[Button] Custom variant

docs/pages/api-docs/button.md

@@ -41,7 +41,7 @@ The `MuiButton` name can be used for providing [default props](/customization/gl
 | <span class="prop-name">href</span> | <span class="prop-type">string</span> |  | The URL to link to when the button is clicked. If defined, an `a` element will be used as the root node. |
 | <span class="prop-name">size</span> | <span class="prop-type">'large'<br>&#124;&nbsp;'medium'<br>&#124;&nbsp;'small'</span> | <span class="prop-default">'medium'</span> | The size of the button. `small` is equivalent to the dense button styling. |
 | <span class="prop-name">startIcon</span> | <span class="prop-type">node</span> |  | Element placed before the children. |
-| <span class="prop-name">variant</span> | <span class="prop-type">'contained'<br>&#124;&nbsp;'outlined'<br>&#124;&nbsp;'text'</span> | <span class="prop-default">'text'</span> | The variant to use. |
+| <span class="prop-name">variant</span> | <span class="prop-type">'contained'<br>&#124;&nbsp;'outlined'<br>&#124;&nbsp;'text'<br>&#124;&nbsp;string</span> | <span class="prop-default">'text'</span> | The variant to use. |
 
 The `ref` is forwarded to the root element.
 

docs/src/pages/customization/components/GlobalThemeVariants.js

@@ -0,0 +1,72 @@
+import React from 'react';
+import {
+  createMuiTheme,
+  makeStyles,
+  ThemeProvider,
+} from '@material-ui/core/styles';
+import Button from '@material-ui/core/Button';
+
+const useStyles = makeStyles((theme) => ({
+  root: {
+    '& > *': {
+      margin: theme.spacing(1),
+    },
+  },
+}));
+
+const defaultTheme = createMuiTheme();
+
+const theme = createMuiTheme({
+  variants: {
+    MuiButton: [
+      {
+        props: { variant: 'dashed' },
+        styles: {
+          textTransform: 'none',
+          border: `2px dashed ${defaultTheme.palette.primary.main}`,
+          color: defaultTheme.palette.primary.main,
+        },
+      },
+      {
+        props: { variant: 'dashed', color: 'secondary' },
+        styles: {
+          border: `2px dashed ${defaultTheme.palette.secondary.main}`,
+          color: defaultTheme.palette.secondary.main,
+        },
+      },
+      {
+        props: { variant: 'dashed', size: 'large' },
+        styles: {
+          borderWidth: 4,
+        },
+      },
+      {
+        props: { variant: 'dashed', color: 'secondary', size: 'large' },
+        styles: {
+          fontSize: 18,
+        },
+      },
+    ],
+  },
+});
+
+export default function GlobalThemeVariants() {
+  const classes = useStyles();
+
+  return (
+    <div className={classes.root}>
+      <ThemeProvider theme={theme}>
+        <Button variant="dashed">Dashed</Button>
+        <Button variant="dashed" color="secondary">
+          Secondary
+        </Button>
+        <Button variant="dashed" size="large">
+          Large
+        </Button>
+        <Button variant="dashed" color="secondary" size="large">
+          Secondary large
+        </Button>
+      </ThemeProvider>
+    </div>
+  );
+}

docs/src/pages/customization/components/GlobalThemeVariants.tsx

@@ -0,0 +1,79 @@
+import React from 'react';
+import {
+  createMuiTheme,
+  makeStyles,
+  Theme,
+  ThemeProvider,
+} from '@material-ui/core/styles';
+import Button from '@material-ui/core/Button';
+
+declare module '@material-ui/core/Button/Button' {
+  interface ButtonPropsVariantOverrides {
+    dashed: true;
+  }
+}
+
+const useStyles = makeStyles((theme: Theme) => ({
+  root: {
+    '& > *': {
+      margin: theme.spacing(1),
+    },
+  },
+}));
+
+const defaultTheme = createMuiTheme();
+
+const theme = createMuiTheme({
+  variants: {
+    MuiButton: [
+      {
+        props: { variant: 'dashed' },
+        styles: {
+          textTransform: 'none',
+          border: `2px dashed ${defaultTheme.palette.primary.main}`,
+          color: defaultTheme.palette.primary.main,
+        },
+      },
+      {
+        props: { variant: 'dashed', color: 'secondary' },
+        styles: {
+          border: `2px dashed ${defaultTheme.palette.secondary.main}`,
+          color: defaultTheme.palette.secondary.main,
+        },
+      },
+      {
+        props: { variant: 'dashed', size: 'large' },
+        styles: {
+          borderWidth: 4,
+        },
+      },
+      {
+        props: { variant: 'dashed', color: 'secondary', size: 'large' },
+        styles: {
+          fontSize: 18,
+        },
+      },
+    ],
+  },
+});
+
+export default function GlobalThemeVariants() {
+  const classes = useStyles();
+
+  return (
+    <div className={classes.root}>
+      <ThemeProvider theme={theme}>
+        <Button variant="dashed">Dashed</Button>
+        <Button variant="dashed" color="secondary">
+          Secondary
+        </Button>
+        <Button variant="dashed" size="large">
+          Large
+        </Button>
+        <Button variant="dashed" color="secondary" size="large">
+          Secondary large
+        </Button>
+      </ThemeProvider>
+    </div>
+  );
+}

