[ScrollArea] Read DirectionProvider and use logical positioning CSS props

packages/react/src/scroll-area/corner/ScrollAreaCorner.tsx

@@ -21,7 +21,7 @@ const ScrollAreaCorner = React.forwardRef(function ScrollAreaCorner(
 ) {
   const { render, className, ...otherProps } = props;
 
-  const { dir, cornerRef, cornerSize, hiddenState } = useScrollAreaRootContext();
+  const { cornerRef, cornerSize, hiddenState } = useScrollAreaRootContext();
 
   const mergedRef = useForkRef(cornerRef, forwardedRef);
 
@@ -34,7 +34,7 @@ const ScrollAreaCorner = React.forwardRef(function ScrollAreaCorner(
       style: {
         position: 'absolute',
         bottom: 0,
-        [dir === 'rtl' ? 'left' : 'right']: 0,
+        insetInlineEnd: 0,
         width: cornerSize.width,
         height: cornerSize.height,
       },

packages/react/src/scroll-area/root/ScrollAreaRoot.tsx

@@ -18,9 +18,9 @@ const ScrollAreaRoot = React.forwardRef(function ScrollAreaRoot(
   props: ScrollAreaRoot.Props,
   forwardedRef: React.ForwardedRef<HTMLDivElement>,
 ) {
-  const { render, className, dir, ...otherProps } = props;
+  const { render, className, ...otherProps } = props;
 
-  const scrollAreaRoot = useScrollAreaRoot({ dir });
+  const scrollAreaRoot = useScrollAreaRoot();
 
   const { rootId } = scrollAreaRoot;
 
@@ -33,13 +33,7 @@ const ScrollAreaRoot = React.forwardRef(function ScrollAreaRoot(
     extraProps: otherProps,
   });
 
-  const contextValue = React.useMemo(
-    () => ({
-      dir,
-      ...scrollAreaRoot,
-    }),
-    [dir, scrollAreaRoot],
-  );
+  const contextValue = React.useMemo(() => scrollAreaRoot, [scrollAreaRoot]);
 
   const viewportId = `[data-id="${rootId}-viewport"]`;
 
@@ -83,10 +77,6 @@ ScrollAreaRoot.propTypes /* remove-proptypes */ = {
    * returns a class based on the component’s state.
    */
   className: PropTypes.oneOfType([PropTypes.func, PropTypes.string]),
-  /**
-   * @ignore
-   */
-  dir: PropTypes.string,
   /**
    * Allows you to replace the component’s HTML element
    * with a different tag, or compose it with another component.

packages/react/src/scroll-area/root/ScrollAreaRootContext.ts

@@ -1,7 +1,6 @@
 import * as React from 'react';
 
 export interface ScrollAreaRootContext {
-  dir: string | undefined;
   cornerSize: { width: number; height: number };
   setCornerSize: React.Dispatch<React.SetStateAction<{ width: number; height: number }>>;
   thumbSize: { width: number; height: number };

packages/react/src/scroll-area/root/useScrollAreaRoot.ts

@@ -1,6 +1,5 @@
 import * as React from 'react';
 import { useEventCallback } from '../../utils/useEventCallback';
-import { useEnhancedEffect } from '../../utils/useEnhancedEffect';
 import { mergeReactProps } from '../../utils/mergeReactProps';
 import { useBaseUiId } from '../../utils/useBaseUiId';
 import { SCROLL_TIMEOUT } from '../constants';
@@ -12,9 +11,7 @@ interface Size {
   height: number;
 }
 
-export function useScrollAreaRoot(params: useScrollAreaRoot.Parameters) {
-  const { dir: dirParam } = params;
-
+export function useScrollAreaRoot() {
   const [hovering, setHovering] = React.useState(false);
   const [scrollingX, setScrollingX] = React.useState(false);
   const [scrollingY, setScrollingY] = React.useState(false);
@@ -47,15 +44,6 @@ export function useScrollAreaRoot(params: useScrollAreaRoot.Parameters) {
     cornerHidden: false,
   });
 
-  const [autoDir, setAutoDir] = React.useState(dirParam);
-  const dir = dirParam ?? autoDir;
-
-  useEnhancedEffect(() => {
-    if (dirParam === undefined && viewportRef.current) {
-      setAutoDir(getComputedStyle(viewportRef.current).direction);
-    }
-  }, [dirParam]);
-
   React.useEffect(() => {
     return () => {
       window.clearTimeout(scrollYTimeoutRef.current);
@@ -193,7 +181,6 @@ export function useScrollAreaRoot(params: useScrollAreaRoot.Parameters) {
   const getRootProps = React.useCallback(
     (externalProps = {}) =>
       mergeReactProps<'div'>(externalProps, {
-        dir,
         onPointerEnter: handlePointerEnterOrMove,
         onPointerMove: handlePointerEnterOrMove,
         onPointerDown({ pointerType }) {
@@ -208,7 +195,7 @@ export function useScrollAreaRoot(params: useScrollAreaRoot.Parameters) {
           [ScrollAreaRootCssVars.scrollAreaCornerWidth as string]: `${cornerSize.width}px`,
         },
       }),
-    [cornerSize, dir, handlePointerEnterOrMove],
+    [cornerSize, handlePointerEnterOrMove],
   );
 
   return React.useMemo(
@@ -266,8 +253,4 @@ export function useScrollAreaRoot(params: useScrollAreaRoot.Parameters) {
   );
 }
 
