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/* * @(#)ImageOutputStreamSpi.java 1.20 05/11/17 * * Copyright 2006 Sun Microsystems, Inc. All rights reserved. * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms. */ package javax.imageio.spi; import java.io.File; import java.io.IOException; import javax.imageio.stream.ImageOutputStream; /** * The service provider interface (SPI) for * <code>ImageOutputStream</code>s. For more information on service * provider interfaces, see the class comment for the * <code>IIORegistry</code> class. * * <p> This interface allows arbitrary objects to be "wrapped" by * instances of <code>ImageOutputStream</code>. For example, a * particular <code>ImageOutputStreamSpi</code> might allow a generic * <code>OutputStream</code> to be used as a destination; another * might output to a <code>File</code> or to a device such as a serial * port. * * <p> By treating the creation of <code>ImageOutputStream</code>s as * a pluggable service, it becomes possible to handle future output * destinations without changing the API. Also, high-performance * implementations of <code>ImageOutputStream</code> (for example, * native implementations for a particular platform) can be installed * and used transparently by applications. * * @see IIORegistry * @see javax.imageio.stream.ImageOutputStream * * @version 0.5 */ public abstract class ImageOutputStreamSpi extends IIOServiceProvider { /** * A <code>Class</code> object indicating the legal object type * for use by the <code>createInputStreamInstance</code> method. */ protected Class<?> outputClass; /** * Constructs a blank <code>ImageOutputStreamSpi</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 ImageOutputStreamSpi() { } /** * Constructs an <code>ImageOutputStreamSpi</code> with a given * set of values. * * @param vendorName the vendor name. * @param version a version identifier. * @param outputClass a <code>Class</code> object indicating the * legal object type for use by the * <code>createOutputStreamInstance</code> method. * * @exception IllegalArgumentException if <code>vendorName</code> * is <code>null</code>. * @exception IllegalArgumentException if <code>version</code> * is <code>null</code>. */ public ImageOutputStreamSpi(String vendorName, String version, Class<?> outputClass) { super(vendorName, version); this.outputClass = outputClass; } /** * Returns a <code>Class</code> object representing the class or * interface type that must be implemented by an output * destination in order to be "wrapped" in an * <code>ImageOutputStream</code> via the * <code>createOutputStreamInstance</code> method. * * <p> Typical return values might include * <code>OutputStream.class</code> or <code>File.class</code>, but * any class may be used. * * @return a <code>Class</code> variable. * * @see #createOutputStreamInstance(Object, boolean, File) */ public Class<?> getOutputClass() { return outputClass; } /** * Returns <code>true</code> if the <code>ImageOutputStream</code> * implementation associated with this service provider can * optionally make use of a cache <code>File</code> for improved * performance and/or memory footrprint. If <code>false</code>, * the value of the <code>cacheFile</code> argument to * <code>createOutputStreamInstance</code> will be ignored. * * <p> The default implementation returns <code>false</code>. * * @return <code>true</code> if a cache file can be used by the * output streams created by this service provider. */ public boolean canUseCacheFile() { return false; } /** * Returns <code>true</code> if the <code>ImageOutputStream</code> * implementation associated with this service provider requires * the use of a cache <code>File</code>. * * <p> The default implementation returns <code>false</code>. * * @return <code>true</code> if a cache file is needed by the * output streams created by this service provider. */ public boolean needsCacheFile() { return false; } /** * Returns an instance of the <code>ImageOutputStream</code> * implementation associated with this service provider. If the * use of a cache file is optional, the <code>useCache</code> * parameter will be consulted. Where a cache is required, or * not applicable, the value of <code>useCache</code> will be ignored. * * @param output an object of the class type returned by * <code>getOutputClass</code>. * @param useCache a <code>boolean</code> indicating whether a * cache file should be used, in cases where it is optional. * @param cacheDir a <code>File</code> indicating where the * cache file should be created, or <code>null</code> to use the * system directory. * * @return an <code>ImageOutputStream</code> instance. * * @exception IllegalArgumentException if <code>output</code> is * not an instance of the correct class or is <code>null</code>. * @exception IllegalArgumentException if a cache file is needed, * but <code>cacheDir</code> is non-<code>null</code> and is not a * directory. * @exception IOException if a cache file is needed but cannot be * created. * * @see #getOutputClass */ public abstract ImageOutputStream createOutputStreamInstance(Object output, boolean useCache, File cacheDir) throws IOException; /** * Returns an instance of the <code>ImageOutputStream</code> * implementation associated with this service provider. A cache * file will be created in the system-dependent default * temporary-file directory, if needed. * * @param output an object of the class type returned by * <code>getOutputClass</code>. * * @return an <code>ImageOutputStream</code> instance. * * @exception IllegalArgumentException if <code>output</code> is * not an instance of the correct class or is <code>null</code>. * @exception IOException if a cache file is needed but cannot be * created. * * @see #getOutputClass() */ public ImageOutputStream createOutputStreamInstance(Object output) throws IOException { return createOutputStreamInstance(output, true, null); } }