bundles/org.eclipse.ui.workbench/Eclipse UI/org/eclipse/ui/internal/presentations/PresentablePart.java

/*******************************************************************************
 * Copyright (c) 2004 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials 
 * are made available under the terms of the Common Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/cpl-v10.html
 * 
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.ui.internal.presentations;

import java.util.ArrayList;
import java.util.List;

import org.eclipse.swt.graphics.Image;
import org.eclipse.swt.graphics.Point;
import org.eclipse.swt.graphics.Rectangle;
import org.eclipse.swt.widgets.Control;
import org.eclipse.ui.IPropertyListener;
import org.eclipse.ui.internal.PartPane;
import org.eclipse.ui.internal.WorkbenchPartReference;
import org.eclipse.ui.presentations.IPartMenu;
import org.eclipse.ui.presentations.IPresentablePart;

/**
 * This is a lightweight adapter that allows PartPanes to be used by a StackPresentation. All methods
 * either redirect directly to PartPane or do trivial type conversions. All listeners registered by
 * the presentation are kept here rather than registering them directly on the PartPane. This allows
 * us to remove all listeners registered by a presentation that has been disposed, offering some
 * protection against memory leaks.
 */
public class PresentablePart implements IPresentablePart {

	private PartPane part;
	
	/**
	 * Local listener list -- we use this rather than registering listeners directly on the part
	 * in order to protect against memory leaks in badly behaved presentations.
	 */
	private List listeners = new ArrayList();
	
	// Lazily initialized. Use getPropertyListenerProxy() to access.
    private IPropertyListener lazyPropertyListenerProxy;
    
    // Lazily initialized. Use getMenu() to access 
    private IPartMenu viewMenu;
	
    /**
     * Constructor
     * 
     * @param part
     */
	public PresentablePart (PartPane part) {
		this.part = part;
	}

	private IPropertyListener getPropertyListenerProxy() {
		if (lazyPropertyListenerProxy == null) {
			lazyPropertyListenerProxy = new IPropertyListener() {
		        public void propertyChanged(Object source, int propId) {
		            firePropertyChange(propId);
		        }
		    };
		}
		
		return lazyPropertyListenerProxy;
	}
	
	private WorkbenchPartReference getPartReference() {
		return (WorkbenchPartReference)part.getPartReference();
	}
	
	/**
	 * Detach this PresentablePart from the real part. No further methods should be invoked
	 * on this object.
	 */
	public void dispose() {
		// Ensure that the property listener is detached (necessary to prevent leaks)
		getPartReference().removePropertyListener(getPropertyListenerProxy());
		
		// Null out the various fields to ease garbage collection (optional)
		part = null;
		listeners.clear();
		listeners = null;
	}
	
	public void firePropertyChange(int propertyId) {
		 for (int i = 0; i < listeners.size(); i++) {
            ((IPropertyListener) listeners.get(i)).propertyChanged(
                    this, propertyId);
		 }
	}
	
    public void addPropertyListener(final IPropertyListener listener) {
        if (listeners.isEmpty()) {
        	getPartReference().addPropertyListener(getPropertyListenerProxy());
        }

        listeners.add(listener);
    }
    
    public void removePropertyListener(final IPropertyListener listener) {
        listeners.remove(listener);

        if (listeners.isEmpty()) {
        	getPartReference().removePropertyListener(getPropertyListenerProxy());
        }
    }
	
	/* (non-Javadoc)
	 * @see org.eclipse.ui.presentations.IPresentablePart#setBounds(org.eclipse.swt.graphics.Rectangle)
	 */
	public void setBounds(Rectangle bounds) {
		part.setBounds(bounds);
	}

	/* (non-Javadoc)
	 * @see org.eclipse.ui.presentations.IPresentablePart#setVisible(boolean)
	 */
	public void setVisible(boolean isVisible) {
		part.setVisible(isVisible);
	}

	/* (non-Javadoc)
	 * @see org.eclipse.ui.presentations.IPresentablePart#setFocus()
	 */
	public void setFocus() {
		part.setFocus();
	}

	/* (non-Javadoc)
	 * @see org.eclipse.ui.presentations.IPresentablePart#getName()
	 */
	public String getName() {
		return getPartReference().getPartName();
	}

	/* (non-Javadoc)
	 * @see org.eclipse.ui.presentations.IPresentablePart#getTitle()
	 */
	public String getTitle() {
		return getPartReference().getTitle();
	}

	/* (non-Javadoc)
	 * @see org.eclipse.ui.presentations.IPresentablePart#getTitleStatus()
	 */
	public String getTitleStatus() {
		return getPartReference().getContentDescription();
	}

	/* (non-Javadoc)
	 * @see org.eclipse.ui.presentations.IPresentablePart#getTitleImage()
	 */
	public Image getTitleImage() {
		return getPartReference().getTitleImage();
	}

	/* (non-Javadoc)
	 * @see org.eclipse.ui.presentations.IPresentablePart#getTitleToolTip()
	 */
	public String getTitleToolTip() {
		return getPartReference().getTitleToolTip();
	}

	/* (non-Javadoc)
	 * @see org.eclipse.ui.presentations.IPresentablePart#isDirty()
	 */
	public boolean isDirty() {
		return getPartReference().isDirty();
	}

	/* (non-Javadoc)
	 * @see org.eclipse.ui.presentations.IPresentablePart#isBusy()
	 */
	public boolean isBusy() {
		return part.isBusy();
	}

	/* (non-Javadoc)
	 * @see org.eclipse.ui.presentations.IPresentablePart#getToolBar()
	 */
	public Control getToolBar() {
		return part.getToolBar();
	}

	/* (non-Javadoc)
	 * @see org.eclipse.ui.presentations.IPresentablePart#getMenu()
	 */
	public IPartMenu getMenu() {
		if (!part.hasViewMenu()) {
			return null;
		}
		
		if (viewMenu == null) {
			viewMenu = new IPartMenu() {
				public void showMenu(Point location) {
					part.showViewMenu(location);
				}
		    };
		}
		
		return viewMenu;
	}

	/* (non-Javadoc)
	 * @see org.eclipse.ui.presentations.IPresentablePart#getControl()
	 */
	public Control getControl() {
		return part.getControl();
	}

}