Source for gnu.javax.sound.sampled.gstreamer.io.GstInputStream

   1: /* GstInputStream.java -- Trampoline class for an InputStream, mean to be used
   2:  by native code.
   3:  Copyright (C) 2007 Free Software Foundation, Inc.
   4: 
   5: This file is part of GNU Classpath.
   6: 
   7: GNU Classpath is free software; you can redistribute it and/or modify
   8: it under the terms of the GNU General Public License as published by
   9: the Free Software Foundation; either version 2, or (at your option)
  10: any later version.
  11: 
  12: GNU Classpath is distributed in the hope that it will be useful, but
  13: WITHOUT ANY WARRANTY; without even the implied warranty of
  14: MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15: General Public License for more details.
  16: 
  17: You should have received a copy of the GNU General Public License
  18: along with GNU Classpath; see the file COPYING.  If not, write to the
  19: Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  20: 02110-1301 USA.
  21: 
  22: Linking this library statically or dynamically with other modules is
  23: making a combined work based on this library.  Thus, the terms and
  24: conditions of the GNU General Public License cover the whole
  25: combination.
  26: 
  27: As a special exception, the copyright holders of this library give you
  28: permission to link this library with independent modules to produce an
  29: executable, regardless of the license terms of these independent
  30: modules, and to copy and distribute the resulting executable under
  31: terms of your choice, provided that you also meet, for each linked
  32: independent module, the terms and conditions of the license of that
  33: module.  An independent module is a module which is not derived from
  34: or based on this library.  If you modify this library, you may extend
  35: this exception to your version of the library, but you are not
  36: obligated to do so.  If you do not wish to do so, delete this
  37: exception statement from your version. */
  38: 
  39: package gnu.javax.sound.sampled.gstreamer.io;
  40: 
  41: import gnu.classpath.Pointer;
  42: 
  43: import java.io.IOException;
  44: import java.io.InputStream;
  45: 
  46: /**
  47:  * Encapsulates the functionality of an InputStream Object.
  48:  *
  49:  * This class is only meant to be used by the native code, to allow reading
  50:  * of the given InputStream as part of a the GStreamer InputStream Source
  51:  * Plugin.
  52:  *
  53:  * <strong>Note:</strong> this class will be not garbage collected as the
  54:  * native code contains strong references to internal fields.
  55:  * The native layer provides a method that can be called by the C code to
  56:  * free the resources and to let the garbage collected to handle this class
  57:  * when not needed anymore.
  58:  *
  59:  * @author Mario Torre <neugens@limasoftware.net>
  60:  */
  61: public class GstInputStream
  62: {
  63:   /** The real InputStream on which to perform reading operations. */
  64:   private InputStream istream;
  65: 
  66:   /**
  67:    * Initialized in the native code, don't change without changes
  68:    * in the native layer.
  69:    */
  70:   private Pointer gstInputStream = null;
  71: 
  72:   public GstInputStream(InputStream istream)
  73:   {
  74:     this.istream = istream;
  75:     init_instance();
  76:   }
  77: 
  78:   public int read(byte[] buf, int off, int len) throws IOException
  79:   {
  80:     return this.istream.read(buf, off, len);
  81:   }
  82: 
  83:   public int available() throws IOException
  84:   {
  85:     return this.istream.available();
  86:   }
  87: 
  88:   /**
  89:    * Return a reference to the GstInputStream native class as a Pointer object.
  90:    * This method is intended as an helper accessor and the returned pointer
  91:    * needs to be casted and used in the native code only.
  92:    *
  93:    * @return Pointer to the native GstInputStream class.
  94:    */
  95:   public Pointer getNativeClass()
  96:   {
  97:     return this.gstInputStream;
  98:   }
  99: 
 100:   /* native methods */
 101: 
 102:   /**
 103:    * Initialize the native peer and enables the object cache.
 104:    * It is meant to be used by the class constructor.
 105:    */
 106:   native private final void init_instance();
 107: 
 108:   /**
 109:    * Initialize the native peer and enables the object cache.
 110:    * It is meant to be used by the static initializer.
 111:    */
 112:   native private static final void init_id_cache();
 113: 
 114:   static
 115:   {
 116:     System.loadLibrary("gstreamerpeer"); //$NON-NLS-1$
 117:     init_id_cache();
 118:   }
 119: }