org.eclipse.graphiti.ui.internal.services.impl.ImageService.java Source code

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Here is the source code for org.eclipse.graphiti.ui.internal.services.impl.ImageService.java

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/*******************************************************************************
 * <copyright>
 *
 * Copyright (c) 2005, 2010 SAP AG.
 * 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
 *
 * Contributors:
 *    SAP AG - initial API, implementation and documentation
 *
 * </copyright>
 *
 *******************************************************************************/
package org.eclipse.graphiti.ui.internal.services.impl;

import org.eclipse.graphiti.ui.internal.GraphitiUIPlugin;
import org.eclipse.graphiti.ui.internal.platform.ExtensionManager;
import org.eclipse.graphiti.ui.platform.IImageProvider;
import org.eclipse.graphiti.ui.services.IImageService;
import org.eclipse.jface.resource.ImageDescriptor;
import org.eclipse.jface.resource.ImageRegistry;
import org.eclipse.swt.graphics.Image;
import org.eclipse.swt.graphics.ImageData;
import org.eclipse.ui.plugin.AbstractUIPlugin;

/**
 * @noinstantiate This class is not intended to be instantiated by clients.
 * @noextend This class is not intended to be subclassed by clients.
 */
public class ImageService implements IImageService {

    @Override
    public ImageDescriptor getImageDescriptorForId(String imageId) {

        if (imageId == null)
            return null;

        ImageRegistry imageRegistry = GraphitiUIPlugin.getDefault().getImageRegistry();
        ImageDescriptor imageDescriptor = imageRegistry.getDescriptor(imageId);
        if (imageDescriptor != null) {
            return imageDescriptor;
        }

        imageDescriptor = createImageDescriptorForId(imageId);
        return imageDescriptor;
    }

    @Override
    public Image getImageForId(String imageId) {

        if (imageId == null)
            return null;

        // if image already available take it
        ImageRegistry imageRegistry = GraphitiUIPlugin.getDefault().getImageRegistry();
        Image result = imageRegistry.get(imageId);
        if (result != null && !result.isDisposed()) {
            return result;
        }

        createImageDescriptorForId(imageId);
        Image image = imageRegistry.get(imageId); // now there is an image
        // registered
        if (image == null) {
            throw new IllegalStateException("No image could be retrieved for imageId '" + imageId + "'"); //$NON-NLS-1$ //$NON-NLS-2$
        }
        return image;
    }

    /**
     * This method fixes a problem for ImageDescriptors. It returns a corrected
     * ImageDescriptor for problematic ImageDescriptors.
     * <p>
     * There is a problem with transparent GIFs. If the RGB value of the
     * transparent color index is identical to the RGB value of other colors
     * indices in the palette, then all those color indices are considered as
     * transparent. So as a result the transparency seems to be on an RGB value
     * instead of a color index.
     */
    private ImageDescriptor fixImageDescriptor(ImageDescriptor descriptor) {
        // Typically the incoming ImageDescriptor is an URLImageDescriptor. The following lines create an ImageDataImageDescriptor
        // from it, which basically describes the same image. But that one works. So there seems to be an error in the
        // URLImageDescriptor.
        ImageData data = descriptor.getImageData();
        return ImageDescriptor.createFromImageData(data);

    }

    private ImageDescriptor createImageDescriptorForId(String imageId) {

        if (imageId == null)
            return null;

        // if image descriptor already exists return it
        ImageRegistry imageRegistry = GraphitiUIPlugin.getDefault().getImageRegistry();
        ImageDescriptor imageDescriptor = imageRegistry.getDescriptor(imageId);
        if (imageDescriptor != null) {
            return imageDescriptor;
        }

        // try get the image-location from the image-providers
        IImageProvider imageProviders[] = ExtensionManager.getSingleton().getImageProviders();
        for (int i = 0; i < imageProviders.length; i++) {
            IImageProvider imageProvider = imageProviders[i];
            String imageFilePath = imageProvider.getImageFilePath(imageId);
            if (imageFilePath != null) {
                String pluginId = imageProvider.getPluginId();
                if (pluginId != null) {
                    // try to create Image from ImageDescriptor (initialize the ImageRegistry on the fly)
                    imageDescriptor = AbstractUIPlugin.imageDescriptorFromPlugin(pluginId, imageFilePath);
                }
                break;
            }
        }

        if (imageDescriptor == null) {
            imageDescriptor = ImageDescriptor.getMissingImageDescriptor();
        }

        imageDescriptor = fixImageDescriptor(imageDescriptor);
        imageRegistry.put(imageId, imageDescriptor);

        return imageDescriptor;
    }
}