Systems analysis and design methods 7th whitten and benley chapter 14

User Interface Design and Prototyping Styles of User Interfaces  Menu Selection  The menu selection strategy of dialogue design presents a list of alternatives or options to the user.

User Interface Design and

Prototyping

Introduction

 The chapter will address the following questions:

 Which features on available terminal and microcomputer displays can be used for effective user interface design?

 What are the backgrounds and problems encountered by different types of terminal and microcomputer users?

 How do you design and evaluate the human engineering in a user interface for a typical information system?

 How do you apply appropriate user interface strategies to an

information system? How do you use a state transition diagram to plan and coordinate a user interface for an information system?

 User interface design is the specification of a conversation

between the system user and the computer

 This conversation generally results in either input or output possibly both

User Interface Design and

Prototyping

Styles of User Interfaces

 Menu Selection

 The menu selection strategy of dialogue design presents a list of

alternatives or options to the user The system user selects the

desired alternative or option by keying in the number or letter that

is associated with that option

 More sophisticated technology allows menu selection by touching the screen, or selecting menu options with a pen, mouse, cursor keys, or other pointing devices

• The choices typically correspond to commands or properties that

the user can select or toggle

• The choices themselves are typically organized from left-to-right

on the basis of the frequency that a choice is selected

 Menu bars are used to identify common and frequently used actions that take place in a wide variety of different windows that make up the application

User Interface Design and

Prototyping

Styles of User Interfaces

 Menu Selection

 Menu Bars:

 Menu bars advantages:

• Always being readily visible to the user

• Consistently located

• Easily selected via the keyboard or mouse

 Menu bars disadvantages:

• Menu choices are organized for left-to-right scanning

– Studies have shown that users can more easily browse and

select from a list that is vertically arranged

User Interface Design and

Prototyping

Menu Bar

User Interface Design and

Prototyping

Styles of User Interfaces

 Menu Selection

 Pull-Down Menus:

 Pull-down menus provide a vertical list of choices to the user

 A pull-down menu is made available once the user selects a choice from a menu bar

 The list of choices are typically organized from top-to-bottom according to the frequency in which they are chosen

 One special type of pull-down menu is called a tear-off menu.

• With a tear-off menu, the user can select the menu and drag to

relocate it elsewhere on the screen

 Pull-down menu advantages:

• Allows the designer to simplify a menu bar that may otherwise

contain too many choices

– Related set of choices are “grouped” into its own separate list.

• Pull-down menu items can be selected via the keyboard or mouse.

User Interface Design and

Prototyping

Styles of User Interfaces

 Pull-Down Menus:

 Pull-down menu disadvantages:

• The user is not provided with a visual clue that suggests the menu

exists

• Pull-down menu may obstruct the user’s view of other areas of interest appearing within the body of the screen/window

• A choice appearing on a pull-down menu may result in yet another

list or menu of choices

– Choices which have a a right-pointing arrow next to the label result in a cascading menu.

User Interface Design and

Prototyping

Pull-down Menu

User Interface Design and

Prototyping

Dialogue Box

 The cascading menu’s existence is suggested by the visual clue

of a right-pointing arrow appearing next to the higher-level menu choice

 When requested, the menu list will appear to the immediate right (in some cases, to the left) of the selected choice from the higher-level menu

User Interface Design and

Prototyping

Styles of User Interfaces

 Menu Selection

 Cascading Menus:

 Cascading menu advantages:

• Cascading menus simplify higher-level menus into a smaller set of

related group of choices

• Vertical arrangement of the choices also makes scanning the

choices easier

 Cascading menu disadvantages:

• Menu must be requested by the user

• User may have to traverse several levels of menus to locate and

select a desired option

User Interface Design and

Prototyping

Cascading Menu

User Interface Design and

Prototyping

Cascading Menu

 A pop-up menu is requested by clicking the right mouse button.

