265 lines
12 KiB
C
265 lines
12 KiB
C
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/*
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==============================================================================
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This file is part of the JUCE library.
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Copyright (c) 2020 - Raw Material Software Limited
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JUCE is an open source library subject to commercial or open-source
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licensing.
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By using JUCE, you agree to the terms of both the JUCE 6 End-User License
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Agreement and JUCE Privacy Policy (both effective as of the 16th June 2020).
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End User License Agreement: www.juce.com/juce-6-licence
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Privacy Policy: www.juce.com/juce-privacy-policy
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Or: You may also use this code under the terms of the GPL v3 (see
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www.gnu.org/licenses).
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JUCE IS PROVIDED "AS IS" WITHOUT ANY WARRANTY, AND ALL WARRANTIES, WHETHER
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EXPRESSED OR IMPLIED, INCLUDING MERCHANTABILITY AND FITNESS FOR PURPOSE, ARE
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DISCLAIMED.
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==============================================================================
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*/
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namespace juce
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{
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//==============================================================================
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/**
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Manages a list of undo/redo commands.
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An UndoManager object keeps a list of past actions and can use these actions
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to move backwards and forwards through an undo history.
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To use it, create subclasses of UndoableAction which perform all the
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actions you need, then when you need to actually perform an action, create one
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and pass it to the UndoManager's perform() method.
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The manager also uses the concept of 'transactions' to group the actions
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together - all actions performed between calls to beginNewTransaction() are
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grouped together and are all undone/redone as a group.
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The UndoManager is a ChangeBroadcaster, so listeners can register to be told
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when actions are performed or undone.
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@see UndoableAction
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@tags{DataStructures}
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*/
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class JUCE_API UndoManager : public ChangeBroadcaster
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{
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public:
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//==============================================================================
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/** Creates an UndoManager.
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@param maxNumberOfUnitsToKeep each UndoableAction object returns a value
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to indicate how much storage it takes up
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(UndoableAction::getSizeInUnits()), so this
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lets you specify the maximum total number of
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units that the undomanager is allowed to
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keep in memory before letting the older actions
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drop off the end of the list.
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@param minimumTransactionsToKeep this specifies the minimum number of transactions
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that will be kept, even if this involves exceeding
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the amount of space specified in maxNumberOfUnitsToKeep
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*/
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UndoManager (int maxNumberOfUnitsToKeep = 30000,
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int minimumTransactionsToKeep = 30);
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/** Destructor. */
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~UndoManager() override;
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//==============================================================================
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/** Deletes all stored actions in the list. */
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void clearUndoHistory();
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/** Returns the current amount of space to use for storing UndoableAction objects.
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@see setMaxNumberOfStoredUnits
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*/
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int getNumberOfUnitsTakenUpByStoredCommands() const;
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/** Sets the amount of space that can be used for storing UndoableAction objects.
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@param maxNumberOfUnitsToKeep each UndoableAction object returns a value
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to indicate how much storage it takes up
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(UndoableAction::getSizeInUnits()), so this
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lets you specify the maximum total number of
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units that the undomanager is allowed to
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keep in memory before letting the older actions
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drop off the end of the list.
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@param minimumTransactionsToKeep this specifies the minimum number of transactions
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that will be kept, even if this involves exceeding
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the amount of space specified in maxNumberOfUnitsToKeep
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@see getNumberOfUnitsTakenUpByStoredCommands
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*/
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void setMaxNumberOfStoredUnits (int maxNumberOfUnitsToKeep,
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int minimumTransactionsToKeep);
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//==============================================================================
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/** Performs an action and adds it to the undo history list.
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@param action the action to perform - this object will be deleted by
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the UndoManager when no longer needed
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@returns true if the command succeeds - see UndoableAction::perform
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@see beginNewTransaction
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*/
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bool perform (UndoableAction* action);
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/** Performs an action and also gives it a name.
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@param action the action to perform - this object will be deleted by
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the UndoManager when no longer needed
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@param actionName if this string is non-empty, the current transaction will be
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given this name; if it's empty, the current transaction name will
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be left unchanged. See setCurrentTransactionName()
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@returns true if the command succeeds - see UndoableAction::perform
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@see beginNewTransaction
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*/
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bool perform (UndoableAction* action, const String& actionName);
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/** Starts a new group of actions that together will be treated as a single transaction.
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All actions that are passed to the perform() method between calls to this
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method are grouped together and undone/redone together by a single call to
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undo() or redo().
