Description

Progress indicators express an unspecified wait time or display the current completed ratio of a process or action.

Types 

Linear & Circular

LUX offers two visually distinct variations of progress indicators: linear and circular progress indicators. Only one type should represent each kind of activity in an application. For example, if a refresh action displays a circular indicator on one screen, that same action shouldn’t use a linear indicator elsewhere in the application.

Usage & Behaviour

Progress indicators inform users about the status of ongoing processes, such as loading a page, submitting a form, or saving updates. They communicate an applications state and indicate available actions, such as whether users can navigate away from the current screen.

A linear indicator can also be integrated into form elements, such as file uploads, to express a connection between a background ongoing process and individual items. They are ideal for long determinate activities (over 10 seconds).

A circular indicator can be integrated into a button or actionable icon to express a connection between an interaction and a specific item. They are typically used to express when an interaction, such as clicking a button again, is not available. They should be used for short, indeterminate activities (between 2-5 seconds).

General guidelines

Structure

Linear progress indicators are composed of two required elements:

Track - The track is a fixed width horizontal rule, with set boundaries for the indicator bar to travel along.
Indicator Bar - The bar animates along the length of the track.

Placement and Positioning

The placement of a progress indicator can indicate the scope of a process. Linear progress indicators should only be placed at the top or in the center of a container or component. For example:

• A linear progress indicator attached to the top a container, such as a card indicates the process applies to that particular item (and that interaction with the rest of the UI is possible)

• A linear progress indicator at the center of the screen should indicate loading all screen content (and that no interaction is possible until complete)

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When integrated to form elements (e.g. file upload), it may be placed to the right of the label\field pair. It may also be placed underneath the field depending on available screen real estate or responsive design.

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A circular progress indicator should only be placed in the center << update when toasts are complete >> of a container or component. For example:

• A circular progress indicator at the center of the screen should indicate loading all screen content (and that no interaction is possible until complete)

• A circular progress indicator at the center of component, such as a button indicates the process applies to that particular item (and that interaction with the rest of the UI is possible)

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Default State

Determinate linear progress indicators may be hidden or shown in their empty state by default depending on how important it is to convey the prior expectation that an action a lengthy operation. As an example, an archival form operation which is expected to take minutes to complete should show the linear progress indicator in its empty state to set a priori expectations for the user.

Indeterminate linear progress indicators should be hidden by default and only appear on screen when they are active. Once complete, the linear progress indicator should return to it's default state (removed from view) and in most cases replaced by the content that was loaded or post-completion message.

Circular progress indicators should be hidden by default and only appear on screen when they are active. Once complete, the circular progress indicator should return to it's default state (removed from view) in most cases replaced by the content that was loaded. In the case of integration with a component like button, the button is returned to it’s default state.

States

There are none of the traditional states such as hover, active, focused and error states for linear progress indicators as user interaction is not applicable.

Linear

State	Determinate	Indeterminate
Empty
Partially complete
Complete
Disabled

Circular

State	Determinate	Indeterminate
Empty
Partially complete
Complete
Disabled

Interaction

Progress indicators do not support user interaction, they are solely used to provide a visual status indicator. The exception to this is where circular progress indicators are integrated into a button with a built in cancel operation.

Best practices

1. Don’t stop a progress indicator - A progress indicator makes users develop an expectation for how fast the action is being processed. As a result, any unexpected freezes will be noticed and will impact user satisfaction. The worst possible case is when a progress indicator approaches 99% and suddenly stops. Most users will be frustrated by this behaviour because it makes them think the app is frozen. You can disguise small delays in your progress indicator by moving it instantly and steadily.

2. Explain why the user is waiting - If users are informed, they may be more patient. It can be helpful to add additional clarity by including text that tells the user what is happening or explains why the user is waiting.

3. Provide a general time estimate for time-consuming tasks - Don’t try to be exact, a simple, “this might take five minutes” can be enough for users and encourage them to wait it out.

4. Make sure that long operations offer the ability to cancel during the process.

5. Avoid using vertical linear indicators - A linear progress indicator is instinctively easier to visualize when oriented horizontally. Avoid orienting it vertically to reduce the cognitive load required for users.

Accessibility Compliance

Unless otherwise specified, see our general compliance information in Fundamentals - Accessibility

Content authors should provide values of aria-valuemin, aria-valuemax and aria-valuenow where the aria-valuemax is known. Further guidelines for optimum compliance can be found at ARIA progressbar role.

Design

Code