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package javax.imageio.metadata;

import org.w3c.dom.Node;

import java.lang.reflect.Method;
import java.security.AccessController;
import java.security.PrivilegedAction;


An abstract class to be extended by objects that represent metadata (non-image data) associated with images and streams. Plug-ins represent metadata using opaque, plug-in specific objects. These objects, however, provide the ability to access their internal information as a tree of IIOMetadataNode objects that support the XML DOM interfaces as well as additional interfaces for storing non-textual data and retrieving information about legal data values. The format of such trees is plug-in dependent, but plug-ins may choose to support a plug-in neutral format described below. A single plug-in may support multiple metadata formats, whose names maybe determined by calling getMetadataFormatNames. The plug-in may also support a single special format, referred to as the "native" format, which is designed to encode its metadata losslessly. This format will typically be designed specifically to work with a specific file format, so that images may be loaded and saved in the same format with no loss of metadata, but may be less useful for transferring metadata between an ImageReader and an ImageWriter for different image formats. To convert between two native formats as losslessly as the image file formats will allow, an ImageTranscoder object must be used. 
See Also:
/**
 * An abstract class to be extended by objects that represent metadata
 * (non-image data) associated with images and streams.  Plug-ins
 * represent metadata using opaque, plug-in specific objects.  These
 * objects, however, provide the ability to access their internal
 * information as a tree of {@code IIOMetadataNode} objects that
 * support the XML DOM interfaces as well as additional interfaces for
 * storing non-textual data and retrieving information about legal
 * data values.  The format of such trees is plug-in dependent, but
 * plug-ins may choose to support a plug-in neutral format described
 * below.  A single plug-in may support multiple metadata formats,
 * whose names maybe determined by calling
 * {@code getMetadataFormatNames}.  The plug-in may also support
 * a single special format, referred to as the "native" format, which
 * is designed to encode its metadata losslessly.  This format will
 * typically be designed specifically to work with a specific file
 * format, so that images may be loaded and saved in the same format
 * with no loss of metadata, but may be less useful for transferring
 * metadata between an {@code ImageReader} and an
 * {@code ImageWriter} for different image formats.  To convert
 * between two native formats as losslessly as the image file formats
 * will allow, an {@code ImageTranscoder} object must be used.
 *
 * @see javax.imageio.ImageReader#getImageMetadata
 * @see javax.imageio.ImageReader#getStreamMetadata
 * @see javax.imageio.ImageReader#readAll
 * @see javax.imageio.ImageWriter#getDefaultStreamMetadata
 * @see javax.imageio.ImageWriter#getDefaultImageMetadata
 * @see javax.imageio.ImageWriter#write
 * @see javax.imageio.ImageWriter#convertImageMetadata
 * @see javax.imageio.ImageWriter#convertStreamMetadata
 * @see javax.imageio.IIOImage
 * @see javax.imageio.ImageTranscoder
 *
 */
public abstract class IIOMetadata {

    
A boolean indicating whether the concrete subclass supports the
standard metadata format, set via the constructor.

/**
     * A boolean indicating whether the concrete subclass supports the
     * standard metadata format, set via the constructor.
     */
    protected boolean standardFormatSupported;

    
The name of the native metadata format for this object, initialized to null and set via the constructor. 
/**
     * The name of the native metadata format for this object,
     * initialized to {@code null} and set via the constructor.
     */
    protected String nativeMetadataFormatName = null;

    
The name of the class implementing IIOMetadataFormat and representing the native metadata format, initialized to null and set via the constructor. 
/**
     * The name of the class implementing {@code IIOMetadataFormat}
     * and representing the native metadata format, initialized to
     * {@code null} and set via the constructor.
     */
    protected String nativeMetadataFormatClassName = null;

    
An array of names of formats, other than the standard and native formats, that are supported by this plug-in, initialized to null and set via the constructor. 
/**
     * An array of names of formats, other than the standard and
     * native formats, that are supported by this plug-in,
     * initialized to {@code null} and set via the constructor.
     */
    protected String[] extraMetadataFormatNames = null;

    
An array of names of classes implementing IIOMetadataFormat and representing the metadata formats, other than the standard and native formats, that are supported by this plug-in, initialized to null and set via the constructor. 
/**
     * An array of names of classes implementing {@code IIOMetadataFormat}
     * and representing the metadata formats, other than the standard and
     * native formats, that are supported by this plug-in,
     * initialized to {@code null} and set via the constructor.
     */
    protected String[] extraMetadataFormatClassNames = null;

    
An IIOMetadataController that is suggested for use as the controller for this IIOMetadata object. It may be retrieved via getDefaultController. To install the default controller, call setController(getDefaultController()). This instance variable should be set by subclasses that choose to provide their own default controller, usually a GUI, for setting parameters. 
See Also:
/**
     * An {@code IIOMetadataController} that is suggested for use
     * as the controller for this {@code IIOMetadata} object.  It
     * may be retrieved via {@code getDefaultController}.  To
     * install the default controller, call
     * {@code setController(getDefaultController())}.  This
     * instance variable should be set by subclasses that choose to
     * provide their own default controller, usually a GUI, for
     * setting parameters.
     *
     * @see IIOMetadataController
     * @see #getDefaultController
     */
    protected IIOMetadataController defaultController = null;

