annotate widgets/CommandHistory.h @ 854:c17719e488c9

Fix some potential null-pointer derefs, and simplify some logic where loops were used with an unconditional "break" that meant they could only happen once (from coverity scan)

/* -*- c-basic-offset: 4 indent-tabs-mode: nil -*-  vi:set ts=8 sts=4 sw=4: */

/*
    Sonic Visualiser
    An audio file viewer and annotation editor.
    Centre for Digital Music, Queen Mary, University of London.
    
    This program is free software; you can redistribute it and/or
    modify it under the terms of the GNU General Public License as
    published by the Free Software Foundation; either version 2 of the
    License, or (at your option) any later version.  See the file
    COPYING included with this distribution for more information.
*/

/*
   This is a modified version of a source file from the Rosegarden
   MIDI and audio sequencer and notation editor, copyright 2000-2006
   Chris Cannam, distributed under the GNU General Public License.

   This file contains traces of the KCommandHistory class from the KDE
   project, copyright 2000 Werner Trobin and David Faure and
   distributed under the GNU Lesser General Public License.
*/

#ifndef _MULTI_VIEW_COMMAND_HISTORY_H_
#define _MULTI_VIEW_COMMAND_HISTORY_H_

#include <QObject>
#include <QString>

#include <stack>
#include <set>
#include <map>

class Command;
class MacroCommand;
class QAction;
class QMenu;
class QToolBar;
class QTimer;

/**
 * The CommandHistory class stores a list of executed commands and
 * maintains Undo and Redo actions synchronised with those commands.
 *
 * CommandHistory allows you to associate more than one Undo and Redo
 * menu or toolbar with the same command history, and it keeps them
 * all up-to-date at once.  This makes it effective in systems where
 * multiple views may be editing the same data.
 */

class CommandHistory : public QObject
{
    Q_OBJECT

public:
    virtual ~CommandHistory();

    static CommandHistory *getInstance();

    void clear();
    
    void registerMenu(QMenu *menu);
    void registerToolbar(QToolBar *toolbar);

    /**
     * Add a command to the command history.
     * 
     * The command will normally be executed before being added; but
     * if a compound operation is in use (see startCompoundOperation
     * below), the execute status of the compound operation will
     * determine whether the command is executed or not.
     */
    void addCommand(Command *command);
    
    /**
     * Add a command to the command history.
     *
     * If execute is true, the command will be executed before being
     * added.  Otherwise it will be assumed to have been already
     * executed -- a command should not be added to the history unless
     * its work has actually been done somehow!
     *
     * If a compound operation is in use (see startCompoundOperation
     * below), the execute value passed to this method will override
     * the execute status of the compound operation.  In this way it's
     * possible to have a compound operation mixing both to-execute
     * and pre-executed commands.
     *
     * If bundle is true, the command will be a candidate for bundling
     * with any adjacent bundleable commands that have the same name,
     * into a single compound command.  This is useful for small
     * commands that may be executed repeatedly altering the same data
     * (e.g. type text, set a parameter) whose number and extent is
     * not known in advance.  The bundle parameter will be ignored if
     * a compound operation is already in use.
     */
    void addCommand(Command *command, bool execute, bool bundle = false);
    
    /// Return the maximum number of items in the undo history.
    int getUndoLimit() const { return m_undoLimit; }

    /// Set the maximum number of items in the undo history.
    void setUndoLimit(int limit);

    /// Return the maximum number of items in the redo history.
    int getRedoLimit() const { return m_redoLimit; }

    /// Set the maximum number of items in the redo history.
    void setRedoLimit(int limit);
    
    /// Return the maximum number of items visible in undo and redo menus.
    int getMenuLimit() const { return m_menuLimit; }

    /// Set the maximum number of items in the menus.
    void setMenuLimit(int limit);

    /// Return the time after which a bundle will be closed if nothing is added.
    int getBundleTimeout() const { return m_bundleTimeout; }

    /// Set the time after which a bundle will be closed if nothing is added.
    void setBundleTimeout(int msec);

    /// Start recording commands to batch up into a single compound command.
    void startCompoundOperation(QString name, bool execute);

    /// Finish recording commands and store the compound command.
    void endCompoundOperation();

public slots:
    /**
     * Checkpoint function that should be called when the document is
     * saved.  If the undo/redo stack later returns to the point at
     * which the document was saved, the documentRestored signal will
     * be emitted.
     */
    virtual void documentSaved();

    /**
     * Add a command to the history that has already been executed,
     * without executing it again.  Equivalent to addCommand(command, false).
     */
    void addExecutedCommand(Command *);

    /**
     * Add a command to the history and also execute it.  Equivalent
     * to addCommand(command, true).
     */
    void addCommandAndExecute(Command *);

    void undo();
    void redo();

protected slots:
    void undoActivated(QAction *);
    void redoActivated(QAction *);
    void bundleTimerTimeout();
    
signals:
    /**
     * Emitted whenever a command has just been executed or
     * unexecuted, whether by addCommand, undo, or redo.
     */
    void commandExecuted();

    /**
     * Emitted whenever a command has just been executed, whether by
     * addCommand or redo.
     */
    void commandExecuted(Command *);

    /**
     * Emitted whenever a command has just been unexecuted, whether by
     * addCommand or undo.
     */
    void commandUnexecuted(Command *);

    /**
     * Emitted when the undo/redo stack has reached the same state at
     * which the documentSaved slot was last called.
     */
    void documentRestored();

    /**
     * Emitted when some activity happened (for activity logging).
     */
    void activity(QString);

protected:
    CommandHistory();
    static CommandHistory *m_instance;

    QAction *m_undoAction;
    QAction *m_redoAction;
    QAction *m_undoMenuAction;
    QAction *m_redoMenuAction;
    QMenu *m_undoMenu;
    QMenu *m_redoMenu;

    std::map<QAction *, int> m_actionCounts;

    typedef std::stack<Command *> CommandStack;
    CommandStack m_undoStack;
    CommandStack m_redoStack;

    int m_undoLimit;
    int m_redoLimit;
    int m_menuLimit;
    int m_savedAt;

    MacroCommand *m_currentCompound;
    bool m_executeCompound;
    void addToCompound(Command *command, bool execute);

    MacroCommand *m_currentBundle;
    bool m_bundling;
    QString m_currentBundleName;
    QTimer *m_bundleTimer;
    int m_bundleTimeout;
    void addToBundle(Command *command, bool execute);
    void closeBundle();
    
    void updateActions();

    void clipCommands();

    void clipStack(CommandStack &stack, int limit);
    void clearStack(CommandStack &stack);
};


#endif