labeldecorator.java

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/*******************************************************************************
 * Copyright (c) 2006 IBM Corporation and others.
 * 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:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/

package org.eclipse.jface.viewers;

import org.eclipse.swt.graphics.Image;

/**
 * The LabelDecorator is an abstract superclass of ILabelDecorators
 * that support IDecorationContext.
 * @see IDecorationContext
 * @since 3.2
 *
 */
public abstract class LabelDecorator implements ILabelDecorator {
	
	 /**
     * Returns an image that is based on the given image,
     * but decorated with additional information relating to the state
     * of the provided element taking into account the provided context.
     * 
     * Text and image decoration updates can occur as a result of other updates
     * within the workbench including deferred decoration by background processes.
     * Clients should handle labelProviderChangedEvents for the given element to get
     * the complete decoration.
     * @see LabelProviderChangedEvent
     * @see IBaseLabelProvider#addListener
     *
     * @param image the input image to decorate, or <code>null</code> if the element has no image
     * @param element the element whose image is being decorated
     * @param context additional context information about the element being decorated
     * @return the decorated image, or <code>null</code> if no decoration is to be applied
     *
     * @see org.eclipse.jface.resource.CompositeImageDescriptor
     */
    public abstract Image decorateImage(Image image, Object element, IDecorationContext context);

    /**
     * Returns a text label that is based on the given text label,
     * but decorated with additional information relating to the state
     * of the provided element taking into account the provided context.
     * 
     * Text and image decoration updates can occur as a result of other updates
     * within the workbench including deferred decoration by background processes.
     * Clients should handle labelProviderChangedEvents for the given element to get
     * the complete decoration.
     * @see LabelProviderChangedEvent
     * @see IBaseLabelProvider#addListener
     *
     * @param text the input text label to decorate
     * @param element the element whose image is being decorated
     * @param context additional context information about the element being decorated
     * @return the decorated text label, or <code>null</code> if no decoration is to be applied
     */
    public abstract String decorateText(String text, Object element, IDecorationContext context);
    
    /**
     * Prepare the element for decoration. If it is already decorated and ready for update
     * return true. If decoration is pending return false.
     * @param element The element to be decorated
     * @param originalText The starting text. 
     * @param context The decoration context
     * @return boolean <code>true</code> if the decoration is ready for this element
     */
    public abstract boolean prepareDecoration(Object element, String originalText, IDecorationContext context);
}