The UndoList class manages a list of undoable commands. More...

#include <FXUndoList.h>

Inheritance diagram for FX::FXUndoList:

Public Types
enum	{ ID_REVERT =FXWindow::ID_LAST, ID_UNDO, ID_REDO, ID_UNDO_ALL, ID_REDO_ALL, ID_UNDO_COUNT, ID_REDO_COUNT, ID_ALT_HISTORY, ID_SIZE, ID_CLEAR, ID_TRIM_MARK, ID_TRIM_COUNT_1K, ID_TRIM_COUNT_10K, ID_TRIM_COUNT_100K, ID_TRIM_COUNT_1M, ID_TRIM_COUNT_10M, ID_TRIM_COUNT_100M, ID_TRIM_COUNT_1G, ID_TRIM_COUNT =ID_TRIM_COUNT_1K, ID_TRIM_SIZE_1K, ID_TRIM_SIZE_10K, ID_TRIM_SIZE_100K, ID_TRIM_SIZE_1M, ID_TRIM_SIZE_10M, ID_TRIM_SIZE_100M, ID_TRIM_SIZE_1G, ID_TRIM_SIZE =ID_TRIM_SIZE_10M, ID_TRIM_ALT_1K, ID_TRIM_ALT_10K, ID_TRIM_ALT_100K, ID_TRIM_ALT_1M, ID_TRIM_ALT_10M, ID_TRIM_ALT_100M, ID_TRIM_ALT_1G, ID_TRIM_ALT =ID_TRIM_ALT_10M, ID_DUMP_STATS, ID_LAST }

Public Member Functions
long	onCmdUndo (FXObject , FXSelector, void )

long	onUpdUndo (FXObject , FXSelector, void )

long	onCmdRedo (FXObject , FXSelector, void )

long	onUpdRedo (FXObject , FXSelector, void )

long	onCmdRevert (FXObject , FXSelector, void )

long	onUpdRevert (FXObject , FXSelector, void )

long	onCmdUndoAll (FXObject , FXSelector, void )

long	onCmdRedoAll (FXObject , FXSelector, void )

long	onUpdUndoCount (FXObject , FXSelector, void )

long	onUpdRedoCount (FXObject , FXSelector, void )

long	onCmdAltHistory (FXObject , FXSelector, void )

long	onUpdAltHistory (FXObject , FXSelector, void )

long	onCmdDumpStats (FXObject , FXSelector, void )

long	onCmdTrimMark (FXObject , FXSelector, void )

long	onCmdTrimSize (FXObject , FXSelector, void )

long	onCmdTrimWrinkles (FXObject , FXSelector, void )

long	onCmdTrimCount (FXObject , FXSelector, void )

long	onCmdClear (FXObject , FXSelector, void )

long	onUpdClear (FXObject , FXSelector, void )

long	onUpdSize (FXObject , FXSelector, void )

	FXUndoList ()
	Make new empty undo list, initially unmarked.

FXbool	busy () const
	Return true if currently inside undo or redo operation; this is useful to avoid generating another undo command while inside an undo operation.

void	mark ()
	Mark the current state of the undo list, which is initially unmarked. More...

void	unmark ()
	Unmark the marked state.

FXbool	marked () const
	Check if the current state was marked, if the application has returned to the previously marked state.

FXbool	add (FXCommand *cmd, FXbool doit=false, FXbool merge=true)
	Add undo command, executing it if desired. More...

FXbool	begin (FXCommandGroup *command)
	Begin undo command sub-group. More...

FXbool	abort ()
	Abort the current command sub-group being compiled. More...

FXbool	end ()
	End undo command sub-group. More...

virtual FXbool	cut () override
	If alternate history mode is in effect, remember the alternate history. More...

virtual void	undo () override
	Undo last command. More...

virtual void	redo () override
	Redo next command. More...

void	undoAll ()
	Undo all recorded commands.

void	redoAll ()
	Redo all recorded commands.

void	revert ()
	Revert to marked state; this will perform a sequence of undos (or redos), and return the document to the marked state.

FXbool	canUndo () const
	Can we undo more commands.

FXbool	canRedo () const
	Can we redo more commands.

FXbool	canRevert () const
	Can revert to marked.

