01: /*******************************************************************************
02: * Copyright (c) 2005, 2006 IBM Corporation and others.
03: * All rights reserved. This program and the accompanying materials
04: * are made available under the terms of the Eclipse Public License v1.0
05: * which accompanies this distribution, and is available at
06: * http://www.eclipse.org/legal/epl-v10.html
07: *
08: * Contributors:
09: * IBM Corporation - initial API and implementation
10: *******************************************************************************/package org.eclipse.jface.viewers;
11:
12: /**
13: * The ILazyTreeContentProvider is the content provider for tree viewers created
14: * using the SWT.VIRTUAL flag that only wish to return their contents as they
15: * are queried.
16: *
17: * @since 3.2
18: */
19: public interface ILazyTreeContentProvider extends IContentProvider {
20: /**
21: * Called when a previously-blank item becomes visible in the TreeViewer. If
22: * the content provider knows the child element for the given parent at this
23: * index, it should respond by calling
24: * {@link TreeViewer#replace(Object, int, Object)}. The content provider
25: * should also update the child count for any replaced element by calling
26: * {@link TreeViewer#setChildCount(Object, int)}. If the given current child
27: * count is already correct, setChildCount does not have to be called since
28: * a call to replace will not change the child count.
29: *
30: * <strong>NOTE</strong> #updateElement(int index) can be used to determine
31: * selection values. If TableViewer#replace(Object, int) is not called
32: * before returning from this method, selections may have missing or stale
33: * elements. In this situation it is suggested that the selection is asked
34: * for again after replace() has been called.
35: *
36: * @param parent
37: * The parent of the element, or the viewer's input if the
38: * element to update is a root element
39: * @param index
40: * The index of the element to update in the tree
41: */
42: public void updateElement(Object parent, int index);
43:
44: /**
45: * Called when the TreeViewer needs an up-to-date child count for the given
46: * element, for example from {@link TreeViewer#refresh()} and
47: * {@link TreeViewer#setInput(Object)}. If the content provider knows the
48: * given element, it should respond by calling
49: * {@link TreeViewer#setChildCount(Object, int)}. If the given current
50: * child count is already correct, no action has to be taken by this content
51: * provider.
52: *
53: * @param element
54: * The element for which an up-to-date child count is needed, or
55: * the viewer's input if the number of root elements is requested
56: * @param currentChildCount
57: * The current child count for the element that needs updating
58: */
59: public void updateChildCount(Object element, int currentChildCount);
60:
61: /**
62: * Returns the parent for the given element, or <code>null</code>
63: * indicating that the parent can't be computed.
64: * In this case the tree-structured viewer can't expand
65: * a given node correctly if requested.
66: *
67: * @param element the element
68: * @return the parent element, or <code>null</code> if it
69: * has none or if the parent cannot be computed
70: */
71: public Object getParent(Object element);
72: }
|