Package org.eclipse.graphiti.features

Interface ICustomUndoRedoFeature

All Known Subinterfaces:

ICustomAbortableUndoRedoFeature

All Known Implementing Classes:

AddFeatureForPattern, CreateConnectionFeatureForPattern, CreateFeatureForPattern, DefaultUpdateDiagramFeature, DeleteFeatureForPattern, DirectEditingFeatureForPattern, LayoutFeatureForPattern, MoveShapeFeatureForPattern, ReconnectionFeatureForPattern, RemoveFeatureForPattern, ResizeShapeFeatureForPattern, UpdateFeatureForPattern

public interface ICustomUndoRedoFeature

This interface can by used and implemented by customers within any feature to signal the need for additional work that needs to be done before or after undo and redo. When a feature implements this interface, and the framework performs an undo or a redo, the framework will call the contained methods.

Implementing this interface is especially helpful if customers want to implement undo/redo functionality for non-EMF changes, e.g. for non-EMF domain models. Note that any EMF-model change (including the changes done to the graphical representation (Graphiti PictogramElements and GraphicsAlgorithms will by handled automatically by the Graphiti framework no matter if this interface is implemented by a feature or not. The feature may use the context object (e.g. the contained properties set) passed to the contained methods while executing the feature in order to collect any information needed for undo.

In case you want to cancel undo/redo operations in preUndo(IContext)/preRedo(IContext), you need to implement ICustomAbortableUndoRedoFeature which offers an ICustomAbortableUndoRedoFeature.isAbort() method that causes the cancellation of undo/redo operation in case true is returned.

Since:

0.12

See Also:

• ICustomAbortableUndoRedoFeature

Method Summary

Modifier and Type	Method	Description
boolean	canRedo(IContext context)	Decides if the processed feature can be re-done.
boolean	canUndo(IContext context)	Decides if the changes done by a processed feature can be undone.
void	postRedo(IContext context)	This method will be called by the Graphiti framework after the EMF undo has finished.
void	postUndo(IContext context)	This method will be called by the Graphiti framework after the EMF undo is finished.
void	preRedo(IContext context)	This method will be called by the Graphiti framework before the EMF undo has triggered.
void	preUndo(IContext context)	This method will be called by the Graphiti framework before the EMF undo is triggered.

Method Details

canUndo

boolean canUndo(IContext context)

Decides if the changes done by a processed feature can be undone. This method is called once by the Graphiti framework just before any undo work is started, e.g. before preUndo(IContext).

Note that as soon as any feature reports false here, also all previous entries in the command stack are no longer reachable for undo.

Note: this method with exactly the same signature is also already part of the IFeature contract. It is repeated here for transparency purposes only.

Parameters:

context - this is the instance of the IContext object that was in use when executing the feature.

Returns:

true if the feature can be undone, false if not

preUndo

void preUndo(IContext context)

This method will be called by the Graphiti framework before the EMF undo is triggered. Customers may revert their non-EMF changes done by the feature here or in postUndo(IContext).

Parameters:

context - this is the instance of the IContext object that was in use when executing the feature

postUndo

void postUndo(IContext context)

This method will be called by the Graphiti framework after the EMF undo is finished. Customers may revert their non-EMF changes done by the feature here or in preUndo(IContext).

Parameters:

context - this is the instance of the IContext object that was in use when executing the feature

canRedo

boolean canRedo(IContext context)

Decides if the processed feature can be re-done. This method is called once by the Graphiti framework just before any redo work is started, e.g. before preRedo(IContext).

Note that as soon as any feature reports false here, also all consecutive entries in the command stack are no longer reachable for redo.

Parameters:

context - this is the instance of the IContext object that was in use when executing the feature

Returns:

true if the feature can be re-done, false if not

preRedo

void preRedo(IContext context)

This method will be called by the Graphiti framework before the EMF undo has triggered. Customers may re-apply their non-EMF changes done by the feature here or in postRedo(IContext). (Usually it might be sufficient to delegate to the execution method of the feature.)

Parameters:

context - this is the instance of the IContext object that was in use when executing the feature

postRedo

void postRedo(IContext context)

This method will be called by the Graphiti framework after the EMF undo has finished. Customers may re-apply their non-EMF changes done by the feature here or in preRedo(IContext). (Usually it might be sufficient to delegate to the execution method of the feature.)

Parameters:

context - this is the instance of the IContext object that was in use when executing the feature