plugins/org.eclipse.graphiti.ui/src/org/eclipse/graphiti/ui/internal/platform/ExtensionManager.java - graphiti/org.eclipse.graphiti - Git at Google

 /*********************************************************************
 * Copyright (c) 2005, 2019 SAP SE
 *
 * This program and the accompanying materials are made
 * available under the terms of the Eclipse Public License 2.0
 * which is available at https://www.eclipse.org/legal/epl-2.0/
 *
 * Contributors:
 *    SAP SE - initial API, implementation and documentation
 *    mwenz - Bug 352709 - invalid image provider id crashes diagram editor
 *    fvelasco - Bug 323349 - Enable external invocation of features
 *    fvelasco - Bug 396247 - ImageDescriptor changes
 *    pjpaulin - Bug 352120 - Now uses IDiagramContainerUI interface
 *
 * SPDX-License-Identifier: EPL-2.0
 **********************************************************************/
 package org.eclipse.graphiti.ui.internal.platform;

 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.HashMap;
 import java.util.HashSet;
 import java.util.List;
 import java.util.Map;
 import java.util.Set;

 import org.eclipse.core.runtime.Assert;
 import org.eclipse.core.runtime.CoreException;
 import org.eclipse.core.runtime.IConfigurationElement;
 import org.eclipse.core.runtime.IContributor;
 import org.eclipse.core.runtime.IExtension;
 import org.eclipse.core.runtime.IExtensionPoint;
 import org.eclipse.core.runtime.IExtensionRegistry;
 import org.eclipse.core.runtime.Platform;
 import org.eclipse.emf.transaction.TransactionalEditingDomain;
 import org.eclipse.emf.transaction.util.TransactionUtil;
 import org.eclipse.graphiti.dt.IDiagramType;
 import org.eclipse.graphiti.dt.IDiagramTypeProvider;
 import org.eclipse.graphiti.features.IFeatureProvider;
 import org.eclipse.graphiti.internal.util.T;
 import org.eclipse.graphiti.mm.pictograms.Diagram;
 import org.eclipse.graphiti.ui.editor.IDiagramContainerUI;
 import org.eclipse.graphiti.ui.internal.editor.DiagramEditorDummy;
 import org.eclipse.graphiti.ui.internal.util.ui.print.IDiagramsExporter;
 import org.eclipse.graphiti.ui.platform.IImageProvider;
 import org.eclipse.graphiti.ui.platform.PlatformImageProvider;
 import org.eclipse.graphiti.ui.services.IExtensionManager;

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

 	private static ExtensionManager singleton;

 	private static String EP_DIAGRAM_TYPES = "org.eclipse.graphiti.ui.diagramTypes"; //$NON-NLS-1$

 	private static String EP_IMAGE_PROVIDERS = "org.eclipse.graphiti.ui.imageProviders"; //$NON-NLS-1$

 	private static String EP_DIAGRAM_TYPE_PROVIDERS = "org.eclipse.graphiti.ui.diagramTypeProviders"; //$NON-NLS-1$

 	private static String EP_DIAGRAM_EXPORTERS = "org.eclipse.graphiti.ui.diagramExporters"; //$NON-NLS-1$

 	private static final String EP_CHILD_NODE_DIAGRAM_EXPORTER = "diagramexporter"; //$NON-NLS-1$

 	private static final String EP_CHILD_NODE_IMAGE_PROVIDER = "imageProvider"; //$NON-NLS-1$

 	private static final String EP_CHILD_NODE_DIAGRAM_TYPE = "diagramType"; //$NON-NLS-1$

 	private static final String EP_CHILD_NODE_DIAGRAM_TYPE_PROVIDER = "diagramTypeProvider"; //$NON-NLS-1$

 	private static final String EP_ATTRIBUTE_CLASS = "class"; //$NON-NLS-1$

 	private static final String EP_ATTRIBUTE_ID = "id"; //$NON-NLS-1$

 	private static final String EP_ATTRIBUTE_TYPE = "type"; //$NON-NLS-1$

 	private static final String EP_ATTRIBUTE_ENABLEUI = "enableScaling"; //$NON-NLS-1$

 	private static final String EP_ATTRIBUTE_NAME = "name"; //$NON-NLS-1$

 	private static final String EP_ATTRIBUTE_DESCRIPTION = "description"; //$NON-NLS-1$

 	private static final String EP_ATTRIBUTE_CONTEXT = "context"; //$NON-NLS-1$

 	private IDiagramType diagramTypes[] = null;

 	private IImageProvider imageProviders[] = null;

 	private IImageProvider platformImageProvider = null;

 	private Map<String, Set<IImageProvider>> dtp2imageProvider = null;

 	/**
 	 *
 	 */
 	private ExtensionManager() {
 		super();
 		dtp2imageProvider = new HashMap<String, Set<IImageProvider>>();
 		searchForExtensions();
 	}

 	public static ExtensionManager getSingleton() {
 		if (singleton == null) {
 			singleton = new ExtensionManager();
 		}
 		return singleton;
 	}

 	public String[] getDiagramTypeProviderIds(String diagramTypeId) {
 		String ret[] = new String[0];
 		if (diagramTypeId == null) {
 			return ret;
 		}
 		List<String> retList = new ArrayList<String>();

