Components: Fix Slot/Fill Emotion StyleProvider (#38237)

* Fix Slot/Fill emotion style provider

* Add slotfill storybook example to `useCx`

* Use iframe from `@wordpress/block-editor`, add `bubblesVirtually` prop

* Fix slotfill name

* Add simpler slotfill example

packages/components/src/slot-fill/bubbles-virtually/fill.js

@@ -8,6 +8,7 @@ import { useRef, useState, useEffect, createPortal } from '@wordpress/element';
  * Internal dependencies
  */
 import useSlot from './use-slot';
+import StyleProvider from '../../style-provider';
 
 function useForceUpdate() {
 	const [ , setState ] = useState( {} );
@@ -48,5 +49,15 @@ export default function Fill( { name, children } ) {
 		children = children( slot.fillProps );
 	}
 
-	return createPortal( children, slot.ref.current );
+	// When using a `Fill`, the `children` will be rendered in the document of the
+	// `Slot`. This means that we need to wrap the `children` in a `StyleProvider`
+	// to make sure we're referencing the right document/iframe (instead of the
+	// context of the `Fill`'s parent).
+	const wrappedChildren = (
+		<StyleProvider document={ slot.ref.current.ownerDocument }>
+			{ children }
+		</StyleProvider>
+	);
+
+	return createPortal( wrappedChildren, slot.ref.current );
 }

packages/components/src/utils/hooks/stories/use-cx.js

@@ -1,79 +1,107 @@
 /**
- * Internal dependencies
+ * External dependencies
  */
-import { useCx } from '..';
-import StyleProvider from '../../../style-provider';
+import { css } from '@emotion/react';
 
 /**
  * WordPress dependencies
  */
-import { useState, createPortal } from '@wordpress/element';
+import { __unstableIframe as Iframe } from '@wordpress/block-editor';
+
 /**
- * External dependencies
+ * Internal dependencies
  */
-import { css } from '@emotion/react';
+import { useCx } from '..';
+import StyleProvider from '../../../style-provider';
+import {
+	createSlotFill,
+	Provider as SlotFillProvider,
+} from '../../../slot-fill';
 
 export default {
 	title: 'Components (Experimental)/useCx',
 };
 
-const IFrame = ( { children } ) => {
-	const [ iframeDocument, setIframeDocument ] = useState();
-
-	const handleRef = ( node ) => {
-		if ( ! node ) {
-			return null;
-		}
+const Example = ( { args, children } ) => {
+	const cx = useCx();
+	const classes = cx( ...args );
+	return <span className={ classes }>{ children }</span>;
+};
 
-		function setIfReady() {
-			const { contentDocument } = node;
-			const { readyState } = contentDocument;
+export const _slotFill = () => {
+	const { Fill, Slot } = createSlotFill( 'UseCxExampleSlot' );
 
-			if ( readyState !== 'interactive' && readyState !== 'complete' ) {
-				return false;
-			}
+	const redText = css`
+		color: red;
+	`;
+	const blueText = css`
+		color: blue;
+	`;
+	const greenText = css`
+		color: green;
+	`;
 
-			setIframeDocument( contentDocument );
-		}
+	return (
+		<SlotFillProvider>
+			<StyleProvider document={ document }>
+				<Iframe>
+					<Iframe>
+						<Example args={ [ redText ] }>
+							This text is inside an iframe and should be red
+						</Example>
+						<Fill name="test-slot">
+							<Example args={ [ blueText ] }>
+								This text is also inside the iframe, but is
+								relocated by a slot/fill and should be blue
+							</Example>
+						</Fill>
+						<Fill name="outside-frame">
+							<Example args={ [ greenText ] }>
+								This text is also inside the iframe, but is
+								relocated by a slot/fill and should be green
+							</Example>
+						</Fill>
+					</Iframe>
+					<StyleProvider document={ document }>
+						<Slot bubblesVirtually name="test-slot" />
+					</StyleProvider>
+				</Iframe>
+				<Slot bubblesVirtually name="outside-frame" />
+			</StyleProvider>
+		</SlotFillProvider>
+	);
+};
 
-		if ( setIfReady() ) {
-			return;
-		}
+export const _slotFillSimple = () => {
+	const { Fill, Slot } = createSlotFill( 'UseCxExampleSlotTwo' );
 
-		node.addEventListener( 'load', () => {
-			// iframe isn't immediately ready in Firefox
-			setIfReady();
-		} );
-	};
+	const redText = css`
+		color: red;
+	`;
 
 	return (
-		<iframe ref={ handleRef } title="use-cx-test-frame">
-			{ iframeDocument &&
-				createPortal(
-					<StyleProvider document={ iframeDocument }>
-						{ children }
-					</StyleProvider>,
-					iframeDocument.body
-				) }
-		</iframe>
+		<SlotFillProvider>
+			<Iframe>
+				<Fill name="test-slot">
+					<Example args={ [ redText ] }>
+						This text should be red
+					</Example>
+				</Fill>
+			</Iframe>
+			<Slot bubblesVirtually name="test-slot" />
+		</SlotFillProvider>
 	);
 };
 
-const Example = ( { args, children } ) => {
-	const cx = useCx();
-	const classes = cx( ...args );
-	return <span className={ classes }>{ children }</span>;
-};
-
 export const _default = () => {
 	const redText = css`
 		color: red;
 	`;
 	return (
-		<IFrame>
+		<Iframe>
 			<Example args={ [ redText ] }>
 				This text is inside an iframe and is red!
 			</Example>
-		</IFrame>
+		</Iframe>
 	);
 };