Programming

Mock-ups 

If software will be used directly by people (rather than running hidden deep in the OS), it needs an interface – a place where people can control the program, enter data and receive output. A successful interface must be carefully designed to make it usable and clear.

To design an interface, use a mock-up, which is a sketch showing how a screen or printout will look. A mock-up should typically include the following features:

→the positions and sizes of controls such as buttons and scrollbars

→the positions, sizes, colours and styles of text such as headings and labels

→menus, status bars and scrollbars

→borders, frames, lines, shapes, images, decoration and colour schemes

→vertical and horizontal object alignments

→the contents of headers and footers.

A mock-up can be considered successful if you can give it to another person and they can create the interface without needing to ask you questions.

Event-driven programming

GUIs are typically built on an event-driven programming model. This means that the flow of the program is determined by events such as user actions (clicks, typing, etc.), sensor outputs or message passing.

Programming languages that are used to build GUIs often have features to support event handling. This includes the ability to detect events and trigger specific functions or methods in response.

Integration with back-end code

In software design, it is common to separate the GUI (front end) from the business logic or data access layer (back end). Programming languages play a crucial role in linking these layers. User interactions captured by the GUI are processed by the back-end code, which performs the necessary operations and updates the GUI accordingly.