    
The IIOMetadataController that will be used to provide settings for this IIOMetadata object when the activateController method is called. This value overrides any default controller, even when null. 
See Also:
/**
     * The {@code IIOMetadataController} that will be
     * used to provide settings for this {@code IIOMetadata}
     * object when the {@code activateController} method
     * is called.  This value overrides any default controller,
     * even when {@code null}.
     *
     * @see IIOMetadataController
     * @see #setController(IIOMetadataController)
     * @see #hasController()
     * @see #activateController()
     */
    protected IIOMetadataController controller = null;

    
Constructs an empty IIOMetadata object. The subclass is responsible for supplying values for all protected instance variables that will allow any non-overridden default implementations of methods to satisfy their contracts. For example, extraMetadataFormatNames should not have length 0. 
/**
     * Constructs an empty {@code IIOMetadata} object.  The
     * subclass is responsible for supplying values for all protected
     * instance variables that will allow any non-overridden default
     * implementations of methods to satisfy their contracts.  For example,
     * {@code extraMetadataFormatNames} should not have length 0.
     */
    protected IIOMetadata() {}

    
Constructs an IIOMetadata object with the given format names and format class names, as well as a boolean indicating whether the standard format is supported. 
 This constructor does not attempt to check the class names for validity. Invalid class names may cause exceptions in subsequent calls to getMetadataFormat. 
Params:
  • standardMetadataFormatSupported – true if this object can return or accept a DOM tree using the standard metadata format.
  • nativeMetadataFormatName – the name of the native metadata format, as a String, or null if there is no native format.
  • nativeMetadataFormatClassName – the name of the class of the native metadata format, or null if there is no native format.
  • extraMetadataFormatNames – an array of Strings indicating additional formats supported by this object, or null if there are none.
  • extraMetadataFormatClassNames – an array of Strings indicating the class names of any additional formats supported by this object, or null if there are none.
Throws:
/**
     * Constructs an {@code IIOMetadata} object with the given
     * format names and format class names, as well as a boolean
     * indicating whether the standard format is supported.
     *
     * <p> This constructor does not attempt to check the class names
     * for validity.  Invalid class names may cause exceptions in
     * subsequent calls to {@code getMetadataFormat}.
     *
     * @param standardMetadataFormatSupported {@code true} if
     * this object can return or accept a DOM tree using the standard
     * metadata format.
     * @param nativeMetadataFormatName the name of the native metadata
     * format, as a {@code String}, or {@code null} if there
     * is no native format.
     * @param nativeMetadataFormatClassName the name of the class of
     * the native metadata format, or {@code null} if there is
     * no native format.
     * @param extraMetadataFormatNames an array of {@code String}s
     * indicating additional formats supported by this object, or
     * {@code null} if there are none.
     * @param extraMetadataFormatClassNames an array of {@code String}s
     * indicating the class names of any additional formats supported by
     * this object, or {@code null} if there are none.
     *
     * @exception IllegalArgumentException if
     * {@code extraMetadataFormatNames} has length 0.
     * @exception IllegalArgumentException if
     * {@code extraMetadataFormatNames} and
     * {@code extraMetadataFormatClassNames} are neither both
     * {@code null}, nor of the same length.
     */
    protected IIOMetadata(boolean standardMetadataFormatSupported,
                          String nativeMetadataFormatName,
                          String nativeMetadataFormatClassName,
                          String[] extraMetadataFormatNames,
                          String[] extraMetadataFormatClassNames) {
        this.standardFormatSupported = standardMetadataFormatSupported;
        this.nativeMetadataFormatName = nativeMetadataFormatName;
        this.nativeMetadataFormatClassName = nativeMetadataFormatClassName;
        if (extraMetadataFormatNames != null) {
            if (extraMetadataFormatNames.length == 0) {
                throw new IllegalArgumentException
                    ("extraMetadataFormatNames.length == 0!");
            }
            if (extraMetadataFormatClassNames == null) {
                throw new IllegalArgumentException
                    ("extraMetadataFormatNames != null && extraMetadataFormatClassNames == null!");
            }
            if (extraMetadataFormatClassNames.length !=
                extraMetadataFormatNames.length) {
                throw new IllegalArgumentException
                    ("extraMetadataFormatClassNames.length != extraMetadataFormatNames.length!");
            }
            this.extraMetadataFormatNames = extraMetadataFormatNames.clone();
            this.extraMetadataFormatClassNames = extraMetadataFormatClassNames.clone();
        } else {
            if (extraMetadataFormatClassNames != null) {
                throw new IllegalArgumentException
                    ("extraMetadataFormatNames == null && extraMetadataFormatClassNames != null!");
            }
        }
    }

