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Eclipse GEF
3.3

org.eclipse.gef
Interface EditPolicy

All Known Implementing Classes:
AbstractEditPolicy

public interface EditPolicy

A pluggable contribution implementing a portion of an EditPart's behavior. EditPolicies contribute to the overall editing behavior of an EditPart. Editing behavior is defined as one or more of the following:

  • Command Creation - Returning a Command in response to getCommand(Request)
  • Feedback Management - Showing/erasing source and/or target feedback in response to Requests.
  • Delegation/Forwarding - Collecting contributions from other EditParts (and therefore their EditPolicies). In response to a given Request, an EditPolicy may create a derived Request and forward it to other EditParts. For example, during the deletion of a composite EditPart, that composite may consult its children for contributions to the delete command. Then, if the children have any additional work to do, they will return additional comands to be executed.

EditPolicies should determine an EditPart's editing capabilities. It is possible to implement an EditPart such that it handles all editing responsibility. However, it is much more flexible and object-oriented to use EditPolicies. Using policies, you can pick and choose the editing behavior for an EditPart without being bound to its class hierarchy. Code reuse is increased, and code management is easier.

IMPORTANT: This interface is not intended to be implemented by clients. Clients should inherit from AbstractEditPolicy. New methods may be added in the future.


Field Summary
static java.lang.String COMPONENT_ROLE
          The key used to install a component EditPolicy.
static java.lang.String CONNECTION_BENDPOINTS_ROLE
          The key used to install a bendpoint EditPolicy.
static java.lang.String CONNECTION_ENDPOINTS_ROLE
          The key used to install a connection endpoint EditPolicy.
static java.lang.String CONNECTION_ROLE
          The key used to install a connection EditPolicy.
static java.lang.String CONTAINER_ROLE
          The key used to install a container EditPolicy.
static java.lang.String DIRECT_EDIT_ROLE
          The key used to install a direct edit EditPolicy.
static java.lang.String GRAPHICAL_NODE_ROLE
          The key used to install a graphical node EditPolicy.
static java.lang.String LAYOUT_ROLE
          The key used to install a layout EditPolicy.
static java.lang.String NODE_ROLE
          The key used to install a node EditPolicy.
static java.lang.String PRIMARY_DRAG_ROLE
          The key used to install a primary drag EditPolicy.
static java.lang.String SELECTION_FEEDBACK_ROLE
          The key used to install a selection feedback EditPolicy.
static java.lang.String TREE_CONTAINER_ROLE
          The key used to install a tree container EditPolicy.
 
Method Summary
 void activate ()
          Activates this EditPolicy.
 void deactivate ()
          Deactivates the EditPolicy, the inverse of activate().
 void eraseSourceFeedback ( Request request)
          Erases source feedback based on the given Request.
 void eraseTargetFeedback ( Request request)
          Erases target feedback based on the given Request.
  Command getCommand ( Request request)
          Returns the Command contribution for the given Request, or null.
  EditPart getHost ()
           
  EditPart getTargetEditPart ( Request request)
          Returns null or the appropriate EditPart for the specified Request.
 void setHost ( EditPart editpart)
          Sets the host in which this EditPolicy is installed.
 void showSourceFeedback ( Request request)
          Shows or updates source feedback for the specified Request.
 void showTargetFeedback ( Request request)
          Shows or updates target feedback for the specified Request.
 boolean understandsRequest ( Request request)
          Returns true if this EditPolicy understand the specified request.
 

Field Detail

COMPONENT_ROLE

public static final java.lang.String COMPONENT_ROLE
The key used to install a component EditPolicy. A component is defined as anything in the model. This EditPolicy should handle the fundamental operations that do not fit under any other EditPolicy role. For example, delete is a fundamental operation. Generally the component EditPolicy knows only about the model, and can be used in any type of EditPartViewer.

See Also:
Constant Field Values

CONNECTION_ENDPOINTS_ROLE

public static final java.lang.String CONNECTION_ENDPOINTS_ROLE
The key used to install a connection endpoint EditPolicy. A connection endpoint EditPolicy is usually a SelectionHandlesEditPolicy subclass. Besides rendering selection by displaying Handles at then ends of the connection, the EditPolicy also understands how to move the endpoints of the connection. If the endpoints are moveable, the EditPolicy will show feedback and provide Commands to perform the move.

See Also:
Constant Field Values

CONNECTION_BENDPOINTS_ROLE

public static final java.lang.String CONNECTION_BENDPOINTS_ROLE
The key used to install a bendpoint EditPolicy. A bendpoint EditPolicy is an optional EditPolicy for connections that are visibile. As with endpoints, bendpoint EditPolicies are porbably SelectionHandlesEditPolicy.

See Also:
Constant Field Values

CONNECTION_ROLE

public static final java.lang.String CONNECTION_ROLE
The key used to install a connection EditPolicy. The behavior of a ConnectionEditPart may be implemented in its component EditPolicy,

See Also:
Constant Field Values

CONTAINER_ROLE

public static final java.lang.String CONTAINER_ROLE
The key used to install a container EditPolicy.

See Also:
Constant Field Values

DIRECT_EDIT_ROLE

public static final java.lang.String DIRECT_EDIT_ROLE
The key used to install a direct edit EditPolicy.

