org.eclipse.jface.viewers.ILazyTreePathContentProvider Maven / Gradle / Ivy
/*******************************************************************************
* Copyright (c) 2005, 2015 IBM Corporation and others.
*
* This program and the accompanying materials
* are made available under the terms of the Eclipse Public License 2.0
* which accompanies this distribution, and is available at
* https://www.eclipse.org/legal/epl-2.0/
*
* SPDX-License-Identifier: EPL-2.0
*
* Contributors:
* IBM Corporation - initial API and implementation
* John Cortell, Freescale - bug 289409
*******************************************************************************/
package org.eclipse.jface.viewers;
/**
* The ILazyTreePathContentProvider is a tree path-based content provider for
* tree viewers created using the SWT.VIRTUAL flag that only wish to return
* their contents as they are queried.
*
* @since 3.3
*/
public interface ILazyTreePathContentProvider extends IContentProvider {
/**
* Called when a previously-blank item becomes visible in the TreeViewer. If
* the content provider knows the child element for the given parent at this
* index, it should respond by calling
* {@link TreeViewer#replace(Object, int, Object)}. The content provider
* should also update the child count for any replaced element by calling
* {@link TreeViewer#setChildCount(Object, int)}. If the given current child
* count is already correct, setChildCount does not have to be called since
* a call to replace will not change the child count. If the content
* provider doesn't know the child count at this point, and can more
* efficiently determine if the element has any children, then it can
* instead call {@link TreeViewer#setHasChildren(Object, boolean)}.
*
*
* NOTE #updateElement(int index) can be used to determine
* selection values. If TableViewer#replace(Object, int) is not called
* before returning from this method, selections may have missing or stale
* elements. In this situation it is suggested that the selection is asked
* for again after replace() has been called.
*
* @param parentPath
* The tree path of parent of the element, or if the element to
* update is a root element, an empty tree path
* @param index
* The index of the element to update in the tree
*/
public void updateElement(TreePath parentPath, int index);
/**
* Called when the TreeViewer needs an up-to-date child count for the given
* tree path, for example from {@link TreeViewer#refresh()} and
* {@link TreeViewer#setInput(Object)}. If the content provider knows the
* element at the given tree path, it should respond by calling
* {@link TreeViewer#setChildCount(Object, int)}. If the given current
* child count is already correct, no action has to be taken by this content
* provider.
*
* @param treePath
* The tree path for which an up-to-date child count is needed, or
* if the number of root elements is requested, the empty tree path
* @param currentChildCount
* The current child count for the element that needs updating
*/
public void updateChildCount(TreePath treePath, int currentChildCount);
/**
* Called when the TreeViewer needs up-to-date information whether the node
* at the given tree path can be expanded. If the content provider knows the
* element at the given tree path, it should respond by calling
* {@link TreeViewer#setHasChildren(Object, boolean)}. The content provider
* may also choose to call {@link TreeViewer#setChildCount(Object, int)}
* instead if it knows the number of children.
*
*
* Intended as an optimization for when the viewer does not need the actual
* children. Clients may be able to implement this more efficiently than
* updateChildCount.
*
*
* @param path
* The tree path for which up-to-date information about children
* is needed
*/
public void updateHasChildren(TreePath path);
/**
* Return the possible parent paths for the given element. An empty array
* can be returned if the paths cannot be computed. In this case the
* tree-structured viewer can't expand a given node correctly if requested.
* If the element is a potential child of the input of the viewer, an empty
* tree path should be an entry in the returned array.
*
* @param element
* the element
* @return the possible parent paths for the given element
*/
public TreePath[] getParents(Object element);
}