docs/src/pages/customization/components/components.md

@@ -319,3 +319,43 @@ const theme = createMuiTheme({
 ```
 
 {{"demo": "pages/customization/components/GlobalThemeOverride.js"}}
+
+### Adding new component variants
+
+You can take advantage of the `variants` key of the `theme` to add new variants to Material-UI components. These new variants, can specify which styles the component should have, if specific properties are defined together.
+
+The definitions are specified in an array, under the component's name. For every one of them a class is added in the head. The order is **important**, so make sure that the styles that should win will be specified lastly.
+
+```jsx
+const theme = createMuiTheme({
+  variants: {
+    MuiButton: [
+      {
+        props: { variant: 'dashed' },
+        styles: {
+          textTransform: 'none',
+          border: `2px dashed grey${blue[500]}`,
+        },
+      },
+      {
+        props: { variant: 'dashed', color: 'secondary' },
+        styles: {
+          border: `4px dashed ${red[500]}`,
+        },
+      },
+    ],
+  },
+});
+```
+
+If you are using TypeScript, you will need to specify your new variants/colors, using module augmentation.
+
+```tsx
+declare module '@material-ui/core/Button/Button' {
+  interface ButtonPropsVariantOverrides {
+    dashed: true;
+  }
+}
+```
+
+{{"demo": "pages/customization/components/GlobalThemeVariants.js"}}

packages/material-ui-styles/src/getStylesCreator/getStylesCreator.js

@@ -1,4 +1,5 @@
 import { deepmerge } from '@material-ui/utils';
+import propsToClassKey from '../propsToClassKey';
 import noopTheme from './noopTheme';
 
 export default function getStylesCreator(stylesOrCreator) {
@@ -36,11 +37,15 @@ export default function getStylesCreator(stylesOrCreator) {
         throw err;
       }
 
-      if (!name || !theme.overrides || !theme.overrides[name]) {
+      if (
+        !name ||
+        ((!theme.overrides || !theme.overrides[name]) && (!theme.variants || !theme.variants[name]))
+      ) {
         return styles;
       }
 
-      const overrides = theme.overrides[name];
+      const overrides = (theme.overrides && theme.overrides[name]) || {};
+      const variants = (theme.variants && theme.variants[name]) || [];
       const stylesWithOverrides = { ...styles };
 
       Object.keys(overrides).forEach((key) => {
@@ -50,12 +55,22 @@ export default function getStylesCreator(stylesOrCreator) {
               [
                 'Material-UI: You are trying to override a style that does not exist.',
                 `Fix the \`${key}\` key of \`theme.overrides.${name}\`.`,
+                '',
+                'If you intentionally wanted to add a new key, please use the theme.variants option.',
               ].join('\n'),
             );
           }
         }
 
-        stylesWithOverrides[key] = deepmerge(stylesWithOverrides[key], overrides[key]);
+        stylesWithOverrides[key] = deepmerge(stylesWithOverrides[key] || {}, overrides[key]);
+      });
+
+      variants.forEach((definition) => {
+        const classKey = propsToClassKey(definition.props);
+        stylesWithOverrides[classKey] = deepmerge(
+          stylesWithOverrides[classKey] || {},
+          definition.styles,
+        );
       });
 
       return stylesWithOverrides;

packages/material-ui-styles/src/index.d.ts

@@ -31,6 +31,9 @@ export * from './ThemeProvider';
 export { default as useTheme } from './useTheme';
 export * from './useTheme';
 
+export { default as useThemeVariants } from './useThemeVariants';
+export * from './useThemeVariants';
+
 export { default as withStyles } from './withStyles';
 export * from './withStyles';
 

packages/material-ui-styles/src/index.js

@@ -58,6 +58,9 @@ export * from './ThemeProvider';
 export { default as useTheme } from './useTheme';
 export * from './useTheme';
 
+export { default as useThemeVariants } from './useThemeVariants';
+export * from './useThemeVariants';
+
 export { default as withStyles } from './withStyles';
 export * from './withStyles';
 

packages/material-ui-styles/src/makeStyles/makeStyles.js

@@ -241,6 +241,23 @@ export default function makeStyles(stylesOrCreator, options = {}) {