See Also:
Constant Field Values

GRAPHICAL_NODE_ROLE

public static final java.lang.String GRAPHICAL_NODE_ROLE
The key used to install a graphical node EditPolicy.

See Also:
Constant Field Values

LAYOUT_ROLE

public static final java.lang.String LAYOUT_ROLE
The key used to install a layout EditPolicy.

See Also:
Constant Field Values

NODE_ROLE

public static final java.lang.String NODE_ROLE
The key used to install a node EditPolicy.

See Also:
Constant Field Values

PRIMARY_DRAG_ROLE

public static final java.lang.String PRIMARY_DRAG_ROLE
The key used to install a primary drag EditPolicy.

See Also:
Constant Field Values

SELECTION_FEEDBACK_ROLE

public static final java.lang.String SELECTION_FEEDBACK_ROLE
The key used to install a selection feedback EditPolicy.

See Also:
Constant Field Values

TREE_CONTAINER_ROLE

public static final java.lang.String TREE_CONTAINER_ROLE
The key used to install a tree container EditPolicy.

See Also:
Constant Field Values
Method Detail

activate

public void activate()
Activates this EditPolicy. The EditPolicy might need to hook listeners. These listeners should be unhooked in deactivate(). The EditPolicy might also contribute feedback/visuals immediately, such as selection handles if the EditPart was selected at the time of activation.

Activate is called after the host has been set, and that host has been activated.

See Also:
EditPart.activate(), deactivate(), EditPart.installEditPolicy(Object, EditPolicy)

deactivate

public void deactivate()
Deactivates the EditPolicy, the inverse of activate(). Deactivate is called when the host is deactivated, or when the EditPolicy is uninstalled from an active host. Deactivate unhooks any listeners, and removes all feedback.

See Also:
EditPart.deactivate(), activate(), EditPart.removeEditPolicy(Object)

eraseSourceFeedback

public void eraseSourceFeedback(
Request request)
Erases source feedback based on the given Request. Does nothing if the EditPolicy does not apply to the given Request.

This method is declared on EditPart, and is redeclared here so that EditPart can delegate its implementation to each of its EditPolicies.

Parameters:
request - the Request

eraseTargetFeedback

public void eraseTargetFeedback(
Request request)
Erases target feedback based on the given Request. Does nothing if the EditPolicy does not apply to the given Request.

This method is declared on EditPart, and is redeclared here so that EditPart can delegate its implementation to each of its EditPolicies.

Parameters:
request - the Request

getCommand

public 
Command getCommand(
Request request)
Returns the Command contribution for the given Request, or null. null is treated as a no-op by the caller, or an empty contribution. The EditPolicy must return an UnexecutableCommand if it wishes to disallow the Request.

This method is declared on EditPart, and is redeclared here so that EditPart can delegate its implementation to each of its EditPolicies. The EditPart will combine each EditPolicy's contribution into a CompoundCommand.

Parameters:
request - the Request
Returns:
null or a Command contribution

getHost

public 
EditPart getHost()
Returns:
the host EditPart on which this policy is installed.

getTargetEditPart

public 
EditPart getTargetEditPart(
Request request)
Returns null or the appropriate EditPart for the specified Request. In general, this EditPolicy will return its host EditPart if it understands the Request. Otherwise, it will return null.

This method is declared on EditPart, and is redeclared here so that EditPart can delegate its implementation to each of its EditPolicies. The first non-null result returned by an EditPolicy is returned by the EditPart.

Parameters:
request - the Request
Returns:
null or the appropriate target EditPart

setHost

public void setHost(
EditPart editpart)
Sets the host in which this EditPolicy is installed.

Parameters:
editpart - the host EditPart

showSourceFeedback

public void showSourceFeedback(
Request request)
Shows or updates source feedback for the specified Request. This method may be called repeatedly for the purpose of updating feedback based on changes to the Request.

Does nothing if the EditPolicy does not recognize the given Request.

This method is declared on EditPart, and is redeclared here so that EditPart can delegate its implementation to each of its EditPolicies.

Parameters:
request - the Request

showTargetFeedback

public void showTargetFeedback(
Request request)
Shows or updates target feedback for the specified Request. This method may be called repeatedly for the purpose of updating feedback based on changes to the Request.

Does nothing if the EditPolicy does not recognize the given request.

This method is declared on EditPart, and is redeclared here so that EditPart can delegate its implementation to each of its EditPolicies.

Parameters:
request - the Request

understandsRequest

public boolean understandsRequest(
Request request)
Returns true if this EditPolicy understand the specified request.

This method is declared on EditPart, and is redeclared here so that EditPart can delegate its implementation to each of its EditPolicies. EditPart returns true if any of its EditPolicies returns true. In other words, it performs a logical OR.

Parameters:
request - the Request
Returns:
boolean true if the EditPolicy understands the specified request
See Also:
EditPart.understandsRequest(Request)

Eclipse GEF
3.3

Copyright (c) IBM Corp. and others 2000, 2007. All Rights Reserved.

 
 
  Published under the terms of the Eclipse Public License Version 1.0 ("EPL") Design by Interspire