INCREMENTAL IMPLEMENTATION OF UNDO/REDO SUPPORT IN LEGACY APPLICATIONS

摘要

Systems and methods are described for incremental implementationof undoedo support in legacy applications. In one implementation,a system enables a per-object undo/redo process to be realized inpre-existing computer programs that have limited or no undo/redofunctionality, while minimizing changes to such pre-existingcomputer programs. An innovative process stores an undo/redoinstruction for each user-initiated operation in a data structure,classifies each undo/redo instruction under one or more objectsaffected by the operation, or vice/versa, and verifies the validity ofeach undo/redo instruction before performing an undo/redo. In oneimplementation, the process stores only undo/redo instructions inthe data structure for those operations that can be validatedbeforehand as being undoable/redoable. Various data structureschemes are available, each of which may increase performancewhile implementing the undo-redo support for a given legacysoftware, e.g., by increasing speed and/or decreasing data size,memory consumption, disk consumption, power consumption, andso forth. The ability to validate undoability/redoability beforeperforming an undo/redo operation gives the architecture versatilityfor updating many different applications.