bundles/org.eclipse.ui.workbench/Eclipse UI/org/eclipse/ui/internal/dialogs/PerspectivesPreferencePage.java - platform/eclipse.platform.ui - Git at Google

 /*******************************************************************************
  * Copyright (c) 2000, 2015 IBM Corporation and others.
  *
  * This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License 2.0
  * which accompanies this distribution, and is available at
  * https://www.eclipse.org/legal/epl-2.0/
  *
  * SPDX-License-Identifier: EPL-2.0
  *
  * Contributors:
  *     IBM Corporation - initial API and implementation
  *     Semion Chichelnitsky (semion@il.ibm.com) - bug 278064
  *     Denis Zygann <d.zygann@web.de> - Bug 330453
  *     Lars Vogel <Lars.Vogel@vogella.com> - Bug 472654
  *******************************************************************************/

 package org.eclipse.ui.internal.dialogs;

 import static org.eclipse.swt.events.SelectionListener.widgetSelectedAdapter;

 import java.text.Collator;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Comparator;
 import java.util.Objects;
 import org.eclipse.e4.ui.model.application.MApplication;
 import org.eclipse.e4.ui.model.application.ui.advanced.MPerspective;
 import org.eclipse.e4.ui.workbench.modeling.EModelService;
 import org.eclipse.jface.dialogs.IDialogConstants;
 import org.eclipse.jface.dialogs.PlainMessageDialog;
 import org.eclipse.jface.dialogs.PlainMessageDialog.Builder;
 import org.eclipse.jface.preference.IPreferenceStore;
 import org.eclipse.jface.preference.PreferencePage;
 import org.eclipse.jface.resource.ImageDescriptor;
 import org.eclipse.osgi.util.NLS;
 import org.eclipse.swt.SWT;
 import org.eclipse.swt.graphics.Font;
 import org.eclipse.swt.layout.GridData;
 import org.eclipse.swt.layout.GridLayout;
 import org.eclipse.swt.widgets.Button;
 import org.eclipse.swt.widgets.Composite;
 import org.eclipse.swt.widgets.Control;
 import org.eclipse.swt.widgets.Group;
 import org.eclipse.swt.widgets.Label;
 import org.eclipse.swt.widgets.Shell;
 import org.eclipse.swt.widgets.Table;
 import org.eclipse.swt.widgets.TableItem;
 import org.eclipse.swt.widgets.Widget;
 import org.eclipse.ui.IPerspectiveDescriptor;
 import org.eclipse.ui.IWorkbench;
 import org.eclipse.ui.IWorkbenchPage;
 import org.eclipse.ui.IWorkbenchPreferenceConstants;
 import org.eclipse.ui.IWorkbenchPreferencePage;
 import org.eclipse.ui.IWorkbenchWindow;
 import org.eclipse.ui.PlatformUI;
 import org.eclipse.ui.internal.IPreferenceConstants;
 import org.eclipse.ui.internal.IWorkbenchHelpContextIds;
 import org.eclipse.ui.internal.Workbench;
 import org.eclipse.ui.internal.WorkbenchMessages;
 import org.eclipse.ui.internal.WorkbenchPlugin;
 import org.eclipse.ui.internal.registry.PerspectiveDescriptor;
 import org.eclipse.ui.internal.registry.PerspectiveRegistry;
 import org.eclipse.ui.internal.util.Descriptors;
 import org.eclipse.ui.internal.util.PrefUtil;

 /**
  * The Workbench / Perspectives preference page.
  */
 public class PerspectivesPreferencePage extends PreferencePage implements IWorkbenchPreferencePage {
 	private IWorkbench workbench;

 	private PerspectiveRegistry perspectiveRegistry;

 	// List of perspectives to populate preference page
 	private ArrayList<IPerspectiveDescriptor> perspectives;

 	private String defaultPerspectiveId;

 	private ArrayList<IPerspectiveDescriptor> perspToDelete = new ArrayList<>();

 	private ArrayList<IPerspectiveDescriptor> perspToRevert = new ArrayList<>();

 	private Table perspectivesTable;

 	private Button revertButton;

 	private Button deleteButton;

 	private Button setDefaultButton;

 	// widgets for open perspective mode;
 	private Button openSameWindowButton;

 	private Button openNewWindowButton;

 	private int openPerspMode;

 	// labels
 	private final String OPM_TITLE = WorkbenchMessages.OpenPerspectiveMode_optionsTitle;

 	private final String OPM_SAME_WINDOW = WorkbenchMessages.OpenPerspectiveMode_sameWindow;

 	private final String OPM_NEW_WINDOW = WorkbenchMessages.OpenPerspectiveMode_newWindow;

 	/**
 	 * <code>Comparator</code> to compare two perspective descriptors
 	 */
 	private Comparator<IPerspectiveDescriptor> comparator = new Comparator<>() {
 		private Collator collator = Collator.getInstance();

 		@Override
 		public int compare(IPerspectiveDescriptor d1, IPerspectiveDescriptor d2) {
 			return collator.compare(d1.getLabel(), d2.getLabel());
 		}
 	};

 	/**
 	 * Creates the page's UI content.
 	 */
 	@Override
 	protected Control createContents(Composite parent) {
 		// @issue if the product subclasses this page, then it should provide
 		// the help content
 		PlatformUI.getWorkbench().getHelpSystem().setHelp(parent,
 				IWorkbenchHelpContextIds.PERSPECTIVES_PREFERENCE_PAGE);