 		IExtensionRegistry extensionRegistry = Platform.getExtensionRegistry();

 		IExtensionPoint extensionPoint = extensionRegistry.getExtensionPoint(EP_DIAGRAM_TYPE_PROVIDERS);
 		IExtension[] extensions = extensionPoint.getExtensions();
 		for (int i = 0; i < extensions.length; i++) {
 			IExtension extension = extensions[i];
 			IConfigurationElement[] configurationElements = extension.getConfigurationElements();
 			for (int j = 0; j < configurationElements.length; j++) {
 				IConfigurationElement element = configurationElements[j];
 				String extensionId = element.getAttribute(EP_ATTRIBUTE_ID);
 				if (extensionId != null) {
 					// read references to diagram types
 					IConfigurationElement[] children = element.getChildren();
 					for (int k = 0; k < children.length; k++) {
 						IConfigurationElement childElement = children[k];
 						String childName = childElement.getName();
 						String childExtensionId = childElement.getAttribute(EP_ATTRIBUTE_ID);
 						if (childName != null && childExtensionId != null) {
 							if (EP_CHILD_NODE_DIAGRAM_TYPE.equals(childName)) {
 								String typeId = getDiagramTypeIdForDiagramTypeProviderId(childExtensionId);
 								if (diagramTypeId.equals(typeId)) {
 									retList.add(extensionId);
 									break;
 								}
 							}
 						}
 					}
 				}
 			}
 		}

 		ret = retList.toArray(ret);
 		return ret;
 	}

 	public Map<String, Boolean> getDiagramExporterTypes() {
 		Map<String, Boolean> ret = new HashMap<String, Boolean>();
 		IExtensionRegistry extensionRegistry = Platform.getExtensionRegistry();
 		IExtensionPoint extensionPoint = extensionRegistry.getExtensionPoint(EP_DIAGRAM_EXPORTERS);
 		IExtension[] extensions = extensionPoint.getExtensions();
 		for (int i = 0; i < extensions.length; i++) {
 			IExtension extension = extensions[i];
 			IConfigurationElement[] configurationElements = extension.getConfigurationElements();
 			for (int j = 0; j < configurationElements.length; j++) {
 				IConfigurationElement element = configurationElements[j];
 				String name = element.getName();
 				String type = element.getAttribute(EP_ATTRIBUTE_TYPE);
 				if (name != null && type != null) {
 					if (EP_CHILD_NODE_DIAGRAM_EXPORTER.equals(name)) {
 						String enableScaling = element.getAttribute(EP_ATTRIBUTE_ENABLEUI);
 						ret.put(type, Boolean.valueOf(enableScaling));
 						break;
 					}
 				}
 			}
 		}
 		return ret;
 	}

 	public IDiagramsExporter getDiagramExporterForType(String type) {
 		IExtensionRegistry extensionRegistry = Platform.getExtensionRegistry();
 		IExtensionPoint extensionPoint = extensionRegistry.getExtensionPoint(EP_DIAGRAM_EXPORTERS);
 		IExtension[] extensions = extensionPoint.getExtensions();
 		for (int i = 0; i < extensions.length; i++) {
 			IExtension extension = extensions[i];
 			IConfigurationElement[] configurationElements = extension.getConfigurationElements();
 			for (int j = 0; j < configurationElements.length; j++) {
 				IConfigurationElement element = configurationElements[j];
 				String name = element.getName();
 				String currType = element.getAttribute(EP_ATTRIBUTE_TYPE);
 				if (name != null && type != null) {
 					if (EP_CHILD_NODE_DIAGRAM_EXPORTER.equals(name) && type.equals(currType)) {
 						try {
 							Object executableExtension = element.createExecutableExtension(EP_ATTRIBUTE_CLASS);
 							if (executableExtension instanceof IDiagramsExporter) {
 								return (IDiagramsExporter) executableExtension;
 							}
 						} catch (CoreException e) {
 							e.printStackTrace();
 						}
 					}
 				}
 			}
 		}

 		return null;
 	}

 	private void searchForExtensions() {

 		// read and store all diagram types which are registered with the
 		// extension point
 		List<IDiagramType> diagramTypeList = createDiagramTypes();
 		diagramTypes = diagramTypeList.toArray(new IDiagramType[0]);

 		imageProviders = new IImageProvider[0];

 		// load image providers from the framework
 		platformImageProvider = loadImageProvider(PlatformImageProvider.ID);
 	}

 	public IDiagramTypeProvider createDiagramTypeProvider(String providerId) {
 		IDiagramTypeProvider diagramTypeProvider = null;

 		if (providerId == null) {
 			return diagramTypeProvider;
 		}
 		IExtensionRegistry extensionRegistry = Platform.getExtensionRegistry();

