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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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package javax.imageio.metadata;
import org.w3c.dom.Node;
import java.lang.reflect.Method;
import java.lang.reflect.Module;
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 {@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.
*/
protected boolean standardFormatSupported;
/**
* 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 {@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 {@code null} and set via the constructor.
*/
protected String[] extraMetadataFormatNames = null;
/**
* 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 {@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 {@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 {@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 {@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 {@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 {@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,
* {@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 {@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 {@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 {@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 {@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 {@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 {@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 {@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 {@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 {@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 {@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 {@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 {@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 {@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-{@code null}.
*/
private void append(IIOMetadataNode root, IIOMetadataNode node) {
if (node != null) {
root.appendChild(node);
}
}
/**
* 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 {@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.
*
* @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 {@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 {@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 {@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 {@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 {@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);
}
}