FXCommand *	current () const
	Current top undo command.

virtual FXString	undoName () const override
	Return name of the first undo command available; if no undo command available this will return the empty string.

virtual FXString	redoName () const override
	Return name of the first redo command available; if no Redo command available this will return the empty string.

FXint	undoCount () const
	Number of undo records.

FXint	redoCount () const
	Number of redo records.

virtual FXuval	size () const override
	Return total amount of space used by undo/redo commands.

void	trimMark ()
	Trim undo list down, starting from the oldest commands, until reaching the marked ("clean" state) point. More...

void	trimSize (FXuval sz)
	Trim undo list down, starting from the oldest commands, until total memory used drops below size sz. More...

void	trimWrinkles (FXuval sz)
	Trim undo list down, starting from the oldest commands. More...

void	trimCount (FXint nc)
	Trim undo list down, starting from the oldest commands, until no more than nc commands are left in the undo list. More...

virtual void	clear () override
	Clear all undo information, releasing all commands and markers.

void	setAlternateHistory (FXbool flag)
	Enable or disable alternate history mode. More...

FXbool	getAlternateHistory () const
	Returns true if alternate history mode is in effect.

void	dumpStats ()
	Dump statistics.

virtual	~FXUndoList ()
	Destroy.

Public Member Functions inherited from FX::FXCommandGroup
	FXCommandGroup ()
	Construct initially empty undo command group.

FXbool	empty () const
	Return true if empty.

virtual	~FXCommandGroup ()
	Delete undo command and sub-commands.

Public Member Functions inherited from FX::FXCommand
FXival	nrefs () const

void	ref ()

void	unref ()

virtual FXbool	canMerge () const
	Return true if this command could possibly be merged with a previous undo command. More...

virtual FXuint	mergeWith (FXCommand *command)
	Called by the undo system to try and merge the new incoming command with this command. More...

Public Member Functions inherited from FX::FXObject
const FXchar *	getClassName () const
	Get class name of some object.

FXbool	isMemberOf (const FXMetaClass *metaclass) const
	Check if object is member of metaclass.

virtual long	tryHandle (FXObject sender, FXSelector sel, void ptr)
	Try handle message safely, catching certain exceptions.

virtual long	onDefault (FXObject , FXSelector, void )
	Called for unhandled messages.

virtual void	save (FXStream &store) const
	Save object to stream.

virtual void	load (FXStream &store)
	Load object from stream.

virtual	~FXObject ()
	Virtual destructor.

Detailed Description

The UndoList class manages a list of undoable commands.

When performing an undo, the document is regressed from its current state to an earlier state. Likewise, performing a redo, a document is advanced from an earlier state to a later state.

A document state may be marked, i.e. a special designated state may be identified. Typically, a freshly loaded document is marked as "clean". Also, any time a document is saved to disk, one can mark that state as "clean".

You can go back to the marked state by invoking revert(). The revert() API will call a sequence of undo's or redo's, depending on whether one need to go to older or newer state of the document.

UndoList can directly receive SEL_UPDATE and SEL_COMMAND messages from widgets. For example, sending ID_UNDO command will invoke the undo() API and cause an undo operation.

Alternate history, when enabled, allows one to revert to any prior state, even back to the path not taken. Supposed we've issued a sequence of commands such as:

A - B - C - D - E - F

If issue undos until we're back at C, and then do commands G,H,I:

A - B - C - G - H - I

Prior to "alternate history" support, we would have permanently lost access to D,E,F. With alternate hostory, however, the undo-buffer would look as follows:

A - B - C - D - E - F - F - E - D - G - H - I

Where overbar indicates a reversed-redo command; notice that the sequence:

D - E - F - F - E - D

has no net effect, it is a sequences of redo's followed by a sequence [in reverse order] of reversed-redo's.

Implementation detail: an redo and the corresponding reversed-redo are one and the same record; the special marked pointer type keeps track of the reversals. Thus, while the undo-buffer can grow quite a lot, the major amount of memory, which lives in the redo-records themselves, may be heavily reused.

Member Function Documentation

◆ abort()

FXbool FX::FXUndoList::abort ( )

Abort the current command sub-group being compiled.

All commands already added to the sub-groups undo list will be discarded. Intermediate command groups will be left intact.