 		IExtensionPoint extensionPoint = extensionRegistry.getExtensionPoint(EP_DIAGRAM_TYPE_PROVIDERS);
 		IExtension[] extensions = extensionPoint.getExtensions();
 		for (int i = 0; i < extensions.length; i++) {
 			IExtension extension = extensions[i];
 			IConfigurationElement[] configurationElements = extension.getConfigurationElements();
 			for (int j = 0; j < configurationElements.length; j++) {
 				IConfigurationElement element = configurationElements[j];
 				String extensionId = element.getAttribute(EP_ATTRIBUTE_ID);
 				if (extensionId != null && extensionId.equals(providerId)) {
 					String name = element.getAttribute(EP_ATTRIBUTE_NAME);
 					String description = element.getAttribute(EP_ATTRIBUTE_DESCRIPTION);
 					if (description == null) {
 						description = ""; //$NON-NLS-1$
 					}
 					String context = element.getAttribute(EP_ATTRIBUTE_CONTEXT);
 					if (context == null) {
 						context = IDiagramContainerUI.DIAGRAM_CONTEXT_ID;
 					}
 					if (name != null) {
 						// read direct references to image extensions and try to
 						// instantiate image provider
 						IConfigurationElement[] children = element.getChildren();
 						for (int k = 0; k < children.length; k++) {
 							IConfigurationElement childElement = children[k];
 							String childName = childElement.getName();
 							String childExtensionId = childElement.getAttribute(EP_ATTRIBUTE_ID);
 							if (childName != null && childExtensionId != null) {
 								if (EP_CHILD_NODE_IMAGE_PROVIDER.equals(childName)) {
 									IImageProvider imageProvider = loadImageProvider(childExtensionId);
 									if (imageProvider == null) {
 										IllegalArgumentException e = new IllegalArgumentException("A Graphiti image provider with id '" //$NON-NLS-1$
 												+ childExtensionId + "' could not be found"); //$NON-NLS-1$
 										T.racer().error("Error while creating the children for '" + providerId + "'", e); //$NON-NLS-1$ //$NON-NLS-2$
 									} else {
 										registerImageProviderForDiagramTypeProvider(providerId, imageProvider);
 									}
 								}
 							}
 						}
 						try {
 							Object executableExtension = element.createExecutableExtension(EP_ATTRIBUTE_CLASS);
 							if (executableExtension instanceof IDiagramTypeProvider) {
 								diagramTypeProvider = (IDiagramTypeProvider) executableExtension;
 								diagramTypeProvider.setProviderId(extensionId);
 								diagramTypeProvider.setContextId(context);
 								// TODO later store also name and description -
 								// is only necessary if this information
 								// are shown in the UI
 							}
 						} catch (CoreException e) {
 							// $JL-EXC$
 							T.racer().error("Unable to create DiagramTypeProvider class", e);
 						}
 					}
 				}
 			}
 		}

 		IExtensionPoint imageProviderExtensionPoint = extensionRegistry.getExtensionPoint(EP_IMAGE_PROVIDERS);
 		// read image providers that point back to this diagramTypeProvider
 		for (IExtension extension : imageProviderExtensionPoint.getExtensions()) {
 			IConfigurationElement[] configurationElements = extension.getConfigurationElements();
 			for (int j = 0; j < configurationElements.length; j++) {
 				IConfigurationElement element = configurationElements[j];
 				String imageProviderId = element.getAttribute(EP_ATTRIBUTE_ID);

 				IConfigurationElement[] children = element.getChildren(EP_CHILD_NODE_DIAGRAM_TYPE_PROVIDER);

 				for (IConfigurationElement child : children) {
 					String referredDiagramTypeProviderId = child.getAttribute(EP_ATTRIBUTE_ID);
 					if (providerId.equals(referredDiagramTypeProviderId)) {
 						IImageProvider imageProvider = loadImageProvider(imageProviderId);
 						registerImageProviderForDiagramTypeProvider(providerId, imageProvider);
 						break;
 					}
 				}
 			}
 		}

 		return diagramTypeProvider;
 	}

 	public IImageProvider getPlatformImageProvider() {
 		return platformImageProvider;
 	}

 	public Collection<IImageProvider> getImageProvidersForDiagramTypeProviderId(String providerId) {
 		Collection<IImageProvider> providers = dtp2imageProvider.get(providerId);
 		if (providers == null)
 			return Collections.singleton(platformImageProvider);
 		else
 			return providers;
 	}

 	public IDiagramType[] getDiagramTypes() {
 		return diagramTypes;
 	}

 	private String getDiagramTypeIdForDiagramTypeProviderId(String providerId) {
 		if (providerId != null) {
 			IDiagramType diagramTypes[] = getDiagramTypes();
 			for (int i = 0; i < diagramTypes.length; i++) {
 				IDiagramType diagramType = diagramTypes[i];
 				if (providerId.equals(diagramType.getProviderId())) {
 					return diagramType.getId();
 				}
 			}
 		}
 		return null;
 	}

 	private IImageProvider loadImageProvider(String imageProviderId) {

 		// check whether the image provider is already loaded
 		for (int i = 0; i < imageProviders.length; i++) {
 			IImageProvider provider = imageProviders[i];
 			if (imageProviderId.equals(provider.getProviderId())) {
 				return provider;
 			}
 		}
 		IImageProvider newProvider = createImageProvider(imageProviderId);
 		if (newProvider != null) {