-export namespace useScrollAreaRoot {
-  export interface Parameters {
-    dir: string | undefined;
-  }
-}
+export namespace useScrollAreaRoot {}

packages/react/src/scroll-area/scrollbar/useScrollAreaScrollbar.ts

@@ -1,15 +1,15 @@
 import * as React from 'react';
-import { useScrollAreaRootContext } from '../root/ScrollAreaRootContext';
+import { useDirection } from '../../direction-provider/DirectionContext';
 import { mergeReactProps } from '../../utils/mergeReactProps';
 import { getOffset } from '../utils/getOffset';
+import { useScrollAreaRootContext } from '../root/ScrollAreaRootContext';
 import { ScrollAreaRootCssVars } from '../root/ScrollAreaRootCssVars';
 import { ScrollAreaScrollbarCssVars } from './ScrollAreaScrollbarCssVars';
 
 export function useScrollAreaScrollbar(params: useScrollAreaScrollbar.Parameters) {
   const { orientation } = params;
 
   const {
-    dir,
     scrollbarYRef,
     scrollbarXRef,
     viewportRef,
@@ -21,6 +21,8 @@ export function useScrollAreaScrollbar(params: useScrollAreaScrollbar.Parameters
     thumbSize,
   } = useScrollAreaRootContext();
 
+  const direction = useDirection();
+
   React.useEffect(() => {
     const viewportEl = viewportRef.current;
     const scrollbarEl = orientation === 'vertical' ? scrollbarYRef.current : scrollbarXRef.current;
@@ -130,7 +132,7 @@ export function useScrollAreaScrollbar(params: useScrollAreaScrollbar.Parameters
             const scrollRatioX = clickX / maxThumbOffsetX;
 
             let newScrollLeft: number;
-            if (dir === 'rtl') {
+            if (direction === 'rtl') {
               // In RTL, invert the scroll direction
               newScrollLeft = (1 - scrollRatioX) * (scrollableContentWidth - viewportWidth);
 
@@ -154,13 +156,12 @@ export function useScrollAreaScrollbar(params: useScrollAreaScrollbar.Parameters
           ...(orientation === 'vertical' && {
             top: 0,
             bottom: `var(${ScrollAreaRootCssVars.scrollAreaCornerHeight})`,
-            [dir === 'rtl' ? 'left' : 'right']: 0,
+            insetInlineEnd: 0,
             [ScrollAreaScrollbarCssVars.scrollAreaThumbHeight as string]: `${thumbSize.height}px`,
           }),
           ...(orientation === 'horizontal' && {
-            [dir === 'rtl' ? 'right' : 'left']: 0,
-            [dir === 'rtl' ? 'left' : 'right']:
-              `var(${ScrollAreaRootCssVars.scrollAreaCornerWidth})`,
+            insetInlineStart: 0,
+            insetInlineEnd: `var(${ScrollAreaRootCssVars.scrollAreaCornerWidth})`,
             bottom: 0,
             [ScrollAreaScrollbarCssVars.scrollAreaThumbWidth as string]: `${thumbSize.width}px`,
           }),
@@ -170,7 +171,7 @@ export function useScrollAreaScrollbar(params: useScrollAreaScrollbar.Parameters
       rootId,
       handlePointerUp,
       orientation,
-      dir,
+      direction,
       thumbSize.height,
       thumbSize.width,
       viewportRef,

packages/react/src/scroll-area/viewport/useScrollAreaViewport.tsx

@@ -1,9 +1,10 @@
 import * as React from 'react';
-import { useScrollAreaRootContext } from '../root/ScrollAreaRootContext';
+import { useDirection } from '../../direction-provider/DirectionContext';
 import { useEventCallback } from '../../utils/useEventCallback';
 import { useEnhancedEffect } from '../../utils/useEnhancedEffect';
 import { mergeReactProps } from '../../utils/mergeReactProps';
 import { clamp } from '../../utils/clamp';
+import { useScrollAreaRootContext } from '../root/ScrollAreaRootContext';
 import { MIN_THUMB_SIZE } from '../constants';
 import { getOffset } from '../utils/getOffset';
 
@@ -17,7 +18,6 @@ export function useScrollAreaViewport(params: useScrollAreaViewport.Parameters)
     thumbYRef,
     thumbXRef,
     cornerRef,
-    dir,
     setCornerSize,
     setThumbSize,
     rootId,
@@ -27,6 +27,8 @@ export function useScrollAreaViewport(params: useScrollAreaViewport.Parameters)
     setHovering,
   } = useScrollAreaRootContext();
 
+  const direction = useDirection();
+
   const contentWrapperRef = React.useRef<HTMLDivElement | null>(null);
 
   const computeThumb = useEventCallback(() => {
@@ -102,7 +104,7 @@ export function useScrollAreaViewport(params: useScrollAreaViewport.Parameters)
       // In Safari, don't allow it to go negative or too far as `scrollLeft` considers the rubber
       // band effect.
       const thumbOffsetX =
-        dir === 'rtl'
+        direction === 'rtl'
           ? clamp(scrollRatioX * maxThumbOffsetX, -maxThumbOffsetX, 0)
           : clamp(scrollRatioX * maxThumbOffsetX, 0, maxThumbOffsetX);
 
@@ -146,7 +148,7 @@ export function useScrollAreaViewport(params: useScrollAreaViewport.Parameters)
 
   useEnhancedEffect(() => {
     computeThumb();
-  }, [computeThumb, hiddenState, dir]);
+  }, [computeThumb, hiddenState, direction]);
 
   useEnhancedEffect(() => {
     // `onMouseEnter` doesn't fire upon load, so we need to check if the viewport is already