImageReader(ImageWriter).

 This mechanism may be used to obtain
ImageReaders that will generated non-pixel
meta-data (see IIOExtraDataInfo) in a structure
understood by an ImageWriter.  By reading the
image and obtaining this data from one of the
ImageReaders obtained with this method and passing
it on to the ImageWriter, a client program can
read an image, modify it in some way, and write it back out
preserving all meta-data, without having to understand anything
about the internal structure of the meta-data, or even about
the image format.

See Also:
Returns:an array of Strings of length at least 1
containing names of ImageReaderSpis, or
null.
/**
     * Returns an array of <code>String</code>s containing all the
     * fully qualified names of all the <code>ImageReaderSpi</code>
     * classes that can understand the internal metadata
     * representation used by the <code>ImageWriter</code> associated
     * with this service provider, or <code>null</code> if there are
     * no such <code>ImageReaders</code> specified.  If a
     * non-<code>null</code> value is returned, it must have non-zero
     * length.
     *
     * <p> The first item in the array must be the name of the service
     * provider for the "preferred" reader, as it will be used to
     * instantiate the <code>ImageReader</code> returned by
     * <code>ImageIO.getImageReader(ImageWriter)</code>.
     *
     * <p> This mechanism may be used to obtain
     * <code>ImageReaders</code> that will generated non-pixel
     * meta-data (see <code>IIOExtraDataInfo</code>) in a structure
     * understood by an <code>ImageWriter</code>.  By reading the
     * image and obtaining this data from one of the
     * <code>ImageReaders</code> obtained with this method and passing
     * it on to the <code>ImageWriter</code>, a client program can
     * read an image, modify it in some way, and write it back out
     * preserving all meta-data, without having to understand anything
     * about the internal structure of the meta-data, or even about
     * the image format.
     *
     * @return an array of <code>String</code>s of length at least 1
     * containing names of <code>ImageReaderSpi</code>s, or
     * <code>null</code>.
     *
     * @see javax.imageio.ImageIO#getImageReader(ImageWriter)
     * @see ImageReaderSpi#getImageWriterSpiNames()
     */
    public String[] getImageReaderSpiNames() {
        return readerSpiNames == null ?
            null : (String[])readerSpiNames.clone();
    }
}