CH_UndoEventHandler.h

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/*
 * PROPRIETARY INFORMATION.  This software is proprietary to
 * Side Effects Software Inc., and is not to be reproduced,
 * transmitted, or disclosed in any way without written permission.
 *
 * NAME:        CH_UndoEventHandler.h (JIVE Library, C++)
 *
 * COMMENTS:    Creates an undo marker to minimize sent events
 */

#ifndef __CH_UNDOEVENTHANDLER_H_INCLUDED__
#define __CH_UNDOEVENTHANDLER_H_INCLUDED__

#include "CH_API.h"
#include <UT/UT_Undo.h>
#include <UT/UT_UndoManager.h>


/// Creates an event handler into the undo manager to minimize sent events. To
/// use this, create a CH_UndoEventHandler::Scope object on the stack to
/// encapsulate the undo actions that we want to batch events for. If the
/// actions span multiple function calls, use matching undoBegin()/undoEnd()
/// invocations.
class CH_API CH_UndoEventHandler : public UT_Undo
{
public:

    class Scope
    {
    public:
        Scope()
        {
            myBlockLevel = CH_UndoEventHandler::start();
        }
        ~Scope()
        {
            CH_UndoEventHandler::stop(myBlockLevel);
        }
    private:
        int     myBlockLevel;
    };

    static int          start()
                        {
                            if (!UTwillAcceptUndoAddition())
                                return -1;

                            UTaddToUndoBlock(new CH_UndoEventHandler(false));
                            return UTgetUndoManager()->blockLevel();
                        }
    static void         stop(int level)
                        {
                            if (level <= -1)
                                return;
                            UTaddToUndoBlock(new CH_UndoEventHandler(true));
                        }

    void                undo() override;
    void                redo() override;

private:
                        CH_UndoEventHandler(bool start_marker);
    void                swap();

private:
    bool                myStartMarker;

    friend class CH_UndoEventHandler::Scope;
};

#endif // __CH_UNDOEVENTHANDLER_H_INCLUDED__