 			// extend current list of image providers
 			IImageProvider imageProvidersDest[] = new IImageProvider[imageProviders.length + 1];
 			System.arraycopy(imageProviders, 0, imageProvidersDest, 0, imageProviders.length);
 			imageProvidersDest[imageProviders.length] = newProvider;
 			imageProviders = imageProvidersDest;

 			return newProvider;
 		}

 		return null;
 	}

 	private List<IDiagramType> createDiagramTypes() {

 		List<IDiagramType> ret = new ArrayList<IDiagramType>();

 		IExtensionRegistry extensionRegistry = Platform.getExtensionRegistry();

 		IExtensionPoint extensionPoint = extensionRegistry.getExtensionPoint(EP_DIAGRAM_TYPES);
 		IExtension[] extensions = extensionPoint.getExtensions();
 		for (int i = 0; i < extensions.length; i++) {
 			IExtension extension = extensions[i];
 			IConfigurationElement[] configurationElements = extension.getConfigurationElements();
 			for (int j = 0; j < configurationElements.length; j++) {
 				IConfigurationElement element = configurationElements[j];
 				String extensionId = element.getAttribute(EP_ATTRIBUTE_ID);
 				String typeId = element.getAttribute(EP_ATTRIBUTE_TYPE);
 				String typeName = element.getAttribute(EP_ATTRIBUTE_NAME);
 				String typeDescription = element.getAttribute(EP_ATTRIBUTE_DESCRIPTION);
 				if (typeDescription == null) {
 					typeDescription = ""; //$NON-NLS-1$
 				}
 				if (extensionId != null && typeId != null && typeName != null) {
 					IDiagramType diagramType = new DiagramTypeImpl(typeId, typeName, typeDescription);
 					diagramType.setProviderId(extensionId);
 					ret.add(diagramType);
 				}
 			}
 		}
 		return ret;
 	}

 	private IImageProvider createImageProvider(String providerId) {

 		if (providerId == null) {
 			return null;
 		}
 		IExtensionRegistry extensionRegistry = Platform.getExtensionRegistry();

 		IExtensionPoint extensionPoint = extensionRegistry.getExtensionPoint(EP_IMAGE_PROVIDERS);
 		IExtension[] extensions = extensionPoint.getExtensions();
 		for (int i = 0; i < extensions.length; i++) {
 			IExtension extension = extensions[i];
 			IConfigurationElement[] configurationElements = extension.getConfigurationElements();
 			for (int j = 0; j < configurationElements.length; j++) {
 				IConfigurationElement element = configurationElements[j];
 				String extensionId = element.getAttribute(EP_ATTRIBUTE_ID);
 				if (providerId.equals(extensionId)) {
 					try {
 						Object executableExtension = element.createExecutableExtension(EP_ATTRIBUTE_CLASS);
 						if (executableExtension instanceof IImageProvider) {
 							IContributor contributor = extension.getContributor();
 							if (contributor != null) {
 								String pluginId = contributor.getName();
 								if (pluginId != null) {
 									IImageProvider imageProvider = (IImageProvider) executableExtension;
 									imageProvider.setProviderId(extensionId);
 									imageProvider.setPluginId(pluginId);
 									return imageProvider;
 								}
 							}
 						}
 					} catch (CoreException e) {
 						// $JL-EXC$
 						e.printStackTrace();
 					}
 				}
 			}
 		}
 		return null;
 	}

 	private void registerImageProviderForDiagramTypeProvider(String providerId, IImageProvider imageProvider) {
 		Set<IImageProvider> providers = dtp2imageProvider.get(providerId);
 		if (providers == null) {
 			providers = new HashSet<IImageProvider>();
 			dtp2imageProvider.put(providerId, providers);
 			providers.add(platformImageProvider);
 		}

 		providers.add(imageProvider);
 	}

 	public IFeatureProvider createFeatureProvider(Diagram diagram) {
 		Assert.isNotNull(diagram);
 		String providerId = getDiagramTypeProviderId(diagram.getDiagramTypeId());
 		if (providerId != null) {
 			IDiagramTypeProvider dtp = createDiagramTypeProvider(diagram, providerId);
 			return dtp.getFeatureProvider();
 		}
 		return null;
 	}

 	public IDiagramTypeProvider createDiagramTypeProvider(Diagram diagram, String providerId) {
 		Assert.isNotNull(diagram);
 		IDiagramTypeProvider dtp = createDiagramTypeProvider(providerId);
 		if (dtp != null) {
 			TransactionalEditingDomain editingDomain = TransactionUtil.getEditingDomain(diagram);
 			DiagramEditorDummy diagramEditor = new DiagramEditorDummy(dtp, editingDomain);
 			dtp.init(diagram, diagramEditor.getDiagramBehavior());
 		}
 		return dtp;
 	}

 	public String getDiagramTypeProviderId(String diagramTypeId) {
 		String diagramTypeProviders[] = getDiagramTypeProviderIds(diagramTypeId);
 		if (diagramTypeProviders != null && diagramTypeProviders.length > 0) {
 			return diagramTypeProviders[0];
 		}
 		return null;
 	}