    
Returns true if the standard metadata format is supported by getMetadataFormat, getAsTree, setFromTree, and mergeTree. 
 The default implementation returns the value of the standardFormatSupported instance variable. 
See Also:
Returns:true if the standard metadata format is supported.
/**
     * Returns {@code true} if the standard metadata format is
     * supported by {@code getMetadataFormat},
     * {@code getAsTree}, {@code setFromTree}, and
     * {@code mergeTree}.
     *
     * <p> The default implementation returns the value of the
     * {@code standardFormatSupported} instance variable.
     *
     * @return {@code true} if the standard metadata format
     * is supported.
     *
     * @see #getAsTree
     * @see #setFromTree
     * @see #mergeTree
     * @see #getMetadataFormat
     */
    public boolean isStandardMetadataFormatSupported() {
        return standardFormatSupported;
    }

    
Returns true if this object does not support the mergeTree, setFromTree, and reset methods. 
Returns:true if this IIOMetadata object cannot be modified.
/**
     * Returns {@code true} if this object does not support the
     * {@code mergeTree}, {@code setFromTree}, and
     * {@code reset} methods.
     *
     * @return true if this {@code IIOMetadata} object cannot be
     * modified.
     */
    public abstract boolean isReadOnly();

    
Returns the name of the "native" metadata format for this plug-in, which typically allows for lossless encoding and transmission of the metadata stored in the format handled by this plug-in. If no such format is supported, null will be returned. 
 The structure and contents of the "native" metadata format are defined by the plug-in that created this IIOMetadata object. Plug-ins for simple formats will usually create a dummy node for the root, and then a series of child nodes representing individual tags, chunks, or keyword/value pairs. A plug-in may choose whether or not to document its native format. 
 The default implementation returns the value of the nativeMetadataFormatName instance variable. 
See Also:
Returns:the name of the native format, or null.
/**
     * Returns the name of the "native" metadata format for this
     * plug-in, which typically allows for lossless encoding and
     * transmission of the metadata stored in the format handled by
     * this plug-in.  If no such format is supported,
     * {@code null} will be returned.
     *
     * <p> The structure and contents of the "native" metadata format
     * are defined by the plug-in that created this
     * {@code IIOMetadata} object.  Plug-ins for simple formats
     * will usually create a dummy node for the root, and then a
     * series of child nodes representing individual tags, chunks, or
     * keyword/value pairs.  A plug-in may choose whether or not to
     * document its native format.
     *
     * <p> The default implementation returns the value of the
     * {@code nativeMetadataFormatName} instance variable.
     *
     * @return the name of the native format, or {@code null}.
     *
     * @see #getExtraMetadataFormatNames
     * @see #getMetadataFormatNames
     */
    public String getNativeMetadataFormatName() {
        return nativeMetadataFormatName;
    }

    
Returns an array of Strings containing the names of additional metadata formats, other than the native and standard formats, recognized by this plug-in's getAsTree, setFromTree, and mergeTree methods. If there are no such additional formats, null is returned. 
 The default implementation returns a clone of the extraMetadataFormatNames instance variable. 
See Also:
Returns:an array of Strings with length at least 1, or null.
/**
     * Returns an array of {@code String}s containing the names
     * of additional metadata formats, other than the native and standard
     * formats, recognized by this plug-in's
     * {@code getAsTree}, {@code setFromTree}, and
     * {@code mergeTree} methods.  If there are no such additional
     * formats, {@code null} is returned.
     *
     * <p> The default implementation returns a clone of the
     * {@code extraMetadataFormatNames} instance variable.
     *
     * @return an array of {@code String}s with length at least
     * 1, or {@code null}.
     *
     * @see #getAsTree
     * @see #setFromTree
     * @see #mergeTree
     * @see #getNativeMetadataFormatName
     * @see #getMetadataFormatNames
     */
    public String[] getExtraMetadataFormatNames() {
        if (extraMetadataFormatNames == null) {
            return null;
        }
        return extraMetadataFormatNames.clone();
    }

    
Returns an array of Strings containing the names of all metadata formats, including the native and standard formats, recognized by this plug-in's getAsTree, setFromTree, and mergeTree methods. If there are no such formats, null is returned. 
 The default implementation calls getNativeMetadataFormatName, isStandardMetadataFormatSupported, and getExtraMetadataFormatNames and returns the combined results. 
See Also:
Returns:an array of Strings.
/**
     * Returns an array of {@code String}s containing the names
     * of all metadata formats, including the native and standard
     * formats, recognized by this plug-in's {@code getAsTree},
     * {@code setFromTree}, and {@code mergeTree} methods.
     * If there are no such formats, {@code null} is returned.
     *
     * <p> The default implementation calls
     * {@code getNativeMetadataFormatName},
     * {@code isStandardMetadataFormatSupported}, and
     * {@code getExtraMetadataFormatNames} and returns the
     * combined results.
     *
     * @return an array of {@code String}s.
     *
     * @see #getNativeMetadataFormatName
     * @see #isStandardMetadataFormatSupported
     * @see #getExtraMetadataFormatNames
     */
    public String[] getMetadataFormatNames() {
        String nativeName = getNativeMetadataFormatName();
        String standardName = isStandardMetadataFormatSupported() ?
            IIOMetadataFormatImpl.standardMetadataFormatName : null;
        String[] extraNames = getExtraMetadataFormatNames();

        int numFormats = 0;
        if (nativeName != null) {
            ++numFormats;
        }
        if (standardName != null) {
            ++numFormats;
        }
        if (extraNames != null) {
            numFormats += extraNames.length;
        }
        if (numFormats == 0) {
            return null;
        }

