Chapter 5:User Interface Design Concepts Of UI Interface Model Internal an External Design Evaluation Interaction Information Display Software

Software Industry Scenario For 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 Interface What 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 Principles Why 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 Rules Theo Mandel [man97]coins three golden rules Place User in Control Reduce the User’s Memory load Make the User Interface Consistent

Place User in Control Define interaction modes in a way that does not force a user into unnecessary or undesired actions Provide for flexible interaction Allow user interaction to be interruptible and undoable Streamline interaction as skill levels advance and allow the interaction to be customized Hide technical details from casual User Design for direct interaction with objects that appear on the screen

Reduce the User’s memory Load Reduce Demand on Short term Memory Establish Meaningful defaults Define Shortcuts that are intuitive The Visual layout of the interface should be based on a Real World Metaphor Disclose information in a Progressive Manner

Make the Interface Consistent Allow the user to put current task into a Meaningful Context Maintain Consistency across Family of Software If past interactive models have created user expectations, than don’t change it

Characteristics of Good UI Speed 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 interface Speed of Use -Speed of Use is depend on time and Effort -This is also referred as Productivity Support of the interface

Speed of Recall Error Prevention Aesthetic & Attractive Consistency Feed back Support for Multiple Skill Levels - A Good user interface should provide Multiple Level of Abstraction Error Recovery(Undo Facility) User Guidelines and Online Help

User Interface Design Models Overall 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 Model  As 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 Users Design Model : User’s Mental Model : example : For Word Processor Software you gets different levels of Abstraction based on User’s Level Implementation Model : - This Model Exhibits actual UI with supporting info. Like Help Files, Manuals - It describes Syntax and Semantics of UI

The Process of UI The 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 Validation Most cases the Construction activities involves prototyping(Only way to Validate what has been Designed)

Interface Analysis focuses on the profile of Users Once 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 Interface Command based User Interface GUI based User Interface Widget-based GUI