/**
* This file is part of muCommander, http://www.mucommander.com
* Copyright (C) 2002-2016 Maxence Bernard
*
* muCommander is free software; you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* muCommander 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 Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
package com.mucommander.commons.file.icon;
import com.mucommander.commons.file.AbstractFile;
import javax.swing.*;
import java.awt.*;
/**
* <code>CacheableFileIconProvider</code> is an interface to be implemented by file icon providers that wish to use
* some icon caching to improve performance. This interface is to be used in conjunction with {@link CachedFileIconProvider}
* to form a functional cached provider.
*
* @author Maxence Bernard
*/
public interface CacheableFileIconProvider extends FileIconProvider {
/**
* Returns <code>true</code> if the icon cache can be used for the specified file and preferred resolution. This
* method allows the icon cache to be used only for certain types of files and/or preferred resolutions.
*
* <p>This method is called by {@link CachedFileIconProvider#getFileIcon(com.mucommander.commons.file.AbstractFile, java.awt.Dimension)}
* each time an icon is requested. If <code>true</code> is returned, the icon cache will be looked up with
* {@link #lookupCache(com.mucommander.commons.file.AbstractFile, java.awt.Dimension)} and if the cache did not return
* an icon, the icon will be be added to the cache with {@link #addToCache(com.mucommander.commons.file.AbstractFile, javax.swing.Icon, java.awt.Dimension)}.
* <br/>
* On the other hand, if <code>false</code> is returned, {@link #getFileIcon(com.mucommander.commons.file.AbstractFile, java.awt.Dimension)}
* will simply be called, without querying or adding to the cache.
*
* @param file the file for which to retrieve an icon
* @param preferredResolution the preferred resolution for the icon
* @return true if the icon cache can be used with the specified file
*/
boolean isCacheable(AbstractFile file, Dimension preferredResolution);
/**
* This method is called by {@link CachedFileIconProvider#getFileIcon(com.mucommander.commons.file.AbstractFile, java.awt.Dimension)}
* to perform a cache lookup and give implementations a chance to re-use a cached icon. If a non-null value is
* returned, the returned icon will be used.
* <br/>
* On the other hand, if <code>null</code> is returned, the icon will be fetched using {@link #getFileIcon(com.mucommander.commons.file.AbstractFile, java.awt.Dimension)}
* followed by a call to {@link #addToCache(com.mucommander.commons.file.AbstractFile, javax.swing.Icon,java.awt.Dimension)}
* to add the freshly-retrieved icon to the cache.
*
* <p>This method is called only if the prior call to {@link #isCacheable(com.mucommander.commons.file.AbstractFile, java.awt.Dimension)}
* returned <code>true</code>.</p>.
*
* @param file the file for which to look for a previously cached icon
* @param preferredResolution the preferred resolution for the icon
* @return a cached icon to re-use, null if there is none
*/
Icon lookupCache(AbstractFile file, Dimension preferredResolution);
/**
* This method is called by {@link CachedFileIconProvider#getFileIcon(com.mucommander.commons.file.AbstractFile, java.awt.Dimension)}
* to give implementations a chance to cache an icon fetched with {@link #getFileIcon(com.mucommander.commons.file.AbstractFile, java.awt.Dimension)}
* and have it returned later by {@link #lookupCache(com.mucommander.commons.file.AbstractFile, java.awt.Dimension)}.
* <br/>
* There is no obligation for this method to cache the given icon, implementations may freely choose whether to
* cache certain icons only.
*
* <p>This method is called only if the prior call to {@link #isCacheable(com.mucommander.commons.file.AbstractFile, java.awt.Dimension)}
* returned <code>true</code>.</p>.
*
* @param file the file that corresponds to the given icon
* @param icon the icon to add to the cache
* @param preferredResolution the preferred icon resolution that was originally requested
*/
void addToCache(AbstractFile file, Icon icon, Dimension preferredResolution);
}