        String[] formats = new String[numFormats];
        int index = 0;
        if (nativeName != null) {
            formats[index++] = nativeName;
        }
        if (standardName != null) {
            formats[index++] = standardName;
        }
        if (extraNames != null) {
            for (int i = 0; i < extraNames.length; i++) {
                formats[index++] = extraNames[i];
            }
        }

        return formats;
    }

    
Returns an IIOMetadataFormat object describing the given metadata format, or null if no description is available. The supplied name must be one of those returned by getMetadataFormatNames (i.e., either the native format name, the standard format name, or one of those returned by getExtraMetadataFormatNames). 
 The default implementation checks the name against the global standard metadata format name, and returns that format if it is supported. Otherwise, it checks against the native format names followed by any additional format names. If a match is found, it retrieves the name of the IIOMetadataFormat class from nativeMetadataFormatClassName or extraMetadataFormatClassNames as appropriate, and constructs an instance of that class using its getInstance method. 
Params:
  • formatName – the desired metadata format.
Throws:
Returns:an IIOMetadataFormat object.
/**
     * Returns an {@code IIOMetadataFormat} object describing the
     * given metadata format, or {@code null} if no description
     * is available.  The supplied name must be one of those returned
     * by {@code getMetadataFormatNames} (<i>i.e.</i>, either the
     * native format name, the standard format name, or one of those
     * returned by {@code getExtraMetadataFormatNames}).
     *
     * <p> The default implementation checks the name against the
     * global standard metadata format name, and returns that format
     * if it is supported.  Otherwise, it checks against the native
     * format names followed by any additional format names.  If a
     * match is found, it retrieves the name of the
     * {@code IIOMetadataFormat} class from
     * {@code nativeMetadataFormatClassName} or
     * {@code extraMetadataFormatClassNames} as appropriate, and
     * constructs an instance of that class using its
     * {@code getInstance} method.
     *
     * @param formatName the desired metadata format.
     *
     * @return an {@code IIOMetadataFormat} object.
     *
     * @exception IllegalArgumentException if {@code formatName}
     * is {@code null} or is not one of the names recognized by
     * the plug-in.
     * @exception IllegalStateException if the class corresponding to
     * the format name cannot be loaded.
     */
    public IIOMetadataFormat getMetadataFormat(String formatName) {
        if (formatName == null) {
            throw new IllegalArgumentException("formatName == null!");
        }
        if (standardFormatSupported
            && formatName.equals
                (IIOMetadataFormatImpl.standardMetadataFormatName)) {
            return IIOMetadataFormatImpl.getStandardFormatInstance();
        }
        String formatClassName = null;
        if (formatName.equals(nativeMetadataFormatName)) {
            formatClassName = nativeMetadataFormatClassName;
        } else if (extraMetadataFormatNames != null) {
            for (int i = 0; i < extraMetadataFormatNames.length; i++) {
                if (formatName.equals(extraMetadataFormatNames[i])) {
                    formatClassName = extraMetadataFormatClassNames[i];
                    break;  // out of for
                }
            }
        }
        if (formatClassName == null) {
            throw new IllegalArgumentException("Unsupported format name");
        }
        try {
            final String className = formatClassName;
            // Try to load from the module of the IIOMetadata implementation
            // for this plugin since the IIOMetadataImpl is part of the plugin
            PrivilegedAction<Class<?>> pa = () -> { return getMetadataFormatClass(className); };
            Class<?> cls = AccessController.doPrivileged(pa);
            Method meth = cls.getMethod("getInstance");
            return (IIOMetadataFormat) meth.invoke(null);
        } catch (Exception e) {
            RuntimeException ex =
                new IllegalStateException ("Can't obtain format");
            ex.initCause(e);
            throw ex;
        }
    }

    // If updating this method also see the same in ImageReaderWriterSpi.java
    private Class<?> getMetadataFormatClass(String formatClassName) {
        Module thisModule = IIOMetadata.class.getModule();
        Module targetModule = this.getClass().getModule();
        Class<?> c = null;
        try {
            ClassLoader cl = this.getClass().getClassLoader();
            c = Class.forName(formatClassName, false, cl);
            if (!IIOMetadataFormat.class.isAssignableFrom(c)) {
                return null;
            }
        } catch (ClassNotFoundException e) {
        }
        if (thisModule.equals(targetModule) || c == null) {
            return c;
        }
        if (targetModule.isNamed()) {
            int i = formatClassName.lastIndexOf(".");
            String pn = i > 0 ? formatClassName.substring(0, i) : "";
            if (!targetModule.isExported(pn, thisModule)) {
                throw new IllegalStateException("Class " + formatClassName +
                   " in named module must be exported to java.desktop module.");
            }
        }
        return c;
    }

