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 ILazyTreePathContentProvider is a tree path-based content provider for
14: * tree viewers created using the SWT.VIRTUAL flag that only wish to return
15: * their contents as they are queried.
16: *
17: * @since 3.3
18: */
19: public interface ILazyTreePathContentProvider 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 parentPath
37: * The tree path of parent of the element, or if the
38: * element to update is a root element, an empty tree path
39: * @param index
40: * The index of the element to update in the tree
41: */
42: public void updateElement(TreePath parentPath, int index);
43:
44: /**
45: * Called when the TreeViewer needs an up-to-date child count for the given
46: * tree path, for example from {@link TreeViewer#refresh()} and
47: * {@link TreeViewer#setInput(Object)}. If the content provider knows the
48: * element at the given tree path, 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 treePath
54: * The tree path for which an up-to-date child count is needed, or
55: * if the number of root elements is requested, the empty tree path
56: * @param currentChildCount
57: * The current child count for the element that needs updating
58: */
59: public void updateChildCount(TreePath treePath,
60: int currentChildCount);
61:
62: /**
63: * Called when the TreeViewer needs up-to-date information whether the node
64: * at the given tree path can be expanded. If the content provider knows the
65: * element at the given tree path, it should respond by calling
66: * {@link TreeViewer#setHasChildren(Object, boolean)}. The content provider
67: * may also choose to call {@link TreeViewer#setChildCount(Object, int)}
68: * instead if it knows the number of children.
69: *
70: * <p>
71: * Intended as an optimization for when the viewer does not need the actual
72: * children. Clients may be able to implement this more efficiently than
73: * <code>updateChildCount</code>.
74: * </p>
75: *
76: * @param path
77: * The tree path for which up-to-date information about children
78: * is needed
79: */
80: public void updateHasChildren(TreePath path);
81:
82: /**
83: * Return the possible parent paths for the given element. An empty array
84: * can be returned if the paths cannot be computed. In this case the
85: * tree-structured viewer can't expand a given node correctly if requested.
86: * If the element is a potential child of the input of the viewer, an empty
87: * tree path should be an entry in the returned array.
88: *
89: * @param element
90: * the element
91: * @return the possible parent paths for the given element
92: */
93: public TreePath[] getParents(Object element);
94: }
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