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

#include <FXUndoList.h>

Inheritance diagram for FX::FXUndoList:

Public Types
enum	{ ID_CLEAR =FXWindow::ID_LAST, ID_REVERT, ID_UNDO, ID_REDO, ID_UNDO_ALL, ID_REDO_ALL, ID_UNDO_COUNT, ID_REDO_COUNT, ID_ALT_HISTORY, 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	onCmdClear (FXObject , FXSelector, void )

long	onUpdClear (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 )

	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.

FXbool	cut ()
	If alternate history mode is in effect, remember the alternate history, moving all the redo-commands into the undolist followed by their corresponding undo-commands, in reverse order. More...

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

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

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

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

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

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

void	undoAll ()
	Undo all commands.

void	redoAll ()
	Redo all commands.

void	revert ()
	Revert to marked.

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
	Return name of the first undo command available; if no undo command available this will return the empty string.

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

virtual FXuval	size () const
	Size of undo information.

virtual void	clear ()
	Clear list.

FXint	undoCount () const
	Number of undo records.

FXint	redoCount () const
	Number of redo records.

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...

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

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

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.

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 ()
	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 back to disk, the latest state could be marked 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.

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 new 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()

FXbool FX::FXUndoList::cut ( )

If alternate history mode is in effect, remember the alternate history, moving all the redo-commands into the undolist followed by their corresponding undo-commands, in reverse order.

The sequence has a net zero effect on the document, as each undo is paired up with a corresponding redo. If alternate history is not in effect, simply delete the redo- commands. This is automatically invoked when a new undo command is added, and not typically called by the user directly.

◆ 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 ( )

virtual

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.

◆ undo()

virtual void FX::FXUndoList::undo ( )