Legends (also known as keys) help users understand the relationship between data and its visual representation.
Categorical color legends make it clear as to which color maps to which item.
Sequential color legends show how colors map to a continuous scale. Ordinal scales are divided into specific pieces (bins), while interval and ratio scales are smooth gradients.
Diverging color legends show how colors map to a continuous scale that includes a meaningful midpoint. Ordinal scales are divided into specific pieces (bins), while interval and ratio scales are smooth gradients.
Legends can have horizontal or vertical orientation. Whenever possible, orient the legend to match the chart.
When there isn’t enough space, wrap legends to ensure that dimension values are shown.
When dimension values are aggregated, a tooltip should display the list of values.
Avoid truncating legends whenever possible. If truncation is necessary for your use case, use a tooltip to show the full name of the dimension value.
Legends should be intuitive to understand. If a chart presents color in a certain order, its legend should mirror that order. In other use cases (e.g., a line chart), use another meaningful order, such as the last values or the average of all values.
Legends help users understand how a variable is displayed on a chart, so they follow the same rule that a chart would: to be true to the data.
For example, if you break a ratio scale into categories to make it ordinal, and those categories are not equally sized, the legend should reflect that through more than just labels.
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Includes all interactive states that are applicable (hover, down, focus, keyboard focus, disabled).
Includes relevant options (variant, style, size, orientation, optional iconography, decorations, selection, error state, etc.)
Works properly across all four color themes (lightest, light, dark, darkest).
Includes a desktop scale (UWP, macOS, web desktop) and a mobile scale (iOS, Android, web mobile).
Includes guidelines for layout (wrapping, truncation, overflow), animation, interactions, etc.
Includes a list of dos and don’ts that highlight best practices and common mistakes.
Follows WCAG 2.0 standards for contrast (AA).
Works properly across various locales and includes guidelines for bi-directionality (RTL).
Follows WCAG 2.0 standards for keyboard accessibility guidelines and includes a description of the keyboard interactions.
Includes a downloadable XD file that has been generated by code and shows multiple variations, states, color themes, and scales.
All design attributes (color, typography, layout, animation, etc.) are included in Spectrum DNA.