org.eclipse.e4mf.common.ui.ImageURIRegistry.java Source code

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Here is the source code for org.eclipse.e4mf.common.ui.ImageURIRegistry.java

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/**
 * Copyright (c) 2012 IBM Corporation and others.
 * All rights reserved.   This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 */
package org.eclipse.e4mf.common.ui;

import java.io.File;
import java.util.HashMap;

import org.eclipse.emf.common.util.URI;
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;

/**
 * A registry for mapping an image or image descriptor to a URI representing a local file system cached location for that image.
 *
 * @since 2.9
 */
public final class ImageURIRegistry {
    /**
     * The static instance for this registry.
     */
    public static final ImageURIRegistry INSTANCE = new ImageURIRegistry();

    private static final String IMAGE_DIR = "emf-common-ui-images";

    private HashMap<ImageDescriptor, URI> descriptorToURIMap;
    private final File imageDirectory;
    private int imageCount;

    private ImageURIRegistry() {
        descriptorToURIMap = new HashMap<ImageDescriptor, URI>();
        imageDirectory = getTempDir();
    }

    /**
     * Returns a URI to the cached local file system instance of this given image.
     */
    public URI getImageURI(Image image) {
        return getImageURI(ImageDescriptor.createFromImage(image));
    }

    /**
     * Returns a URI to the cached local file system instance of this given image descriptor.
     */
    public synchronized URI getImageURI(ImageDescriptor descriptor) {
        if (imageDirectory == null)
            return null;

        URI uri = descriptorToURIMap.get(descriptor);
        if (uri != null)
            return uri;

        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);

        uri = URI.createURI(imageFile.toURI().toString());
        descriptorToURIMap.put(descriptor, uri);
        return uri;
    }

    private File getTempDir() {
        try {
            File imageDirectory = CommonUIPlugin.getPlugin().getStateLocation().append(IMAGE_DIR).toFile();
            if (imageDirectory.exists()) {
                delete(imageDirectory);
            }
            if (!imageDirectory.exists()) {
                imageDirectory.mkdir();
            }
            if (!imageDirectory.isDirectory()) {
                CommonUIPlugin.INSTANCE.log("Failed to create image directory " + imageDirectory.toString()); //$NON-NLS-1$
                return null;
            }
            return imageDirectory;
        } catch (IllegalStateException e) {
            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();
    }

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

    void dispose() {
        if (imageDirectory != null) {
            delete(imageDirectory);
        }
        descriptorToURIMap = null;
    }
}