       // eslint-disable-next-line react-hooks/rules-of-hooks
       React.useDebugValue(classes);
     }
+    if (process.env.NODE_ENV !== 'production') {
+      const whitelistedComponents = ['MuiButton'];
+
+      if (
+        name &&
+        whitelistedComponents.indexOf(name) >= 0 &&
+        props.variant &&
+        !classes[props.variant]
+      ) {
+        console.error(
+          [
+            `Material-UI: You are using a variant value \`${props.variant}\` for which you didn't define styles.`,
+            `Please create a new variant matcher in your theme for this variant. To learn more about matchers visit https://material-ui.com/customization/components/#adding-new-component-variants.`,
+          ].join('\n'),
+        );
+      }
+    }
 
     return classes;
   };

packages/material-ui-styles/src/propsToClassKey/index.d.ts

@@ -0,0 +1,2 @@
+export { default } from './propsToClassKey';
+export * from './propsToClassKey';

packages/material-ui-styles/src/propsToClassKey/index.js

@@ -0,0 +1 @@
+export { default } from './propsToClassKey';

packages/material-ui-styles/src/propsToClassKey/propsToClassKey.d.ts

@@ -0,0 +1 @@
+export default function propsToClassKey(props: object): string;

packages/material-ui-styles/src/propsToClassKey/propsToClassKey.js

@@ -0,0 +1,38 @@
+import MuiError from '@material-ui/utils/macros/MuiError.macro';
+
+// TODO: remove this once the capitalize method is moved to the @material-ui/utils package
+export function capitalize(string) {
+  if (typeof string !== 'string') {
+    throw new MuiError('Material-UI: capitalize(string) expects a string argument.');
+  }
+
+  return string.charAt(0).toUpperCase() + string.slice(1);
+}
+
+function isEmpty(string) {
+  return string.length === 0;
+}
+
+/**
+ * Generates string classKey based on the properties provided. It starts with the
+ * variant if defined, and then it appends all other properties in alphabetical order.
+ *
+ * @param {object} props - the properties for which the classKey should be created
+ */
+export default function propsToClassKey(props) {
+  const { variant, ...rest } = props;
+
+  let classKey = variant || '';
+
+  Object.keys(rest)
+    .sort()
+    .forEach((key) => {
+      if (key === 'color') {
+        classKey += isEmpty(classKey) ? props[key] : capitalize(props[key]);
+      } else {
+        classKey += `${isEmpty(classKey) ? key : capitalize(key)}${capitalize(props[key])}`;
+      }
+    });
+
+  return classKey;
+}

packages/material-ui-styles/src/propsToClassKey/propsToClassKey.test.js

@@ -0,0 +1,34 @@
+import { expect } from 'chai';
+import propsToClassKey from './propsToClassKey';
+
+describe('propsToClassKey', () => {
+  it('should return the variant value as string', () => {
+    expect(propsToClassKey({ variant: 'custom' })).to.equal('custom');
+  });
+
+  it('should combine the variant with other props', () => {
+    expect(propsToClassKey({ variant: 'custom', size: 'large' })).to.equal('customSizeLarge');
+  });
+
+  it('should append the props after the variant in alphabetical order', () => {
+    expect(propsToClassKey({ variant: 'custom', size: 'large', mode: 'static' })).to.equal(
+      'customModeStaticSizeLarge',
+    );
+  });
+
+  it('should not prefix the color prop', () => {
+    expect(propsToClassKey({ variant: 'custom', color: 'primary' })).to.equal('customPrimary');
+  });
+
+  it('should work without variant in props', () => {
+    expect(propsToClassKey({ color: 'primary', size: 'large', mode: 'static' })).to.equal(
+      'primaryModeStaticSizeLarge',
+    );
+  });
+
+  it('should not capitalize the first prop ', () => {
+    expect(propsToClassKey({ size: 'large', zIndex: 'toolbar' })).to.equal(
+      'sizeLargeZIndexToolbar',
+    );
+  });
+});

packages/material-ui-styles/src/useThemeVariants/index.d.ts

@@ -0,0 +1,2 @@
+export { default } from './useThemeVariants';
+export * from './useThemeVariants';

packages/material-ui-styles/src/useThemeVariants/index.js

@@ -0,0 +1 @@
+export { default } from './useThemeVariants';

packages/material-ui-styles/src/useThemeVariants/useThemeVariants.d.ts

@@ -0,0 +1 @@
+export default function useThemeVariants(props: object, name: string): string;