User Interface Layer
Gerard Jounghyun Kim · Human-Computer Interaction · 2015
Interactive applications are implemented and executed using the user interface (UI) software layers (collectively the UI layer). e UI layer refers to a set of software that operates above the core operating system (and underneath the application). It encapsulates and exposes system functions for • Fluid input and output (I/O) • Facilitation of development of I/O functionalities (in the form of an application programming interface/library [API] or toolkit) • Run-time management of graphical applications and UI elements often manifested as windows or graphical user interface (GUI) elements (in the form of separate application often called the window manager) Since most interfaces are graphical, the UI layer uses a two-or three-dimensional (2-D or 3-D) graphical system based on which GUI elements are implemented (lower part of Figure 5.1). us, to summarize, the UI layer is largely composed of (a) an API for creating and managing the user interface elements (e.g., windows, buttons, menus) and (b) a window manager to allow users to operate and manage the applications through its own user interfaces.