/*
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* 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).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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*/
/**
* An interface to be implemented by objects that can determine the
* settings of an <code>IIOMetadata</code> object, either by putting
* up a GUI to obtain values from a user, or by other means. This
* interface merely specifies a generic <code>activate</code> method
* that invokes the controller, without regard for how the controller
* obtains values (<i>i.e.</i>, whether the controller puts up a GUI
* or merely computes a set of values is irrelevant to this
* interface).
*
* <p> Within the <code>activate</code> method, a controller obtains
* initial values by querying the <code>IIOMetadata</code> object's
* settings, either using the XML DOM tree or a plug-in specific
* interface, modifies values by whatever means, then modifies the
* <code>IIOMetadata</code> object's settings, using either the
* <code>setFromTree</code> or <code>mergeTree</code> methods, or a
* plug-in specific interface. In general, applications may expect
* that when the <code>activate</code> method returns
* <code>true</code>, the <code>IIOMetadata</code> object is ready for
* use in a write operation.
*
* <p> Vendors may choose to provide GUIs for the
* <code>IIOMetadata</code> subclasses they define for a particular
* plug-in. These can be set up as default controllers in the
* corresponding <code>IIOMetadata</code> subclasses.
*
* <p> 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 <code>activate</code> method would simply look up or
* compute the settings, call methods on <code>IIOMetadata</code> to
* set its state, and return <code>true</code>.
*
* @see IIOMetadata#setController
* @see IIOMetadata#getController
* @see IIOMetadata#getDefaultController
* @see IIOMetadata#hasController
* @see IIOMetadata#activateController
*
*/
public interface IIOMetadataController {
/**
* Activates the controller. If <code>true</code> is returned,
* all settings in the <code>IIOMetadata</code> object should be
* ready for use in a write operation. If <code>false</code> is
* returned, no settings in the <code>IIOMetadata</code> object
* will be disturbed (<i>i.e.</i>, the user canceled the
* operation).
*
* @param metadata the <code>IIOMetadata</code> object to be modified.
*
* @return <code>true</code> if the <code>IIOMetadata</code> has been
* modified, <code>false</code> otherwise.
*
* @exception IllegalArgumentException if <code>metadata</code> is
* <code>null</code> or is not an instance of the correct class.
*/
}