LabelDecorator


1   /*******************************************************************************
2    * Copyright (c) 2006 IBM Corporation and others.
3    * All rights reserved. This program and the accompanying materials
4    * are made available under the terms of the Eclipse Public License v1.0
5    * which accompanies this distribution, and is available at
6    * http://www.eclipse.org/legal/epl-v10.html
7    *
8    * Contributors:
9    *     IBM Corporation - initial API and implementation
10   *******************************************************************************/
11  
12  package org.eclipse.jface.viewers;
13  
14  import org.eclipse.swt.graphics.Image;
15  
16  /**
17   * The LabelDecorator is an abstract superclass of ILabelDecorators
18   * that support IDecorationContext.
19   * @see IDecorationContext
20   * @since 3.2
21   *
22   */
23  public abstract class LabelDecorator implements ILabelDecorator {
24      
25       /**
26       * Returns an image that is based on the given image,
27       * but decorated with additional information relating to the state
28       * of the provided element taking into account the provided context.
29       * 
30       * Text and image decoration updates can occur as a result of other updates
31       * within the workbench including deferred decoration by background processes.
32       * Clients should handle labelProviderChangedEvents for the given element to get
33       * the complete decoration.
34       * @see LabelProviderChangedEvent
35       * @see IBaseLabelProvider#addListener
36       *
37       * @param image the input image to decorate, or <code>null</code> if the element has no image
38       * @param element the element whose image is being decorated
39       * @param context additional context information about the element being decorated
40       * @return the decorated image, or <code>null</code> if no decoration is to be applied
41       *
42       * @see org.eclipse.jface.resource.CompositeImageDescriptor
43       */
44      public abstract Image decorateImage(Image image, Object   element, IDecorationContext context);
45  
46      /**
47       * Returns a text label that is based on the given text label,
48       * but decorated with additional information relating to the state
49       * of the provided element taking into account the provided context.
50       * 
51       * Text and image decoration updates can occur as a result of other updates
52       * within the workbench including deferred decoration by background processes.
53       * Clients should handle labelProviderChangedEvents for the given element to get
54       * the complete decoration.
55       * @see LabelProviderChangedEvent
56       * @see IBaseLabelProvider#addListener
57       *
58       * @param text the input text label to decorate
59       * @param element the element whose image is being decorated
60       * @param context additional context information about the element being decorated
61       * @return the decorated text label, or <code>null</code> if no decoration is to be applied
62       */
63      public abstract String   decorateText(String   text, Object   element, IDecorationContext context);
64      
65      /**
66       * Prepare the element for decoration. If it is already decorated and ready for update
67       * return true. If decoration is pending return false.
68       * @param element The element to be decorated
69       * @param originalText The starting text. 
70       * @param context The decoration context
71       * @return boolean <code>true</code> if the decoration is ready for this element
72       */
73      public abstract boolean prepareDecoration(Object   element, String   originalText, IDecorationContext context);
74  }
75
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