@material-ui/core/es/styles/createTypography.js

React components that implement Google's Material Design.

import _extends from "@babel/runtime/helpers/esm/extends";
import _objectWithoutPropertiesLoose from "@babel/runtime/helpers/esm/objectWithoutPropertiesLoose";
import { deepmerge } from '@material-ui/utils';

function round(value) {
  return Math.round(value * 1e5) / 1e5;
}

let warnedOnce = false;

function roundWithDeprecationWarning(value) {
  if (process.env.NODE_ENV !== 'production') {
    if (!warnedOnce) {
      console.warn(['Material-UI: The `theme.typography.round` helper is deprecated.', 'Head to https://mui.com/r/migration-v4/#theme for a migration path.'].join('\n'));
      warnedOnce = true;
    }
  }

  return round(value);
}

const caseAllCaps = {
  textTransform: 'uppercase'
};
const defaultFontFamily = '"Roboto", "Helvetica", "Arial", sans-serif';
/**
 * @see @link{https://material.io/design/typography/the-type-system.html}
 * @see @link{https://material.io/design/typography/understanding-typography.html}
 */

export default function createTypography(palette, typography) {
  const _ref = typeof typography === 'function' ? typography(palette) : typography,
        {
    fontFamily = defaultFontFamily,
    // The default font size of the Material Specification.
    fontSize = 14,
    // px
    fontWeightLight = 300,
    fontWeightRegular = 400,
    fontWeightMedium = 500,
    fontWeightBold = 700,
    // Tell Material-UI what's the font-size on the html element.
    // 16px is the default font-size used by browsers.
    htmlFontSize = 16,
    // Apply the CSS properties to all the variants.
    allVariants,
    pxToRem: pxToRem2
  } = _ref,
        other = _objectWithoutPropertiesLoose(_ref, ["fontFamily", "fontSize", "fontWeightLight", "fontWeightRegular", "fontWeightMedium", "fontWeightBold", "htmlFontSize", "allVariants", "pxToRem"]);

  if (process.env.NODE_ENV !== 'production') {
    if (typeof fontSize !== 'number') {
      console.error('Material-UI: `fontSize` is required to be a number.');
    }

    if (typeof htmlFontSize !== 'number') {
      console.error('Material-UI: `htmlFontSize` is required to be a number.');
    }
  }

  const coef = fontSize / 14;

  const pxToRem = pxToRem2 || (size => `${size / htmlFontSize * coef}rem`);

  const buildVariant = (fontWeight, size, lineHeight, letterSpacing, casing) => _extends({
    fontFamily,
    fontWeight,
    fontSize: pxToRem(size),
    // Unitless following https://meyerweb.com/eric/thoughts/2006/02/08/unitless-line-heights/
    lineHeight
  }, fontFamily === defaultFontFamily ? {
    letterSpacing: `${round(letterSpacing / size)}em`
  } : {}, casing, allVariants);

  const variants = {
    h1: buildVariant(fontWeightLight, 96, 1.167, -1.5),
    h2: buildVariant(fontWeightLight, 60, 1.2, -0.5),
    h3: buildVariant(fontWeightRegular, 48, 1.167, 0),
    h4: buildVariant(fontWeightRegular, 34, 1.235, 0.25),
    h5: buildVariant(fontWeightRegular, 24, 1.334, 0),
    h6: buildVariant(fontWeightMedium, 20, 1.6, 0.15),
    subtitle1: buildVariant(fontWeightRegular, 16, 1.75, 0.15),
    subtitle2: buildVariant(fontWeightMedium, 14, 1.57, 0.1),
    body1: buildVariant(fontWeightRegular, 16, 1.5, 0.15),
    body2: buildVariant(fontWeightRegular, 14, 1.43, 0.15),
    button: buildVariant(fontWeightMedium, 14, 1.75, 0.4, caseAllCaps),
    caption: buildVariant(fontWeightRegular, 12, 1.66, 0.4),
    overline: buildVariant(fontWeightRegular, 12, 2.66, 1, caseAllCaps)
  };
  return deepmerge(_extends({
    htmlFontSize,
    pxToRem,
    round: roundWithDeprecationWarning,
    // TODO v5: remove
    fontFamily,
    fontSize,
    fontWeightLight,
    fontWeightRegular,
    fontWeightMedium,
    fontWeightBold
  }, variants), other, {
    clone: false // No need to clone deep

  });
}