Frontend: Update frontend styleguide emotion example (#55608)

* Frontend: Update frontend styleguide emotion example

* Update styling guide

* Fixes

* Add back link to cx

* prettier

* Update contribute/style-guides/frontend.md

Co-authored-by: Ashley Harrison <ashley.harrison@grafana.com>

* prettier

Co-authored-by: Ashley Harrison <ashley.harrison@grafana.com>

contribute/style-guides/frontend.md

@@ -166,17 +166,22 @@ interface ModalState {
 ##### Emotion class names
 
 ```typescript
-const getStyles  = = () => ({
+const getStyles = (theme: GrafanaTheme2) => ({
   // bad
   ElementWrapper: css`...`,
   // bad
-  ["element-wrapper"]: css`...`,
+  ['element-wrapper']: css`...`,
 
   // good
-  elementWrapper: css`...`,
+  elementWrapper: css({
+    padding: theme.spacing(1, 2),
+    background: theme.colors.background.secondary,
+  }),
 });
 ```
 
+Use hook useStyles2(getStyles) to memoize the styles generation and try to avoid passing props to the the getStyles function and instead compose classes using emotion cx function.
+
 #### Use `ALL_CAPS` for constants.
 
 ```typescript

contribute/style-guides/styling.md

@@ -4,26 +4,9 @@
 
 ## Usage
 
-### Basic styling
-
 For styling components, use [Emotion's `css` function](https://emotion.sh/docs/emotion#css).
 
-```tsx
-import React from 'react';
-import { css } from '@emotion/css';
-
-const ComponentA = () => (
-  <div
-    className={css`
-      background: red;
-    `}
-  >
-    As red as you can get
-  </div>
-);
-```
-
-### Styling with theme
+### Basic styling
 
 To access the theme in your styles, use the `useStyles` hook. It provides basic memoization and access to the theme object.
 
@@ -31,33 +14,35 @@ To access the theme in your styles, use the `useStyles` hook. It provides basic
 
 ```tsx
 import React, { FC } from 'react';
-import { GrafanaTheme } from '@grafana/data';
-import { useStyles } from '@grafana/ui';
+import { GrafanaTheme2 } from '@grafana/data';
+import { useStyles2 } from '@grafana/ui';
 import { css } from '@emotion/css';
 
 const Foo: FC<FooProps> = () => {
-  const styles = useStyles(getStyles);
+  const styles = useStyles2(getStyles);
 
   // Use styles with classNames
   return <div className={styles}>...</div>;
 };
 
-const getStyles = (theme: GrafanaTheme) => css`
-  padding: ${theme.spacing.md};
-`;
+const getStyles = (theme: GrafanaTheme2) =>
+  css({
+    padding: theme.spacing(1, 2), // will result in 8px 16px padding
+  });
 ```
 
 ### Styling complex components
 
-In more complex cases, especially when you need to style multiple DOM elements in one component, or when using styles that depend on properties and/or state, you should create a helper function that returns an object of styles. This function should also be wrapped in the `stylesFactory` helper function, which will provide basic memoization.
+In more complex cases, especially when you need to style multiple DOM elements in one component, or when using styles that depend on properties and/or state you
+can have your getStyles function return an object with many class names and use [Emotion's `cx` function](https://emotion.sh/docs/emotion#cx) to compose them.
 
 Let's say you need to style a component that has a different background depending on the `isActive` property :
 
 ```tsx
 import React from 'react';
-import { css } from '@emotion/css';
-import { GrafanaTheme } from '@grafana/data';
-import { selectThemeVariant, stylesFactory, useTheme } from '@grafana/ui';
+import { css, cx } from '@emotion/css';
+import { GrafanaTheme2 } from '@grafana/data';
+import { useStyles2 } from '@grafana/ui';
 
 interface ComponentAProps {
   isActive: boolean;
@@ -65,10 +50,10 @@ interface ComponentAProps {
 
 const ComponentA: React.FC<ComponentAProps> = ({ isActive }) => {
   const theme = useTheme();
-  const styles = getStyles(theme, isActive);
+  const styles = useStyles2(theme);
 
   return (
-    <div className={styles.wrapper}>
+    <div className={cx(styles.wrapper, isActive && styles.active)}>
       As red as you can get
       <i className={styles.icon} />
     </div>
@@ -76,42 +61,20 @@ const ComponentA: React.FC<ComponentAProps> = ({ isActive }) => {
 };
 
 // Mind, that you can pass multiple arguments, theme included
-const getStyles = stylesFactory((theme: GrafanaTheme, isActive: boolean) => {
-  const backgroundColor = isActive ? theme.colors.red : theme.colors.blue;
-
+const getStyles = (theme: GrafanaTheme2) => {
   return {
-    wrapper: css`
-      background: ${backgroundColor};
-    `,
-    icon: css`
-      font-size: ${theme.typography.size.sm};
-    `,
+    wrapper: css({
+      background: theme.colors.background.secondary;
+    }),
+    active: css({
+      background: theme.colors.primary.main,
+      text: theme.colors.primary.contrastText,
+    },
+    icon: css({
+      fontSize: theme.typography.bodySmall.fontSize;
+    })
   };
-});
+};
 ```
 
 For more information about themes at Grafana please see the [themes guide](./themes.md).
-
-### Composing class names
-
-For class composition, use [Emotion's `cx` function](https://emotion.sh/docs/emotion#cx).
-
-```tsx
-import React from 'react';
-import { css, cx } from '@emotion/css';
-
-interface Props {
-  className?: string;
-}
-
-function ComponentA({ className }: Props) {
-  const finalClassName = cx(
-    className,
-    css`
-      background: red;
-    `
-  );
-
-  return <div className={finalClassName}>As red as you can ge</div>;
-}
-```