 		Composite composite = createComposite(parent);

 		createOpenPerspButtonGroup(composite);
 		createCustomizePerspective(composite);

 		return composite;
 	}

 	/**
 	 * Creates the composite which will contain all the preference controls for this
 	 * page.
 	 *
 	 * @param parent the parent composite
 	 * @return the composite for this page
 	 */
 	protected Composite createComposite(Composite parent) {
 		Composite composite = new Composite(parent, SWT.NONE);
 		GridData data = new GridData(GridData.FILL_BOTH);
 		composite.setLayoutData(data);
 		composite.setFont(parent.getFont());
 		GridLayout layout = new GridLayout();
 		layout.marginWidth = 0;
 		layout.marginHeight = 0;
 		layout.verticalSpacing = 10;
 		composite.setLayout(layout);
 		return composite;
 	}

 	/**
 	 * Create a composite that contains buttons for selecting the open perspective
 	 * mode.
 	 *
 	 * @param composite the parent composite
 	 */
 	protected void createOpenPerspButtonGroup(Composite composite) {

 		Font font = composite.getFont();

 		Group buttonComposite = new Group(composite, SWT.LEFT);
 		buttonComposite.setText(OPM_TITLE);
 		buttonComposite.setLayoutData(new GridData(GridData.FILL_HORIZONTAL));
 		buttonComposite.setFont(composite.getFont());
 		GridLayout layout = new GridLayout();
 		layout.numColumns = 2;
 		buttonComposite.setLayout(layout);

 		openSameWindowButton = new Button(buttonComposite, SWT.RADIO);
 		openSameWindowButton.setText(OPM_SAME_WINDOW);
 		openSameWindowButton.setSelection(IPreferenceConstants.OPM_ACTIVE_PAGE == openPerspMode);
 		openSameWindowButton.setFont(font);
 		openSameWindowButton
 				.addSelectionListener(widgetSelectedAdapter(e -> openPerspMode = IPreferenceConstants.OPM_ACTIVE_PAGE));

 		openNewWindowButton = new Button(buttonComposite, SWT.RADIO);
 		openNewWindowButton.setText(OPM_NEW_WINDOW);
 		openNewWindowButton.setSelection(IPreferenceConstants.OPM_NEW_WINDOW == openPerspMode);
 		openNewWindowButton.setFont(font);
 		openNewWindowButton
 				.addSelectionListener(widgetSelectedAdapter(e -> openPerspMode = IPreferenceConstants.OPM_NEW_WINDOW));

 	}

 	/**
 	 * Create a table of 3 buttons to enable the user to manage customized
 	 * perspectives.
 	 *
 	 * @param parent the parent for the button parent
 	 * @return Composite that the buttons are created in.
 	 */
 	protected Composite createCustomizePerspective(Composite parent) {

 		Font font = parent.getFont();

 		// define container & its gridding
 		Composite perspectivesComponent = new Composite(parent, SWT.NONE);
 		perspectivesComponent.setLayoutData(new GridData(GridData.FILL_BOTH));
 		perspectivesComponent.setFont(parent.getFont());

 		GridLayout layout = new GridLayout();
 		layout.numColumns = 2;
 		layout.marginWidth = 0;
 		layout.marginHeight = 0;
 		perspectivesComponent.setLayout(layout);

 		// Add the label
 		Label label = new Label(perspectivesComponent, SWT.LEFT);
 		label.setText(WorkbenchMessages.PerspectivesPreference_available);
 		GridData data = new GridData();
 		data.horizontalSpan = 2;
 		label.setLayoutData(data);
 		label.setFont(font);

 		// Add perspectivesTable.
 		perspectivesTable = new Table(perspectivesComponent, SWT.H_SCROLL | SWT.V_SCROLL | SWT.BORDER);
 		perspectivesTable.addSelectionListener(widgetSelectedAdapter(e -> updateButtons()));
 		perspectivesTable.setFont(font);

 		data = new GridData(GridData.FILL_BOTH);
 		data.grabExcessHorizontalSpace = true;
 		data.grabExcessVerticalSpace = true;
 		perspectivesTable.setLayoutData(data);

 		// Populate the perspectivesTable
 		IPerspectiveDescriptor[] persps = perspectiveRegistry.getPerspectives();
 		perspectives = new ArrayList<>(persps.length);
 		for (int i = 0; i < persps.length; i++) {
 			perspectives.add(i, persps[i]);
 		}
 		perspectives.sort(comparator);
 		defaultPerspectiveId = perspectiveRegistry.getDefaultPerspective();
 		updatePerspectivesTable();

 		// Create vertical button bar.
 		Composite buttonBar = (Composite) createVerticalButtonBar(perspectivesComponent);
 		data = new GridData(GridData.FILL_VERTICAL);
 		buttonBar.setLayoutData(data);

 		// Add note label
 		String NOTE_LABEL = WorkbenchMessages.Preference_note;
 		String REVERT_NOTE = WorkbenchMessages.RevertPerspective_note;
 		Composite noteComposite = createNoteComposite(font, parent, NOTE_LABEL, REVERT_NOTE);
 		GridData noteData = new GridData();
 		noteData.horizontalSpan = 2;
 		noteComposite.setLayoutData(noteData);
 		return perspectivesComponent;
 	}

