User Interface Design

Overview The Developer’s Responsibilities Goals and Considerations of UI Design Common UI Methods A UI Design Process Guidelines + Helpful Resources

The Developer’s Responsibilities

Software engineers must often take responsibility for user interface design Only large organizations normally employ special interface designers

Technologies for GUIs Java Swing Win32/MFC HTML QT GTK Aqua

Programmers may be proficient using these technologies However, the UIs they develop are often unattractive and inappropriate for their target users

Good user interface design is critical for system dependability Many “user errors” are caused by user interfaces that don’t consider the capabilities of real users in their working environments

Goals and Considerations of UI Design

Important Factors to Keep in Mind when Creating UIs People have limited short-term memory We all make mistakes We have a diverse range of physical capabilities We have different interaction preferences

People have limited short-term memory We can instantaneously remember about seven items of information If you present too much information to the user at once, he/she may not be able to take it all in

We all make mistakes Especially when we have to handle too much information, or are stressed When systems go wrong and issue warning messages and alarms, this often puts more stress on the user

We have a diverse range of physical capabilities Some people see and hear better than others Some people are color-blind Some people are better than others at physical manipulation Don’t design for just your own capabilities

We have different interaction preferences Some people like to work with pictures Others, with text Direct manipulation is natural for some Others like command-oriented systems

Basic Considerations of UI Design User familiarity Consistency Minimal surprise Recoverability User guidance User diversity

User familiarity The interface should use terms and concepts drawn from the experience of the people who will make the most use of the system

Consistency The interface should be consistent in that, wherever possible, comparable operations should be activated in the same way

Minimal surprise Users should never be surprised by the behavior of a system

Recoverability The interface should include mechanisms to allow users to recover from errors Confirmation of destructive actions Undo/Multiple-Undo (checkpointing)

User guidance The interface should provide meaningful feedback when errors occur and provide context-sensitive user help facilities

User diversity The interface should provide appropriate interaction facilities for different types of system users

Common UI Methods

Five Common Approaches for User Interaction Direct manipulation Menu selection Form fill-in Command language Natural language

Direct manipulation The user interacts directly with objects on the screen Usually involves a pointing device (mouse, stylus, touchpad/finger)

Menu selection Possible commands are categorized and listed in menus So the user doesn’t have to remember exact command syntax

Form fill-in The user fills in fields of a form Some fields have associated menus and/or action buttons

Command language Similar to command-line input The user enters a command and possibly a list of parameters

Natural language Similar to command language, except that the language is more flexible (I.e. English) This could also be used for spoken interfaces

A GUI Design Process

UI design is an iterative process where users interact with designers and prototypes Decide on features, organization, and the look-and-feel of the system user interface

Guidelines

Presenting information? Answer the following Is the user interested in precise information or in the relationships between data values? How quickly do the information values change? Should the change value be indicated immediately to the user? Must the user take some action in response to a change in information? Does the user need to interact with the displayed information via a direct manipulation interface? Is the information to be displayed textual or numeric? Are relative values of information items important?

Text vs. Graphics Text requires less space and is more precise, but cannot be interpreted at a glance Graphics are useful for data that changes quickly or when relationships between data values are more important than precise values

Guidelines for Using Color Limit the number of colors –4 to 5 in a window –≤ 7 in a system interface Use color change to show a change in system status Use color coding to support tasks –Highlight anomalies and/or similarities –Be consistent and thoughtful Be careful about color pairing

Error Messages

Error Messages: A Video Clip WWDC 2003 Disc #1, Session 001, 15: :45

Guidelines for Layout See Apple Human Interface Guidelines and MSDN User Interface Guidelines –Links on Software Engineering website

Layout: A Video Clip WWDC 2003 Disc #1, Session 001, 22: :47

Cross-Platform Best Practices Be consistent yet adaptive Provide identical functionality Deliver a platform-appropriate experience Deliver platform-appropriate behaviors Leverage platform strengths Embrace file name extensions and their display name Avoid lowest common denominator user experience

Overall, Good Design: A Video Clip WWDC 2003 Disc #1, Session 001, 17: :15