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<?xml version="1.0"?>
<!DOCTYPE gsdoc PUBLIC "-//GNUstep//DTD gsdoc 1.0.4//EN" "http://www.gnustep.org/gsdoc-1_0_4.dtd">
<gsdoc base="NSUndoManager" up="Base">
<head>
<title>NSUndoManager class reference</title>
<author name="Richard Frith-Macdonald">
<email address="richard@brainstorm.co.uk">
richard@brainstorm.co.uk
</email>
</author>
<copy>1998 Free Software Foundation, Inc.</copy>
</head>
<body>
<front><contents /></front>
<chapter>
<heading>
Software documentation for the NSUndoManager class
</heading>
<class name="NSUndoManager" super="NSObject" ovadd="10.0.0">
<declared>Foundation/NSUndoManager.h</declared>
<desc>
NSUndoManager provides a general mechanism
supporting implementation of user action "undo" in
applications. Essentially, it allows you to
store sequences of messages and receivers that need to
be invoked to undo or redo an action. The various methods
in this class provide for grouping of sets of actions,
execution of undo or redo actions, and tuning
behavior parameters such as the size of the undo
stack. Each application entity with its own editing
history (e.g., a document) should have its own undo
manager instance. Obtain an instance through a simple
<code>[[NSUndoManager alloc] init]</code> message.
</desc>
<method type="void" ovadd="10.0.0">
<sel>beginUndoGrouping</sel>
<desc>
Starts a new grouping of undo actions which can be
atomically undone by an
<ref type="method" id="-undo">
[-undo]
</ref>
invocation. <br /> This method posts an
NSUndoManagerDidOpenUndoGroupNotification
upon creating the grouping. <br /> It first posts an
NSUndoManagerCheckpointNotification
unless an undo is currently in progress. <br /> The
order of these notifications is undefined, but the
GNUstep implementation currently mimics the
observed order in MacOS X 10.5
</desc>
</method>
<method type="BOOL" ovadd="10.0.0">
<sel>canRedo</sel>
<desc>
Returns whether the receiver can service redo
requests and posts a
NSUndoManagerCheckpointNotification.
</desc>
</method>
<method type="BOOL" ovadd="10.0.0">
<sel>canUndo</sel>
<desc>
Returns whether the receiver has any action
groupings on the stack to undo. It does not
imply, that the receiver is currently in a state to
service an undo request. Make sure
<ref type="method" id="-endUndoGrouping">
[-endUndoGrouping]
</ref>
is invoked before requesting either an
<ref type="method" id="-undo">
[-undo]
</ref>
or an
<ref type="method" id="-undoNestedGroup">
-undoNestedGroup
</ref>
.
</desc>
</method>
<method type="void" ovadd="10.0.0">
<sel>disableUndoRegistration</sel>
<desc>
Disables the registration of operations with with
either
<ref type="method" id="-registerUndoWithTarget:selector:object:">[-registerUndoWithTarget:selector:object:]</ref> or <ref type="method" id="-forwardInvocation:">-forwardInvocation:</ref>. This method may be called multiple times. Each will need to be paired to a call of <ref type="method" id="-enableUndoRegistration">[-enableUndoRegistration]</ref> before registration is actually reenabled.
</desc>
</method>
<method type="void" ovadd="10.0.0">
<sel>enableUndoRegistration</sel>
<desc>
Matches previous calls of to
<ref type="method" id="-disableUndoRegistration">
-disableUndoRegistration
</ref>
. Only call this method to that end. Once all are
matched, the registration of
<ref type="method" id="-registerUndoWithTarget:selector:object:">[-registerUndoWithTarget:selector:object:]</ref> and <ref type="method" id="-forwardInvocation:">[-forwardInvocation:]</ref> are reenabled. If this method is called without a matching <ref type="method" id="-disableUndoRegistration">-disableUndoRegistration</ref>, it will raise an NSInternalInconsistencyException.
</desc>
</method>
<method type="void" ovadd="10.0.0">
<sel>endUndoGrouping</sel>
<desc>
Matches previous calls of to
<ref type="method" id="-beginUndoGrouping">
[-beginUndoGrouping]
</ref>
and puts the group on the undo stack. This method posts
an NSUndoManagerCheckpointNotification and a
NSUndoManagerWillCloseUndoGroupNotification.
If there was no matching call to
<ref type="method" id="-beginUndoGrouping">
-beginUndoGrouping
</ref>
, this method will raise an
NSInternalInconsistencyException.