 	/**
 	 * Creates a new vertical button with the given id.
 	 * <p>
 	 * The default implementation of this framework method creates a standard push
 	 * button, registers for selection events including button presses and help
 	 * requests, and registers default buttons with its shell. The button id is
 	 * stored as the buttons client data.
 	 * </p>
 	 *
 	 * @param parent        the parent composite
 	 * @param label         the label from the button
 	 * @param defaultButton <code>true</code> if the button is to be the default
 	 *                      button, and <code>false</code> otherwise
 	 * @return Button The created button.
 	 */
 	protected Button createVerticalButton(Composite parent, String label, boolean defaultButton) {
 		Button button = new Button(parent, SWT.PUSH);

 		button.setText(label);

 		GridData data = setButtonLayoutData(button);
 		data.horizontalAlignment = GridData.FILL;

 		button.addSelectionListener(widgetSelectedAdapter(event -> verticalButtonPressed(event.widget)));
 		button.setToolTipText(label);
 		if (defaultButton) {
 			Shell shell = parent.getShell();
 			if (shell != null) {
 				shell.setDefaultButton(button);
 			}
 		}
 		button.setFont(parent.getFont());
 		return button;
 	}

 	/**
 	 * Creates and returns the vertical button bar.
 	 *
 	 * @param parent the parent composite to contain the button bar
 	 * @return the button bar control
 	 */
 	protected Control createVerticalButtonBar(Composite parent) {
 		// Create composite.
 		Composite composite = new Composite(parent, SWT.NULL);

 		// create a layout with spacing and margins appropriate for the font
 		// size.
 		GridLayout layout = new GridLayout();
 		layout.numColumns = 1;
 		layout.marginWidth = 5;
 		layout.marginHeight = 0;
 		layout.horizontalSpacing = convertHorizontalDLUsToPixels(IDialogConstants.HORIZONTAL_SPACING);
 		layout.verticalSpacing = convertVerticalDLUsToPixels(IDialogConstants.VERTICAL_SPACING);
 		composite.setLayout(layout);
 		composite.setFont(parent.getFont());

 		// Add the buttons to the button bar.
 		setDefaultButton = createVerticalButton(composite, WorkbenchMessages.PerspectivesPreference_MakeDefault, false);
 		setDefaultButton.setToolTipText(WorkbenchMessages.PerspectivesPreference_MakeDefaultTip);

 		revertButton = createVerticalButton(composite, WorkbenchMessages.PerspectivesPreference_Reset, false);
 		revertButton.setToolTipText(WorkbenchMessages.PerspectivesPreference_ResetTip);

 		deleteButton = createVerticalButton(composite, WorkbenchMessages.PerspectivesPreference_Delete, false);
 		deleteButton.setToolTipText(WorkbenchMessages.PerspectivesPreference_DeleteTip);
 		updateButtons();

 		return composite;
 	}

 	/**
 	 * @see IWorkbenchPreferencePage
 	 */
 	@Override
 	public void init(IWorkbench aWorkbench) {
 		this.workbench = aWorkbench;
 		this.perspectiveRegistry = (PerspectiveRegistry) workbench.getPerspectiveRegistry();
 		IPreferenceStore store = WorkbenchPlugin.getDefault().getPreferenceStore();
 		setPreferenceStore(store);

 		openPerspMode = store.getInt(IPreferenceConstants.OPEN_PERSP_MODE);
 	}

 	/**
 	 * The default button has been pressed.
 	 */
 	@Override
 	protected void performDefaults() {
 		// Project perspective preferences
 		IPreferenceStore store = WorkbenchPlugin.getDefault().getPreferenceStore();

 		openPerspMode = store.getDefaultInt(IPreferenceConstants.OPEN_PERSP_MODE);
 		openSameWindowButton.setSelection(IPreferenceConstants.OPM_ACTIVE_PAGE == openPerspMode);
 		openNewWindowButton.setSelection(IPreferenceConstants.OPM_NEW_WINDOW == openPerspMode);

 		String currentDefault = perspectiveRegistry.getDefaultPerspective();

 		int index = indexOf(currentDefault);
 		if (index >= 0) {
 			defaultPerspectiveId = currentDefault;
 			updatePerspectivesTable();
 			perspectivesTable.setSelection(index);
 		}

 		String newDefault = PrefUtil.getAPIPreferenceStore()
 				.getDefaultString(IWorkbenchPreferenceConstants.DEFAULT_PERSPECTIVE_ID);

 		IPerspectiveDescriptor desc = null;
 		if (newDefault != null) {
 			desc = workbench.getPerspectiveRegistry().findPerspectiveWithId(newDefault);
 		}
 		if (desc == null) {
 			newDefault = workbench.getPerspectiveRegistry().getDefaultPerspective();
 		}

 		defaultPerspectiveId = newDefault;
 		updatePerspectivesTable();

 	}

 	/**
 	 * Look up the index of the perpective with the given if.
 	 *
 	 * @param perspectiveId or <code>null</code>
 	 * @return int -1 if it cannot be found
 	 */
 	private int indexOf(String perspectiveId) {
 		if (perspectiveId == null) {
 			return -1;
 		}
 		PerspectiveDescriptor[] descriptors = new PerspectiveDescriptor[perspectives.size()];
 		perspectives.toArray(descriptors);
 		for (int i = 0; i < descriptors.length; i++) {
 			PerspectiveDescriptor descriptor = descriptors[i];
 			if (descriptor.getId().equals(perspectiveId)) {
 				return i;
 			}
 		}
 		return -1;
 	}

