path: root/libjava/classpath/javax/imageio/metadata/IIOMetadata.java

/* IIOMetadata.java --
   Copyright (C) 2004  Free Software Foundation, Inc.

This file is part of GNU Classpath.

GNU Classpath is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2, or (at your option)
any later version.

GNU Classpath is distributed in the hope that it will be useful, but
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
General Public License for more details.

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02110-1301 USA.

Linking this library statically or dynamically with other modules is
making a combined work based on this library.  Thus, the terms and
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As a special exception, the copyright holders of this library give you
permission to link this library with independent modules to produce an
executable, regardless of the license terms of these independent
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package javax.imageio.metadata;

import org.w3c.dom.Node;

/**
 * Represents metadata that describe an image or an image stream.
 * Each ImageIO plugin will represent image data using an opaque
 * object but all such objects should expose their internal
 * information as a tree of IIOMetadataNodes.
 *
 * There are three formats of metadata that a plugin can support:
 *
 * <ul>
 *   <li>a "native" format</li>
 *   <li>a custom format</li>
 *   <li>a standard plugin-neutral format</li>
 * </ul>
 *
 * If a plugin supports more than one format of metadata, the other
 * formats can be retrieved by calling getMetadataFormatNames.
 *
 * The native format is used to transfer metadata from one image to
 * another image of the same type, losslessly.
 *
 * The custom format describes the image metadata and exposes a tree
 * of IIOMetadataNodes but its internal representation is specific to
 * this plugin.
 *
 * The plugin-neutral format uses a generic tree structure as its
 * internal representation.
 *
 * ImageTranscoders may be used to convert metadata understood by one
 * plugin to metadata understood by another, however the conversion
 * may be lossy.
 *
 * @author Michael Koch (konqueror@gmx.de)
 * @author Thomas Fitzsimmons (fitzsim@redhat.com)
 */
public abstract class IIOMetadata
{
  protected IIOMetadataController controller;
  protected IIOMetadataController defaultController;
  protected String[] extraMetadataFormatClassNames;
  protected String[] extraMetadataFormatNames;
  protected String nativeMetadataFormatClassName;
  protected String nativeMetadataFormatName;
  protected boolean standardFormatSupported;

  /**
   * Construct an IIOMetadata object.
   */
  protected IIOMetadata()
  {
    // Do nothing here.
  }

  /**
   * Construct an IIOMetadata object.
   *
   * @param standardMetadataFormatSupported
   * @param nativeMetadataFormatName
   * @param nativeMetadataFormatClassName
   * @param extraMetadataFormatNames
   * @param extraMetadataFormatClassNames
   *
   * @throws IllegalArgumentException if extraMetadataFormatNames has length of
   * zero or extraMetadataFormatNames and extraMetadataFormatClassNames are
   * neither both null, not have the same length
   */
  protected IIOMetadata(boolean standardMetadataFormatSupported,
                        String nativeMetadataFormatName,
                        String nativeMetadataFormatClassName,
                        String[] extraMetadataFormatNames,
                        String[] extraMetadataFormatClassNames)
  {
    if (extraMetadataFormatNames != null
        && extraMetadataFormatNames.length == 0)
      throw new IllegalArgumentException
        ("extraMetadataFormatNames may not be empty");

    if (((extraMetadataFormatNames == null)
         && (extraMetadataFormatClassNames != null))
        || ((extraMetadataFormatNames != null)
            && (extraMetadataFormatClassNames == null))
        || ((extraMetadataFormatNames != null)
            && (extraMetadataFormatClassNames != null)
            && (extraMetadataFormatNames.length !=
                extraMetadataFormatClassNames.length)))
      throw new IllegalArgumentException
        ("extraMetadataFormatNames and extraMetadataFormatClassNames " +
         "have different lengths");

    this.standardFormatSupported = standardMetadataFormatSupported;
    this.nativeMetadataFormatName = nativeMetadataFormatName;
    this.nativeMetadataFormatClassName = nativeMetadataFormatClassName;
    this.extraMetadataFormatNames = extraMetadataFormatNames;
    this.extraMetadataFormatClassNames = extraMetadataFormatClassNames;
  }

  public boolean activateController()
  {
    if (! hasController())
      return false;

    return getDefaultController().activate(this);
  }

  public IIOMetadataController getController()
  {
    return controller;
  }

  public IIOMetadataController getDefaultController()
  {
    return defaultController;
  }

  public String[] getExtraMetadataFormatNames()
  {
    return (String[]) extraMetadataFormatNames.clone();
  }

  public IIOMetadataFormat getMetadataFormat(String formatName)
  {
    if (formatName == null)
      throw new IllegalArgumentException("formatName may not be null");
    