 }
	/*********************************************************************
	* Copyright (c) 2005, 2019 SAP SE
	*
	* This program and the accompanying materials are made
	* available under the terms of the Eclipse Public License 2.0
	* which is available at https://www.eclipse.org/legal/epl-2.0/
	*
	* Contributors:
	* SAP SE - initial API, implementation and documentation
	* mwenz - Bug 352709 - invalid image provider id crashes diagram editor
	* fvelasco - Bug 323349 - Enable external invocation of features
	* fvelasco - Bug 396247 - ImageDescriptor changes
	* pjpaulin - Bug 352120 - Now uses IDiagramContainerUI interface
	*
	* SPDX-License-Identifier: EPL-2.0
	**********************************************************************/
	package org.eclipse.graphiti.ui.internal.platform;

	import java.util.ArrayList;
	import java.util.Collection;
	import java.util.Collections;
	import java.util.HashMap;
	import java.util.HashSet;
	import java.util.List;
	import java.util.Map;
	import java.util.Set;

	import org.eclipse.core.runtime.Assert;
	import org.eclipse.core.runtime.CoreException;
	import org.eclipse.core.runtime.IConfigurationElement;
	import org.eclipse.core.runtime.IContributor;
	import org.eclipse.core.runtime.IExtension;
	import org.eclipse.core.runtime.IExtensionPoint;
	import org.eclipse.core.runtime.IExtensionRegistry;
	import org.eclipse.core.runtime.Platform;
	import org.eclipse.emf.transaction.TransactionalEditingDomain;
	import org.eclipse.emf.transaction.util.TransactionUtil;
	import org.eclipse.graphiti.dt.IDiagramType;
	import org.eclipse.graphiti.dt.IDiagramTypeProvider;
	import org.eclipse.graphiti.features.IFeatureProvider;
	import org.eclipse.graphiti.internal.util.T;
	import org.eclipse.graphiti.mm.pictograms.Diagram;
	import org.eclipse.graphiti.ui.editor.IDiagramContainerUI;
	import org.eclipse.graphiti.ui.internal.editor.DiagramEditorDummy;
	import org.eclipse.graphiti.ui.internal.util.ui.print.IDiagramsExporter;
	import org.eclipse.graphiti.ui.platform.IImageProvider;
	import org.eclipse.graphiti.ui.platform.PlatformImageProvider;
	import org.eclipse.graphiti.ui.services.IExtensionManager;

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

	private static ExtensionManager singleton;

	private static String EP_DIAGRAM_TYPES = "org.eclipse.graphiti.ui.diagramTypes"; //$NON-NLS-1$

	private static String EP_IMAGE_PROVIDERS = "org.eclipse.graphiti.ui.imageProviders"; //$NON-NLS-1$

	private static String EP_DIAGRAM_TYPE_PROVIDERS = "org.eclipse.graphiti.ui.diagramTypeProviders"; //$NON-NLS-1$

	private static String EP_DIAGRAM_EXPORTERS = "org.eclipse.graphiti.ui.diagramExporters"; //$NON-NLS-1$

	private static final String EP_CHILD_NODE_DIAGRAM_EXPORTER = "diagramexporter"; //$NON-NLS-1$

	private static final String EP_CHILD_NODE_IMAGE_PROVIDER = "imageProvider"; //$NON-NLS-1$

	private static final String EP_CHILD_NODE_DIAGRAM_TYPE = "diagramType"; //$NON-NLS-1$

	private static final String EP_CHILD_NODE_DIAGRAM_TYPE_PROVIDER = "diagramTypeProvider"; //$NON-NLS-1$

	private static final String EP_ATTRIBUTE_CLASS = "class"; //$NON-NLS-1$

	private static final String EP_ATTRIBUTE_ID = "id"; //$NON-NLS-1$

	private static final String EP_ATTRIBUTE_TYPE = "type"; //$NON-NLS-1$

	private static final String EP_ATTRIBUTE_ENABLEUI = "enableScaling"; //$NON-NLS-1$

	private static final String EP_ATTRIBUTE_NAME = "name"; //$NON-NLS-1$

	private static final String EP_ATTRIBUTE_DESCRIPTION = "description"; //$NON-NLS-1$

	private static final String EP_ATTRIBUTE_CONTEXT = "context"; //$NON-NLS-1$

	private IDiagramType diagramTypes[] = null;

	private IImageProvider imageProviders[] = null;

	private IImageProvider platformImageProvider = null;

	private Map<String, Set<IImageProvider>> dtp2imageProvider = null;

