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109 lines
4 KiB
C++
109 lines
4 KiB
C++
/*
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==============================================================================
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This file is part of the JUCE framework.
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Copyright (c) Raw Material Software Limited
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JUCE is an open source framework subject to commercial or open source
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licensing.
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By downloading, installing, or using the JUCE framework, or combining the
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JUCE framework with any other source code, object code, content or any other
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copyrightable work, you agree to the terms of the JUCE End User Licence
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Agreement, and all incorporated terms including the JUCE Privacy Policy and
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the JUCE Website Terms of Service, as applicable, which will bind you. If you
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do not agree to the terms of these agreements, we will not license the JUCE
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framework to you, and you must discontinue the installation or download
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process and cease use of the JUCE framework.
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JUCE End User Licence Agreement: https://juce.com/legal/juce-8-licence/
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JUCE Privacy Policy: https://juce.com/juce-privacy-policy
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JUCE Website Terms of Service: https://juce.com/juce-website-terms-of-service/
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Or:
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You may also use this code under the terms of the AGPLv3:
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https://www.gnu.org/licenses/agpl-3.0.en.html
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THE JUCE FRAMEWORK IS PROVIDED "AS IS" WITHOUT ANY WARRANTY, AND ALL
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WARRANTIES, WHETHER EXPRESSED OR IMPLIED, INCLUDING WARRANTY OF
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MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, ARE 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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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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@tags{DataStructures}
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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() = default;
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public:
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/** Destructor. */
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virtual ~UndoableAction() = default;
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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 a nullptr.
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*/
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virtual UndoableAction* createCoalescedAction (UndoableAction* nextAction);
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};
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} // namespace juce
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