    
Returns an XML DOM Node object that represents the root of a tree of metadata contained within this object according to the conventions defined by a given metadata format. 
 The names of the available metadata formats may be queried using the getMetadataFormatNames method. 
Params:
  • formatName – the desired metadata format.
Throws:
See Also:
Returns:an XML DOM Node object forming the root of a tree.
/**
     * Returns an XML DOM {@code Node} object that represents the
     * root of a tree of metadata contained within this object
     * according to the conventions defined by a given metadata
     * format.
     *
     * <p> The names of the available metadata formats may be queried
     * using the {@code getMetadataFormatNames} method.
     *
     * @param formatName the desired metadata format.
     *
     * @return an XML DOM {@code Node} object forming the
     * root of a tree.
     *
     * @exception IllegalArgumentException if {@code formatName}
     * is {@code null} or is not one of the names returned by
     * {@code getMetadataFormatNames}.
     *
     * @see #getMetadataFormatNames
     * @see #setFromTree
     * @see #mergeTree
     */
    public abstract Node getAsTree(String formatName);

    
Alters the internal state of this IIOMetadata object from a tree of XML DOM Nodes whose syntax is defined by the given metadata format. The previous state is altered only as necessary to accommodate the nodes that are present in the given tree. If the tree structure or contents are invalid, an IIOInvalidTreeException will be thrown. 
 As the semantics of how a tree or subtree may be merged with
another tree are completely format-specific, plug-in authors may
implement this method in whatever manner is most appropriate for
the format, including simply replacing all existing state with the
contents of the given tree.

Params:
  • formatName – the desired metadata format.
  • root – an XML DOM Node object forming the root of a tree.
Throws:
See Also:
/**
     * Alters the internal state of this {@code IIOMetadata}
     * object from a tree of XML DOM {@code Node}s whose syntax
     * is defined by the given metadata format.  The previous state is
     * altered only as necessary to accommodate the nodes that are
     * present in the given tree.  If the tree structure or contents
     * are invalid, an {@code IIOInvalidTreeException} will be
     * thrown.
     *
     * <p> As the semantics of how a tree or subtree may be merged with
     * another tree are completely format-specific, plug-in authors may
     * implement this method in whatever manner is most appropriate for
     * the format, including simply replacing all existing state with the
     * contents of the given tree.
     *
     * @param formatName the desired metadata format.
     * @param root an XML DOM {@code Node} object forming the
     * root of a tree.
     *
     * @exception IllegalStateException if this object is read-only.
     * @exception IllegalArgumentException if {@code formatName}
     * is {@code null} or is not one of the names returned by
     * {@code getMetadataFormatNames}.
     * @exception IllegalArgumentException if {@code root} is
     * {@code null}.
     * @exception IIOInvalidTreeException if the tree cannot be parsed
     * successfully using the rules of the given format.
     *
     * @see #getMetadataFormatNames
     * @see #getAsTree
     * @see #setFromTree
     */
    public abstract void mergeTree(String formatName, Node root)
        throws IIOInvalidTreeException;

    
Returns an IIOMetadataNode representing the chroma information of the standard javax_imageio_1.0 metadata format, or null if no such information is available. This method is intended to be called by the utility routine getStandardTree. 
 The default implementation returns null. 
 Subclasses should override this method to produce an
appropriate subtree if they wish to support the standard
metadata format.

See Also:
Returns:an IIOMetadataNode, or null.
/**
     * Returns an {@code IIOMetadataNode} representing the chroma
     * information of the standard {@code javax_imageio_1.0}
     * metadata format, or {@code null} if no such information is
     * available.  This method is intended to be called by the utility
     * routine {@code getStandardTree}.
     *
     * <p> The default implementation returns {@code null}.
     *
     * <p> Subclasses should override this method to produce an
     * appropriate subtree if they wish to support the standard
     * metadata format.
     *
     * @return an {@code IIOMetadataNode}, or {@code null}.
     *
     * @see #getStandardTree
     */
    protected IIOMetadataNode getStandardChromaNode() {
        return null;
    }

    
Returns an IIOMetadataNode representing the compression information of the standard javax_imageio_1.0 metadata format, or null if no such information is available. This method is intended to be called by the utility routine getStandardTree. 
 The default implementation returns null. 
 Subclasses should override this method to produce an
appropriate subtree if they wish to support the standard
metadata format.

See Also:
Returns:an IIOMetadataNode, or null.
/**
     * Returns an {@code IIOMetadataNode} representing the
     * compression information of the standard
     * {@code javax_imageio_1.0} metadata format, or
     * {@code null} if no such information is available.  This
     * method is intended to be called by the utility routine
     * {@code getStandardTree}.
     *
     * <p> The default implementation returns {@code null}.
     *
     * <p> Subclasses should override this method to produce an
     * appropriate subtree if they wish to support the standard
     * metadata format.
     *
     * @return an {@code IIOMetadataNode}, or {@code null}.
     *
     * @see #getStandardTree
     */
    protected IIOMetadataNode getStandardCompressionNode() {
        return null;
    }

    
Returns an IIOMetadataNode representing the data format information of the standard javax_imageio_1.0 metadata format, or null if no such information is available. This method is intended to be called by the utility routine getStandardTree. 
 The default implementation returns null. 
 Subclasses should override this method to produce an
appropriate subtree if they wish to support the standard
metadata format.

