/* ******************************************************************************
* Copyright (c) 2006-2012 XMind Ltd. and others.
*
* This file is a part of XMind 3. XMind releases 3 and
* above are dual-licensed under the Eclipse Public License (EPL),
* which is available at http://www.eclipse.org/legal/epl-v10.html
* and the GNU Lesser General Public License (LGPL),
* which is available at http://www.gnu.org/licenses/lgpl.html
* See http://www.xmind.net/license.html for details.
*
* Contributors:
* XMind Ltd. - initial API and implementation
*******************************************************************************/
package org.xmind.gef.graphicalpolicy;
import org.xmind.gef.part.IGraphicalPart;
/**
* @author Frank Shaka
*/
public interface IStyleSelector {
/**
* Selects a proper style value for this part by the given key.
* <p>
* An implementor may take into account following ways of acquiring a value:
* <br>
* <ul>
* <li>defined by user (may be directly provided by the part's model);</li>
* <li>inherited from the parent part;</li>
* <li>derived from parent styles;</li>
* <li>provided by a default style sheet;</li>
* <li>restricted by other specific attributes, e.g. position, layout,
* index, etc.</li>
* </ul>
* </p>
* <p>
* The order of the above methods are not specified and none of them is
* guaranteed to be performed by an implementor, but commonly it's a good
* practice to try fetching user-defined value before the others unless
* there's some sort of restrictions encountered. If there's no value
* acquirable from any of the above sources, <code>null</code> may be
* returned.
* </p>
* <p>
*
* </p>
*
* @param part
* The part on which the returned style is applied
* @param key
* The key to find the value
* @return A value specified by this style selector; may by
* <code>null</code>
*/
String getStyleValue(IGraphicalPart part, String key);
/**
* Selects a proper style value for this part by the given key.
* <p>
* An implementor may take into account following ways of acquiring a value:
* <br>
* <ul>
* <li>defined by user (may be directly provided by the part's model);</li>
* <li>inherited from the parent part;</li>
* <li>derived from parent styles;</li>
* <li>provided by a default style sheet;</li>
* <li>restricted by other specific attributes, e.g. position, layout,
* index, etc.</li>
* </ul>
* </p>
* <p>
* The order of the above methods are not specified and none of them is
* guaranteed to be performed by an implementor, but commonly it's a good
* practice to try fetching user-defined value before the others unless
* there's some sort of restrictions encountered. If there's no value
* acquirable from any of the above sources, <code>null</code> may be
* returned.
* </p>
*
* @param part
* The part on which the returned style is applied
* @param key
* The key to find the value
* @param defaultValueProvider
* The default value provider
* @return A value specified by this style selector; may by
* <code>null</code>
*/
String getStyleValue(IGraphicalPart part, String key,
IStyleValueProvider defaultValueProvider);
/**
* Gets the user-defined value for this part by the given key.
*
* @param part
* The part on which the returned style is applied
* @param key
* The key to find the value
* @return A user-defined value acquired from the part
*/
String getUserValue(IGraphicalPart part, String key);
/**
* Selects a value that's not defined by user for this part by the given
* key.
*
* @param part
* The part on which the returned style is applied
* @param key
* The key to find the value
* @return A value that's not defined by user
*/
String getAutoValue(IGraphicalPart part, String key);
/**
*
* @param part
* @param key
* @param defaultValue
* @return
*/
String getAutoValue(IGraphicalPart part, String key,
IStyleValueProvider defaultValueProvider);
String getOverridedValue(IGraphicalPart part, String key, String layerName);
}