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*/
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void beginNewTransaction();
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/** Starts a new group of actions that together will be treated as a single transaction.
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All actions that are passed to the perform() method between calls to this
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method are grouped together and undone/redone together by a single call to
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undo() or redo().
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@param actionName a description of the transaction that is about to be
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performed
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*/
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void beginNewTransaction (const String& actionName);
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/** Changes the name stored for the current transaction.
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Each transaction is given a name when the beginNewTransaction() method is
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called, but this can be used to change that name without starting a new
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transaction.
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*/
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void setCurrentTransactionName (const String& newName);
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/** Returns the name of the current transaction.
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@see setCurrentTransactionName
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*/
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String getCurrentTransactionName() const;
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//==============================================================================
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/** Returns true if there's at least one action in the list to undo.
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@see getUndoDescription, undo, canRedo
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*/
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bool canUndo() const;
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/** Tries to roll-back the last transaction.
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@returns true if the transaction can be undone, and false if it fails, or
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if there aren't any transactions to undo
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@see undoCurrentTransactionOnly
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*/
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bool undo();
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/** Tries to roll-back any actions that were added to the current transaction.
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This will perform an undo() only if there are some actions in the undo list
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that were added after the last call to beginNewTransaction().
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This is useful because it lets you call beginNewTransaction(), then
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perform an operation which may or may not actually perform some actions, and
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then call this method to get rid of any actions that might have been done
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without it rolling back the previous transaction if nothing was actually
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done.
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@returns true if any actions were undone.
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*/
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bool undoCurrentTransactionOnly();
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/** Returns the name of the transaction that will be rolled-back when undo() is called.
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@see undo, canUndo, getUndoDescriptions
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*/
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String getUndoDescription() const;
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/** Returns the names of the sequence of transactions that will be performed if undo()
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is repeatedly called. Note that for transactions where no name was provided, the
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corresponding string will be empty.
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@see undo, canUndo, getUndoDescription
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*/
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StringArray getUndoDescriptions() const;
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/** Returns the time to which the state would be restored if undo() was to be called.
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If an undo isn't currently possible, it'll return Time().
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*/
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Time getTimeOfUndoTransaction() const;
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/** Returns a list of the UndoableAction objects that have been performed during the
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transaction that is currently open.
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Effectively, this is the list of actions that would be undone if undoCurrentTransactionOnly()
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were to be called now.
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The first item in the list is the earliest action performed.
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*/
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void getActionsInCurrentTransaction (Array<const UndoableAction*>& actionsFound) const;
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/** Returns the number of UndoableAction objects that have been performed during the
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transaction that is currently open.
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@see getActionsInCurrentTransaction
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*/
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int getNumActionsInCurrentTransaction() const;
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//==============================================================================
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/** Returns true if there's at least one action in the list to redo.
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@see getRedoDescription, redo, canUndo
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*/
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bool canRedo() const;
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/** Tries to redo the last transaction that was undone.
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@returns true if the transaction can be redone, and false if it fails, or
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if there aren't any transactions to redo
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*/
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bool redo();
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/** Returns the name of the transaction that will be redone when redo() is called.
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@see redo, canRedo, getRedoDescriptions
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*/
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String getRedoDescription() const;
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/** Returns the names of the sequence of transactions that will be performed if redo()
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is repeatedly called. Note that for transactions where no name was provided, the
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corresponding string will be empty.
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@see redo, canRedo, getRedoDescription
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*/
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StringArray getRedoDescriptions() const;
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/** Returns the time to which the state would be restored if redo() was to be called.
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If a redo isn't currently possible, it'll return Time::getCurrentTime().
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@see redo, canRedo
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*/
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Time getTimeOfRedoTransaction() const;
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/** Returns true if the caller code is in the middle of an undo or redo action. */
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bool isPerformingUndoRedo() const;
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private:
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//==============================================================================
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struct ActionSet;
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OwnedArray<ActionSet> transactions, stashedFutureTransactions;
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String newTransactionName;
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int totalUnitsStored = 0, maxNumUnitsToKeep = 0, minimumTransactionsToKeep = 0, nextIndex = 0;
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bool newTransaction = true, isInsideUndoRedoCall = false;
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ActionSet* getCurrentSet() const;
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ActionSet* getNextSet() const;
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void moveFutureTransactionsToStash();
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void restoreStashedFutureTransactions();
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void dropOldTransactionsIfTooLarge();
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JUCE_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR (UndoManager)
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};
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} // namespace juce
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