Source for javax.imageio.spi.ImageInputStreamSpi

   1: /* ImageInputStreamSpi.java -- Service provider for image input streams.
   2:    Copyright (C) 2004, 2005  Free Software Foundation, Inc.
   3: 
   4: This file is part of GNU Classpath.
   5: 
   6: GNU Classpath is free software; you can redistribute it and/or modify
   7: it under the terms of the GNU General Public License as published by
   8: the Free Software Foundation; either version 2, or (at your option)
   9: any later version.
  10: 
  11: GNU Classpath is distributed in the hope that it will be useful, but
  12: WITHOUT ANY WARRANTY; without even the implied warranty of
  13: MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14: General Public License for more details.
  15: 
  16: You should have received a copy of the GNU General Public License
  17: along with GNU Classpath; see the file COPYING.  If not, write to the
  18: Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  19: 02110-1301 USA.
  20: 
  21: Linking this library statically or dynamically with other modules is
  22: making a combined work based on this library.  Thus, the terms and
  23: conditions of the GNU General Public License cover the whole
  24: combination.
  25: 
  26: As a special exception, the copyright holders of this library give you
  27: permission to link this library with independent modules to produce an
  28: executable, regardless of the license terms of these independent
  29: modules, and to copy and distribute the resulting executable under
  30: terms of your choice, provided that you also meet, for each linked
  31: independent module, the terms and conditions of the license of that
  32: module.  An independent module is a module which is not derived from
  33: or based on this library.  If you modify this library, you may extend
  34: this exception to your version of the library, but you are not
  35: obligated to do so.  If you do not wish to do so, delete this
  36: exception statement from your version. */
  37: 
  38: 
  39: package javax.imageio.spi;
  40: 
  41: import java.io.File;
  42: import java.io.IOException;
  43: 
  44: import javax.imageio.stream.ImageInputStream;
  45: 
  46: /**
  47:  * An abstract superclass for service providers that create
  48:  * {@linkplain javax.imageio.stream.ImageInputStream image input
  49:  * streams} for a file, URL, byte array or any other source.
  50:  *
  51:  * @since 1.4
  52:  *
  53:  * @author Sascha Brawer (brawer@dandelis.ch)
  54:  */
  55: public abstract class ImageInputStreamSpi
  56:   extends IIOServiceProvider
  57: {
  58:   /**
  59:    * Indicates which kind of input is processable by the streams
  60:    * created by {@link #createInputStreamInstance(Object)}.
  61:    */
  62:   protected Class<?> inputClass;
  63: 
  64: 
  65:   /**
  66:    * Constructs a service provider for image input streams, given no
  67:    * parameters. It is up to the sub-class to set {@link #vendorName},
  68:    * {@link #version} and {@link #inputClass} to non-null values.
  69:    */
  70:   protected ImageInputStreamSpi()
  71:   {
  72:   }
  73: 
  74: 
  75:   /**
  76:    * Constructs a service provider for image input streams, given the
  77:    * vendor name and a version string.
  78:    *
  79:    * @throws IllegalArgumentException if <code>vendorName</code>
  80:    * or <code>version</code> is <code>null</code>.
  81:    */
  82:   public ImageInputStreamSpi(String vendorName, String version,
  83:                              Class<?> inputClass)
  84:   {
  85:     super(vendorName, version);
  86:     this.inputClass = inputClass;
  87:   }
  88: 
  89: 
  90:   /**
  91:    * Determines which kind of input is processable by the streams
  92:    * created by {@link #createInputStreamInstance(Object)}.
  93:    */
  94:   public Class<?> getInputClass()
  95:   {
  96:     return inputClass;
  97:   }
  98: 
  99: 
 100:   /**
 101:    * Determines whether <code>ImageInputStreams</code> created
 102:    * by this service provider benefit from using a cache file.
 103:    *
 104:    * <p>The default behavior is to return <code>false</code>.
 105:    *
 106:    * @return <code>true</code> if the created streams are faster or
 107:    * need less memory when a cache file is being used;
 108:    * <code>false</code> if no positive effect results from the cache
 109:    * file.
 110:    */
 111:   public boolean canUseCacheFile()
 112:   {
 113:     return false;
 114:   }
 115: 
 116: 
 117:   /**
 118:    * Determines whether <code>ImageInputStreams</code> created
 119:    * by this service provider require the use of a cache file.
 120:    *
 121:    * <p>The default behavior is to return <code>false</code>.
 122:    *
 123:    * @return <code>true</code> if the created streams can only work
 124:    * when a cache file is being used; <code>false</code> if no cache
 125:    * file is needed.
 126:    */
 127:   public boolean needsCacheFile()
 128:   {
 129:     return false;
 130:   }
 131: 
 132: 
 133:   public abstract ImageInputStream createInputStreamInstance(Object input,
 134:                                                              boolean useCache,
 135:                                                              File cacheDir)
 136:     throws IOException;
 137: 
 138: 
 139:   public ImageInputStream createInputStreamInstance(Object input)
 140:     throws IOException
 141:   {
 142:     return createInputStreamInstance(input, canUseCacheFile(), null);
 143:   }
 144: }