Fix playground handling of visible scrollbars (#1514)

Summary:
Pull Request resolved: https://github.com/facebook/yoga/pull/1514

On machines with scrollbars, we shouldn't show them unconditionally, and the toolbar should be in the area within them.

This also fixes a couple bugs:
1. Preview not rendering based on correct code when light/dark mode changes
2. Crash on start on mobile safari
3. Incorrect rendering of preview on mobile safari

This also fixes a bug where the playground re-rendering (e.g. on theme change) makes the preview snap back to the initial code passes.

https://yoga-website-next-git-fork-nickgerleman-exp-194d90-fbopensource.vercel.app/

Reviewed By: shwanton

Differential Revision: D52145666

fbshipit-source-id: 50184305987aab4cbcd066f37582997dfdc78c02

website-next/src/components/EditorToolbar.module.css

@@ -8,9 +8,6 @@
 .toolbar {
   display: flex;
   column-gap: 8px;
-  position: absolute;
-  top: 10px;
-  right: 10px;
 }
 
 .toolbar button {

website-next/src/components/EditorToolbar.tsx

@@ -18,9 +18,15 @@ import styles from './EditorToolbar.module.css';
 
 export type Props = Readonly<{
   getCode: () => string;
+  className?: string;
+  style?: React.CSSProperties;
 }>;
 
-export default function EditorToolbar({getCode}: Props): JSX.Element {
+export default function EditorToolbar({
+  getCode,
+  className,
+  style,
+}: Props): JSX.Element {
   const handleCopy = useCallback(
     () => navigator.clipboard.writeText(getCode()),
     [],
@@ -36,7 +42,7 @@ export default function EditorToolbar({getCode}: Props): JSX.Element {
   );
 
   return (
-    <div className={clsx(styles.toolbar)}>
+    <div className={clsx(styles.toolbar, className)} style={style}>
       <ToolbarButton Icon={CopyIcon} label="Copy" onClick={handleCopy} />
       <ToolbarButton Icon={LinkIcon} label="Share" onClick={handleShare} />
     </div>

website-next/src/components/Playground.module.css

@@ -26,30 +26,42 @@ html[data-theme='dark'] {
   background-color: var(--yg-color-playground-background);
 }
 
-.editorColumn {
-  position: relative;
-  flex: 8;
-  min-width: 0;
-}
-
 .playgroundRow {
   display: flex;
   flex-direction: row;
   column-gap: 16px;
 }
 
+.editorColumn {
+  flex: 8;
+  min-width: 0;
+  overflow-y: auto;
+  border: 1px solid var(--yg-color-editor-border);
+  border-radius: var(--ifm-pre-border-radius);
+  position: relative;
+}
+
+.editorScroll {
+ overflow-y: auto;
+}
+
+.editorToolbar {
+  position: absolute;
+  top: 10px;
+  right: 10px;
+}
+
 .playgroundEditor {
   font: var(--ifm-code-font-size) / var(--ifm-pre-line-height)
     var(--ifm-font-family-monospace) !important;
   direction: ltr;
   height: calc(var(--yg-playground-height, 400px) - 32px);
-  overflow: scroll;
 }
 
 .playgroundEditor :global(.prism-code) {
-  height: 100%;
   box-shadow: var(--ifm-global-shadow-lw);
-  border: 1px solid var(--yg-color-editor-border);
+  min-height: 100%;
+  border-radius: 0;
 }
 
 .previewColumn {
@@ -86,8 +98,7 @@ html[data-theme='dark'] {
   }
 
   .playgroundEditor {
-    height: max-content;
-    overflow: visible;
+    height: unset;
   }
 
   .playgroundRow {
@@ -97,12 +108,13 @@ html[data-theme='dark'] {
 
   .editorColumn {
     padding: 0;
-    flex: 0 !important;
     margin-bottom: 10px;
+    flex: unset;
   }
 
   .previewColumn {
     padding: 10px;
     width: 100%;
+    flex: unset;
   }
 }

website-next/src/components/Playground.tsx

@@ -13,6 +13,7 @@ import React, {
   lazy,
   useCallback,
   useEffect,
+  useLayoutEffect,
   useRef,
   useState,
 } from 'react';
@@ -45,7 +46,11 @@ export type Props = Readonly<{
 export default function Playground({code, height, autoFocus}: Props) {
   const prismTheme = usePrismTheme();
   const playgroundRef = useRef<HTMLDivElement>(null);
+  const editorScrollRef = useRef<HTMLDivElement>(null);
+
   const [isLoaded, setIsLoaded] = useState(false);
+  const [liveCode, setLiveCode] = useState(code ?? defaultCode);
+  const [scrollbarWidth, setScrollbarWidth] = useState(0);
 
   const LivePreviewWrapper = useCallback(
     (props: React.ComponentProps<'div'>) => {
@@ -64,35 +69,52 @@ export default function Playground({code, height, autoFocus}: Props) {
     if (isLoaded && autoFocus) {
       const codeElem = playgroundRef?.current?.querySelector('.prism-code');
       const sel = window.getSelection();
-      if (codeElem != null && sel != null) {
+      if (codeElem?.clientHeight && sel != null) {
         sel.selectAllChildren(codeElem);
         sel.collapseToStart();
       }
     }
   }, [isLoaded, autoFocus]);
 
+  useLayoutEffect(() => {
+    // The toolbar is positioned relative to the outside of the scrolling
+    // container so it stays in the same place when scrolling, but this means
+    // it isn't automatically adjusted for scrollbar width
+    if (editorScrollRef.current) {
+      setScrollbarWidth(
+        editorScrollRef.current.offsetWidth -
+          editorScrollRef.current.clientWidth,
+      );
+    }
+  });
+
   const heightStyle = height
     ? ({'--yg-playground-height': height} as React.CSSProperties)
     : undefined;
 
-  const resolvedCode = code ?? defaultCode;
-
   return (
-    <LiveProvider code={resolvedCode} theme={prismTheme} scope={{Layout, Node}}>
+    <LiveProvider code={liveCode} theme={prismTheme} scope={{Layout, Node}}>
       <div className={styles.wrapper} ref={playgroundRef} style={heightStyle}>
         <div className={clsx(styles.playgroundRow, 'container')}>
-          <div className={clsx(styles.editorColumn)}>
-            <EditorToolbar
-              getCode={useCallback(
-                () =>
-                  nullthrows(
-                    playgroundRef.current?.querySelector('.prism-code')
-                      ?.textContent,
-                  ),
-                [],
-              )}
-            />
-            <LiveEditor className={clsx(styles.playgroundEditor)} />
+          <div className={clsx(styles.editorColumn, 'playground-editor')}>
+            <div className={styles.editorScroll} ref={editorScrollRef}>
+              <EditorToolbar
+                className={styles.editorToolbar}
+                style={{paddingRight: scrollbarWidth + 'px'}}
+                getCode={useCallback(
+                  () =>
+                    nullthrows(
+                      playgroundRef.current?.querySelector('.prism-code')
+                        ?.textContent,
+                    ),
+                  [],
+                )}
+              />
+              <LiveEditor
+                className={clsx(styles.playgroundEditor)}
+                onChange={setLiveCode}
+              />
+            </div>
           </div>
           <div className={clsx(styles.previewColumn)}>
             <LivePreview

website-next/src/pages/index.module.css

@@ -22,11 +22,11 @@
 @media (max-width: 996px) {
   .heroLogo {
     display: none;
-   }
+  }
 
-   .playgroundSection :global(.prism-code) {
+  .playgroundSection :global(.playground-editor) {
     display: none;
-   }
+  }
 }
 
 .bg {