com.nextep.datadesigner.gui.service.ImageService.java Source code

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Here is the source code for com.nextep.datadesigner.gui.service.ImageService.java

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/*******************************************************************************
 * Copyright (c) 2011 neXtep Software and contributors.
 * All rights reserved.
 *
 * This file is part of neXtep designer.
 *
 * NeXtep designer is free software: you can redistribute it 
 * and/or modify it under the terms of the GNU General Public 
 * License as published by the Free Software Foundation, either 
 * version 3 of the License, or any later version.
 *
 * NeXtep designer 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 for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with Foobar.  If not, see <http://www.gnu.org/licenses/>.
 *
 * Contributors:
 *     neXtep Softwares - initial API and implementation
 *******************************************************************************/
package com.nextep.datadesigner.gui.service;

import java.io.File;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.HashMap;
import java.util.Map;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.eclipse.jface.resource.ImageDescriptor;
import org.eclipse.swt.SWT;
import org.eclipse.swt.graphics.Image;
import org.eclipse.swt.graphics.ImageData;
import org.eclipse.swt.graphics.ImageLoader;
import com.nextep.designer.ui.CoreUiPlugin;

/**
 * Image registry that keeps its images on the local file system.
 *
 * @since 1.0.3
 */
public class ImageService {

    private static final String IMAGE_DIR = "core-ui-images"; //$NON-NLS-1$

    private Map<ImageDescriptor, URL> fURLMap;
    private final File fTempDir;
    private int fImageCount;
    private static final Log log = LogFactory.getLog(ImageService.class);
    private static ImageService instance = null;

    public static final ImageService getInstance() {
        if (instance == null) {
            instance = new ImageService();
        }
        return instance;
    }

    private ImageService() {
        fURLMap = new HashMap<ImageDescriptor, URL>();
        fTempDir = getTempDir();
        fImageCount = 0;
    }

    private File getTempDir() {
        try {
            File imageDir = CoreUiPlugin.getDefault().getStateLocation().append(IMAGE_DIR).toFile();
            if (imageDir.exists()) {
                // has not been deleted on previous shutdown
                delete(imageDir);
            }
            if (!imageDir.exists()) {
                imageDir.mkdir();
            }
            if (!imageDir.isDirectory()) {
                log.error("Failed to create image directory " + imageDir.toString()); //$NON-NLS-1$
                return null;
            }
            return imageDir;
        } catch (IllegalStateException e) {
            // no state location
            return null;
        }
    }

    private void delete(File file) {
        if (file.isDirectory()) {
            File[] listFiles = file.listFiles();
            for (int i = 0; i < listFiles.length; i++) {
                delete(listFiles[i]);
            }
        }
        file.delete();
    }

    public URL getImageURL(Image img) {
        ImageDescriptor descriptor = ImageDescriptor.createFromImage(img);
        if (descriptor == null)
            return null;
        return getImageURL(descriptor);
    }

    public URL getImageURL(ImageDescriptor descriptor) {
        if (fTempDir == null)
            return null;

        URL url = (URL) fURLMap.get(descriptor);
        if (url != null)
            return url;

        File imageFile = getNewFile();
        ImageData imageData = descriptor.getImageData();
        if (imageData == null) {
            return null;
        }

        ImageLoader loader = new ImageLoader();
        loader.data = new ImageData[] { imageData };
        loader.save(imageFile.getAbsolutePath(), SWT.IMAGE_PNG);

        try {
            url = imageFile.toURI().toURL();
            fURLMap.put(descriptor, url);
            return url;
        } catch (MalformedURLException e) {
            log.error("Incorrect external image URL", e);
        }
        return null;
    }

    private File getNewFile() {
        File file;
        do {
            file = new File(fTempDir, String.valueOf(getImageCount()) + ".png"); //$NON-NLS-1$
        } while (file.exists());
        return file;
    }

    private synchronized int getImageCount() {
        return fImageCount++;
    }

    public void dispose() {
        if (fTempDir != null) {
            delete(fTempDir);
        }
        fURLMap = null;
    }
}