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Eclipse Platform
Release 3.5

org.eclipse.ui.progress
Class DeferredTreeContentManager

java.lang.Object
  extended by 
org.eclipse.ui.progress.DeferredTreeContentManager

public class DeferredTreeContentManager
extends Object

The DeferredContentManager is a class that helps an ITreeContentProvider get its deferred input. NOTE AbstractTreeViewer#isExpandable may need to be implemented in AbstractTreeViewer subclasses with deferred content that use filtering as a call to #getChildren may be required to determine the correct state of the expanding control. AbstractTreeViewers which use this class may wish to sacrifice accuracy of the expandable state indicator for the performance benefits of deferring content.

Since:
3.0
See Also:
IDeferredWorkbenchAdapter

Constructor Summary
DeferredTreeContentManager ( AbstractTreeViewer viewer)
          Create a new instance of the receiver using the supplied content provider and viewer.
DeferredTreeContentManager ( AbstractTreeViewer viewer, IWorkbenchPartSite site)
          Create a new instance of the receiver using the supplied content provider and viewer.
DeferredTreeContentManager ( ITreeContentProvider provider, AbstractTreeViewer viewer)
          Deprecated. in 3.4. provider is not used by this class
DeferredTreeContentManager ( ITreeContentProvider provider, AbstractTreeViewer viewer, IWorkbenchPartSite site)
          Deprecated. in 3.4. provider is not used by this class
 
Method Summary
protected  void addChildren ( Object parent, Object[] children, IProgressMonitor monitor)
          Create a UIJob to add the children to the parent in the tree viewer.
 void addUpdateCompleteListener ( IJobChangeListener listener)
          Add a listener to the job that updates the content after all has been loaded by clearing the Pending entry etc.
 void cancel ( Object parent)
          Cancel all jobs that are fetching content for the given parent or any of its children.
protected   IElementCollector createElementCollector ( Object parent, PendingUpdateAdapter placeholder)
          Create the element collector for the receiver.
protected   PendingUpdateAdapter createPendingUpdateAdapter ()
          Factory method for creating the pending update adapter representing the placeholder node.
protected   IDeferredWorkbenchAdapter getAdapter ( Object element)
          Return the IDeferredWorkbenchAdapter for element or the element if it is an instance of IDeferredWorkbenchAdapter.
  Object[] getChildren ( Object parent)
          Returns the child elements of the given element, or in the case of a deferred element, returns a placeholder.
protected   String getFetchJobName ( Object parent, IDeferredWorkbenchAdapter adapter)
          Returns a name to use for the job that fetches children of the given parent.
 boolean isDeferredAdapter ( Object element)
          Return whether or not the element is or adapts to an IDeferredWorkbenchAdapter.
 boolean mayHaveChildren ( Object element)
          Provides an optimized lookup for determining if an element has children.
protected  void runClearPlaceholderJob ( PendingUpdateAdapter placeholder)
          Run a job to clear the placeholder.
protected  void startFetchingDeferredChildren ( Object parent, IDeferredWorkbenchAdapter adapter, PendingUpdateAdapter placeholder)
          Starts a job and creates a collector for fetching the children of this deferred adapter.
 
Methods inherited from class java.lang. Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

DeferredTreeContentManager

public DeferredTreeContentManager(
ITreeContentProvider provider,
                                  
AbstractTreeViewer viewer,
                                  
IWorkbenchPartSite site)
Deprecated. in 3.4. provider is not used by this class

Create a new instance of the receiver using the supplied content provider and viewer. Run any jobs using the site.

Parameters:
provider -
viewer -
site -

DeferredTreeContentManager

public DeferredTreeContentManager(
ITreeContentProvider provider,
                                  
AbstractTreeViewer viewer)
Deprecated. in 3.4. provider is not used by this class

Create a new instance of the receiver using the supplied content provider and viewer.

Parameters:
provider - The content provider that will be updated
viewer - The tree viewer that the results are added to

DeferredTreeContentManager

public DeferredTreeContentManager(
AbstractTreeViewer viewer,
                                  
IWorkbenchPartSite site)
Create a new instance of the receiver using the supplied content provider and viewer. Run any jobs using the site.