	/**
	*
	*/
	private ExtensionManager() {
	super();
	dtp2imageProvider = new HashMap<String, Set<IImageProvider>>();
	searchForExtensions();
	}

	public static ExtensionManager getSingleton() {
	if (singleton == null) {
	singleton = new ExtensionManager();
	}
	return singleton;
	}

	public String[] getDiagramTypeProviderIds(String diagramTypeId) {
	String ret[] = new String[0];
	if (diagramTypeId == null) {
	return ret;
	}
	List<String> retList = new ArrayList<String>();

	IExtensionRegistry extensionRegistry = Platform.getExtensionRegistry();

	IExtensionPoint extensionPoint = extensionRegistry.getExtensionPoint(EP_DIAGRAM_TYPE_PROVIDERS);
	IExtension[] extensions = extensionPoint.getExtensions();
	for (int i = 0; i < extensions.length; i++) {
	IExtension extension = extensions[i];
	IConfigurationElement[] configurationElements = extension.getConfigurationElements();
	for (int j = 0; j < configurationElements.length; j++) {
	IConfigurationElement element = configurationElements[j];
	String extensionId = element.getAttribute(EP_ATTRIBUTE_ID);
	if (extensionId != null) {
	// read references to diagram types
	IConfigurationElement[] children = element.getChildren();
	for (int k = 0; k < children.length; k++) {
	IConfigurationElement childElement = children[k];
	String childName = childElement.getName();
	String childExtensionId = childElement.getAttribute(EP_ATTRIBUTE_ID);
	if (childName != null && childExtensionId != null) {
	if (EP_CHILD_NODE_DIAGRAM_TYPE.equals(childName)) {
	String typeId = getDiagramTypeIdForDiagramTypeProviderId(childExtensionId);
	if (diagramTypeId.equals(typeId)) {
	retList.add(extensionId);
	break;
	}
	}
	}
	}
	}
	}
	}

	ret = retList.toArray(ret);
	return ret;
	}

	public Map<String, Boolean> getDiagramExporterTypes() {
	Map<String, Boolean> ret = new HashMap<String, Boolean>();
	IExtensionRegistry extensionRegistry = Platform.getExtensionRegistry();
	IExtensionPoint extensionPoint = extensionRegistry.getExtensionPoint(EP_DIAGRAM_EXPORTERS);
	IExtension[] extensions = extensionPoint.getExtensions();
	for (int i = 0; i < extensions.length; i++) {
	IExtension extension = extensions[i];
	IConfigurationElement[] configurationElements = extension.getConfigurationElements();
	for (int j = 0; j < configurationElements.length; j++) {
	IConfigurationElement element = configurationElements[j];
	String name = element.getName();
	String type = element.getAttribute(EP_ATTRIBUTE_TYPE);
	if (name != null && type != null) {
	if (EP_CHILD_NODE_DIAGRAM_EXPORTER.equals(name)) {
	String enableScaling = element.getAttribute(EP_ATTRIBUTE_ENABLEUI);
	ret.put(type, Boolean.valueOf(enableScaling));
	break;
	}
	}
	}
	}
	return ret;
	}

	public IDiagramsExporter getDiagramExporterForType(String type) {
	IExtensionRegistry extensionRegistry = Platform.getExtensionRegistry();
	IExtensionPoint extensionPoint = extensionRegistry.getExtensionPoint(EP_DIAGRAM_EXPORTERS);
	IExtension[] extensions = extensionPoint.getExtensions();
	for (int i = 0; i < extensions.length; i++) {
	IExtension extension = extensions[i];
	IConfigurationElement[] configurationElements = extension.getConfigurationElements();
	for (int j = 0; j < configurationElements.length; j++) {
	IConfigurationElement element = configurationElements[j];
	String name = element.getName();
	String currType = element.getAttribute(EP_ATTRIBUTE_TYPE);
	if (name != null && type != null) {
	if (EP_CHILD_NODE_DIAGRAM_EXPORTER.equals(name) && type.equals(currType)) {
	try {
	Object executableExtension = element.createExecutableExtension(EP_ATTRIBUTE_CLASS);
	if (executableExtension instanceof IDiagramsExporter) {
	return (IDiagramsExporter) executableExtension;
	}
	} catch (CoreException e) {
	e.printStackTrace();
	}
	}
	}
	}
	}

	return null;
	}

	private void searchForExtensions() {

	// read and store all diagram types which are registered with the
	// extension point
	List<IDiagramType> diagramTypeList = createDiagramTypes();
	diagramTypes = diagramTypeList.toArray(new IDiagramType[0]);

	imageProviders = new IImageProvider[0];

	// load image providers from the framework
	platformImageProvider = loadImageProvider(PlatformImageProvider.ID);
	}

	public IDiagramTypeProvider createDiagramTypeProvider(String providerId) {
	IDiagramTypeProvider diagramTypeProvider = null;

	if (providerId == null) {
	return diagramTypeProvider;
	}
	IExtensionRegistry extensionRegistry = Platform.getExtensionRegistry();