 	/**
 	 * Return true if there are no open instances of the perspective. If there are
 	 * open instances of the perspective prompt the user and return true if the user
 	 * answers "yes" to the delete prompt.
 	 *
 	 * @return boolean <code>true</code> if it is OK to delete the perspective
 	 *         either because there are no open instances or the user has confirmed
 	 *         the deletion.
 	 */
 	private boolean canDeletePerspective(IPerspectiveDescriptor desc) {

 		MApplication application = ((Workbench) workbench).getApplication();
 		EModelService modelService = application.getContext().get(EModelService.class);

 		if (modelService.findElements(application, desc.getId(), MPerspective.class).isEmpty())
 			return true;

 		Builder builder = PlainMessageDialog.getBuilder(getShell(),
 				WorkbenchMessages.PerspectivesPreference_perspectiveopen_title);
 		builder.message(NLS.bind(WorkbenchMessages.PerspectivesPreference_perspectiveopen_message, desc.getLabel()));
 		builder.image(getShell().getDisplay().getSystemImage(SWT.ICON_QUESTION));
 		builder.buttonLabels(Arrays.asList(IDialogConstants.YES_LABEL, IDialogConstants.NO_LABEL));
 		return builder.build().open() == 0;
 	}

 	/**
 	 * Apply the user's changes if any
 	 */
 	@Override
 	public boolean performOk() {
 		// Set the default perspective
 		if (!Objects.equals(defaultPerspectiveId, perspectiveRegistry.getDefaultPerspective())) {
 			perspectiveRegistry.setDefaultPerspective(defaultPerspectiveId);
 		}

 		// Don't bother figuring out which window a perspective may be open in,
 		// the number of windows will be small.

 		for (IPerspectiveDescriptor perspective : perspToDelete) {
 			IWorkbenchWindow[] windows = workbench.getWorkbenchWindows();
 			for (IWorkbenchWindow window : windows) {
 				IWorkbenchPage[] pages = window.getPages();
 				for (IWorkbenchPage page : pages) {
 					page.closePerspective(perspective, true, false);
 				}
 			}
 			perspectiveRegistry.deletePerspectives(perspToDelete);
 		}

 		// Revert perspectives
 		for (IPerspectiveDescriptor perspective : perspToRevert) {
 			perspectiveRegistry.revertPerspective(perspective);
 		}

 		IPreferenceStore store = getPreferenceStore();

 		// store the open perspective mode setting
 		store.setValue(IPreferenceConstants.OPEN_PERSP_MODE, openPerspMode);

 		// save both the API prefs and the internal prefs
 		// the API prefs are modified by
 		// PerspectiveRegistry.setDefaultPerspective
 		PrefUtil.savePrefs();

 		return true;
 	}

 	/**
 	 * Update the button enablement state.
 	 */
 	protected void updateButtons() {
 		// Get selection.
 		int index = perspectivesTable.getSelectionIndex();

 		// Map it to the perspective descriptor
 		PerspectiveDescriptor desc = null;
 		if (index > -1) {
 			desc = (PerspectiveDescriptor) perspectives.get(index);
 		}

 		// Do enable.
 		if (desc != null) {
 			revertButton.setEnabled(desc.isPredefined() && desc.hasCustomDefinition() && !perspToRevert.contains(desc));
 			deleteButton.setEnabled(!desc.isPredefined());
 			setDefaultButton.setEnabled(true);
 		} else {
 			revertButton.setEnabled(false);
 			deleteButton.setEnabled(false);
 			setDefaultButton.setEnabled(false);
 		}
 	}

 	/**
 	 * Update the perspectivesTable.
 	 */
 	protected void updatePerspectivesTable() {
 		// Populate the table with the items
 		perspectivesTable.removeAll();
 		for (int i = 0; i < perspectives.size(); i++) {
 			PerspectiveDescriptor persp = (PerspectiveDescriptor) perspectives.get(i);
 			newPerspectivesTableItem(persp, i, false);
 		}
 	}

 	/**
 	 * Create a new tableItem using given perspective, and set image for the new
 	 * item.
 	 */
 	protected TableItem newPerspectivesTableItem(IPerspectiveDescriptor persp, int index, boolean selected) {

 		ImageDescriptor image = persp.getImageDescriptor();

 		TableItem item = new TableItem(perspectivesTable, SWT.NULL, index);
 		if (image != null) {
 			Descriptors.setImage(item, image);
 		}
 		String label = persp.getLabel();
 		if (persp.getId().equals(defaultPerspectiveId)) {
 			label = NLS.bind(WorkbenchMessages.PerspectivesPreference_defaultLabel, label);

 		}
 		item.setText(label);
 		item.setData(persp);
 		if (selected) {
 			perspectivesTable.setSelection(index);
 		}

 		return item;
 	}

 	/**
 	 * Notifies that this page's button with the given id has been pressed.
 	 *
 	 * @param button the button that was pressed
 	 */
 	protected void verticalButtonPressed(Widget button) {
 		// Get selection.
 		int index = perspectivesTable.getSelectionIndex();

 		// Map it to the perspective descriptor
 		PerspectiveDescriptor desc = null;
 		if (index > -1) {
 			desc = (PerspectiveDescriptor) perspectives.get(index);
 		} else {
 			return;
 		}

