An implementation of the IUndoUnit interface that uses delegates for the actual undo and redo operations.
Type Parameters
- T
- The type of the single parameter that is passed to the delegate.
Type Details
- yfiles module
- view-component
- yfiles-umd modules
- All view modules
- Legacy UMD name
- yfiles.graph.DelegateUndoUnit
Constructors
Creates a new instance using the provided name and a undo/redo handler as well as the parameters to pass to the delegates.
Parameters
A map of options to pass to the method.
- undoName - string
- The name of the undo.
- undoRedo - function(T):void
- The undo and redo handler delegate.
Signature Details
function(param: T)The delegate that is used by DelegateUndoUnit<T>.Parameters
- param - T
- An usage dependent parameter that is passed to the delegate.
- undoParam - T
- The undo parameter to pass to the delegate.
- redoParam - T
- The redo parameter to pass to the delegate.
DelegateUndoUnit
(undoName: string, undo: function(T):void, redo: function(T):void, undoParam: T, redoParam: T)Creates a new instance using the provided name and a undo and redo handler as well as the parameters to pass to the delegates.
Parameters
A map of options to pass to the method.
- undoName - string
- The name of the undo.
- undo - function(T):void
- The undo handler delegate.
Signature Details
function(param: T)The delegate that is used by DelegateUndoUnit<T>.Parameters
- param - T
- An usage dependent parameter that is passed to the delegate.
- redo - function(T):void
- The redo handler delegate.
Signature Details
function(param: T)The delegate that is used by DelegateUndoUnit<T>.Parameters
- param - T
- An usage dependent parameter that is passed to the delegate.
- undoParam - T
- The undo parameter to pass to the delegate.
- redoParam - T
- The redo parameter to pass to the delegate.
Properties
Gets the name of the redo unit.
Remarks
Implements
Gets the name of the undo unit.
Remarks
Implements
Methods
Called by the UndoEngine and client code to let the unit dispose of references aren't needed anymore.
Remarks
Implements
Calls the redo delegate using the redo parameter.
Returns a string representation for this object.
Tries to merge the given unit with this one.
Remarks
This method is called when this unit is the head of an UndoEngine's or CompositeUndoUnit's queue and a new unit is added. It is meant to try to incorporate the change of the given unit into this and if successful return true. This should be the case when the end state of this unit is equal to the start state of the given unit.
For example, if this unit is the head of the queue and represents the work from state A to state B and the given unit the work from state B to state C, then this method should try to make this unit shift from state A to state C. If this is successful, the method is expected to return true. The other unit is then disposed by the UndoEngine afterwards.
Clients don't necessarily have to implement this method if the unit doesn't happen very often. In fact, the default implementation of tryMergeUnit simply returns false. Implementing this method faithfully will cause multiple units of work to inseparably appear as one and undoing/redoing it will undo/redo the work of all collapsed units. Depending on the situation this may be reasonable, for example when there are potentially a lot of changes where not every intermediate step is required to be recorded. In this case implementing this method faithfully will greatly improve the performance and reduce the required amount of memory of the undo process. If you want to group together multiple units as a single block but still want to be able to separate each step, consider to use a CompositeUndoUnit instead.
Parameters
A map of options to pass to the method.
- unit - IUndoUnit
- The unit to incorporate that happened after this unit.
Returns
- ↪boolean
- Whether the state change of
unithas been incorporated into this unit andunitcan be disposed of.
See Also
Implements
Tries to replace the given unit with this one.
Remarks
This method is called if a newly added unit couldn't be merged with the head unit of the queue (i.e. returned false). Instead of trying to merge a newly added unit, this method tries to replace the given unit (which is the head of the queue) with this by incorporating the change of the given unit into this and if successful return true. This should be the case when the start state of this unit is equal to the end state of the given unit.
For example, if the given unit represents the work from state A to state B and this unit the work from state B to state C, then this method should try to make this unit shift from state A to state C. If this is successful, the method is expected to return true. The given unit is then disposed by the UndoEngine afterwards and replaced with this unit in the queue.
Clients don't necessarily have to implement this method if the unit doesn't happen very often. In fact, the default implementation of tryReplaceUnit simply returns false. Implementing this method faithfully will cause multiple units of work to inseparably appear as one and undoing/redoing it will undo/redo the work of all collapsed units. Depending on the situation this may be reasonable, for example when there are potentially a lot of changes where not every intermediate step is required to be recorded. In this case implementing this method faithfully will greatly improve the performance and reduce the required amount of memory of the undo process. If you want to group together multiple units as a single block but still want to be able to separate each step, consider to use a CompositeUndoUnit instead.
Parameters
A map of options to pass to the method.
- unit - IUndoUnit
- The unit to incorporate that happened before this unit.
Returns
- ↪boolean
- Whether the state change of
thisunit has been incorporated into the givenunitandthiscan be disposed of.
See Also
Implements
Calls the undo delegate using the undo parameter.