Non-destructive chronological undo timeline. More...

#include "donner/editor/UndoTimeline.h"

Public Member Functions
void	beginTransaction (std::string_view label, UndoSnapshot before)
	Begin a drag transaction. The before snapshot is captured now; the after snapshot is captured on commit. Nested calls are ignored (outermost transaction wins).
void	commitTransaction (UndoSnapshot after)
	Commit the current transaction with the given after snapshot.
void	abortTransaction ()
	Discard the current transaction without recording an entry.
bool	inTransaction () const
	Whether a transaction is currently open.
void	record (std::string_view label, UndoSnapshot before, UndoSnapshot after)
	Record a complete single-step action (breaks any active undo chain).
std::optional< UndoSnapshot >	undo ()
	Undo the next entry in the current undo chain. If no chain is active, starts a new chain from the end of the timeline. Returns the snapshot the caller should apply, or nullopt if there is nothing to undo.
bool	canUndo () const
	Whether there is an entry to undo (either in the current chain or by starting a new one).
std::optional< std::string_view >	nextUndoLabel () const
	The label of the entry that would be undone next.
size_t	entryCount () const
	Number of entries in the timeline.
void	breakUndoChain ()
	Break the current undo chain (called on any non-undo user action).
void	clear ()
	Clear all history.

Detailed Description

Non-destructive chronological undo timeline.

Uses an Emacs-style undo model: consecutive undos walk backward through the entry list, reversing each entry. Any non-undo action breaks the chain. After a break, subsequent undos traverse the entire list (including previous undo entries), allowing undo-of-undo to re-apply a previously reversed action.

No entries are ever removed. The full editing history is preserved indefinitely.

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

donner/editor/UndoTimeline.h

Public Member Functions

Detailed Description