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/*
==============================================================================
This file is part of the JUCE library.
Copyright (c) 2017 - ROLI Ltd.
JUCE is an open source library subject to commercial or open-source
licensing.
By using JUCE, you agree to the terms of both the JUCE 5 End-User License
Agreement and JUCE 5 Privacy Policy (both updated and effective as of the
27th April 2017).
End User License Agreement: www.juce.com/juce-5-licence
Privacy Policy: www.juce.com/juce-5-privacy-policy
Or: You may also use this code under the terms of the GPL v3 (see
www.gnu.org/licenses).
JUCE IS PROVIDED "AS IS" WITHOUT ANY WARRANTY, AND ALL WARRANTIES, WHETHER
EXPRESSED OR IMPLIED, INCLUDING MERCHANTABILITY AND FITNESS FOR PURPOSE, ARE
DISCLAIMED.
==============================================================================
*/
namespace juce
{
//==============================================================================
/**
Manages a list of undo/redo commands.
An UndoManager object keeps a list of past actions and can use these actions
to move backwards and forwards through an undo history.
To use it, create subclasses of UndoableAction which perform all the
actions you need, then when you need to actually perform an action, create one
and pass it to the UndoManager's perform() method.
The manager also uses the concept of 'transactions' to group the actions
together - all actions performed between calls to beginNewTransaction() are
grouped together and are all undone/redone as a group.
The UndoManager is a ChangeBroadcaster, so listeners can register to be told
when actions are performed or undone.
@see UndoableAction
@tags{DataStructures}
*/
class JUCE_API UndoManager : public ChangeBroadcaster
{
public:
//==============================================================================
/** Creates an UndoManager.
@param maxNumberOfUnitsToKeep each UndoableAction object returns a value
to indicate how much storage it takes up
(UndoableAction::getSizeInUnits()), so this
lets you specify the maximum total number of
units that the undomanager is allowed to
keep in memory before letting the older actions
drop off the end of the list.
@param minimumTransactionsToKeep this specifies the minimum number of transactions
that will be kept, even if this involves exceeding
the amount of space specified in maxNumberOfUnitsToKeep
*/
UndoManager (int maxNumberOfUnitsToKeep = 30000,
int minimumTransactionsToKeep = 30);
/** Destructor. */
~UndoManager() override;
//==============================================================================
/** Deletes all stored actions in the list. */
void clearUndoHistory();
/** Returns the current amount of space to use for storing UndoableAction objects.
@see setMaxNumberOfStoredUnits
*/
int getNumberOfUnitsTakenUpByStoredCommands() const;
/** Sets the amount of space that can be used for storing UndoableAction objects.
@param maxNumberOfUnitsToKeep each UndoableAction object returns a value
to indicate how much storage it takes up
(UndoableAction::getSizeInUnits()), so this
lets you specify the maximum total number of
units that the undomanager is allowed to
keep in memory before letting the older actions
drop off the end of the list.
@param minimumTransactionsToKeep this specifies the minimum number of transactions
that will be kept, even if this involves exceeding
the amount of space specified in maxNumberOfUnitsToKeep
@see getNumberOfUnitsTakenUpByStoredCommands
*/
void setMaxNumberOfStoredUnits (int maxNumberOfUnitsToKeep,
int minimumTransactionsToKeep);
//==============================================================================
/** Performs an action and adds it to the undo history list.
@param action the action to perform - this object will be deleted by
the UndoManager when no longer needed
@returns true if the command succeeds - see UndoableAction::perform
@see beginNewTransaction
*/
bool perform (UndoableAction* action);
/** Performs an action and also gives it a name.
@param action the action to perform - this object will be deleted by
the UndoManager when no longer needed
@param actionName if this string is non-empty, the current transaction will be
given this name; if it's empty, the current transaction name will
be left unchanged. See setCurrentTransactionName()
@returns true if the command succeeds - see UndoableAction::perform
@see beginNewTransaction
*/
bool perform (UndoableAction* action, const String& actionName);
/** Starts a new group of actions that together will be treated as a single transaction.
All actions that are passed to the perform() method between calls to this
method are grouped together and undone/redone together by a single call to
undo() or redo().
