O’zaro ta’sirli interfeysni loyihalashda hisobga olinishi kerak bo‘lgan operatorning asosiy xususiyatlari

Operatorning qisqa muddatli xotirasi miqdori. Operator uchun boshqarish muammosini hal qilishning chiziqli algoritmi

User Interface Design Adaptation
This chapter aims to help user interface designers and developers understand the issues involved in multi-device interactive applications, which can be accessed through mobile and stationary devices, even exploiting different interaction modalities (graphical, vocal, etc.). The chapter provides a discussion of the possible solutions in terms of concepts, techniques, languages, and tools, with particular attention to Web environments. The chapter deals with the various strategies for adapting, distributing, and migrating the user interface according to the context of use. It considers how to address such issues both when authoring multi-device interfaces and when user interfaces for different devices are dynamically adapted, distributed, or even migrated seamlessly across devices to follow the mobile user. Thus, it discusses task continuity across multiple devices in migratory interfaces as well as related usability issues.
2.1 Introduction
One of the main reasons for the increasing importance of adaptation is that we interact with our applications in contexts of use which are more and more varied because of the advent of mobile technologies and smart environments.
Various aspects can be part of the possible contexts of use and can be grouped along four dimensions (see Figure 1):

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  user-related aspects: preferences, goals and tasks, physical state (e.g. position), emotional state, etc.;
  
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  technology-related aspects: screen resolution, connectivity, browser, battery, etc.;
  
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  environment-related aspects: location, light, noise, etc.;
  
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  social aspects: privacy rules, collaboration, etc.
  

According to changes in those aspects of the context of use any aspect characterising a user interface can be modified. Thus, the user interface can be adapted in its: presentation—the perceivable aspects, including media and interaction techniques, layout, graphical attributes; dynamic behaviour, including navigation structure, dynamic activation, and deactivation of interaction techniques; and content, including texts, labels, and images.
Various adaptation strategies are possible, which can be classified according to the impact they have on the user interface: conservation, e.g. simple scaling of UI elements; rearrangement, e.g. changing the layout; simplification / magnification, same UI elements but with modified presentation; increase (also called progressive enhancement) / reduction (also called graceful degradation), in terms of UI elements.

Figure 2.1: The Context of Use
One of the main reasons for the increasing interest in user interface adaptation is the device fragmentation stimulated by technological evolution, in particular in mobile devices. Device fragmentation concerns hardware and support for formats, browsers, audio/video playback/streaming, etc. For example, in terms of screens we can notice that the screen resolutions of personal computers (PCs) usually vary between 800x600 and 1920x1200 pixels, whereas those of mobile devices have a variation of between 320x240 and 1136x640 pixels (iPhone 5) and up to 1920×1080 (Galaxy S 4). Thus, screen resolution varies more with mobile devices than with desktop ones. The interesting point is that Moore’s Law continually changes these numbers, and we can expect even more variance in the near future.
In recent years mobile technology has evolved considerably. We can easily realise this if we look at how interaction has changed in our smartphones. The oldest devices have focus-based interactions, in which the browser focus cycles through elements; the current focus of the page is easily determined because the focus element is highlighted, and the focus moves from one selectable element to another (e.g. from link to link) only sequentially, even when widely spaced (this can take some time). Then, devices supporting pointer-based interaction have been proposed, in which key-based navigation controls a pointer that can cover any part of the screen. With this solution selectable elements need to be large enough to be easily selected, since the pointer often moves in steps of 5—10 pixels, and selectable elements should have rollovers to make it clear when the pointer has entered their active area. Following the pointer-based interaction we now have the success of touch-based interaction, where events are related directly to a finger or stylus touch position on the screen; selectable elements should be widely spaced in order to allow users to select them precisely (studies suggest between 7mm and 9.6mm), selectable elements must be large enough to be easily selected; no elements are in focus until they are selected so extra information cannot be passed to the user (e.g. rollovers ineffective).
Various design aspects can be useful in supporting usability in mobile interaction. We have to consider that the user can be on the move and able to pay limited attention to the interaction. Thus, it is important to minimize text input, keep consistency between platforms so that application knowledge acquired through desktop interaction can be reused in mobile access and hence prevent user error, avoid overloading the user interface with too many elements, limit the need for zooming, and prevent touch selections that miss intended targets. Generally, we have to consider that mobile users often have short access time available, and thus they prefer access to small pieces of information.
More generally, we have to consider that our life is becoming a multi-device user experience. Indeed, a recent study (Google, 2012) found that our time online is spread across four device types (smartphones, tablets, PC/laptops, TVs). There are two modes of using them: sequential usage, moving from one device to another at different times to accomplish a task; and simultaneous usage, using more than one device at the same time for either a related or an unrelated activity. Managing information across such devices is one challenging aspect of using multiple devices. In general the main issues in multi-device UIs are: poor adaptation to the context of use, lack of coordination among tasks performed through different devices, inadequate support for seamless cross-device task performance.
Some studies have started to investigate what characterises the user experience in cross-device application access. For example, in Waljas et al. (2010) the authors have identified three important dimensions for improving cross-device user experience: appropriateness for task performance, so that the structure of the interactive application provides an effective fit with what the users expect to perform in each device type; continuity, so that the flow of interaction with and across devices is perceived as fluent and connected; consistency, the user interfaces for the various device types should be perceived as coherent, still parts of the same application.