Not in Text CP212 Winter 2012

No VBA Required

“Regular” Programming

• traditional programming is sequential in nature o one command executed after another o even with looping and conditional statements o program has a “flow” to it Sub myProgram() Dim var As String ' Do this result = Msgbox ("Welcome") ' Then do this If result = vbYes Then ' check this Msgbox "Great!" ' Either do this...

Else MsgBox "Not good!" ' or this End Sub

Event-Driven Programming

• modern, graphical oriented programs are driven by events • a program will be running in memory, waiting for the user to do something o or possibly waiting for the system to do something • things the user does (or the system) are called

events

A Typical Event Driven Program

Events and Event Handlers

• typical events would include clicking a button, moving the mouse, or typing in text • when an event happens, the code that responds to that event is executed o this code is called an “event handler” • the event is said to have fired or been triggered

Graphical User Interfaces

• in the early days programs were written to run from command prompts such as DOS or Unix o the only “event” was a user typing something and pressing enter • creating a program with a graphical user interface (GUI pronounced “gooey”) uses event-driven programming • windows, buttons, forms, icons, desktop, dialog boxes are standard terms in graphical user interface design • user interface design is an art and a science • google "user interface design" "human-computer interaction" "hci" "human factors" or other related topics

GUI Controls

• the primary layer for a GUI is a window or a form • as a programmer, you add controls (also called widgets) to the form

GUI Controls

o Java has a complete library of controls called the Swing library  makes writing GUIs quick and easy  well...easier than doing it by hand!

o VB and VBA (and Microsoft Visual [Anything]) allows for drag-and-drop GUI design o simply make a form, add some controls and you have a very fast prototype  a (usually non-functioning) sample of your application

Simple Events

• you can then add code to the event handlers for each widget • some code you write will never be executed!

• try it out: drop a control on a form o double-click the control to display the default event handler

• click the drop-down list on the right side to see the events you can program for the current object • the list on the left allows you to choose from the objects on the form

Basic Events

•

Userform events:

o Initialize (default), Activate, Click, DblClick, KeyPress, Resize •

Button events:

o Click (default), Enter, MouseUp, MouseDown, Exit (will fire when the form closes) •

TextBox events:

o Change (default), AfterUpdate, BeforeUpdate

Other Events

• Application, Workbook, Worksheets and Charts can all have events • Workbook_Open: runs code as soon as file is opened, not recommended when distributing to the public, most apps have macros disabled anyway.

• Chart_Activate: fires when a chart is activated (clicked on) • Worksheet_Change: cells on the worksheet are changed • Worksheet_Activate: a worksheet is activated • Worksheet_Deactivate: a worksheet is deactivated • Experiment in the VBE to find other events

Design Options

• developing GUI software can start with simple sketches on a napkin • software mockups can be created in a graphics program like Adobe Photoshop o nice to look at but no interaction • other software is availble to help design the look of the software

iPhone Design Template (Photoshop) Layered, to make changing layouts easy.

Rapid Prototyping

• one of the benefits of VB / VBA • quickly and easily create a mockup of your software o no code required!

• can let users see it and play with it o can add basic message boxes to make it interactive • allows users to work with the product and see what works and doesn't work • can easily make changes based on their feedback

UX - User Experience

• UX - the intersection of Art, Science and Craftsmanship • The subjective experience a user has when performing a task while using your software (make them happy, not angry)

References

• Jakob Nielsen: A User Design Specialist o http://www.useit.com/ • User Interface Design Tips, Techniques and Principles o http://www.ambysoft.com/essays/userInterfaceDesign.html

• Excel 2007 Power Programming with VBA by John • Walkenbach (now in an Excel 2010 version) • Mockup Screens - $99 software! ( video ) Free GUI design add-on for Firefox: http://www.evolus.vn/pencil/