*/
void beginNewTransaction();
/** Starts a new group of actions that together will be treated as a single transaction.
All actions that are passed to the perform() method between calls to this
method are grouped together and undone/redone together by a single call to
undo() or redo().
@param actionName a description of the transaction that is about to be
performed
*/
void beginNewTransaction (const String& actionName);
/** Changes the name stored for the current transaction.
Each transaction is given a name when the beginNewTransaction() method is
called, but this can be used to change that name without starting a new
transaction.
*/
void setCurrentTransactionName (const String& newName);
/** Returns the name of the current transaction.
@see setCurrentTransactionName
*/
String getCurrentTransactionName() const;
//==============================================================================
/** Returns true if there's at least one action in the list to undo.
@see getUndoDescription, undo, canRedo
*/
bool canUndo() const;
/** Tries to roll-back the last transaction.
@returns true if the transaction can be undone, and false if it fails, or
if there aren't any transactions to undo
@see undoCurrentTransactionOnly
*/
bool undo();
/** Tries to roll-back any actions that were added to the current transaction.
This will perform an undo() only if there are some actions in the undo list
that were added after the last call to beginNewTransaction().
This is useful because it lets you call beginNewTransaction(), then
perform an operation which may or may not actually perform some actions, and
then call this method to get rid of any actions that might have been done
without it rolling back the previous transaction if nothing was actually
done.
@returns true if any actions were undone.
*/
bool undoCurrentTransactionOnly();
/** Returns the name of the transaction that will be rolled-back when undo() is called.
@see undo, canUndo, getUndoDescriptions
*/
String getUndoDescription() const;
/** Returns the names of the sequence of transactions that will be performed if undo()
is repeatedly called. Note that for transactions where no name was provided, the
corresponding string will be empty.
@see undo, canUndo, getUndoDescription
*/
StringArray getUndoDescriptions() const;
/** Returns the time to which the state would be restored if undo() was to be called.
If an undo isn't currently possible, it'll return Time().
*/
Time getTimeOfUndoTransaction() const;
/** Returns a list of the UndoableAction objects that have been performed during the
transaction that is currently open.
Effectively, this is the list of actions that would be undone if undoCurrentTransactionOnly()
were to be called now.
The first item in the list is the earliest action performed.
*/
void getActionsInCurrentTransaction (Array<const UndoableAction*>& actionsFound) const;
/** Returns the number of UndoableAction objects that have been performed during the
transaction that is currently open.
@see getActionsInCurrentTransaction
*/
int getNumActionsInCurrentTransaction() const;
//==============================================================================
/** Returns true if there's at least one action in the list to redo.
@see getRedoDescription, redo, canUndo
*/
bool canRedo() const;
/** Tries to redo the last transaction that was undone.
@returns true if the transaction can be redone, and false if it fails, or
if there aren't any transactions to redo
*/
bool redo();
/** Returns the name of the transaction that will be redone when redo() is called.
@see redo, canRedo, getRedoDescriptions
*/
String getRedoDescription() const;
/** Returns the names of the sequence of transactions that will be performed if redo()
is repeatedly called. Note that for transactions where no name was provided, the
corresponding string will be empty.
@see redo, canRedo, getRedoDescription
*/
StringArray getRedoDescriptions() const;
/** Returns the time to which the state would be restored if redo() was to be called.
If a redo isn't currently possible, it'll return Time::getCurrentTime().
@see redo, canRedo
*/
Time getTimeOfRedoTransaction() const;
/** Returns true if the caller code is in the middle of an undo or redo action. */
bool isPerformingUndoRedo() const;
private:
//==============================================================================
struct ActionSet;
OwnedArray<ActionSet> transactions, stashedFutureTransactions;
String newTransactionName;
int totalUnitsStored = 0, maxNumUnitsToKeep = 0, minimumTransactionsToKeep = 0, nextIndex = 0;
bool newTransaction = true, isInsideUndoRedoCall = false;
ActionSet* getCurrentSet() const;
ActionSet* getNextSet() const;
void moveFutureTransactionsToStash();
void restoreStashedFutureTransactions();
void dropOldTransactionsIfTooLarge();
JUCE_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR (UndoManager)
};
} // namespace juce
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