See Also:
Returns:an IIOMetadataNode, or null.
/**
     * Returns an {@code IIOMetadataNode} representing the data
     * format information of the standard
     * {@code javax_imageio_1.0} metadata format, or
     * {@code null} if no such information is available.  This
     * method is intended to be called by the utility routine
     * {@code getStandardTree}.
     *
     * <p> The default implementation returns {@code null}.
     *
     * <p> Subclasses should override this method to produce an
     * appropriate subtree if they wish to support the standard
     * metadata format.
     *
     * @return an {@code IIOMetadataNode}, or {@code null}.
     *
     * @see #getStandardTree
     */
    protected IIOMetadataNode getStandardDataNode() {
        return null;
    }

    
Returns an IIOMetadataNode representing the dimension information of the standard javax_imageio_1.0 metadata format, or null if no such information is available. This method is intended to be called by the utility routine getStandardTree. 
 The default implementation returns null. 
 Subclasses should override this method to produce an
appropriate subtree if they wish to support the standard
metadata format.

See Also:
Returns:an IIOMetadataNode, or null.
/**
     * Returns an {@code IIOMetadataNode} representing the
     * dimension information of the standard
     * {@code javax_imageio_1.0} metadata format, or
     * {@code null} if no such information is available.  This
     * method is intended to be called by the utility routine
     * {@code getStandardTree}.
     *
     * <p> The default implementation returns {@code null}.
     *
     * <p> Subclasses should override this method to produce an
     * appropriate subtree if they wish to support the standard
     * metadata format.
     *
     * @return an {@code IIOMetadataNode}, or {@code null}.
     *
     * @see #getStandardTree
     */
    protected IIOMetadataNode getStandardDimensionNode() {
        return null;
    }

    
Returns an IIOMetadataNode representing the document information of the standard javax_imageio_1.0 metadata format, or null if no such information is available. This method is intended to be called by the utility routine getStandardTree. 
 The default implementation returns null. 
 Subclasses should override this method to produce an
appropriate subtree if they wish to support the standard
metadata format.

See Also:
Returns:an IIOMetadataNode, or null.
/**
     * Returns an {@code IIOMetadataNode} representing the document
     * information of the standard {@code javax_imageio_1.0}
     * metadata format, or {@code null} if no such information is
     * available.  This method is intended to be called by the utility
     * routine {@code getStandardTree}.
     *
     * <p> The default implementation returns {@code null}.
     *
     * <p> Subclasses should override this method to produce an
     * appropriate subtree if they wish to support the standard
     * metadata format.
     *
     * @return an {@code IIOMetadataNode}, or {@code null}.
     *
     * @see #getStandardTree
     */
    protected IIOMetadataNode getStandardDocumentNode() {
        return null;
    }

    
Returns an IIOMetadataNode representing the textual information of the standard javax_imageio_1.0 metadata format, or null if no such information is available. This method is intended to be called by the utility routine getStandardTree. 
 The default implementation returns null. 
 Subclasses should override this method to produce an
appropriate subtree if they wish to support the standard
metadata format.

See Also:
Returns:an IIOMetadataNode, or null.
/**
     * Returns an {@code IIOMetadataNode} representing the textual
     * information of the standard {@code javax_imageio_1.0}
     * metadata format, or {@code null} if no such information is
     * available.  This method is intended to be called by the utility
     * routine {@code getStandardTree}.
     *
     * <p> The default implementation returns {@code null}.
     *
     * <p> Subclasses should override this method to produce an
     * appropriate subtree if they wish to support the standard
     * metadata format.
     *
     * @return an {@code IIOMetadataNode}, or {@code null}.
     *
     * @see #getStandardTree
     */
    protected IIOMetadataNode getStandardTextNode() {
        return null;
    }

    
Returns an IIOMetadataNode representing the tiling information of the standard javax_imageio_1.0 metadata format, or null if no such information is available. This method is intended to be called by the utility routine getStandardTree. 
 The default implementation returns null. 
 Subclasses should override this method to produce an
appropriate subtree if they wish to support the standard
metadata format.

See Also:
Returns:an IIOMetadataNode, or null.
/**
     * Returns an {@code IIOMetadataNode} representing the tiling
     * information of the standard {@code javax_imageio_1.0}
     * metadata format, or {@code null} if no such information is
     * available.  This method is intended to be called by the utility
     * routine {@code getStandardTree}.
     *
     * <p> The default implementation returns {@code null}.
     *
     * <p> Subclasses should override this method to produce an
     * appropriate subtree if they wish to support the standard
     * metadata format.
     *
     * @return an {@code IIOMetadataNode}, or {@code null}.
     *
     * @see #getStandardTree
     */
    protected IIOMetadataNode getStandardTileNode() {
        return null;
    }

    
Returns an IIOMetadataNode representing the transparency information of the standard javax_imageio_1.0 metadata format, or null if no such information is available. This method is intended to be called by the utility routine getStandardTree. 
 The default implementation returns null. 
 Subclasses should override this method to produce an
appropriate subtree if they wish to support the standard
metadata format.

