fix: rtl switch issue https://github.com/ant-design/ant-design/issues/40128

assets/index.less

@@ -79,8 +79,8 @@
     .segmented-item-selected();
 
     position: absolute;
-    top: 0;
-    left: 0;
+    // top: 0;
+    // left: 0;
     width: 0;
     height: 100%;
     padding: 4px 0;
@@ -93,4 +93,8 @@
       width 0.3s cubic-bezier(0.645, 0.045, 0.355, 1);
     will-change: transform, width;
   }
+
+  &-rtl {
+    direction: rtl;
+  }
 }

docs/demo/rtl.tsx

@@ -0,0 +1,42 @@
+import '../../assets/style.less';
+import React, { useState } from 'react';
+import Segmented from 'rc-segmented';
+
+export default function App() {
+  const [direction, setDirection] = useState<'rtl' | 'ltr'>('rtl');
+  return (
+    <div className="wrapper">
+      <button
+        onClick={() => {
+          setDirection('rtl');
+        }}
+        style={{
+          padding: '0 8px',
+          marginRight: 8,
+        }}
+      >
+        rtl
+      </button>
+      <button
+        onClick={() => {
+          setDirection('ltr');
+        }}
+        style={{
+          padding: '0 8px',
+        }}
+      >
+        ltr
+      </button>
+      <p
+        style={{
+          marginBottom: 8,
+        }}
+      />
+      <Segmented
+        options={['iOS', 'Android', 'Web']}
+        onChange={(value) => console.log(value, typeof value)}
+        direction={direction}
+      />
+    </div>
+  );
+}

docs/example.md

@@ -28,3 +28,7 @@ nav:
 ## refs
 
 <code src="./demo/refs.tsx"></code>
+
+## rtl
+
+<code src="./demo/rtl.tsx"></code>

src/MotionThumb.tsx

@@ -1,12 +1,13 @@
-import * as React from 'react';
-import CSSMotion from 'rc-motion';
 import classNames from 'classnames';
+import CSSMotion from 'rc-motion';
 import useLayoutEffect from 'rc-util/lib/hooks/useLayoutEffect';
 import { composeRef } from 'rc-util/lib/ref';
+import * as React from 'react';
 import type { SegmentedValue } from '.';
 
 type ThumbReact = {
   left: number;
+  right: number;
   width: number;
 } | null;
 
@@ -18,6 +19,7 @@ export interface MotionThumbInterface {
   motionName: string;
   onMotionStart: VoidFunction;
   onMotionEnd: VoidFunction;
+  direction?: 'ltr' | 'rtl';
 }
 
 const calcThumbStyle = (
@@ -26,6 +28,10 @@ const calcThumbStyle = (
   targetElement
     ? {
         left: targetElement.offsetLeft,
+        right:
+          (targetElement.parentElement!.clientWidth as number) -
+          targetElement.clientWidth -
+          targetElement.offsetLeft,
         width: targetElement.clientWidth,
       }
     : null;
@@ -42,6 +48,7 @@ export default function MotionThumb(props: MotionThumbInterface) {
     motionName,
     onMotionStart,
     onMotionEnd,
+    direction,
   } = props;
 
   const thumbRef = React.useRef<HTMLDivElement>(null);
@@ -81,6 +88,21 @@ export default function MotionThumb(props: MotionThumbInterface) {
     }
   }, [value]);
 
+  const thumbStart = React.useMemo(
+    () =>
+      direction === 'rtl'
+        ? toPX(-(prevStyle?.right as number))
+        : toPX(prevStyle?.left as number),
+    [direction, prevStyle],
+  );
+  const thumbActive = React.useMemo(
+    () =>
+      direction === 'rtl'
+        ? toPX(-(nextStyle?.right as number))
+        : toPX(nextStyle?.left as number),
+    [direction, nextStyle],
+  );
+
   // =========================== Motion ===========================
   const onAppearStart = () => {
     return {
@@ -118,9 +140,9 @@ export default function MotionThumb(props: MotionThumbInterface) {
       {({ className: motionClassName, style: motionStyle }, ref) => {
         const mergedStyle = {
           ...motionStyle,
-          '--thumb-start-left': toPX(prevStyle?.left),
+          '--thumb-start-left': thumbStart,
           '--thumb-start-width': toPX(prevStyle?.width),
-          '--thumb-active-left': toPX(nextStyle?.left),
+          '--thumb-active-left': thumbActive,
           '--thumb-active-width': toPX(nextStyle?.width),
         } as React.CSSProperties;
 

src/index.tsx

@@ -184,6 +184,7 @@ const Segmented = React.forwardRef<HTMLDivElement, SegmentedProps>(
             value={rawValue}
             containerRef={containerRef}
             motionName={`${prefixCls}-${motionName}`}
+            direction={direction}
             getValueIndex={(val) =>
               segmentedOptions.findIndex((n) => n.value === val)
             }

tests/index.test.tsx

@@ -27,7 +27,7 @@ describe('rc-segmented', () => {
     const styleText = container
       .querySelector('.rc-segmented-thumb')
       ?.getAttribute('data-test-style');
-    const style = JSON.parse(styleText!) || {};
+    const style = styleText ? JSON.parse(styleText!) : {};
 
     expect(style).toMatchObject(matchStyle);
   }
@@ -523,4 +523,36 @@ describe('rc-segmented', () => {
 
     expectMatchChecked(container, [true, false, false]);
   });
+
+  it('click can work as expected with rtl', () => {
+    const offsetParentSpy = jest
+      .spyOn(HTMLElement.prototype, 'offsetParent', 'get')
+      .mockImplementation(() => {
+        return container;
+      });
+    const handleValueChange = jest.fn();
+    const { container } = render(
+      <Segmented
+        direction="rtl"
+        options={['iOS', 'Android', 'Web']}
+        onChange={(value) => handleValueChange(value)}
+      />,
+    );
+
+    fireEvent.click(container.querySelectorAll('.rc-segmented-item-input')[1]);
+    expectMatchChecked(container, [false, true, false]);
+    expect(handleValueChange).toBeCalledWith('Android');
+
+    // Motion to active
+    act(() => {
+      jest.runAllTimers();
+    });
+
+    exceptThumbHaveStyle(container, {
+      '--thumb-active-left': '-22px',
+      '--thumb-active-width': '118px',
+    });
+
+    offsetParentSpy.mockRestore();
+  });
 });