Providing adjustable and dynamic spatial layouts for multimedia applications with STyLe

Abstract

Interactive multimedia applications may be presented on multiple devices with different screen sizes. Therefore, application layouts should be adapted during runtime. Besides adapting layouts to different devices, the number of visual multimedia objects may vary, thus it is desirable to provide an automatic application layout adjustment to ease the authoring effort and provide good user quality of experience. In this article, the term adjustable layout is used to refer to an application spatial layout that adjusts itself to the number of media objects to be presented. The term dynamic layout is used to refer to an application spatial layout that can change at runtime in reaction to presentation events. Multimedia declarative authoring languages, such as NCL and SMIL, provide simple layout construction using nested rectangular regions to design the application layout. However, these languages do not provide native facilities for authors to develop adjustable and dynamic layouts. This article proposes STyLe, a constraint-based template language for providing adjustable and dynamic spatial layouts for multimedia documents. It also presents an architecture that is capable of interpreting STyLe when used together with NCL to provide dynamic layouts for interactive digital TV applications. The results show that STyLe has more expressiveness and abstraction when compared to NCL and that the language is simple and effective for building adjustable and dynamic layouts.