Returns:an IIOMetadataNode, or null.
/**
     * Returns an {@code IIOMetadataNode} representing the
     * transparency information of the standard
     * {@code javax_imageio_1.0} metadata format, or
     * {@code null} if no such information is available.  This
     * method is intended to be called by the utility routine
     * {@code getStandardTree}.
     *
     * <p> The default implementation returns {@code null}.
     *
     * <p> Subclasses should override this method to produce an
     * appropriate subtree if they wish to support the standard
     * metadata format.
     *
     * @return an {@code IIOMetadataNode}, or {@code null}.
     */
    protected IIOMetadataNode getStandardTransparencyNode() {
        return null;
    }

    
Appends a new node to an existing node, if the new node is non-null. 
/**
     * Appends a new node to an existing node, if the new node is
     * non-{@code null}.
     */
    private void append(IIOMetadataNode root, IIOMetadataNode node) {
        if (node != null) {
            root.appendChild(node);
        }
    }

    
A utility method to return a tree of IIOMetadataNodes representing the metadata contained within this object according to the conventions of the standard javax_imageio_1.0 metadata format. 
 This method calls the various getStandard*Node methods to supply each of the subtrees rooted at the children of the root node. If any of those methods returns null, the corresponding subtree will be omitted. If all of them return null, a tree consisting of a single root node will be returned. 
See Also:
Returns:an IIOMetadataNode representing the root of a metadata tree in the javax_imageio_1.0 format.
/**
     * A utility method to return a tree of
     * {@code IIOMetadataNode}s representing the metadata
     * contained within this object according to the conventions of
     * the standard {@code javax_imageio_1.0} metadata format.
     *
     * <p> This method calls the various {@code getStandard*Node}
     * methods to supply each of the subtrees rooted at the children
     * of the root node.  If any of those methods returns
     * {@code null}, the corresponding subtree will be omitted.
     * If all of them return {@code null}, a tree consisting of a
     * single root node will be returned.
     *
     * @return an {@code IIOMetadataNode} representing the root
     * of a metadata tree in the {@code javax_imageio_1.0}
     * format.
     *
     * @see #getStandardChromaNode
     * @see #getStandardCompressionNode
     * @see #getStandardDataNode
     * @see #getStandardDimensionNode
     * @see #getStandardDocumentNode
     * @see #getStandardTextNode
     * @see #getStandardTileNode
     * @see #getStandardTransparencyNode
     */
    protected final IIOMetadataNode getStandardTree() {
        IIOMetadataNode root = new IIOMetadataNode
                (IIOMetadataFormatImpl.standardMetadataFormatName);
        append(root, getStandardChromaNode());
        append(root, getStandardCompressionNode());
        append(root, getStandardDataNode());
        append(root, getStandardDimensionNode());
        append(root, getStandardDocumentNode());
        append(root, getStandardTextNode());
        append(root, getStandardTileNode());
        append(root, getStandardTransparencyNode());
        return root;
    }

    
Sets the internal state of this IIOMetadata object from a tree of XML DOM Nodes whose syntax is defined by the given metadata format. The previous state is discarded. If the tree's structure or contents are invalid, an IIOInvalidTreeException will be thrown. 
 The default implementation calls reset followed by mergeTree(formatName, root). 
Params:
  • formatName – the desired metadata format.
  • root – an XML DOM Node object forming the root of a tree.
Throws:
See Also:
/**
     * Sets the internal state of this {@code IIOMetadata} object
     * from a tree of XML DOM {@code Node}s whose syntax is
     * defined by the given metadata format.  The previous state is
     * discarded.  If the tree's structure or contents are invalid, an
     * {@code IIOInvalidTreeException} will be thrown.
     *
     * <p> The default implementation calls {@code reset}
     * followed by {@code mergeTree(formatName, root)}.
     *
     * @param formatName the desired metadata format.
     * @param root an XML DOM {@code Node} object forming the
     * root of a tree.
     *
     * @exception IllegalStateException if this object is read-only.
     * @exception IllegalArgumentException if {@code formatName}
     * is {@code null} or is not one of the names returned by
     * {@code getMetadataFormatNames}.
     * @exception IllegalArgumentException if {@code root} is
     * {@code null}.
     * @exception IIOInvalidTreeException if the tree cannot be parsed
     * successfully using the rules of the given format.
     *
     * @see #getMetadataFormatNames
     * @see #getAsTree
     * @see #mergeTree
     */
    public void setFromTree(String formatName, Node root)
        throws IIOInvalidTreeException {
        reset();
        mergeTree(formatName, root);
    }

    
Resets all the data stored in this object to default values,
usually to the state this object was in immediately after
construction, though the precise semantics are plug-in specific.
Note that there are many possible default values, depending on
how the object was created.