</desc>
</method>
<method type="void" ovadd="10.0.0">
<sel>forwardInvocation:</sel>
<arg type="NSInvocation*">anInvocation</arg>
<desc>
Registers the invocation with the current undo
grouping. This method is part of the
NSInvocation-based undo registration as
opposed to the simpler
<ref type="method" id="-registerUndoWithTarget:selector:object:">[-registerUndoWithTarget:selector:object:]</ref> technique. <br /> You generally never invoke this method directly. Instead invoke <ref type="method" id="-prepareWithInvocationTarget:">[-prepareWithInvocationTarget:]</ref> with the target of the undo action and then invoke the targets method to undo the action on the return value of <ref type="method" id="-prepareWithInvocationTarget:">-prepareWithInvocationTarget:</ref> which actually is the undo manager. The runtime will then fallback to <ref type="method" id="-forwardInvocation:">-forwardInvocation:</ref> to do the actual registration of the invocation. The invocation will added to the current grouping. <br /> If the registrations have been disabled through <ref type="method" id="-disableUndoRegistration">-disableUndoRegistration</ref>, this method does nothing. <br /> Unless the receiver implicitly groups operations by event, the this method must have been preceded with a <ref type="method" id="-beginUndoGrouping">[-beginUndoGrouping]</ref> message. Otherwise it will raise an NSInternalInconsistencyException. <br /> Unless this method is invoked as part of a <ref type="method" id="-undo">[-undo]</ref> or <ref type="method" id="-undoNestedGroup">[-undoNestedGroup]</ref> processing, the redo stack is cleared. <br /> If the receiver <ref type="method" id="-groupsByEvent">[-groupsByEvent]</ref> and this is the first call to this method since the last run loop processing, this method sets up the receiver to process the <ref type="method" id="-endUndoGrouping">[-endUndoGrouping]</ref> at the end of the event loop.
</desc>
</method>
<method type="NSInteger" ovadd="10.0.0">
<sel>groupingLevel</sel>
<desc>
Returns the current number of groupings. These are
the current groupings which can be nested, not the
number of of groups on either the undo or redo
stack.
</desc>
</method>
<method type="BOOL" ovadd="10.0.0">
<sel>groupsByEvent</sel>
<desc>
Returns whether the receiver currently groups undo
operations by events. When it does, so it
implicitly invokes
<ref type="method" id="-beginUndoGrouping">
[-beginUndoGrouping]
</ref>
upon registration of undo operations and registers an
internal call to insure the invocation of
<ref type="method" id="-endUndoGrouping">
[-endUndoGrouping]
</ref>
at the end of the run loop.
</desc>
</method>
<method type="BOOL" ovadd="10.0.0">
<sel>isRedoing</sel>
<desc>
Returns whether the receiver is currently
processing a redo.
</desc>
</method>
<method type="BOOL" ovadd="10.0.0">
<sel>isUndoRegistrationEnabled</sel>
<desc>
Returns whether the receiver will currently
register undo operations.
</desc>
</method>
<method type="BOOL" ovadd="10.0.0">
<sel>isUndoing</sel>
<desc>
Returns whether the receiver is currently
processing an undo.
</desc>
</method>
<method type="NSUInteger" ovadd="10.0.0">
<sel>levelsOfUndo</sel>
<desc>
Returns the maximum number of undo groupings the
receiver will maintain. The default value is 0
meaning the number is only limited by memory
availability.
</desc>
</method>
<method type="id" ovadd="10.0.0">
<sel>prepareWithInvocationTarget:</sel>
<arg type="id">target</arg>
<desc>
Prepares the receiver to registers an
invocation-based undo operation. This
method is part of the NSInvocation-based undo
registration as opposed to the simpler
<ref type="method" id="-registerUndoWithTarget:selector:object:">[-registerUndoWithTarget:selector:object:]</ref> technique. <br /> You invoke this method with the <var>target</var> of the undo action and then invoke the targets method to undo the action on the return value of this invocation which actually is the undo manager. The runtime will then fallback to <ref type="method" id="-forwardInvocation:">[-forwardInvocation:]</ref> to do the actual registration of the invocation.
</desc>
</method>
<method type="void" ovadd="10.0.0">
<sel>redo</sel>
<desc>
Performs a redo of previous undo request by taking
the top grouping from the redo stack and invoking them.