	IExtensionPoint extensionPoint = extensionRegistry.getExtensionPoint(EP_DIAGRAM_TYPE_PROVIDERS);
	IExtension[] extensions = extensionPoint.getExtensions();
	for (int i = 0; i < extensions.length; i++) {
	IExtension extension = extensions[i];
	IConfigurationElement[] configurationElements = extension.getConfigurationElements();
	for (int j = 0; j < configurationElements.length; j++) {
	IConfigurationElement element = configurationElements[j];
	String extensionId = element.getAttribute(EP_ATTRIBUTE_ID);
	if (extensionId != null && extensionId.equals(providerId)) {
	String name = element.getAttribute(EP_ATTRIBUTE_NAME);
	String description = element.getAttribute(EP_ATTRIBUTE_DESCRIPTION);
	if (description == null) {
	description = ""; //$NON-NLS-1$
	}
	String context = element.getAttribute(EP_ATTRIBUTE_CONTEXT);
	if (context == null) {
	context = IDiagramContainerUI.DIAGRAM_CONTEXT_ID;
	}
	if (name != null) {
	// read direct references to image extensions and try to
	// instantiate image provider
	IConfigurationElement[] children = element.getChildren();
	for (int k = 0; k < children.length; k++) {
	IConfigurationElement childElement = children[k];
	String childName = childElement.getName();
	String childExtensionId = childElement.getAttribute(EP_ATTRIBUTE_ID);
	if (childName != null && childExtensionId != null) {
	if (EP_CHILD_NODE_IMAGE_PROVIDER.equals(childName)) {
	IImageProvider imageProvider = loadImageProvider(childExtensionId);
	if (imageProvider == null) {
	IllegalArgumentException e = new IllegalArgumentException("A Graphiti image provider with id '" //$NON-NLS-1$
	+ childExtensionId + "' could not be found"); //$NON-NLS-1$
	T.racer().error("Error while creating the children for '" + providerId + "'", e); //$NON-NLS-1$ //$NON-NLS-2$
	} else {
	registerImageProviderForDiagramTypeProvider(providerId, imageProvider);
	}
	}
	}
	}
	try {
	Object executableExtension = element.createExecutableExtension(EP_ATTRIBUTE_CLASS);
	if (executableExtension instanceof IDiagramTypeProvider) {
	diagramTypeProvider = (IDiagramTypeProvider) executableExtension;
	diagramTypeProvider.setProviderId(extensionId);
	diagramTypeProvider.setContextId(context);
	// TODO later store also name and description -
	// is only necessary if this information
	// are shown in the UI
	}
	} catch (CoreException e) {
	// $JL-EXC$
	T.racer().error("Unable to create DiagramTypeProvider class", e);
	}
	}
	}
	}
	}

	IExtensionPoint imageProviderExtensionPoint = extensionRegistry.getExtensionPoint(EP_IMAGE_PROVIDERS);
	// read image providers that point back to this diagramTypeProvider
	for (IExtension extension : imageProviderExtensionPoint.getExtensions()) {
	IConfigurationElement[] configurationElements = extension.getConfigurationElements();
	for (int j = 0; j < configurationElements.length; j++) {
	IConfigurationElement element = configurationElements[j];
	String imageProviderId = element.getAttribute(EP_ATTRIBUTE_ID);

	IConfigurationElement[] children = element.getChildren(EP_CHILD_NODE_DIAGRAM_TYPE_PROVIDER);

	for (IConfigurationElement child : children) {
	String referredDiagramTypeProviderId = child.getAttribute(EP_ATTRIBUTE_ID);
	if (providerId.equals(referredDiagramTypeProviderId)) {
	IImageProvider imageProvider = loadImageProvider(imageProviderId);
	registerImageProviderForDiagramTypeProvider(providerId, imageProvider);
	break;
	}
	}
	}
	}

	return diagramTypeProvider;
	}

	public IImageProvider getPlatformImageProvider() {
	return platformImageProvider;
	}

	public Collection<IImageProvider> getImageProvidersForDiagramTypeProviderId(String providerId) {
	Collection<IImageProvider> providers = dtp2imageProvider.get(providerId);
	if (providers == null)
	return Collections.singleton(platformImageProvider);
	else
	return providers;
	}

	public IDiagramType[] getDiagramTypes() {
	return diagramTypes;
	}

	private String getDiagramTypeIdForDiagramTypeProviderId(String providerId) {
	if (providerId != null) {
	IDiagramType diagramTypes[] = getDiagramTypes();
	for (int i = 0; i < diagramTypes.length; i++) {
	IDiagramType diagramType = diagramTypes[i];
	if (providerId.equals(diagramType.getProviderId())) {
	return diagramType.getId();
	}
	}
	}
	return null;
	}

	private IImageProvider loadImageProvider(String imageProviderId) {

	// check whether the image provider is already loaded
	for (int i = 0; i < imageProviders.length; i++) {
	IImageProvider provider = imageProviders[i];
	if (imageProviderId.equals(provider.getProviderId())) {
	return provider;
	}
	}
	IImageProvider newProvider = createImageProvider(imageProviderId);
	if (newProvider != null) {

