User Interface Layer

What is a User Interface (UI)?

A user interface (UI) is a channel between human and computer interaction, where a user interacts with and controls a computer or machine to complete tasks effectively and efficiently.

What does the User Interface determine?

It determines how commands are given to a computer or a program and how information is going to be displayed.

Where does the User Interface layer operate?

It is a set of software that operates above the core operating system but under the application layer.

What composes the UI layer?

The UI layer is largely composed of APIs and a window manager.

What is an Application Programming Interface (API)?

An application programming interface (API) is a set of routines, protocols, and tools for building software applications, especially when programming a graphical user interface (GUI).

What does an API specify?

It specifies how software components should interact.

How do APIs work with applications and servers?

When an application in a device is used, it connects to the Internet and sends data to a server. The server retrieves and interprets the data, performs necessary actions, and sends the data back. The application interprets and presents the data to the user.

What is a Window Manager?

A window manager is a software utility found in most GUI-based software and applications that manage the overall alignment and layout of graphical windows.

What does a Window Manager define and control?

It defines and controls the appearance and positioning of the application interface of windows.

What abilities does a Window Manager provide?

It provides the ability of a software or program to open, minimize, maximize, and close windows.

What additional features can Window Managers include?

Placement, effects, colors, and transitioning depending on the operating system, graphical libraries, and system in use.

What are the characteristics of a successful UI?

• It should be intuitive.

• It should be efficient.

• It should be user-friendly.

What is a Natural Language Interface?

It requires the user to enter responses to questions asked by the computer, displayed on a monitor, with answers entered via keyboard.

Why is it called Natural Language Interface?

Because the computer and the user seem to have a conversation as their mode of interaction.

What is a Menu-Based Interface?

It provides the user with an on-screen list of available selections, although the options displayed are limited.

What is the advantage of a Menu-Based Interface?

The user need not know the system, but only the tasks to be accomplished.

What is a Form-Based Interface?

It consists of on-screen forms or Web-based forms displaying fields containing data items or parameters that need to be communicated to or solicited from the user.

What is the design of a Form-Based Interface based on?

The form often is a facsimile of a paper form.

What is a Command Line Interface (CLI)?

It allows the user to control the application with a series of keystrokes, commands, phrases, or some sequence of these three methods.

What is the drawback of CLI?

It requires memorization of syntax, is not intuitive, and can take a long time to learn.

Why do experienced users prefer CLI?

Because of the faster completion time.

What is a Graphical User Interface (GUI)?

Most interfaces today are graphical, expected in multitasking environments or applications involving complexity.

What challenge does GUI creation pose?

The challenge of inventing an appropriate or acceptable conceptual model of representation.

Why does GUI design require careful planning?

Because designing GUIs for use on the Internet, extranets, and Web requires careful planning.

What is Input in computing?

Input pertains to any information or data that is sent to a computer for processing.

What are examples of input devices?

Keyboard, mouse, microphone.

What is Output in computing?

Output refers to any information that was processed by and sent out from a computer or electronic device.

What are examples of outputs?

Anything that can be viewed on a screen, such as typed words and images.

How are Inputs and Outputs handled at low level?

Inputs and outputs (I/O) are handled by the interrupt mechanism of an operating system.

What is an Interrupt?

An interrupt is a signal to the processor indicating that an I/O event has occurred and must be handled.

How does the processor handle interrupts?

The processor suspends the ongoing process, executes the handler procedure, then resumes the suspended process.

How often does the processor check for interrupts?

At a very fast rate as part of the execution cycle.

How are Inputs and Outputs described at higher level?

In terms of events and event handler, based on the lower-level interrupt mechanism.

What is an Event-Driven Program Structure?

A program structure in which programs are developed in terms of events and their corresponding handlers.

What is Event-Driven Programming?

A programming paradigm in which the flow of program execution is determined by events like mouse clicks, keypresses, or OS messages.

Which languages support Event-Driven Programming?

Visual Basic, Visual C++, and Java.

What is an Event in Java?

An object created when something changes within a GUI, such as clicking a button or typing in a text field.

What is an Event Source?

It refers to the object that is triggered in an event and generates the event.

What is an Event Listener?

A program code that listens for changes or user interaction and performs tasks based on the event.

How does Event Handling work?

A source generates an event, sends it to listeners, and the listeners process and return the event.

What do UI frameworks use for interaction?

An event-driven structure where hardware input devices generate events, processed by the software interface.

What is an ActionEvent in Java?

Occurs when a graphical element is clicked, such as a button or an item in a list.

What is a ContainerEvent in Java?

Occurs when an event happens to the GUI’s container itself, like adding or removing an object.

What is a KeyEvent in Java?

Occurs when the user presses, types, or releases a key on the keyboard.

What is a WindowEvent in Java?

Represents an event relating to a window, like activation or closing.

What is a MouseEvent in Java?

Represents mouse actions such as clicking, pressing, or dragging.

What is a TextEvent in Java?

Generated when the value of a textarea or textfield is changed.

What is a ComponentEvent in Java?

Generated when a component is hidden, moved, or resized.

What is an AdjustmentEvent in Java?

Generated when the scroll bar is used.

Can one listener handle multiple events?

Yes, if they are of the same type.

Can one event be bound to multiple listeners?

Yes, although not common, it is possible if program design requires it.