This method posts an
NSUndoManagerCheckpointNotification
notification to allow the client to process
any pending changes before proceeding. If there are
groupings on the redo stack, the top object is
popped off the stack and invoked within a nested
<ref type="method" id="-beginUndoGrouping">
-beginUndoGrouping
</ref>
/[-endUndoGrouping]. During this
processing, the operations registered for undo
are recorded on the undo stack again. <br />
</desc>
</method>
<method type="NSString*" ovadd="10.0.0">
<sel>redoActionName</sel>
<desc>
If the receiver can perform a redo, this method returns
the action name previously associated with the top
grouping with
<ref type="method" id="-setActionName:">
-setActionName:
</ref>
. This name should identify the action to be redone. If
there are no items on the redo stack this method
returns <code>nil</code>. If no action name has
been set, this method returns an empty string.
</desc>
</method>
<method type="NSString*" ovadd="10.0.0">
<sel>redoMenuItemTitle</sel>
<desc>
Returns the full localized title of the actions to
be displayed as a menu item. This method first invokes
<ref type="method" id="-redoActionName">
[-redoActionName]
</ref>
and passes it to
<ref type="method" id="-redoMenuTitleForUndoActionName:">
[-redoMenuTitleForUndoActionName:]
</ref>
and returns the result.
</desc>
</method>
<method type="NSString*" ovadd="10.0.0">
<sel>redoMenuTitleForUndoActionName:</sel>
<arg type="NSString*">actionName</arg>
<desc>
Returns the localized title of the actions to be
displayed as a menu item identified by
<var>actionName</var>, by appending a localized
command string like @"Redo <localized(
<var>actionName</var>)>".
</desc>
</method>
<method type="void" ovadd="10.0.0">
<sel>registerUndoWithTarget:</sel>
<arg type="id">target</arg>
<sel>selector:</sel>
<arg type="SEL">aSelector</arg>
<sel>object:</sel>
<arg type="id">anObject</arg>
<desc>
Registers an undo operation. This method is the
simple target-action-based undo registration as
opposed to the sophisticated
<ref type="method" id="-forwardInvocation:">
[-forwardInvocation:]
</ref>
mechanism. <br /> You invoke this method with
the <var>target</var> of the undo action providing the
selector which can perform the undo with the
provided object. The object is often a dictionary
of the identifying the attribute and their values before
the change. The object will be retained. The invocation
will added to the current grouping. <br /> If the
registrations have been disabled through
<ref type="method" id="-disableUndoRegistration">
-disableUndoRegistration
</ref>
, this method does nothing. <br /> Unless the receiver
implicitly groups operations by event, the this
method must have been preceded with a
<ref type="method" id="-beginUndoGrouping">
[-beginUndoGrouping]
</ref>
message. Otherwise it will raise an
NSInternalInconsistencyException.
<br /> Unless this method is invoked as part of a
<ref type="method" id="-undo">
[-undo]
</ref>
or
<ref type="method" id="-undoNestedGroup">
[-undoNestedGroup]
</ref>
processing, the redo stack is cleared. <br />
If the receiver
<ref type="method" id="-groupsByEvent">
[-groupsByEvent]
</ref>
and this is the first call to this method since the
last run loop processing, this method sets up the
receiver to process the
<ref type="method" id="-endUndoGrouping">
[-endUndoGrouping]
</ref>
at the end of the event loop.
</desc>
</method>
<method type="void" ovadd="10.0.0">
<sel>removeAllActions</sel>
<desc>
Removes all grouping stored in the receiver. This
clears the both the undo and the redo stacks. This
method is if the sole client of the undo manager
will be unable to service any undo or redo events. The
client can call this method in its
<ref type="method" id="-dealloc">
-dealloc
</ref>
method, unless the undo manager has several
clients, in which case
<ref type="method" id="-removeAllActionsWithTarget:">
[-removeAllActionsWithTarget:]
</ref>
is more appropriate.
</desc>
</method>
<method type="void" ovadd="10.0.0">
<sel>removeAllActionsWithTarget:</sel>
<arg type="id">target</arg>
<desc>
Removes all actions recorded for the given
<var>target</var>. This method is is useful when a
client of the undo manager will be unable to service
any undo or redo events. Clients should call this
method in their dealloc method, unless they are the
sole client of the undo manager in which case
<ref type="method" id="-removeAllActions">
[-removeAllActions]
</ref>
is more appropriate.
</desc>
</method>
<method type="NSArray*" ovadd="10.0.0">
<sel>runLoopModes</sel>
<desc>
Returns the run loop modes in which the receiver
registers the
<ref type="method" id="-endUndoGrouping">
[-endUndoGrouping]
</ref>
processing when it
<ref type="method" id="-groupsByEvent">
-groupsByEvent
</ref>
.