    String formatClassName = null;

    if (isStandardMetadataFormatSupported()
	&& formatName.equals(nativeMetadataFormatName))
      formatClassName = nativeMetadataFormatClassName;
    else
      {
	String[] extraFormatNames = getExtraMetadataFormatNames();
	
	for (int i = extraFormatNames.length - 1; i >= 0; --i)
	  if (extraFormatNames[i].equals(formatName))
	    {
	      formatClassName = extraFormatNames[i];
	      break;
	    }
      }

    if (formatClassName == null)
      throw new IllegalArgumentException("unknown format");

    IIOMetadataFormat format;
    
    try
      {
	format = (IIOMetadataFormat) Class.forName(formatClassName)
					  .newInstance();
      }
    catch (Exception e)
      {
	IllegalStateException ise = new IllegalStateException();
	ise.initCause(e);
	throw ise;
      }

    return format;
  }

  public String[] getMetadataFormatNames()
  {
    String[] formatNames = getExtraMetadataFormatNames();
    
    if (isStandardMetadataFormatSupported())
      {
        // Combine native metadata format name and extra metadata format names
	// into one String array.
	String[] tmp = new String[formatNames.length + 1];
	tmp[0] = getNativeMetadataFormatName();

	for (int i = 1; i < tmp.length; ++i)
	  tmp[i] = formatNames[i - 1];

	formatNames = tmp;
      }

    return formatNames;
  }

  public String getNativeMetadataFormatName()
  {
    return nativeMetadataFormatName;
  }

  public boolean hasController()
  {
    return getController() != null;
  }

  public abstract boolean isReadOnly();

  public boolean isStandardMetadataFormatSupported()
  {
    return standardFormatSupported;
  }

  public abstract void reset();

  public void setController(IIOMetadataController controller)
  {
    this.controller = controller;
  }

  public abstract Node getAsTree (String formatName);

  protected IIOMetadataNode getStandardChromaNode ()
  {
    return null;
  }

  protected IIOMetadataNode getStandardCompressionNode ()
  {
    return null;
  }

  protected IIOMetadataNode getStandardDataNode ()
  {
    return null;
  }

  protected IIOMetadataNode getStandardDimensionNode ()
  {
    return null;
  }

  protected IIOMetadataNode getStandardDocumentNode ()
  {
    return null;
  }

  protected IIOMetadataNode getStandardTextNode ()
  {
    return null;
  }

  protected IIOMetadataNode getStandardTileNode ()
  {
    return null;
  }

  protected IIOMetadataNode getStandardTransparencyNode ()
  {
    return null;
  }

  private void appendChild (IIOMetadataNode node,
			    IIOMetadataNode child)
  {
    if (child != null)
      node.appendChild(child);
  }

  protected final IIOMetadataNode getStandardTree ()
  {
    IIOMetadataNode node = new IIOMetadataNode();

    appendChild (node, getStandardChromaNode());
    appendChild (node, getStandardCompressionNode());
    appendChild (node, getStandardDataNode());
    appendChild (node, getStandardDimensionNode());
    appendChild (node, getStandardDocumentNode());
    appendChild (node, getStandardTextNode());
    appendChild (node, getStandardTileNode());
    appendChild (node, getStandardTransparencyNode());

    return node;
  }

  public abstract void mergeTree (String formatName,
                                  Node root)
    throws IIOInvalidTreeException;

  public void setFromTree (String formatName, Node root)
    throws IIOInvalidTreeException
  {
    reset();

    mergeTree (formatName, root);
  }
}