bundles/org.eclipse.jface/src/org/eclipse/jface/viewers/DecoratingLabelProvider.java

/*******************************************************************************
 * Copyright (c) 2000, 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.jface.viewers;

import org.eclipse.swt.graphics.Image;

import org.eclipse.jface.util.Assert;
import org.eclipse.jface.util.ListenerList;

/**
 * A decorating label provider is a label provider which combines 
 * a nested label provider and an optional decorator.
 * The decorator decorates the label text and image provided by the nested label provider.
 */
public class DecoratingLabelProvider extends LabelProvider implements ILabelProvider,IViewerLabelProvider {
	private ILabelProvider provider;	
	private ILabelDecorator decorator;
	// Need to keep our own list of listeners
	private ListenerList listeners = new ListenerList();
/**
 * Creates a decorating label provider which uses the given label decorator
 * to decorate labels provided by the given label provider.
 *
 * @param provider the nested label provider
 * @param decorator the label decorator, or <code>null</code> if no decorator is to be used initially
 */
public DecoratingLabelProvider(ILabelProvider provider, ILabelDecorator decorator) {
	Assert.isNotNull(provider);
	this.provider = provider;
	this.decorator = decorator;
}


/**
 * The <code>DecoratingLabelProvider</code> implementation of this <code>IBaseLabelProvider</code> method
 * adds the listener to both the nested label provider and the label decorator.
 *
 * @param listener a label provider listener
 */
public void addListener(ILabelProviderListener listener) {
	super.addListener(listener);
	provider.addListener(listener);
	if (decorator != null) {
		decorator.addListener(listener);
	}
	listeners.add(listener);
}
/**
 * The <code>DecoratingLabelProvider</code> implementation of this <code>IBaseLabelProvider</code> method
 * disposes both the nested label provider and the label decorator.
 */
public void dispose() {
	provider.dispose();
	if (decorator != null) {
		decorator.dispose();
	}
}
/**
 * The <code>DecoratingLabelProvider</code> implementation of this 
 * <code>ILabelProvider</code> method returns the image provided
 * by the nested label provider's <code>getImage</code> method, 
 * decorated with the decoration provided by the label decorator's
 * <code>decorateImage</code> method.
 */
public Image getImage(Object element) {
	Image image = provider.getImage(element);
	if (decorator != null) {
		Image decorated = decorator.decorateImage(image, element);
		if (decorated != null) {
			return decorated;
		}
	}
	return image;
}
/**
 * Returns the label decorator, or <code>null</code> if none has been set.
 *
 * @return the label decorator, or <code>null</code> if none has been set.
 */
public ILabelDecorator getLabelDecorator() {
	return decorator;
}
/**
 * Returns the nested label provider.
 *
 * @return the nested label provider
 */
public ILabelProvider getLabelProvider() {
	return provider;
}
/**
 * The <code>DecoratingLabelProvider</code> implementation of this 
 * <code>ILabelProvider</code> method returns the text label provided
 * by the nested label provider's <code>getText</code> method, 
 * decorated with the decoration provided by the label decorator's
 * <code>decorateText</code> method.
 */
public String getText(Object element) {
	String text = provider.getText(element);
	if (decorator != null) {
		String decorated = decorator.decorateText(text, element);
		if (decorated != null) {
			return decorated;
		}
	}
	return text;
}
/**
 * The <code>DecoratingLabelProvider</code> implementation of this 
 * <code>IBaseLabelProvider</code> method returns <code>true</code> if the corresponding method
 * on the nested label provider returns <code>true</code> or if the corresponding method on the 
 * decorator returns <code>true</code>.
 */
public boolean isLabelProperty(Object element, String property) {
	if (provider.isLabelProperty(element, property))
		return true;
	if (decorator != null && decorator.isLabelProperty(element, property))
		return true;
	return false;
}
/**
 * The <code>DecoratingLabelProvider</code> implementation of this <code>IBaseLabelProvider</code> method
 * removes the listener from both the nested label provider and the label decorator.
 *
 * @param listener a label provider listener
 */
public void removeListener(ILabelProviderListener listener) {
	super.removeListener(listener);
	provider.removeListener(listener);
	if (decorator != null) {
		decorator.removeListener(listener);
	}
	listeners.remove(listener);
}
/**
 * Sets the label decorator.
 * Removes all known listeners from the old decorator, and adds all known listeners to the new decorator.
 * The old decorator is not disposed.
 * Fires a label provider changed event indicating that all labels should be updated.
 * Has no effect if the given decorator is identical to the current one.
 *
 * @param decorator the label decorator, or <code>null</code> if no decorations are to be applied
 */
public void setLabelDecorator(ILabelDecorator decorator) {
	ILabelDecorator oldDecorator = this.decorator;
	if (oldDecorator != decorator) {
		Object[] listenerList = this.listeners.getListeners();
		if (oldDecorator != null) {
			for (int i = 0; i < listenerList.length; ++i) {
				oldDecorator.removeListener((ILabelProviderListener) listenerList[i]);
			}
		}
		this.decorator = decorator;
		if (decorator != null) {
			for (int i = 0; i < listenerList.length; ++i) {
				decorator.addListener((ILabelProviderListener) listenerList[i]);
			}
		}
		fireLabelProviderChanged(new LabelProviderChangedEvent(this));
	}
}



/**
 * Return whether the two image handles are equal.
 * @param oldImage
 * @param newImage
 * @return
 */
private boolean equals(Image oldImage, Image newImage) {
	return ((oldImage == null && newImage == null) ||
		(oldImage!= null && newImage != null && oldImage.equals(newImage)));
}


/*
 *  (non-Javadoc)
 * @see org.eclipse.jface.viewers.IViewerLabelProvider#updateLabel(org.eclipse.jface.viewers.ViewerLabel, java.lang.Object)
 */
public void updateLabel(ViewerLabel settings, Object element) {

	ILabelDecorator currentDecorator = getLabelDecorator();
	String oldText = settings.getText();
	boolean decorationReady = true;
	if (currentDecorator instanceof IDelayedLabelDecorator) {
		IDelayedLabelDecorator delayedDecorator = (IDelayedLabelDecorator) currentDecorator;
		if (!delayedDecorator.prepareDecoration(element,oldText)) {
			// The decoration is not ready but has been queued for processing
			decorationReady = false;
		}
	}
	// update icon and label
	
	if (decorationReady || oldText == null || settings.getText().length() == 0) 
		settings.setText(getText(element));
	
	Image oldImage = settings.getImage();
	if (decorationReady || oldImage == null) {
		settings.setImage(getImage(element));
	}

}

}