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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
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* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
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*
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
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*
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package javax.imageio.metadata;
/**
* An interface to be implemented by objects that can determine the
* settings of an IIOMetadata
object, either by putting
* up a GUI to obtain values from a user, or by other means. This
* interface merely specifies a generic activate
method
* that invokes the controller, without regard for how the controller
* obtains values (i.e., whether the controller puts up a GUI
* or merely computes a set of values is irrelevant to this
* interface).
*
*
Within the activate
method, a controller obtains
* initial values by querying the IIOMetadata
object's
* settings, either using the XML DOM tree or a plug-in specific
* interface, modifies values by whatever means, then modifies the
* IIOMetadata
object's settings, using either the
* setFromTree
or mergeTree
methods, or a
* plug-in specific interface. In general, applications may expect
* that when the activate
method returns
* true
, the IIOMetadata
object is ready for
* use in a write operation.
*
*
Vendors may choose to provide GUIs for the
* IIOMetadata
subclasses they define for a particular
* plug-in. These can be set up as default controllers in the
* corresponding IIOMetadata
subclasses.
*
*
Alternatively, an algorithmic process such as a database lookup
* or the parsing of a command line could be used as a controller, in
* which case the activate
method would simply look up or
* compute the settings, call methods on IIOMetadata
to
* set its state, and return true
.
*
* @see IIOMetadata#setController
* @see IIOMetadata#getController
* @see IIOMetadata#getDefaultController
* @see IIOMetadata#hasController
* @see IIOMetadata#activateController
*
*/
public interface IIOMetadataController {
/**
* Activates the controller. If true
is returned,
* all settings in the IIOMetadata
object should be
* ready for use in a write operation. If false
is
* returned, no settings in the IIOMetadata
object
* will be disturbed (i.e., the user canceled the
* operation).
*
* @param metadata the IIOMetadata
object to be modified.
*
* @return true
if the IIOMetadata
has been
* modified, false
otherwise.
*
* @exception IllegalArgumentException if metadata
is
* null
or is not an instance of the correct class.
*/
boolean activate(IIOMetadata metadata);
}