mark dixon, socce soft 131page 1 02 – software development lifecycle, & user interface design

Mark Dixon, SoCCE SOFT 131

02 – Software Development Lifecycle, &

User Interface Design


Admin

• Lecture Room change (next week onwards)– Portland Square Stonehouse lecture theatre

• Teaching Evaluation– Student Perception Questionnaire

– Continuous Informal Feedback

• Formative Assessment– Exercises in practical sessions


Session Aims & Objectives• Aims

– tidy up from last session, and– introduce you to fundamental user interface design

concepts

• Objectives, by end of this week’s sessions, you should be able to:

– Run through the software development cycle.– Implement simple software design

• Create (draw) user interface• Put instructions in:

– correct event handler procedure for desired result

– correct sequence for desired result

– Identify & correct simple user interface (usability) problems


Software Development Cycle

• Software development follows this pattern:– analyse problem– design solution– implement (code) solution– test & debug solution (code)

• However, it is:– cyclic/iterative (not linear)


Example 1 v1: Analysis

• User Requirement: – to teach students about

• fundamentals of software development process

• Software Requirements Specificationsoftware should include:– setting property at design time– setting property at run time– …– code has to fit on single slide

Non-functionalrequirement

Functionalrequirements


Example 1 v1: Design

• User interface design:

• Functional design:Trigger (when) Actions (what)

click event of Red button Change Result label background to blue.

click event of Blue button Change Result label background to red.

double click event of Result label

Change Result label background to white.


Example 1 v1: UI Implementation• Properties (setting at design-time):

– initial value only– change using properties window

name: used internally to identify object (programmer)

caption: displayed on button (user)


Example 1 v1: Code Implementation

Private Sub btnBlue_Click() lblResult.BackColor = vbBlueEnd Sub

Private Sub btnRed_Click() lblResult.BackColor = vbRedEnd Sub

Private Sub lblResult_DblClick() lblResult.BackColor = vbWhiteEnd Sub

• Properties (setting at run-time)– use code, assignment operator (=)– can change while program is running

VB


Sequence

• Execution sequence controlled in two ways:– procedures controlled by order of events– instructions (lines) controlled by order in code

Private Sub btnBlue_Click() lblResult.BackColor = vbBlueEnd Sub

Private Sub btnRed_Click() lblResult.BackColor = vbGreen lblResult.BackColor = vbRedEnd Sub

Private Sub lblResult_DblClick() lblResult.BackColor = vbWhiteEnd Sub


Example 1 v2: DesignUser Interface Functionality

Trigger (when) Actions (what)click event of Red button

Change Result label background to blue.

click event of Blue button

Change Result label background to red.

double click event of Result label

Change Result label background to white.

click event of Hello button

Change Result label caption to "Hello!"

click event of Bye button

Change Result label caption to "Good bye!"

click event of Move button

Move Result label background colour and caption to Result2 label


Example 1 v2: ImplementationOption Explicit

Private Sub Form_Load() lblResult.BackColor = vbGreenEnd Sub

Private Sub btnHello_Click() lblResult = "Hello!"End Sub

Private Sub btnBye_Click() lblResult = "Good bye!"End Sub

... (code from v1)

Private Sub btnMove_Click() lblResult2.BackColor = lblResult.BackColor lblResult2.Caption = lblResult.Caption lblResult.BackColor = vbButtonFace lblResult.Caption = ""End SubVB


Example 2: disks & files


Human-Computer Interaction‘Human-Computer Interaction (HCI) is about designing computer systems that support people so that can carry out their activities productively and safely.’ Preece et al, 1994 (p. 1)

• three main concerns:– usefulness: is software functionality of use to user– usability: is software easy to use– learnability: is software easy to learn

• software may be:– ‘simple to use, but of no value to me’– ‘really helpful, but awkward to use’– ‘really helpful, if only I could figure out how’


HCI – why bother?

• ‘The Day the Phones Stopped’

(Preece et al, 1994 p. 25)


Design Guidelines• Some issues:

– Consistency– Fast feedback– Manage errors– Reduce cognitive load– User variety– User testing with actual users– …– …


Direct Manipulation

• Direct Manipulation Interfaces (Shneiderman 1998, p. 205)

– ‘Continuous representation of the objects and actions [information] of interest with meaningful visual metaphors’

– ‘Physical actions or presses of labelled buttons, instead of complex syntax’

– ‘Rapid incremental reversible operations whose effect on the object of interest is visible immediately’


Example 3: Holiday

• User Requirement– ‘I want a cheap holiday, so I need to know times

and prices of ferries and flights’

• Can solve this by– visit company offices– phone– www, compare the following:

• Brittany Ferries• EasyJet

http://www.brittany-ferries.co.uk

http://www.easyjet.co.uk


Example 4: Music Player

• Compare the following User Interface Designs:

V0 V1


Example 5: Music Player v2

V2

Option Explicit

Private Sub drvMain_Change() dirMain.Path = drvMain.DriveEnd Sub

Private Sub dirMain_Change() filMain.Path = dirMain.PathEnd Sub

Private Sub filMain_Click() mmcMain.Command = "Close" mmcMain.FileName = filMain.Path & "\" & filMain.FileName mmcMain.Command = "Open" pgbMain.Max = mmcMain.Length pgbMain.Value = 0End Sub

Private Sub mmcMain_StatusUpdate() pgbMain.Value = mmcMain.PositionEnd Sub


Example 6: Address Book


Project Files & Version Control

• Create new folder for each project

• Save all project files into that folder– project file (.vbp)– form files (.frm)

• At regular intervals copy whole folder to create new version.– this is a very simple approach– there are software packages that do this for you

mark dixon, socce soft 131page 1 02 – software development lifecycle, & user interface design

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