# User Interfaces
###### tags: `UI`
*It's all about Interactions*
1. How the system accept input
2. How the user respond to the input
3. How the system output

## Types of UI
- Device-free AI
- Don't need user input to perform user's desired action
- Device-free but tracking user movements
- [Eye-tracking interface](https://newatlas.com/mouseless-invisible-mouse-prototype/15644/)
- [Apple's Foveated display glasses](https://www.patentlyapple.com/patently-apple/2018/08/a-european-patent-application-reveals-more-details-of-apples-ar-glasses-system-that-will-use-a-foveated-display.html)
- Hand-tracking interface
- [Mouseless mouse via infrared](https://newatlas.com/mouseless-invisible-mouse-prototype/15644/)

## Human Computer Interaction (HCI)

Interactions in HCI are defined by
- Communication, direct/indirect
- Dialogue + feedback/batch
- Task oriented

There are many [guidelines, principles and theories to HCI](https://hackmd.io/@lyqht/HkFA1KUGU).

## :question: What is a good UI design
- When well designed, **the interface almost disappears**, enabling users to concentrate on their work, exploration, or pleasure.
- Good designs generate positive feelings of **success, competence, mastery and clarity** in the user community.

### Design according to users' skill levels

- Novice users
- Limit the actions that they can do (small no.of icons and actions)
- quickstart instructions & demo
- good error messages
- Knowledge intermittent
- consistency and grouping of objects and actions
- allow reversal of actions to encoourage exploration and learning
- Expert Frequent Users
- Would enjoy macros, shortcuts, repeat actions
- Don't need detailed feedback about their actions: they already know what they would expect from their interactions

It would be good to have multi-layer designs to support users at their initial skill level and transit them as they increase their skill.

> e.g. Visual Studio Code
> - allow novice users to code normally (create new file, make new file with usual click and rightclick commands)
> - allow advanced users to create their own keymaps / configuration settings through a single config.json.

### Prevent errors

Mistakes and Slips
- If the intention is not appropriate,this is a mistake
- If the action is not what was intended, it is a slip.

Either could be the user/designer's fault, but it would be better if the designer helps to prevent and reduce such errors by
- providing automatic completion
- encourage recognition vs recall (selection rather than freestyle typing)
- gray out inappropriate actions so they won't try to do it (don't just gray it out, make it UNCLICKABLE)
- organize info better
- better error messages

### Jakob Nielsen's Usability Heuristics
[**10 Heuristic Principles**](https://www.nngroup.com/articles/ten-usability-heuristics/)

> [Designs related to this](https://hackmd.io/jYYM-kJxQCOpMcIVAL6kLQ)

1. Visibility of system status
- The system should always keep users informed about what is going on, through appropriate feedback
within reasonable time.
2. Match between system and the real world
- The system should speak the users' language, with words, phrases and concepts familiar to the user, rather than system-oriented terms. Follow real-world conventions, making information appear in a natural and logical order.
3. User control and freedom
- Users often choose system functions by mistake and will need a clearly marked "emergency exit" to leave the unwanted state without having to go through an extended dialogue. Support undo and redo.
4. Consistency and standards
- Users should not have to wonder whether different words, situations, or actions mean the same thing.
- Follow platform conventions.
5. Error prevention
- Even better than good error messages is a careful design which prevents a problem from occurring in the first place.
6. Recognition rather than recall
- Make objects, actions, and options visible. The user should not have to remember information from one part of the dialogue to another. Instructions for use of the system should be visible or easily retrievable whenever appropriate.
7. Flexibility and efficiency of use
- Accelerators -- unseen by the novice user -- may often speed up the interaction for the expert user such that the system can cater to both inexperienced and experienced users. Allow users to tailor frequent actions.
8. Aesthetic and minimalist design
- Dialogues should not contain information which is irrelevant or rarely needed. Every extra unit of information in a dialogue competes with the relevant units of information and diminishes their relative visibility.
9. Help users recognize, diagnose, and recover from errors
- Error messages should be expressed in plain language (no codes), precisely indicate the problem, and constructively suggest a solution.
10. Help and documentation
- Even though it is better if the system can be used without documentation, it may be necessary to provide help and documentation. Any such information should be easy to search, focused on the user's task, list concrete steps to be carried out, and not be too large.

## Challenges of UI Design

- People no time to learn new system
- Systems need to be easy to use, to learn, and without errors.
- Designers have difficulty thinking like users
- they can't unlearn something xD