Java example source code file (ImageWriterSpi.java)

This example Java source code file (ImageWriterSpi.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

awt, class, deprecated, illegalargumentexception, image, imageio, imagereaderwriterspi, imagewriterspi, ioexception, mimetypes, standard_output_type, string

The ImageWriterSpi.java Java example source code

/*
 * Copyright (c) 1999, 2013, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

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 <code>ImageWriters.
 * For more information on service provider classes, see the class comment
 * for the <code>IIORegistry class.
 *
 * <p> Each ImageWriterSpi provides several types of information
 * about the <code>ImageWriter 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, getDescription,
 * and <code>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.
 *
 * <p> Lists of format names, file suffixes, and MIME types associated
 * with the service may be obtained by means of the
 * <code>getFormatNames, getFileSuffixes, and
 * <code>getMIMEType methods.  These methods may be used to
 * identify candidate <code>ImageWriters 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 ImageWriters
 * are likely to be able to parse a particular data stream is provided
 * by the <code>canEncodeImage method.  This methods allows the
 * service provider to inspect the actual image contents.
 *
 * <p> Finally, an instance of the ImageWriter class
 * associated with this service provider may be obtained by calling
 * the <code>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 IIORegistry
 * @see javax.imageio.ImageTypeSpecifier
 * @see javax.imageio.ImageWriter
 *
 */
public abstract class ImageWriterSpi extends ImageReaderWriterSpi {

    /**
     * A single-element array, initially containing
     * <code>ImageOutputStream.class, to be returned from
     * <code>getOutputTypes.
     * @deprecated Instead of using this field, directly create
     * the equivalent array <code>{ ImageOutputStream.class }.
     */
    @Deprecated
    public static final Class[] STANDARD_OUTPUT_TYPE =
        { ImageOutputStream.class };

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

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

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

    /**
     * Constructs a blank <code>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.
     */
    protected ImageWriterSpi() {
    }

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

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

    /**
     * Returns <code>true if the ImageWriter
     * implementation associated with this service provider is able to
     * encode an image with the given layout.  The layout
     * (<i>i.e., the image's SampleModel and
     * <code>ColorModel) is described by an
     * <code>ImageTypeSpecifier object.
     *
     * <p> 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
     * <code>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.
     *
     * <p> 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.
     *
     * @param type an <code>ImageTypeSpecifier specifying the
     * layout of the image to be written.
     *
     * @return <code>true if this writer is likely to be able
     * to encode images with the given layout.
     *
     * @exception IllegalArgumentException if <code>type
     * is <code>null.
     */
    public abstract boolean canEncodeImage(ImageTypeSpecifier type);

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

    /**
     * Returns an instance of the <code>ImageWriter
     * implementation associated with this service provider.
     * The returned object will initially be in an initial state as if
     * its <code>reset method had been called.
     *
     * <p> The default implementation simply returns
     * <code>createWriterInstance(null).
     *
     * @return an <code>ImageWriter 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 <code>ImageWriter
     * implementation associated with this service provider.
     * The returned object will initially be in an initial state
     * as if its <code>reset method had been called.
     *
     * <p> An Object 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).
     *
     * @param extension a plug-in specific extension object, which may
     * be <code>null.
     *
     * @return an <code>ImageWriter instance.
     *
     * @exception IOException if the attempt to instantiate
     * the writer fails.
     * @exception IllegalArgumentException if the
     * <code>ImageWriter's constructor throws an
     * <code>IllegalArgumentException to indicate that the
     * extension object is unsuitable.
     */
    public abstract ImageWriter createWriterInstance(Object extension)
        throws IOException;

    /**
     * Returns <code>true if the ImageWriter object
     * passed in is an instance of the <code>ImageWriter
     * associated with this service provider.
     *
     * @param writer an <code>ImageWriter instance.
     *
     * @return <code>true if writer is recognized
     *
     * @exception IllegalArgumentException if <code>writer is
     * <code>null.
     */
    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 <code>Strings containing all the
     * fully qualified names of all the <code>ImageReaderSpi
     * classes that can understand the internal metadata
     * representation used by the <code>ImageWriter associated
     * with this service provider, or <code>null if there are
     * no such <code>ImageReaders specified.  If a
     * non-<code>null 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 returned by
     * <code>ImageIO.getImageReader(ImageWriter).
     *
     * <p> This mechanism may be used to obtain
     * <code>ImageReaders that will generated non-pixel
     * meta-data (see <code>IIOExtraDataInfo) in a structure
     * understood by an <code>ImageWriter.  By reading the
     * image and obtaining this data from one of the
     * <code>ImageReaders obtained with this method and passing
     * it on to the <code>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.
     *
     * @return an array of <code>Strings of length at least 1
     * containing names of <code>ImageReaderSpis, or
     * <code>null.
     *
     * @see javax.imageio.ImageIO#getImageReader(ImageWriter)
     * @see ImageReaderSpi#getImageWriterSpiNames()
     */
    public String[] getImageReaderSpiNames() {
        return readerSpiNames == null ?
            null : (String[])readerSpiNames.clone();
    }
}