 		// Take action.
 		if (button == revertButton) {
 			if (!perspToRevert.contains(desc)) {
 				perspToRevert.add(desc);
 			}
 		} else if (button == deleteButton) {
 			if (!perspToDelete.contains(desc)) {
 				if (canDeletePerspective(desc)) {
 					perspToDelete.add(desc);
 					perspToRevert.remove(desc);
 					perspectives.remove(desc);
 					updatePerspectivesTable();
 				}

 			}
 		} else if (button == setDefaultButton) {
 			defaultPerspectiveId = desc.getId();
 			updatePerspectivesTable();
 			perspectivesTable.setSelection(index);
 		}

 		updateButtons();
 	}
 }
	/*******************************************************************************
	* Copyright (c) 2000, 2015 IBM Corporation and others.
	*
	* This program and the accompanying materials
	* are made available under the terms of the Eclipse Public License 2.0
	* which accompanies this distribution, and is available at
	* https://www.eclipse.org/legal/epl-2.0/
	*
	* SPDX-License-Identifier: EPL-2.0
	*
	* Contributors:
	* IBM Corporation - initial API and implementation
	* Semion Chichelnitsky (semion@il.ibm.com) - bug 278064
	* Denis Zygann <d.zygann@web.de> - Bug 330453
	* Lars Vogel <Lars.Vogel@vogella.com> - Bug 472654
	*******************************************************************************/

	package org.eclipse.ui.internal.dialogs;

	import static org.eclipse.swt.events.SelectionListener.widgetSelectedAdapter;

	import java.text.Collator;
	import java.util.ArrayList;
	import java.util.Arrays;
	import java.util.Comparator;
	import java.util.Objects;
	import org.eclipse.e4.ui.model.application.MApplication;
	import org.eclipse.e4.ui.model.application.ui.advanced.MPerspective;
	import org.eclipse.e4.ui.workbench.modeling.EModelService;
	import org.eclipse.jface.dialogs.IDialogConstants;
	import org.eclipse.jface.dialogs.PlainMessageDialog;
	import org.eclipse.jface.dialogs.PlainMessageDialog.Builder;
	import org.eclipse.jface.preference.IPreferenceStore;
	import org.eclipse.jface.preference.PreferencePage;
	import org.eclipse.jface.resource.ImageDescriptor;
	import org.eclipse.osgi.util.NLS;
	import org.eclipse.swt.SWT;
	import org.eclipse.swt.graphics.Font;
	import org.eclipse.swt.layout.GridData;
	import org.eclipse.swt.layout.GridLayout;
	import org.eclipse.swt.widgets.Button;
	import org.eclipse.swt.widgets.Composite;
	import org.eclipse.swt.widgets.Control;
	import org.eclipse.swt.widgets.Group;
	import org.eclipse.swt.widgets.Label;
	import org.eclipse.swt.widgets.Shell;
	import org.eclipse.swt.widgets.Table;
	import org.eclipse.swt.widgets.TableItem;
	import org.eclipse.swt.widgets.Widget;
	import org.eclipse.ui.IPerspectiveDescriptor;
	import org.eclipse.ui.IWorkbench;
	import org.eclipse.ui.IWorkbenchPage;
	import org.eclipse.ui.IWorkbenchPreferenceConstants;
	import org.eclipse.ui.IWorkbenchPreferencePage;
	import org.eclipse.ui.IWorkbenchWindow;
	import org.eclipse.ui.PlatformUI;
	import org.eclipse.ui.internal.IPreferenceConstants;
	import org.eclipse.ui.internal.IWorkbenchHelpContextIds;
	import org.eclipse.ui.internal.Workbench;
	import org.eclipse.ui.internal.WorkbenchMessages;
	import org.eclipse.ui.internal.WorkbenchPlugin;
	import org.eclipse.ui.internal.registry.PerspectiveDescriptor;
	import org.eclipse.ui.internal.registry.PerspectiveRegistry;
	import org.eclipse.ui.internal.util.Descriptors;
	import org.eclipse.ui.internal.util.PrefUtil;

	/**
	* The Workbench / Perspectives preference page.
	*/
	public class PerspectivesPreferencePage extends PreferencePage implements IWorkbenchPreferencePage {
	private IWorkbench workbench;

	private PerspectiveRegistry perspectiveRegistry;

	// List of perspectives to populate preference page
	private ArrayList<IPerspectiveDescriptor> perspectives;

	private String defaultPerspectiveId;

	private ArrayList<IPerspectiveDescriptor> perspToDelete = new ArrayList<>();

	private ArrayList<IPerspectiveDescriptor> perspToRevert = new ArrayList<>();

	private Table perspectivesTable;

	private Button revertButton;

	private Button deleteButton;

	private Button setDefaultButton;

	// widgets for open perspective mode;
	private Button openSameWindowButton;

	private Button openNewWindowButton;

	private int openPerspMode;

	// labels
	private final String OPM_TITLE = WorkbenchMessages.OpenPerspectiveMode_optionsTitle;

	private final String OPM_SAME_WINDOW = WorkbenchMessages.OpenPerspectiveMode_sameWindow;

	private final String OPM_NEW_WINDOW = WorkbenchMessages.OpenPerspectiveMode_newWindow;

	/**
	* <code>Comparator</code> to compare two perspective descriptors
	*/
	private Comparator<IPerspectiveDescriptor> comparator = new Comparator<>() {
	private Collator collator = Collator.getInstance();

