Chapter 5:User Interface DesignConcepts Of UIInterface ModelInternal an External DesignEvaluationInteractionInformation Display Software

Software Industry ScenarioFor the first Three decades of the Computing era

, usability was not a dominant concern among who buid the software.

As Technologies Studied Human interaction two issues arose.

1)Three Golden Rules

2)A set of interaction Mechanisms were defined to enable software Designers to build Software that properly implemented Golden Rules

These Interaction Mechanisms called GUI

Quick Look on User InterfaceWhat is UI? -User Interface Design Creates effective

communication between a Human and a Computer.Who does it? -A Software Engineer designs the UI by applying an

interactive process that draws on predefined PrinciplesWhy it is so important? -If Software is difficult to use ,if it forces you to do

mistakes if it frustrates you to accomplish your goal ,you won't like it.

Continue…..What are the Steps? -UID begins with the identification of

user ,task and environment requirements -Once User tasks identified ,User Scenarios What is the Work Product?How do I ensure that I’ve done it right?

Three Golden RulesTheo Mandel [man97]coins three golden

rulesPlace User in ControlReduce the User’s Memory loadMake the User Interface Consistent

Place User in ControlDefine interaction modes in a way that does not

force a user into unnecessary or undesired actions

Provide for flexible interactionAllow user interaction to be interruptible and

undoableStreamline interaction as skill levels advance and

allow the interaction to be customizedHide technical details from casual UserDesign for direct interaction with objects that

appear on the screen

Reduce the User’s memory LoadReduce Demand on Short term MemoryEstablish Meaningful defaultsDefine Shortcuts that are intuitiveThe Visual layout of the interface should be

based on a Real World MetaphorDisclose information in a Progressive Manner

Make the Interface ConsistentAllow the user to put current task into a

Meaningful ContextMaintain Consistency across Family of

SoftwareIf past interactive models have created user

expectations , than don’t change it

Characteristics of Good UISpeed of Learning -Good Interface is should be easy to Learn three issues related to speed of Learning 1)Use of Metaphors 2)Consistency 3)Component Based interfaceSpeed of Use -Speed of Use is depend on time and Effort -This is also referred as Productivity Support of

the interface

Speed of RecallError PreventionAesthetic & AttractiveConsistencyFeed backSupport for Multiple Skill Levels - A Good user interface should provide Multiple

Level of AbstractionError Recovery(Undo Facility)User Guidelines and Online Help

User Interface Design ModelsOverall Process of Design Analyzing and Designing

a User interface begins with the creation of different models

Four Models are play vital role in User Interface 1) A Software Engineer builds a User Model 2) A Software Engineer creates Design Model 3) End User imagine a Mental image of software

called as Mental Model or System Perception Model 4) Implementers creates Implementation ModelAs a Interface Engineer have to combine and enable

all Functionalities and properties of Models

User Model : - User Model Establishes the profile of Users 1) Novice Users 2) Knowledgeable , intermittent Users 3) Knowledgeable , Frequent UsersDesign Model :User’s Mental Model : example : For Word Processor Software you gets

different levels of Abstraction based on User’s LevelImplementation Model : - This Model Exhibits actual UI with supporting

info. Like Help Files , Manuals - It describes Syntax and Semantics of UI

The Process of UIThe Analysis and Design process for UI is

interactive and can be represented using a spiral Model

Process begins at a interior of the spiral and encompasses four distinct framework

1) Interface analysis and Modeling 2) Interface Design 3) Interface Construction 4) Interface ValidationMost cases the Construction activities involves

prototyping(Only way to Validate what has been Designed)

Interface Analysis focuses on the profile of UsersOnce Requirements are elicited than detailed task

analysis is conducted

Figure shows Process of UI

In Analysis Model Following Questions are Asked 1) Where is UI located Physically? 2) Will user perform tasks which are unrelated

with UI 3) Does the interface Accommodate space ,

Light? 4) Are the Environmental factors effects ?

Types of User InterfaceCommand based User InterfaceGUI based User InterfaceWidget-based GUI