IIOMetadata (Java Platform SE 7 b118)

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Java™ Platform
Standard Ed. 7
DRAFT ea-b118

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javax.imageio.metadata
Class IIOMetadata

java.lang.Object
  javax.imageio.metadata.IIOMetadata

public abstract class IIOMetadata
extends Object

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 transfering 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:: ImageReader.getImageMetadata(int), ImageReader.getStreamMetadata(), ImageReader.readAll(int, javax.imageio.ImageReadParam), ImageWriter.getDefaultStreamMetadata(javax.imageio.ImageWriteParam), ImageWriter.getDefaultImageMetadata(javax.imageio.ImageTypeSpecifier, javax.imageio.ImageWriteParam), ImageWriter.write(javax.imageio.metadata.IIOMetadata, javax.imageio.IIOImage, javax.imageio.ImageWriteParam), ImageWriter.convertImageMetadata(javax.imageio.metadata.IIOMetadata, javax.imageio.ImageTypeSpecifier, javax.imageio.ImageWriteParam), ImageWriter.convertStreamMetadata(javax.imageio.metadata.IIOMetadata, javax.imageio.ImageWriteParam), IIOImage, ImageTranscoder

Field Summary
Modifier and Type	Field and Description
`protected IIOMetadataController`	`controller` The `IIOMetadataController` that will be used to provide settings for this `IIOMetadata` object when the `activateController` method is called.
`protected IIOMetadataController`	`defaultController` An `IIOMetadataController` that is suggested for use as the controller for this `IIOMetadata` object.
`protected String[]`	`extraMetadataFormatClassNames` 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.
`protected String[]`	`extraMetadataFormatNames` 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.
`protected String`	`nativeMetadataFormatClassName` The name of the class implementing `IIOMetadataFormat` and representing the native metadata format, initialized to `null` and set via the constructor.
`protected String`	`nativeMetadataFormatName` The name of the native metadata format for this object, initialized to `null` and set via the constructor.
`protected boolean`	`standardFormatSupported` A boolean indicating whether the concrete subclass supports the standard metadata format, set via the constructor.

Constructor Summary
Modifier	Constructor and Description
`protected`	`IIOMetadata()` Constructs an empty `IIOMetadata` object.
`protected`	`IIOMetadata(boolean standardMetadataFormatSupported, String nativeMetadataFormatName, String nativeMetadataFormatClassName, String[] extraMetadataFormatNames, String[] extraMetadataFormatClassNames)` 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.

Method Summary
Modifier and Type	Method and Description
`boolean`	`activateController()` Activates the installed `IIOMetadataController` for this `IIOMetadata` object and returns the resulting value.
`abstract Node`	`getAsTree(String formatName)` 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.
`IIOMetadataController`	`getController()` Returns whatever `IIOMetadataController` is currently installed.
`IIOMetadataController`	`getDefaultController()` Returns the default `IIOMetadataController`, if there is one, regardless of the currently installed controller.
`String[]`	`getExtraMetadataFormatNames()` Returns an array of `String`s 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.
`IIOMetadataFormat`	`getMetadataFormat(String formatName)` Returns an `IIOMetadataFormat` object describing the given metadata format, or `null` if no description is available.
`String[]`	`getMetadataFormatNames()` Returns an array of `String`s containing the names of all metadata formats, including the native and standard formats, recognized by this plug-in's `getAsTree`, `setFromTree`, and `mergeTree` methods.
`String`	`getNativeMetadataFormatName()` 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.
`protected IIOMetadataNode`	`getStandardChromaNode()` Returns an `IIOMetadataNode` representing the chroma information of the standard `javax_imageio_1.0` metadata format, or `null` if no such information is available.
`protected IIOMetadataNode`	`getStandardCompressionNode()` Returns an `IIOMetadataNode` representing the compression information of the standard `javax_imageio_1.0` metadata format, or `null` if no such information is available.
`protected IIOMetadataNode`	`getStandardDataNode()` 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.
`protected IIOMetadataNode`	`getStandardDimensionNode()` Returns an `IIOMetadataNode` representing the dimension information of the standard `javax_imageio_1.0` metadata format, or `null` if no such information is available.
`protected IIOMetadataNode`	`getStandardDocumentNode()` Returns an `IIOMetadataNode` representing the document information of the standard `javax_imageio_1.0` metadata format, or `null` if no such information is available.
`protected IIOMetadataNode`	`getStandardTextNode()` Returns an `IIOMetadataNode` representing the textual information of the standard `javax_imageio_1.0` metadata format, or `null` if no such information is available.
`protected IIOMetadataNode`	`getStandardTileNode()` Returns an `IIOMetadataNode` representing the tiling information of the standard `javax_imageio_1.0` metadata format, or `null` if no such information is available.
`protected IIOMetadataNode`	`getStandardTransparencyNode()` Returns an `IIOMetadataNode` representing the transparency information of the standard `javax_imageio_1.0` metadata format, or `null` if no such information is available.
`protected IIOMetadataNode`	`getStandardTree()` A utility method to return a tree of `IIOMetadataNode`s representing the metadata contained within this object according to the conventions of the standard `javax_imageio_1.0` metadata format.
`boolean`	`hasController()` Returns `true` if there is a controller installed for this `IIOMetadata` object.
`abstract boolean`	`isReadOnly()` Returns `true` if this object does not support the `mergeTree`, `setFromTree`, and `reset` methods.
`boolean`	`isStandardMetadataFormatSupported()` Returns `true` if the standard metadata format is supported by `getMetadataFormat`, `getAsTree`, `setFromTree`, and `mergeTree`.
`abstract void`	`mergeTree(String formatName, Node root)` Alters the internal state of this `IIOMetadata` object from a tree of XML DOM `Node`s whose syntax is defined by the given metadata format.
`abstract void`	`reset()` 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.
`void`	`setController(IIOMetadataController controller)` Sets the `IIOMetadataController` to be used to provide settings for this `IIOMetadata` object when the `activateController` method is called, overriding any default controller.
`void`	`setFromTree(String formatName, Node root)` Sets the internal state of this `IIOMetadata` object from a tree of XML DOM `Node`s whose syntax is defined by the given metadata format.

