grafana/contribute/style-guides/themes.md

Work with Grafana themes

Overview

Themes in Grafana are implemented in TypeScript. We chose the TypeScript language in part because it shares variables between Grafana TypeScript and Sass code.

Theme definitions are located in the following files:

• packages/grafana-data/src/themes/createTheme.ts
• packages/grafana-data/src/themes/createColors.ts

Usage

This section provides usage guidelines for themes.

Use themes in React components

The following section describes how to use Grafana themes in React components.

The useStyles2 hook

The useStyles2 hook memoizes the function and provides access to the theme.

import { FC } from 'react';
import { GrafanaTheme2 } from '@grafana/data';
import { useStyles2 } from '@grafana/ui';
import { css } from '@emotion/css';

function Foo(props: FooProps) {
  const styles = useStyles2(getStyles);
  // Use styles with className
}

const getStyles = (theme: GrafanaTheme2) =>
  css({
    padding: theme.spacing(1, 2),
  });

Get the theme object

Use code similar to the following to give your component access to the theme variables:

import { FC } from 'react';
import { useTheme2 } from '@grafana/ui';

const Foo: FC<FooProps> = () => {
  const theme = useTheme2();

  // Your component has access to the theme variables now
};

Select a variable

This section explains how to select the correct variables in your theme.

The rich color object and the state colors

The theme.colors object has six rich color objects:

• primary
• secondary
• info
• success
• warning
• error

All these objects use the same secondary colors which are associated with different use cases.

Property	When to use
main	For backgrounds
shade	For hover highlight
text	For text color
border	For borders, currently always the same as text color
contrastText	Text color to use for text placed on top of the main color

Example use cases:

• Want a red background? Use theme.colors.error.main.
• Want green text? Use theme.colors.success.text.
• Want text to be visible when placed inside a background that uses theme.colors.error.main? Use theme.colors.error.contrastText.

Text colors

Property	When to use
theme.colors.text.primary	The default text color
theme.colors.text.secondary	Text color for things that should be a bit less prominent
theme.colors.text.disabled	Text color for disabled or faint things
theme.colors.text.link	Text link color
theme.colors.text.maxContrast	Maximum contrast (absolute white in dark theme, absolute black in white theme)

Background colors

Property	When to use
theme.colors.background.canvas	Dashboard background. A background surface for panels and panes that use primary background
theme.colors.background.primary	The default content background for content panes and panels
theme.colors.background.secondary	For cards and other surfaces that need to stand out when placed on top of the primary background

Borders

Property	When to use
theme.colors.border.weak	Primary border for panels and panes and other subtle borders
theme.colors.border.medium	For stronger borders like inputs
theme.colors.border.strong	For even stronger border like hover highlighted border

Actions

Property	When to use
theme.colors.action.hover	Background color for hover on card, menu or list item
theme.colors.action.focus	Background color for focused card, menu or list item
theme.colors.action.selected	Background color for selected card, menu or list item

Paddings and margins

Example	Result
theme.spacing(1)	8px
theme.spacing(1, 2)	8px 16px
theme.spacing(1, 2, 0.5, 4)	8px 16px 4px 32px

Border radius

Example	Result
theme.shape.borderRadius(1)	2px
theme.shape.borderRadius(2)	4px

Typography

To customize font family, font sizes, and line heights, use the variables under theme.typography.

Set the context directly

Use ThemeContext like this:

import { ThemeContext } from '@grafana/data';

<ThemeContext.Consumer>{(theme) => <Foo theme={theme} />}</ThemeContext.Consumer>;

Use withTheme higher-order component

With this method your component will be automatically wrapped in ThemeContext.Consumer and provided with current theme via the theme prop. Components used with withTheme must implement the Themeable interface.

import  { ThemeContext, Themeable } from '@grafana/ui';

interface FooProps extends Themeable2 {}

const Foo: React.FunctionComponent<FooProps> = () => ...

export default withTheme2(Foo);

Use a theme in tests

If you need to pass a theme object to a function that you are testing, then import createTheme and call it without any arguments. For example:

import { createTheme } from '@grafana/data';

describe('MyComponent', () => {
  it('should work', () => {
    result = functionThatNeedsTheme(createTheme());
    expect(result).toBe(true);
  });
});

Modify Sass variables

If you need to modify the Sass variable files, we recommend that you migrate the styles to Emotion.

For the following variables to apply, you need to run this yarn dev task:

• [_variables|_variables.dark|_variables.light].generated.scss: These files must be referenced in the main Sass files for Sass variables to be available.

If you need to modify the Sass variable files, be sure to update the files that end with .tmpl.ts and not the .generated.scss files.

Important: These variable files are automatically generated and should never be modified by hand.