Throws:
  • IllegalStateException – if this object is read-only.
See Also:
/**
     * Resets all the data stored in this object to default values,
     * usually to the state this object was in immediately after
     * construction, though the precise semantics are plug-in specific.
     * Note that there are many possible default values, depending on
     * how the object was created.
     *
     * @exception IllegalStateException if this object is read-only.
     *
     * @see javax.imageio.ImageReader#getStreamMetadata
     * @see javax.imageio.ImageReader#getImageMetadata
     * @see javax.imageio.ImageWriter#getDefaultStreamMetadata
     * @see javax.imageio.ImageWriter#getDefaultImageMetadata
     */
    public abstract void reset();

    
Sets the IIOMetadataController to be used to provide settings for this IIOMetadata object when the activateController method is called, overriding any default controller. If the argument is null, no controller will be used, including any default. To restore the default, use setController(getDefaultController()). 
 The default implementation sets the controller instance variable to the supplied value. 
Params:
  • controller – An appropriate IIOMetadataController, or null.
See Also:
/**
     * Sets the {@code IIOMetadataController} to be used
     * to provide settings for this {@code IIOMetadata}
     * object when the {@code activateController} method
     * is called, overriding any default controller.  If the
     * argument is {@code null}, no controller will be
     * used, including any default.  To restore the default, use
     * {@code setController(getDefaultController())}.
     *
     * <p> The default implementation sets the {@code controller}
     * instance variable to the supplied value.
     *
     * @param controller An appropriate
     * {@code IIOMetadataController}, or {@code null}.
     *
     * @see IIOMetadataController
     * @see #getController
     * @see #getDefaultController
     * @see #hasController
     * @see #activateController()
     */
    public void setController(IIOMetadataController controller) {
        this.controller = controller;
    }

    
Returns whatever IIOMetadataController is currently installed. This could be the default if there is one, null, or the argument of the most recent call to setController. 
 The default implementation returns the value of the controller instance variable. 
See Also:
Returns:the currently installed IIOMetadataController, or null.
/**
     * Returns whatever {@code IIOMetadataController} is currently
     * installed.  This could be the default if there is one,
     * {@code null}, or the argument of the most recent call
     * to {@code setController}.
     *
     * <p> The default implementation returns the value of the
     * {@code controller} instance variable.
     *
     * @return the currently installed
     * {@code IIOMetadataController}, or {@code null}.
     *
     * @see IIOMetadataController
     * @see #setController
     * @see #getDefaultController
     * @see #hasController
     * @see #activateController()
     */
    public IIOMetadataController getController() {
        return controller;
    }

    
Returns the default IIOMetadataController, if there is one, regardless of the currently installed controller. If there is no default controller, returns null. 
 The default implementation returns the value of the defaultController instance variable. 
See Also:
Returns:the default IIOMetadataController, or null.
/**
     * Returns the default {@code IIOMetadataController}, if there
     * is one, regardless of the currently installed controller.  If
     * there is no default controller, returns {@code null}.
     *
     * <p> The default implementation returns the value of the
     * {@code defaultController} instance variable.
     *
     * @return the default {@code IIOMetadataController}, or
     * {@code null}.
     *
     * @see IIOMetadataController
     * @see #setController(IIOMetadataController)
     * @see #getController
     * @see #hasController
     * @see #activateController()
     */
    public IIOMetadataController getDefaultController() {
        return defaultController;
    }

    
Returns true if there is a controller installed for this IIOMetadata object. 
 The default implementation returns true if the getController method returns a non-null value. 
See Also:
Returns:true if a controller is installed.
/**
     * Returns {@code true} if there is a controller installed
     * for this {@code IIOMetadata} object.
     *
     * <p> The default implementation returns {@code true} if the
     * {@code getController} method returns a
     * non-{@code null} value.
     *
     * @return {@code true} if a controller is installed.
     *
     * @see IIOMetadataController
     * @see #setController(IIOMetadataController)
     * @see #getController
     * @see #getDefaultController
     * @see #activateController()
     */
    public boolean hasController() {
        return (getController() != null);
    }

    
Activates the installed IIOMetadataController for this IIOMetadata object and returns the resulting value. When this method returns true, all values for this IIOMetadata object will be ready for the next write operation. If false is returned, no settings in this object will have been disturbed (i.e., the user canceled the operation).

 Ordinarily, the controller will be a GUI providing a user interface for a subclass of IIOMetadata for a particular plug-in. Controllers need not be GUIs, however. 
 The default implementation calls getController and the calls activate on the returned object if hasController returns true. 
Throws:
See Also:
Returns:true if the controller completed normally.
/**
     * Activates the installed {@code IIOMetadataController} for
     * this {@code IIOMetadata} object and returns the resulting
     * value.  When this method returns {@code true}, all values for this
     * {@code IIOMetadata} object will be ready for the next write
     * operation.  If {@code false} is
     * returned, no settings in this object will have been disturbed
     * (<i>i.e.</i>, the user canceled the operation).
     *
     * <p> Ordinarily, the controller will be a GUI providing a user
     * interface for a subclass of {@code IIOMetadata} for a
     * particular plug-in.  Controllers need not be GUIs, however.
     *
     * <p> The default implementation calls {@code getController}
     * and the calls {@code activate} on the returned object if
     * {@code hasController} returns {@code true}.
     *
     * @return {@code true} if the controller completed normally.
     *
     * @exception IllegalStateException if there is no controller
     * currently installed.
     *
     * @see IIOMetadataController
     * @see #setController(IIOMetadataController)
     * @see #getController
     * @see #getDefaultController
     * @see #hasController
     */
    public boolean activateController() {
        if (!hasController()) {
            throw new IllegalStateException("hasController() == false!");
        }
        return getController().activate(this);
    }
}