Snapshot damage handling for rendering objects in a zooming graphical user interface

Abstract

A computer interface is provided for zooming representation objects in a zooming graphical user interface. Information is displayed as a collection of zooming spaces containing graphical objects that may be manipulated with interactive input devices. The damage handling method of the invention limits data processing undertaken to make the result of user manipulations apparent. A copy of least one instance variable defining a visual characteristic for each zooming object is stored as snapshot data prior to user manipulation. Ensuing modification requiring re-rendering is determined by comparison of snapshot data and current object data. The region to be re-rendered is determined by a bounding box that circumscribes the bounding boxes of the snapshot data and the current object data. In this manner, the region to be re-rendered need only be calculated once, after a series of user manipulations of an object is complete. Timing of the damaging necessary to make the result of user manipulation apparent is also selectively controlled. A series of modifications may be made to the displayed zooming space and stored by a region manager before any modifications are made apparent by explicitly calling a damage method. In addition, since the zooming graphical user interface is implemented in a platform-independent object-oriented language, the interface is portable and modular. providing increased flexibility, efficiency and functionality.