	@Override
	public int compare(IPerspectiveDescriptor d1, IPerspectiveDescriptor d2) {
	return collator.compare(d1.getLabel(), d2.getLabel());
	}
	};

	/**
	* Creates the page's UI content.
	*/
	@Override
	protected Control createContents(Composite parent) {
	// @issue if the product subclasses this page, then it should provide
	// the help content
	PlatformUI.getWorkbench().getHelpSystem().setHelp(parent,
	IWorkbenchHelpContextIds.PERSPECTIVES_PREFERENCE_PAGE);

	Composite composite = createComposite(parent);

	createOpenPerspButtonGroup(composite);
	createCustomizePerspective(composite);

	return composite;
	}

	/**
	* Creates the composite which will contain all the preference controls for this
	* page.
	*
	* @param parent the parent composite
	* @return the composite for this page
	*/
	protected Composite createComposite(Composite parent) {
	Composite composite = new Composite(parent, SWT.NONE);
	GridData data = new GridData(GridData.FILL_BOTH);
	composite.setLayoutData(data);
	composite.setFont(parent.getFont());
	GridLayout layout = new GridLayout();
	layout.marginWidth = 0;
	layout.marginHeight = 0;
	layout.verticalSpacing = 10;
	composite.setLayout(layout);
	return composite;
	}

	/**
	* Create a composite that contains buttons for selecting the open perspective
	* mode.
	*
	* @param composite the parent composite
	*/
	protected void createOpenPerspButtonGroup(Composite composite) {

	Font font = composite.getFont();

	Group buttonComposite = new Group(composite, SWT.LEFT);
	buttonComposite.setText(OPM_TITLE);
	buttonComposite.setLayoutData(new GridData(GridData.FILL_HORIZONTAL));
	buttonComposite.setFont(composite.getFont());
	GridLayout layout = new GridLayout();
	layout.numColumns = 2;
	buttonComposite.setLayout(layout);

	openSameWindowButton = new Button(buttonComposite, SWT.RADIO);
	openSameWindowButton.setText(OPM_SAME_WINDOW);
	openSameWindowButton.setSelection(IPreferenceConstants.OPM_ACTIVE_PAGE == openPerspMode);
	openSameWindowButton.setFont(font);
	openSameWindowButton
	.addSelectionListener(widgetSelectedAdapter(e -> openPerspMode = IPreferenceConstants.OPM_ACTIVE_PAGE));

	openNewWindowButton = new Button(buttonComposite, SWT.RADIO);
	openNewWindowButton.setText(OPM_NEW_WINDOW);
	openNewWindowButton.setSelection(IPreferenceConstants.OPM_NEW_WINDOW == openPerspMode);
	openNewWindowButton.setFont(font);
	openNewWindowButton
	.addSelectionListener(widgetSelectedAdapter(e -> openPerspMode = IPreferenceConstants.OPM_NEW_WINDOW));

	}

	/**
	* Create a table of 3 buttons to enable the user to manage customized
	* perspectives.
	*
	* @param parent the parent for the button parent
	* @return Composite that the buttons are created in.
	*/
	protected Composite createCustomizePerspective(Composite parent) {

	Font font = parent.getFont();

	// define container & its gridding
	Composite perspectivesComponent = new Composite(parent, SWT.NONE);
	perspectivesComponent.setLayoutData(new GridData(GridData.FILL_BOTH));
	perspectivesComponent.setFont(parent.getFont());

	GridLayout layout = new GridLayout();
	layout.numColumns = 2;
	layout.marginWidth = 0;
	layout.marginHeight = 0;
	perspectivesComponent.setLayout(layout);

	// Add the label
	Label label = new Label(perspectivesComponent, SWT.LEFT);
	label.setText(WorkbenchMessages.PerspectivesPreference_available);
	GridData data = new GridData();
	data.horizontalSpan = 2;
	label.setLayoutData(data);
	label.setFont(font);

	// Add perspectivesTable.
	perspectivesTable = new Table(perspectivesComponent, SWT.H_SCROLL \| SWT.V_SCROLL \| SWT.BORDER);
	perspectivesTable.addSelectionListener(widgetSelectedAdapter(e -> updateButtons()));
	perspectivesTable.setFont(font);

	data = new GridData(GridData.FILL_BOTH);
	data.grabExcessHorizontalSpace = true;
	data.grabExcessVerticalSpace = true;
	perspectivesTable.setLayoutData(data);

	// Populate the perspectivesTable
	IPerspectiveDescriptor[] persps = perspectiveRegistry.getPerspectives();
	perspectives = new ArrayList<>(persps.length);
	for (int i = 0; i < persps.length; i++) {
	perspectives.add(i, persps[i]);
	}
	perspectives.sort(comparator);
	defaultPerspectiveId = perspectiveRegistry.getDefaultPerspective();
	updatePerspectivesTable();

	// Create vertical button bar.
	Composite buttonBar = (Composite) createVerticalButtonBar(perspectivesComponent);
	data = new GridData(GridData.FILL_VERTICAL);
	buttonBar.setLayoutData(data);

	// Add note label
	String NOTE_LABEL = WorkbenchMessages.Preference_note;
	String REVERT_NOTE = WorkbenchMessages.RevertPerspective_note;
	Composite noteComposite = createNoteComposite(font, parent, NOTE_LABEL, REVERT_NOTE);
	GridData noteData = new GridData();
	noteData.horizontalSpan = 2;
	noteComposite.setLayoutData(noteData);
	return perspectivesComponent;
	}