 Unlike pull-down and cascading menus, the pop-up menu’s appearance depends on where the pointer was located when the menu was requested

User Interface Design and

Prototyping

Styles of User Interfaces

 Menu Selection

 Pop-up Menus:

 Pop-up menu advantages:

• Provide a list of options that pertain to a specific object that the

user selected

– When the cursor is positioned over an object of interest and the

right mouse button is clicked, a pop-menu containing commands or properties pertaining to that object appears in the vicinity of the object

• Allows the user to obtain a list of actions without changing their

focus away from the object or work area on the screen.

 Pop-up menu disadvantages:

• No visual clue that suggests their existence.

• Users must learn about the existence pop-up menus.

• May obstruct portions of the viewing area of interest to the user

User Interface Design and

Prototyping

 An iconic menu uses graphic representations for menu options.

• These types of menus are typically used to present the user with

options that pertain to special functions that can be performed within the application

 Iconic menu advantages:

• Easy recognition of options.

– The use of graphic images helps the user to memorize and

recognize the functions available within an application

• The choice presented in the form of an icon also provide a

relatively larger selection target than the previously discussed menus

User Interface Design and

Prototyping

Styles of User Interfaces

 Menu Selection

 Iconic Menus:

 Iconic menu disadvantages:

• May be difficult to find or create meaningful graphic images.

• Not everything can easily be represented as a picture

• What is a readily identifiable and meaningful picture to one person

may not be to the next person.

User Interface Design and

Prototyping

Iconic Menu

User Interface Design and

 Users must learn the syntax of the instruction set and this approach is suitable only for dedicated users

 There are three types of syntax

• A form of Structured English can be defined as a set of

commands that control the system.

• A mnemonic syntax is built around meaningful abbreviations for

all commands.

 There are three types of syntax (continued)

• Natural language syntax is when the system user enters

commands using natural English (either conversational or formal, written English).The system interprets these commands against a known syntax and requests clarification if it doesn't understand what the user wants As new interpretations become known, the system learns the system user's vocabulary by saving it for future reference.

User Interface Design and

Prototyping

User Interface Design and

Prototyping

User Interface Design and

Prototyping

Styles of User Interfaces

 Question-Answer Dialogues

 Question-answer dialogue strategy is an style that was primarily

used supplement either menu driven or syntax-driven dialogues

 This strategy involves the system asking the system user

questions

 The simplest questions involve yes or no answers

 This strategy requires that you make sure to consider all possible correct answers and deal with the actions to be taken if incorrect answers are entered

 Question-answer dialogue is difficult because you must try to

User Interface Design and

 Icons can work in conjunction with one another

 A pointing device can be used to drag the icon of a file folder (representing a named file) to a trash can icon — intuitively

User Interface Design and

Prototyping

User Interface Design and

 A dedicated system user is one who will spend considerable

time using specific programs This user is likely to become more comfortable and familiar with the terminal or PC's operation

 The casual system user may only use a specific program on an

occasional basis This user may never become truly comfortable with the terminal or the program

 General Human Engineering Guidelines

 Guideline 1: The system user should always be aware of what to

do next

 Tell the user what the system expects right now

 Tell the user that data has been entered correctly

 Tell the user that data has not been entered correctly

 Explain to the user the reason for a delay in processing

 Tell the user that a task was completed or was not completed.

 Guideline 2: The screen should always be formatted so that the

various types of information, instructions, and messages always appear in the same general display area

User Interface Design and

Prototyping

Human Factors for User Interface

Design

 General Human Engineering Guidelines

 Guideline 3: Messages, instructions, or information should be

displayed long enough to allow the system user to read them

 Guideline 4: Use display attributes sparingly

 Guideline 5: Default values for fields and answers to be entered

by the user should be specified

 Guideline 6: Anticipate the errors users might make.

 Dialogue Tone and Terminology

 The overall tone and terminology of a dialogue are important and the session should be user friendly

 With respect to the tone of the dialogue, the following guidelines are offered:

 Use simple, grammatically correct sentences

 Don't be funny or cute!

 Don't be condescending; that is, don't insult the intelligence of the system user

User Interface Design and

Prototyping

Human Factors for User Interface

Design

 Dialogue Tone and Terminology

 With respect to the terminology used in the dialogue, the following guidelines are offered:

 Don't use computer jargon.