◆ add()

FXbool FX::FXUndoList::add	(	FXCommand *	cmd,
		FXbool	doit = `false`,
		FXbool	merge = `true`
	)

Add undo command, executing it if desired.

The new command will be merged with the previous command if merge is true and we're not at a marked position and the commands are mergeable. Otherwise the new command will be appended after the last undo command in the currently active undo group. If the new command is successfully merged, it will be deleted.

◆ begin()

FXbool FX::FXUndoList::begin ( FXCommandGroup * command )

Begin undo command sub-group.

This begins a new group of commands that are treated as a single command. Must eventually be followed by a matching end() after recording the sub-commands. The new sub-group will be appended to its parent group's undo list when end() is called.

◆ cut()

virtual FXbool FX::FXUndoList::cut ( )

overridevirtual

If alternate history mode is in effect, remember the alternate history.

All commands on the redo-list are paired up with their inverses, then transferred to the undo list. A sequence of commands:

C1 C2 C3 ... CN CN ... C3 C2 C1

Has no effect on the state of the document; however, moving backwards and forwards allows every state in the edit-history of the document to be reached.

If alternate history is not in effect, simply delete the commands on the redo-list.

This is automatically invoked when a new undo command is added, and not typically called by the user directly.

Reimplemented from FX::FXCommandGroup.

◆ end()

FXbool FX::FXUndoList::end ( )

End undo command sub-group.

If the sub-group is still empty, it will be deleted; otherwise, the sub-group will be added as a new command into parent group. A matching begin() must have been called previously.

◆ mark()

void FX::FXUndoList::mark ( )

Mark the current state of the undo list, which is initially unmarked.

There can be only one active mark at any time. Call mark() at any time when you know your document to be "clean"; for example when you save the document to disk. If you don't need to undo past this marked point, consider calling trimMark() to delete all undo commands for states prior to the mark.

◆ redo()

virtual void FX::FXUndoList::redo ( )

overridevirtual

Redo next command.

This will move the command back to the undo list.

Reimplemented from FX::FXCommandGroup.

◆ setAlternateHistory()

void FX::FXUndoList::setAlternateHistory ( FXbool flag )

inline

Enable or disable alternate history mode.

In alternate history mode, adding a new command after performing a number of undo's will remember the alternate history, and allow a sequence of undo's and redo's to navigate back through this alternate history.

◆ trimCount()

void FX::FXUndoList::trimCount ( FXint nc )

Trim undo list down, starting from the oldest commands, until no more than nc commands are left in the undo list.

Call this periodically to prevent the undo-list from growing beyond a certain number of records.

◆ trimMark()

void FX::FXUndoList::trimMark ( )

Trim undo list down, starting from the oldest commands, until reaching the marked ("clean" state) point.

If no mark was set this does nothing.

◆ trimSize()

void FX::FXUndoList::trimSize ( FXuval sz )

Trim undo list down, starting from the oldest commands, until total memory used drops below size sz.

Call this periodically to prevent the undo-list from growing beyond a certain maximum amount of memory.

◆ trimWrinkles()

void FX::FXUndoList::trimWrinkles ( FXuval sz )

Trim undo list down, starting from the oldest commands.

Unlike trimSize(), trimWrinkles() will try bring down space usage by linearizing wrinkles in the command-history, i.e. removing matching command-pairs in sequences like:

C1 C2 C3 ... CN CN ... C3 C2 C1 __ starting from CN - CN moving outward, until the desired aount of space is reclaimed, or until all such "wrinkles" of alternate history have been removed and only linear edit history remains.

If alternate history is not in effect, or there is no alternate history to be removed, this command reclaims no space at all.

◆ undo()

virtual void FX::FXUndoList::undo ( )

overridevirtual

Undo last command.

This will move the command to the redo list.

Reimplemented from FX::FXCommandGroup.

The documentation for this class was generated from the following file:

/home/jeroen/FOX/fox/fox-1.7.93/include/FXUndoList.h

Public Types

Public Member Functions

Detailed Description

Member Function Documentation

◆ abort()

◆ add()

◆ begin()

◆ cut()

◆ end()

◆ mark()

◆ redo()

◆ setAlternateHistory()

◆ trimCount()

◆ trimMark()

◆ trimSize()

◆ trimWrinkles()

◆ undo()