	/**
	* Creates a new vertical button with the given id.
	* <p>
	* The default implementation of this framework method creates a standard push
	* button, registers for selection events including button presses and help
	* requests, and registers default buttons with its shell. The button id is
	* stored as the buttons client data.
	* </p>
	*
	* @param parent the parent composite
	* @param label the label from the button
	* @param defaultButton <code>true</code> if the button is to be the default
	* button, and <code>false</code> otherwise
	* @return Button The created button.
	*/
	protected Button createVerticalButton(Composite parent, String label, boolean defaultButton) {
	Button button = new Button(parent, SWT.PUSH);

	button.setText(label);

	GridData data = setButtonLayoutData(button);
	data.horizontalAlignment = GridData.FILL;

	button.addSelectionListener(widgetSelectedAdapter(event -> verticalButtonPressed(event.widget)));
	button.setToolTipText(label);
	if (defaultButton) {
	Shell shell = parent.getShell();
	if (shell != null) {
	shell.setDefaultButton(button);
	}
	}
	button.setFont(parent.getFont());
	return button;
	}

	/**
	* Creates and returns the vertical button bar.
	*
	* @param parent the parent composite to contain the button bar
	* @return the button bar control
	*/
	protected Control createVerticalButtonBar(Composite parent) {
	// Create composite.
	Composite composite = new Composite(parent, SWT.NULL);

	// create a layout with spacing and margins appropriate for the font
	// size.
	GridLayout layout = new GridLayout();
	layout.numColumns = 1;
	layout.marginWidth = 5;
	layout.marginHeight = 0;
	layout.horizontalSpacing = convertHorizontalDLUsToPixels(IDialogConstants.HORIZONTAL_SPACING);
	layout.verticalSpacing = convertVerticalDLUsToPixels(IDialogConstants.VERTICAL_SPACING);
	composite.setLayout(layout);
	composite.setFont(parent.getFont());

	// Add the buttons to the button bar.
	setDefaultButton = createVerticalButton(composite, WorkbenchMessages.PerspectivesPreference_MakeDefault, false);
	setDefaultButton.setToolTipText(WorkbenchMessages.PerspectivesPreference_MakeDefaultTip);

	revertButton = createVerticalButton(composite, WorkbenchMessages.PerspectivesPreference_Reset, false);
	revertButton.setToolTipText(WorkbenchMessages.PerspectivesPreference_ResetTip);

	deleteButton = createVerticalButton(composite, WorkbenchMessages.PerspectivesPreference_Delete, false);
	deleteButton.setToolTipText(WorkbenchMessages.PerspectivesPreference_DeleteTip);
	updateButtons();

	return composite;
	}

	/**
	* @see IWorkbenchPreferencePage
	*/
	@Override
	public void init(IWorkbench aWorkbench) {
	this.workbench = aWorkbench;
	this.perspectiveRegistry = (PerspectiveRegistry) workbench.getPerspectiveRegistry();
	IPreferenceStore store = WorkbenchPlugin.getDefault().getPreferenceStore();
	setPreferenceStore(store);

	openPerspMode = store.getInt(IPreferenceConstants.OPEN_PERSP_MODE);
	}

	/**
	* The default button has been pressed.
	*/
	@Override
	protected void performDefaults() {
	// Project perspective preferences
	IPreferenceStore store = WorkbenchPlugin.getDefault().getPreferenceStore();

	openPerspMode = store.getDefaultInt(IPreferenceConstants.OPEN_PERSP_MODE);
	openSameWindowButton.setSelection(IPreferenceConstants.OPM_ACTIVE_PAGE == openPerspMode);
	openNewWindowButton.setSelection(IPreferenceConstants.OPM_NEW_WINDOW == openPerspMode);

	String currentDefault = perspectiveRegistry.getDefaultPerspective();

	int index = indexOf(currentDefault);
	if (index >= 0) {
	defaultPerspectiveId = currentDefault;
	updatePerspectivesTable();
	perspectivesTable.setSelection(index);
	}

	String newDefault = PrefUtil.getAPIPreferenceStore()
	.getDefaultString(IWorkbenchPreferenceConstants.DEFAULT_PERSPECTIVE_ID);

	IPerspectiveDescriptor desc = null;
	if (newDefault != null) {
	desc = workbench.getPerspectiveRegistry().findPerspectiveWithId(newDefault);
	}
	if (desc == null) {
	newDefault = workbench.getPerspectiveRegistry().getDefaultPerspective();
	}

	defaultPerspectiveId = newDefault;
	updatePerspectivesTable();

	}

	/**
	* Look up the index of the perpective with the given if.
	*
	* @param perspectiveId or <code>null</code>
	* @return int -1 if it cannot be found
	*/
	private int indexOf(String perspectiveId) {
	if (perspectiveId == null) {
	return -1;
	}
	PerspectiveDescriptor[] descriptors = new PerspectiveDescriptor[perspectives.size()];
	perspectives.toArray(descriptors);
	for (int i = 0; i < descriptors.length; i++) {
	PerspectiveDescriptor descriptor = descriptors[i];
	if (descriptor.getId().equals(perspectiveId)) {
	return i;
	}
	}
	return -1;
	}

