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.
Display Properties
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.
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.
Pointer Options
There are many selection options, such as touch-sensitive screens, voice recognition, and pointers.
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.
How to Design & Prototype a User Interface
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.
Step 2: Prototype the Dialogue and User Interface
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.
Step 2: Prototype the Dialogue and User Interface
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.
Step 3: Obtain User Feedback
Exercising (or testing) the user interface is a key advantage of all prototyping environments.
Exercising (or testing) the user interface means that system users literally experiment with and test the interface design prior to extensive programming and actual implementation of the working system. Analysts can observe this testing to improve on the design.
Step 3: Obtain User Feedback
In the absence of prototyping tools, the analyst should at least simulate the dialogue by walking through the screen sketches with system users.