</desc>
</method>
<method type="void" ovadd="10.0.0">
<sel>setActionName:</sel>
<arg type="NSString*">name</arg>
<desc>
Sets the <var>name</var> associated with the actions
of the current group. Typically you can call this method
while registering the actions for the current group.
This <var>name</var> will be used to determine the
<var>name</var> in the
<ref type="method" id="-undoMenuTitleForUndoActionName:">
[-undoMenuTitleForUndoActionName:]
</ref>
and
<ref type="method" id="-redoMenuTitleForUndoActionName:">
[-redoMenuTitleForUndoActionName:]
</ref>
names typically displayed in the menu.
</desc>
</method>
<method type="void" ovadd="10.0.0">
<sel>setGroupsByEvent:</sel>
<arg type="BOOL">flag</arg>
<desc>
Sets whether the receiver should implicitly call
<ref type="method" id="-beginUndoGrouping">
[-beginUndoGrouping]
</ref>
when necessary and register a call to invoke
<ref type="method" id="-endUndoGrouping">
[-endUndoGrouping]
</ref>
at the end of the current event loop. The grouping is
turned on by default.
</desc>
</method>
<method type="void" ovadd="10.0.0">
<sel>setLevelsOfUndo:</sel>
<arg type="NSUInteger">num</arg>
<desc>
Sets the maximum number of groups in either the undo
or redo stack. Use this method to limit memory usage if
you either expect very many actions to be recorded or
the recorded objects require a lot of memory. When set
to 0 the stack size is limited by the range of a
<strong>unsigned</strong> <strong>int</strong>,
available memory.
</desc>
</method>
<method type="void" ovadd="10.0.0">
<sel>setRunLoopModes:</sel>
<arg type="NSArray*">newModes</arg>
<desc>
Sets the modes in which the receiver registers the
calls with the current run loop to invoke
<ref type="method" id="-endUndoGrouping">
[-endUndoGrouping]
</ref>
when it
<ref type="method" id="-groupsByEvent">
-groupsByEvent
</ref>
. This method first cancels any pending registrations in
the old modes and registers the invocation in the new
modes.
</desc>
</method>
<method type="void" ovadd="10.0.0">
<sel>undo</sel>
<desc>
This method performs an undo by invoking
<ref type="method" id="-undoNestedGroup">
-undoNestedGroup
</ref>
. If current group of the receiver is the top group this
method first calls
<ref type="method" id="-endUndoGrouping">
-endUndoGrouping
</ref>
. This method may only be called on the top level group,
otherwise it will raise an
NSInternalInconsistencyException.
</desc>
</method>
<method type="NSString*" ovadd="10.0.0">
<sel>undoActionName</sel>
<desc>
If the receiver can perform an undo, this method returns
the action name previously associated with the top
grouping with
<ref type="method" id="-setActionName:">
-setActionName:
</ref>
. This name should identify the action to be undone. If
there are no items on the undo stack this method
returns <code>nil</code>. If no action name has
been set, this method returns an empty string.
</desc>
</method>
<method type="NSString*" ovadd="10.0.0">
<sel>undoMenuItemTitle</sel>
<desc>
Returns the full localized title of the actions to
be displayed as a menu item. This method first invokes
<ref type="method" id="-undoActionName">
[-undoActionName]
</ref>
and passes it to
<ref type="method" id="-undoMenuTitleForUndoActionName:">
[-undoMenuTitleForUndoActionName:]
</ref>
and returns the result.
</desc>
</method>
<method type="NSString*" ovadd="10.0.0">
<sel>undoMenuTitleForUndoActionName:</sel>
<arg type="NSString*">actionName</arg>
<desc>
Returns the localized title of the actions to be
displayed as a menu item identified by
<var>actionName</var>, by appending a localized
command string like @"Undo <localized(
<var>actionName</var>)>".
</desc>
</method>
<method type="void" ovadd="10.0.0">
<sel>undoNestedGroup</sel>
<desc>
Performs an undo by taking the top grouping from
the undo stack and invoking them. This method posts an
NSUndoManagerCheckpointNotification
notification to allow the client to process
any pending changes before proceeding. If there are
groupings on the undo stack, the top object is
popped off the stack and invoked within a nested
beginUndoGrouping/endUndoGrouping.
During this processing, the undo operations
registered for undo are recorded on the redo
stack. <br />
</desc>
</method>
</class>
</chapter>
</body>
</gsdoc>
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