	// extend current list of image providers
	IImageProvider imageProvidersDest[] = new IImageProvider[imageProviders.length + 1];
	System.arraycopy(imageProviders, 0, imageProvidersDest, 0, imageProviders.length);
	imageProvidersDest[imageProviders.length] = newProvider;
	imageProviders = imageProvidersDest;

	return newProvider;
	}

	return null;
	}

	private List<IDiagramType> createDiagramTypes() {

	List<IDiagramType> ret = new ArrayList<IDiagramType>();

	IExtensionRegistry extensionRegistry = Platform.getExtensionRegistry();

	IExtensionPoint extensionPoint = extensionRegistry.getExtensionPoint(EP_DIAGRAM_TYPES);
	IExtension[] extensions = extensionPoint.getExtensions();
	for (int i = 0; i < extensions.length; i++) {
	IExtension extension = extensions[i];
	IConfigurationElement[] configurationElements = extension.getConfigurationElements();
	for (int j = 0; j < configurationElements.length; j++) {
	IConfigurationElement element = configurationElements[j];
	String extensionId = element.getAttribute(EP_ATTRIBUTE_ID);
	String typeId = element.getAttribute(EP_ATTRIBUTE_TYPE);
	String typeName = element.getAttribute(EP_ATTRIBUTE_NAME);
	String typeDescription = element.getAttribute(EP_ATTRIBUTE_DESCRIPTION);
	if (typeDescription == null) {
	typeDescription = ""; //$NON-NLS-1$
	}
	if (extensionId != null && typeId != null && typeName != null) {
	IDiagramType diagramType = new DiagramTypeImpl(typeId, typeName, typeDescription);
	diagramType.setProviderId(extensionId);
	ret.add(diagramType);
	}
	}
	}
	return ret;
	}

	private IImageProvider createImageProvider(String providerId) {

	if (providerId == null) {
	return null;
	}
	IExtensionRegistry extensionRegistry = Platform.getExtensionRegistry();

	IExtensionPoint extensionPoint = extensionRegistry.getExtensionPoint(EP_IMAGE_PROVIDERS);
	IExtension[] extensions = extensionPoint.getExtensions();
	for (int i = 0; i < extensions.length; i++) {
	IExtension extension = extensions[i];
	IConfigurationElement[] configurationElements = extension.getConfigurationElements();
	for (int j = 0; j < configurationElements.length; j++) {
	IConfigurationElement element = configurationElements[j];
	String extensionId = element.getAttribute(EP_ATTRIBUTE_ID);
	if (providerId.equals(extensionId)) {
	try {
	Object executableExtension = element.createExecutableExtension(EP_ATTRIBUTE_CLASS);
	if (executableExtension instanceof IImageProvider) {
	IContributor contributor = extension.getContributor();
	if (contributor != null) {
	String pluginId = contributor.getName();
	if (pluginId != null) {
	IImageProvider imageProvider = (IImageProvider) executableExtension;
	imageProvider.setProviderId(extensionId);
	imageProvider.setPluginId(pluginId);
	return imageProvider;
	}
	}
	}
	} catch (CoreException e) {
	// $JL-EXC$
	e.printStackTrace();
	}
	}
	}
	}
	return null;
	}

	private void registerImageProviderForDiagramTypeProvider(String providerId, IImageProvider imageProvider) {
	Set<IImageProvider> providers = dtp2imageProvider.get(providerId);
	if (providers == null) {
	providers = new HashSet<IImageProvider>();
	dtp2imageProvider.put(providerId, providers);
	providers.add(platformImageProvider);
	}

	providers.add(imageProvider);
	}

	public IFeatureProvider createFeatureProvider(Diagram diagram) {
	Assert.isNotNull(diagram);
	String providerId = getDiagramTypeProviderId(diagram.getDiagramTypeId());
	if (providerId != null) {
	IDiagramTypeProvider dtp = createDiagramTypeProvider(diagram, providerId);
	return dtp.getFeatureProvider();
	}
	return null;
	}

	public IDiagramTypeProvider createDiagramTypeProvider(Diagram diagram, String providerId) {
	Assert.isNotNull(diagram);
	IDiagramTypeProvider dtp = createDiagramTypeProvider(providerId);
	if (dtp != null) {
	TransactionalEditingDomain editingDomain = TransactionUtil.getEditingDomain(diagram);
	DiagramEditorDummy diagramEditor = new DiagramEditorDummy(dtp, editingDomain);
	dtp.init(diagram, diagramEditor.getDiagramBehavior());
	}
	return dtp;
	}

	public String getDiagramTypeProviderId(String diagramTypeId) {
	String diagramTypeProviders[] = getDiagramTypeProviderIds(diagramTypeId);
	if (diagramTypeProviders != null && diagramTypeProviders.length > 0) {
	return diagramTypeProviders[0];
	}
	return null;
	}

	}