Parameters:
viewer -
site -
Since:
3.4

DeferredTreeContentManager

public DeferredTreeContentManager(
AbstractTreeViewer viewer)
Create a new instance of the receiver using the supplied content provider and viewer.

Parameters:
viewer - The tree viewer that the results are added to
Since:
3.4
Method Detail

mayHaveChildren

public boolean mayHaveChildren(
Object element)
Provides an optimized lookup for determining if an element has children. This is required because elements that are populated lazilly can't answer getChildren just to determine the potential for children. Throw an AssertionFailedException if element is null.

Parameters:
element - The Object being tested. This should not be null.
Returns:
boolean true if there are potentially children.
Throws:
RuntimeException - if the element is null.

getChildren

public 
Object[] getChildren(
Object parent)
Returns the child elements of the given element, or in the case of a deferred element, returns a placeholder. If a deferred element is used, a job is created to fetch the children in the background.

Parameters:
parent - The parent object.
Returns:
Object[] or null if parent is not an instance of IDeferredWorkbenchAdapter.

createPendingUpdateAdapter

protected 
PendingUpdateAdapter createPendingUpdateAdapter()
Factory method for creating the pending update adapter representing the placeholder node. Subclasses may override.

Returns:
a pending update adapter
Since:
3.2

getAdapter

protected 
IDeferredWorkbenchAdapter getAdapter(
Object element)
Return the IDeferredWorkbenchAdapter for element or the element if it is an instance of IDeferredWorkbenchAdapter. If it does not exist return null.

Parameters:
element -
Returns:
IDeferredWorkbenchAdapter or null

startFetchingDeferredChildren

protected void startFetchingDeferredChildren(
Object parent,
                                             
IDeferredWorkbenchAdapter adapter,
                                             
PendingUpdateAdapter placeholder)
Starts a job and creates a collector for fetching the children of this deferred adapter. If children are waiting to be retrieved for this parent already, that job is cancelled and another is started.

Parameters:
parent - The parent object being filled in,
adapter - The adapter being used to fetch the children.
placeholder - The adapter that will be used to indicate that results are pending.

getFetchJobName

protected 
String getFetchJobName(
Object parent,
                                 
IDeferredWorkbenchAdapter adapter)
Returns a name to use for the job that fetches children of the given parent. Subclasses may override. Default job name is parent's label.

Parameters:
parent - parent that children are to be fetched for
adapter - parent's deferred adapter
Returns:
job name

addChildren

protected void addChildren(
Object parent,
                           
Object[] children,
                           
IProgressMonitor monitor)
Create a UIJob to add the children to the parent in the tree viewer.

Parameters:
parent -
children -
monitor -

isDeferredAdapter

public boolean isDeferredAdapter(
Object element)
Return whether or not the element is or adapts to an IDeferredWorkbenchAdapter.

Parameters:
element -
Returns:
boolean true if the element is an IDeferredWorkbenchAdapter

runClearPlaceholderJob

protected void runClearPlaceholderJob(
PendingUpdateAdapter placeholder)
Run a job to clear the placeholder. This is used when the update for the tree is complete so that the user is aware that no more updates are pending.

Parameters:
placeholder -

cancel

public void cancel(
Object parent)
Cancel all jobs that are fetching content for the given parent or any of its children.

Parameters:
parent -

createElementCollector

protected 
IElementCollector createElementCollector(
Object parent,
                                                   
PendingUpdateAdapter placeholder)
Create the element collector for the receiver.

Parameters:
parent - The parent object being filled in,
placeholder - The adapter that will be used to indicate that results are pending.
Returns:
IElementCollector

addUpdateCompleteListener

public void addUpdateCompleteListener(
IJobChangeListener listener)
Add a listener to the job that updates the content after all has been loaded by clearing the Pending entry etc.

Parameters:
listener -
Since:
3.4

Eclipse Platform
Release 3.5

Guidelines for using Eclipse APIs.

Copyright (c) Eclipse contributors and others 2000, 2008. All rights reserved.


 
 
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