Methods inherited from class java.lang.Object
`clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

Field Detail

standardFormatSupported

protected boolean standardFormatSupported

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

nativeMetadataFormatName

protected String nativeMetadataFormatName

The name of the native metadata format for this object, initialized to null and set via the constructor.

nativeMetadataFormatClassName

protected String nativeMetadataFormatClassName

The name of the class implementing IIOMetadataFormat and representing the native metadata format, initialized to null and set via the constructor.

extraMetadataFormatNames

protected String[] extraMetadataFormatNames

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.

extraMetadataFormatClassNames

protected String[] extraMetadataFormatClassNames

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.

defaultController

protected IIOMetadataController defaultController

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:: IIOMetadataController, getDefaultController()

controller

protected IIOMetadataController controller

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:: IIOMetadataController, setController(IIOMetadataController), hasController(), activateController()

Constructor Detail

IIOMetadata

protected IIOMetadata()

Constructs an empty IIOMetadata object. The subclass is responsible for suppying values for all protected instance variables that will allow any non-overridden default implemtations of methods to satisfy their contracts. For example, extraMetadataFormatNames should not have length 0.

IIOMetadata

protected IIOMetadata(boolean standardMetadataFormatSupported,
                      String nativeMetadataFormatName,
                      String nativeMetadataFormatClassName,
                      String[] extraMetadataFormatNames,
                      String[] extraMetadataFormatClassNames)

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.

Parameters:: 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:: IllegalArgumentException - if extraMetadataFormatNames has length 0.; IllegalArgumentException - if extraMetadataFormatNames and extraMetadataFormatClassNames are neither both null, nor of the same length.

Method Detail

isStandardMetadataFormatSupported

public boolean isStandardMetadataFormatSupported()

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.

Returns:: true if the standard metadata format is supported.
See Also:: getAsTree(java.lang.String), setFromTree(java.lang.String, org.w3c.dom.Node), mergeTree(java.lang.String, org.w3c.dom.Node), getMetadataFormat(java.lang.String)

isReadOnly

public abstract boolean isReadOnly()

Returns true if this object does not support the mergeTree, setFromTree, and reset methods.

Returns:: true if this IIOMetadata object cannot be modified.

getNativeMetadataFormatName

public String getNativeMetadataFormatName()

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, nullwill 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.

Returns:: the name of the native format, or null.
See Also:: getExtraMetadataFormatNames(), getMetadataFormatNames()

getExtraMetadataFormatNames

public String[] getExtraMetadataFormatNames()

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.

Returns:: an array of Strings with length at least 1, or null.
See Also:: getAsTree(java.lang.String), setFromTree(java.lang.String, org.w3c.dom.Node), mergeTree(java.lang.String, org.w3c.dom.Node), getNativeMetadataFormatName(), getMetadataFormatNames()

getMetadataFormatNames

public String[] getMetadataFormatNames()

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.

Returns:: an array of Strings.
See Also:: getNativeMetadataFormatName(), isStandardMetadataFormatSupported(), getExtraMetadataFormatNames()

getMetadataFormat

public IIOMetadataFormat getMetadataFormat(String formatName)

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.

Parameters:: formatName - the desired metadata format.
Returns:: an IIOMetadataFormat object.
Throws:: IllegalArgumentException - if formatName is null or is not one of the names recognized by the plug-in.; IllegalStateException - if the class corresponding to the format name cannot be loaded.

getAsTree

public abstract Node getAsTree(String formatName)

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.

Parameters:: formatName - the desired metadata format.
Returns:: an XML DOM Node object forming the root of a tree.
Throws:: IllegalArgumentException - if formatName is null or is not one of the names returned by getMetadataFormatNames.
See Also:: getMetadataFormatNames(), setFromTree(java.lang.String, org.w3c.dom.Node), mergeTree(java.lang.String, org.w3c.dom.Node)

mergeTree

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

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 accomodate 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.

Parameters:: formatName - the desired metadata format.; root - an XML DOM Node object forming the root of a tree.
Throws:: IllegalStateException - if this object is read-only.; IllegalArgumentException - if formatName is null or is not one of the names returned by getMetadataFormatNames.; IllegalArgumentException - if root is null.; IIOInvalidTreeException - if the tree cannot be parsed successfully using the rules of the given format.
See Also:: getMetadataFormatNames(), getAsTree(java.lang.String), setFromTree(java.lang.String, org.w3c.dom.Node)

getStandardChromaNode

protected IIOMetadataNode getStandardChromaNode()

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.