	/**
	* Return true if there are no open instances of the perspective. If there are
	* open instances of the perspective prompt the user and return true if the user
	* answers "yes" to the delete prompt.
	*
	* @return boolean <code>true</code> if it is OK to delete the perspective
	* either because there are no open instances or the user has confirmed
	* the deletion.
	*/
	private boolean canDeletePerspective(IPerspectiveDescriptor desc) {

	MApplication application = ((Workbench) workbench).getApplication();
	EModelService modelService = application.getContext().get(EModelService.class);

	if (modelService.findElements(application, desc.getId(), MPerspective.class).isEmpty())
	return true;

	Builder builder = PlainMessageDialog.getBuilder(getShell(),
	WorkbenchMessages.PerspectivesPreference_perspectiveopen_title);
	builder.message(NLS.bind(WorkbenchMessages.PerspectivesPreference_perspectiveopen_message, desc.getLabel()));
	builder.image(getShell().getDisplay().getSystemImage(SWT.ICON_QUESTION));
	builder.buttonLabels(Arrays.asList(IDialogConstants.YES_LABEL, IDialogConstants.NO_LABEL));
	return builder.build().open() == 0;
	}

	/**
	* Apply the user's changes if any
	*/
	@Override
	public boolean performOk() {
	// Set the default perspective
	if (!Objects.equals(defaultPerspectiveId, perspectiveRegistry.getDefaultPerspective())) {
	perspectiveRegistry.setDefaultPerspective(defaultPerspectiveId);
	}

	// Don't bother figuring out which window a perspective may be open in,
	// the number of windows will be small.

	for (IPerspectiveDescriptor perspective : perspToDelete) {
	IWorkbenchWindow[] windows = workbench.getWorkbenchWindows();
	for (IWorkbenchWindow window : windows) {
	IWorkbenchPage[] pages = window.getPages();
	for (IWorkbenchPage page : pages) {
	page.closePerspective(perspective, true, false);
	}
	}
	perspectiveRegistry.deletePerspectives(perspToDelete);
	}

	// Revert perspectives
	for (IPerspectiveDescriptor perspective : perspToRevert) {
	perspectiveRegistry.revertPerspective(perspective);
	}

	IPreferenceStore store = getPreferenceStore();

	// store the open perspective mode setting
	store.setValue(IPreferenceConstants.OPEN_PERSP_MODE, openPerspMode);

	// save both the API prefs and the internal prefs
	// the API prefs are modified by
	// PerspectiveRegistry.setDefaultPerspective
	PrefUtil.savePrefs();

	return true;
	}

	/**
	* Update the button enablement state.
	*/
	protected void updateButtons() {
	// Get selection.
	int index = perspectivesTable.getSelectionIndex();

	// Map it to the perspective descriptor
	PerspectiveDescriptor desc = null;
	if (index > -1) {
	desc = (PerspectiveDescriptor) perspectives.get(index);
	}

	// Do enable.
	if (desc != null) {
	revertButton.setEnabled(desc.isPredefined() && desc.hasCustomDefinition() && !perspToRevert.contains(desc));
	deleteButton.setEnabled(!desc.isPredefined());
	setDefaultButton.setEnabled(true);
	} else {
	revertButton.setEnabled(false);
	deleteButton.setEnabled(false);
	setDefaultButton.setEnabled(false);
	}
	}

	/**
	* Update the perspectivesTable.
	*/
	protected void updatePerspectivesTable() {
	// Populate the table with the items
	perspectivesTable.removeAll();
	for (int i = 0; i < perspectives.size(); i++) {
	PerspectiveDescriptor persp = (PerspectiveDescriptor) perspectives.get(i);
	newPerspectivesTableItem(persp, i, false);
	}
	}

	/**
	* Create a new tableItem using given perspective, and set image for the new
	* item.
	*/
	protected TableItem newPerspectivesTableItem(IPerspectiveDescriptor persp, int index, boolean selected) {

	ImageDescriptor image = persp.getImageDescriptor();

	TableItem item = new TableItem(perspectivesTable, SWT.NULL, index);
	if (image != null) {
	Descriptors.setImage(item, image);
	}
	String label = persp.getLabel();
	if (persp.getId().equals(defaultPerspectiveId)) {
	label = NLS.bind(WorkbenchMessages.PerspectivesPreference_defaultLabel, label);

	}
	item.setText(label);
	item.setData(persp);
	if (selected) {
	perspectivesTable.setSelection(index);
	}

	return item;
	}

	/**
	* Notifies that this page's button with the given id has been pressed.
	*
	* @param button the button that was pressed
	*/
	protected void verticalButtonPressed(Widget button) {
	// Get selection.
	int index = perspectivesTable.getSelectionIndex();

	// Map it to the perspective descriptor
	PerspectiveDescriptor desc = null;
	if (index > -1) {
	desc = (PerspectiveDescriptor) perspectives.get(index);
	} else {
	return;
	}

	// Take action.
	if (button == revertButton) {
	if (!perspToRevert.contains(desc)) {
	perspToRevert.add(desc);
	}
	} else if (button == deleteButton) {
	if (!perspToDelete.contains(desc)) {
	if (canDeletePerspective(desc)) {
	perspToDelete.add(desc);
	perspToRevert.remove(desc);
	perspectives.remove(desc);
	updatePerspectivesTable();
	}

	}
	} else if (button == setDefaultButton) {
	defaultPerspectiveId = desc.getId();
	updatePerspectivesTable();
	perspectivesTable.setSelection(index);
	}

	updateButtons();
	}
	}