com.google.dart.tools.ui.internal.viewsupport.ImageDescriptorRegistry.java Source code

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Here is the source code for com.google.dart.tools.ui.internal.viewsupport.ImageDescriptorRegistry.java

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/*
 * Copyright (c) 2011, the Dart project authors.
 * 
 * Licensed under the Eclipse Public License v1.0 (the "License"); you may not use this file except
 * in compliance with the License. You may obtain a copy of the License at
 * 
 * http://www.eclipse.org/legal/epl-v10.html
 * 
 * Unless required by applicable law or agreed to in writing, software distributed under the License
 * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
 * or implied. See the License for the specific language governing permissions and limitations under
 * the License.
 */
package com.google.dart.tools.ui.internal.viewsupport;

import com.google.dart.tools.ui.internal.util.SWTUtil;

import org.eclipse.core.runtime.Assert;
import org.eclipse.jface.resource.ImageDescriptor;
import org.eclipse.swt.graphics.Image;
import org.eclipse.swt.widgets.Display;

import java.util.HashMap;
import java.util.Iterator;

/**
 * A registry that maps <code>ImageDescriptors</code> to <code>Image</code>.
 */
public class ImageDescriptorRegistry {

    private HashMap<ImageDescriptor, Image> fRegistry = new HashMap<ImageDescriptor, Image>(10);
    private Display fDisplay;

    /**
     * Creates a new image descriptor registry for the current or default display, respectively.
     */
    public ImageDescriptorRegistry() {
        this(SWTUtil.getStandardDisplay());
    }

    /**
     * Creates a new image descriptor registry for the given display. All images managed by this
     * registry will be disposed when the display gets disposed.
     * 
     * @param display the display the images managed by this registry are allocated for
     */
    public ImageDescriptorRegistry(Display display) {
        fDisplay = display;
        Assert.isNotNull(fDisplay);
        hookDisplay();
    }

    /**
     * Disposes all images managed by this registry.
     */
    public void dispose() {
        for (Iterator<Image> iter = fRegistry.values().iterator(); iter.hasNext();) {
            Image image = iter.next();
            image.dispose();
        }
        fRegistry.clear();
    }

    /**
     * Returns the image associated with the given image descriptor.
     * 
     * @param descriptor the image descriptor for which the registry manages an image, or
     *          <code>null</code> for a missing image descriptor
     * @return the image associated with the image descriptor or <code>null</code> if the image
     *         descriptor can't create the requested image.
     */
    public Image get(ImageDescriptor descriptor) {
        if (descriptor == null) {
            descriptor = ImageDescriptor.getMissingImageDescriptor();
        }

        Image result = fRegistry.get(descriptor);
        if (result != null) {
            return result;
        }

        Assert.isTrue(fDisplay == SWTUtil.getStandardDisplay(), "Allocating image for wrong display."); //$NON-NLS-1$
        result = descriptor.createImage();
        if (result != null) {
            fRegistry.put(descriptor, result);
        }
        return result;
    }

    private void hookDisplay() {
        fDisplay.disposeExec(new Runnable() {
            @Override
            public void run() {
                dispose();
            }
        });
    }
}