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# Class w3c.tools.widgets.TreeBrowser

    java.lang.Object
       |
       +----java.awt.Component
               |
               +----java.awt.Canvas
                       |
                       +----w3c.tools.widgets.TreeBrowser

public class TreeBrowser
extends Canvas
implements AdjustmentListener

The TreeBrowser class. This class is a generic framework to browser any hierachical structure. Genericity is obtained through the use of 'handlers': the TreeBrowser itself does not perform any action in response to user events, but simply forward them as notifications to handlers. Each item inserted may have ots own handler, but handlers may also (this is the most common case) be shared between handlers. Any item added in the Tree is displayed with an icon and a label. When a handler receive a notification on a node, it may change this node, to modify or update its appearance.

See Also:
  DirectoryBrowser, TreeNode

##

fontHeight
items
MULTIPLE
selection
selectionPolicy
SINGLE
topItem
visibleItemCount

##

TreeBrowser()
TreeBrowser(Object, String, NodeHandler, Image)
  Builds a new browser instance

##

adjustmentValueChanged(AdjustmentEvent)
  Updates graphical appearance in response to a scroll.
collapse(TreeNode)
  contracts the representation of this node.
getNode(Object)
getParent(TreeNode)
  Returns parent node.
getSelectionPolicy()
  Gets the selection policy.
initialize(Object, String, NodeHandler, Image)
insert(TreeNode, Object, NodeHandler, String, Image)
  Inserts new node.
paint(Graphics)
  repaints the View.
remove(TreeNode)
  Removes a node.
removeBranch(TreeNode)
  Removes a node and its children NOTE: if two threads are doing adds and removes, this can lead to IndexOutOfBound exception.
select(TreeNode)
  Selects a node.
selection()
  return an Enumeraiton of selected items.
setSelectionPolicy(int)
  Sets the selection policy.
setVerticalScrollbar(Scrollbar)
  Sets 'a' as vertical Scrollbar.
unselect(TreeNode)
  Selects a node.
unselectAll()
  Unselects any selected item.
update(Graphics)
  Redraws the current context, using double buffering.

##

SINGLE

     public static final int SINGLE

MULTIPLE

     public static final int MULTIPLE

items

     protected Vector items

selection

     protected Vector selection

topItem

     protected int topItem

visibleItemCount

     protected int visibleItemCount

selectionPolicy

     protected int selectionPolicy

fontHeight

     protected int fontHeight

##

TreeBrowser

     public TreeBrowser(Object root,
                        String label,
                        NodeHandler handler,
                        Image icon)

  Builds a new browser instance

  Parameters:
    root - the root node for this hierarchy
    label - the label that should be displayed for this item
    handler - the handler for this node
    icon - the icon that must be displayed for this item

TreeBrowser

     protected TreeBrowser()

##

initialize

     protected void initialize(Object item,
                               String label,
                               NodeHandler handler,
                               Image icon)

update

     public void update(Graphics pg)

  Redraws the current context, using double buffering.

  Overrides:
    update in class Component

paint

     public void paint(Graphics g)

  repaints the View.

  Overrides:
    paint in class Canvas

insert

     public void insert(TreeNode parent,
                        Object item,
                        NodeHandler handler,
                        String label,
                        Image icon)

  Inserts new node.

  Parameters:
    parent - the parent node.

remove

     public void remove(TreeNode node)

  Removes a node. This simply removes a node, without modifying its children if any. USE WITH CAUTION.

removeBranch

     public void removeBranch(TreeNode node)

  Removes a node and its children NOTE: if two threads are doing adds and removes, this can lead to IndexOutOfBound exception. You will probably have to use locks to get rid of that problem

collapse

     public synchronized void collapse(TreeNode item)

  contracts the representation of this node. removes all the children nodes of 'item'. It is caller's responsibility to call repaint() afterwards.

setSelectionPolicy

     public void setSelectionPolicy(int policy)

  Sets the selection policy.

  Parameters:
    policy: - SINGLE or MULTIPLE

getSelectionPolicy

     public int getSelectionPolicy()

  Gets the selection policy.

select

     public void select(TreeNode node)

  Selects a node. Selects the given node. If selectionPolicy is SINGLE any previously selected node is unselected first. It is caller's responsibility to call repaint()

unselect

     public void unselect(TreeNode node)

  Selects a node. Unselects the given node. It is caller's responsibility to call repaint()

unselectAll

     public void unselectAll()

  Unselects any selected item.

selection

     public Enumeration selection()

  return an Enumeraiton of selected items.

setVerticalScrollbar

     public void setVerticalScrollbar(Scrollbar a)

  Sets 'a' as vertical Scrollbar. The Browser becomes an AdjustmentListener of this scrollbar.

adjustmentValueChanged

     public void adjustmentValueChanged(AdjustmentEvent evt)

  Updates graphical appearance in response to a scroll.

getParent

     public TreeNode getParent(TreeNode child)

  Returns parent node. If 'child' is a valid node belonging to the Tree and has a parent node, returns its parent. Returns null otherwise.

getNode

     public TreeNode getNode(Object o)

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