Eclipse Plug-in Developer Guide (Galileo) - ILazyTreePathContentProvider (Eclipse Platform API Specification)

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Eclipse Platform
Release 3.5

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org.eclipse.jface.viewers
Interface ILazyTreePathContentProvider

All Superinterfaces:: IContentProvider

public interface ILazyTreePathContentProvider
extends IContentProvider
extends IContentProvider

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

Method Summary

TreePath[] getParents ( Object element)
          Return the possible parent paths for the given element.

void updateChildCount ( TreePath treePath, int currentChildCount)
          Called when the TreeViewer needs an up-to-date child count for the given tree path, for example from StructuredViewer.refresh() and StructuredViewer.setInput(Object).

void updateElement ( TreePath parentPath, int index)
          Called when a previously-blank item becomes visible in the TreeViewer.

void updateHasChildren ( TreePath path)
          Called when the TreeViewer needs up-to-date information whether the node at the given tree path can be expanded.

Methods inherited from interface org.eclipse.jface.viewers. IContentProvider

dispose, inputChanged

Method Detail

updateElement

void updateElement(
TreePath parentPath,
                   int index)

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 TreeViewer.replace(Object, int, Object). The content provider should also update the child count for any replaced element by calling 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. 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.

Parameters:: parentPath - The tree path of parent of the element, or if the element to update is a root element, an empty tree path; index - The index of the element to update in the tree

updateChildCount

void updateChildCount(
TreePath treePath,
                      int currentChildCount)

Called when the TreeViewer needs an up-to-date child count for the given tree path, for example from StructuredViewer.refresh() and StructuredViewer.setInput(Object). If the content provider knows the element at the given tree path, it should respond by calling TreeViewer.setChildCount(Object, int). If the given current child count is already correct, no action has to be taken by this content provider.

Parameters:: 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; currentChildCount - The current child count for the element that needs updating

updateHasChildren

void updateHasChildren(
TreePath path)

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 TreeViewer.setHasChildren(Object, boolean). The content provider may also choose to call 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.

Parameters:: path - The tree path for which up-to-date information about children is needed

getParents

TreePath[] getParents(
Object element)

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.