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99 lines
3.5 KiB
99 lines
3.5 KiB
/*
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==============================================================================
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This file is part of the JUCE library.
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Copyright (c) 2013 - Raw Material Software Ltd.
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Permission is granted to use this software under the terms of either:
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a) the GPL v2 (or any later version)
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b) the Affero GPL v3
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Details of these licenses can be found at: www.gnu.org/licenses
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JUCE is distributed in the hope that it will be useful, but WITHOUT ANY
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WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
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A PARTICULAR PURPOSE. See the GNU General Public License for more details.
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------------------------------------------------------------------------------
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To release a closed-source product which uses JUCE, commercial licenses are
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available: visit www.juce.com for more information.
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==============================================================================
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*/
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#ifndef JUCE_UNDOABLEACTION_H_INCLUDED
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#define JUCE_UNDOABLEACTION_H_INCLUDED
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//==============================================================================
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/**
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Used by the UndoManager class to store an action which can be done
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and undone.
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@see UndoManager
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*/
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class JUCE_API UndoableAction
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{
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protected:
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/** Creates an action. */
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UndoableAction() noexcept {}
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public:
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/** Destructor. */
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virtual ~UndoableAction() {}
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//==============================================================================
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/** Overridden by a subclass to perform the action.
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This method is called by the UndoManager, and shouldn't be used directly by
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applications.
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Be careful not to make any calls in a perform() method that could call
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recursively back into the UndoManager::perform() method
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@returns true if the action could be performed.
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@see UndoManager::perform
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*/
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virtual bool perform() = 0;
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/** Overridden by a subclass to undo the action.
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This method is called by the UndoManager, and shouldn't be used directly by
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applications.
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Be careful not to make any calls in an undo() method that could call
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recursively back into the UndoManager::perform() method
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@returns true if the action could be undone without any errors.
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@see UndoManager::perform
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*/
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virtual bool undo() = 0;
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//==============================================================================
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/** Returns a value to indicate how much memory this object takes up.
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Because the UndoManager keeps a list of UndoableActions, this is used
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to work out how much space each one will take up, so that the UndoManager
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can work out how many to keep.
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The default value returned here is 10 - units are arbitrary and
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don't have to be accurate.
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@see UndoManager::getNumberOfUnitsTakenUpByStoredCommands,
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UndoManager::setMaxNumberOfStoredUnits
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*/
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virtual int getSizeInUnits() { return 10; }
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/** Allows multiple actions to be coalesced into a single action object, to reduce storage space.
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If possible, this method should create and return a single action that does the same job as
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this one followed by the supplied action.
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If it's not possible to merge the two actions, the method should return zero.
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*/
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virtual UndoableAction* createCoalescedAction (UndoableAction* nextAction) { (void) nextAction; return nullptr; }
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};
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#endif // JUCE_UNDOABLEACTION_H_INCLUDED
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