 Avoid most abbreviations

 Use simple terms

 Be consistent in your use of terminology

 Dialogue Tone and Terminology

 With respect to the terminology used in the dialogue, the following guidelines are offered: (continued)

 Instructions should be carefully phrased, and appropriate action verbs should be used

• The following recommendations should prove helpful:

– Try SELECT instead of PICK when referring to a list of options

– Use TYPE, not ENTER, to request the user to input specific data

or instructions.

– Use PRESS, not HIT or DEPRESS, to refer to keyboard actions

– When referring to the cursor, use the term POSITION THE

CURSOR, not POINT THE CURSOR.

User Interface Design and

Prototyping

Display Features That Affect User

Interface Design

 Display Area

 The size of the display area is critical to user interface design

 For terminal displays, the two most common display areas are 25 (lines) by 80 (columns) and 25 by 132

 For microcomputer and workstation display monitors, display size

 Character Sets and Graphics

 Every display uses a predefined character set

 Most displays use the common ASCII character set

 Some displays allow the programmer to supplement or replace the predefined character set

 Most displays today offer graphics capabilities

 Graphics capabilities must be supported by graphics controllers and software that allow the programmer to take advantage of the graphics capabilities

 Graphics-based displays may support a virtually unlimited character set

User Interface Design and

Prototyping

Display Features That Affect User

Interface Design

 Paging and Scrolling

 The manner in which the display area is shown to the user is

controlled by both the technical capabilities of the display and the software capabilities of the computer system

 Paging displays a complete screen of characters at a time The

complete display area is known as a page (also called a screen

or frame) The page is replaced on demand by the next or previous page

 Scrolling moves the displayed characters up or down, one line

at a time

 Most displays in use today provide a wide variety of display

properties that may be manipulated to more effectively present data and information

 Display properties are characteristics that change the way in

which a character or group of characters is displayed on a screen

User Interface Design and

Prototyping

Display Features That Affect User

Interface Design

 Split-Screen and Windowing Capabilities

 Split-screen capability is a variation on the windows concept

 The display screen, under software control, can be divided into different areas (called windows)

 Each window can act independently of the other windows, using features such as paging, scrolling, display attributes, and color

 Each window can be defined to serve a different purpose

Windows can be resized, moved, and hidden or recalled on user demand

 Keyboards and Function Keys

 Most modern terminals and monitors are integrated with

keyboards

 The number of keys and their layout may vary, but most keyboards contain special keys called function keys

• Function keys (usually labeled F1, F2, and so on) can be used to

implement certain common, repetitive operations in a user interface (for example, START, HELP, PAGE UP, PAGE DOWN, EXIT) These keys can be programmed to perform common

functions.

 Function keys should be used consistently

• A system's programs should consistently use the same function

keys for the same purposes.

User Interface Design and

 The most common pointer is the mouse

• A mouse is a small hand-sized device that sits on a flat surface

near the terminal It has a small roller ball on the underside As you move the mouse on the flat surface, it causes the pointer to move across the screen Buttons on the mouse allow you to select objects or commands to which the cursor has been moved

Alternatives include trackballs, pens, and trackpoints.

 Step 1: Chart the Dialogue

 A state transition diagram is used to depict the sequence and

variations of screens that can occur when the system user sits at

the terminal (PC or workstation)

 Rectangles are used to represent display screens

 The arrows represent the flow of control and triggering event causing the screen to become active or receive focus

 The rectangles only describe what can appear during the dialogue

 The direction of the arrows indicate the order in which these screens occur

User Interface Design and

Prototyping

1

1 1

2

3 4

 Many screens may have to be designed and prototyped.

 Some screens were identified for the purpose of bringing together the application and its input and output screens.

 Some screens were identified for the purpose to provide the user some flexibility with customizing the application’s interaction to suit their own preferences

 Other screens may have been identified to deal with system controls such as backup and recovery.

 It is through studying the entire collection of screens that you may discover the need to make revisions to some screens.

 It is likely that such issues as color, naming consistencies of common buttons and menu options, and other look-and-feel conflicts may need

to be resolved