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feat(motion): adopt spring tokens and add shared CSS-transition helper #5112

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feat(motion): adopt spring tokens and add shared CSS-transition helper #5112

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1d75730
feat(motion): adopt spring tokens and add shared CSS-transition helper
rjmreis Sep 4, 2026
b72a8d3
test(motion): cover getTransition and TextInput label float/blur
rjmreis Sep 7, 2026
ece44d4
fix(text-input): correct comment mislabeling active-indicator variant
rjmreis Sep 8, 2026
dc639e3
refactor(badge): type the transition style as CSSStyle<TextStyle>
rjmreis Sep 15, 2026
cea214b
fix: address PR review feedback on spring tier and transition typing
rjmreis Oct 5, 2026
6c5697b
fix(motion): reapply animation.scale, exempt opacity from reduced motion
rjmreis Oct 28, 2026
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17 changes: 9 additions & 8 deletions src/components/Badge.tsx
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Original file line number Diff line number Diff line change
@@ -1,9 +1,13 @@
import type { StyleProp, TextProps, TextStyle } from 'react-native';
import { StyleSheet } from 'react-native';

import Animated, { type AnimatedStyle } from 'react-native-reanimated';
import Animated, {
type AnimatedStyle,
type CSSStyle,
} from 'react-native-reanimated';

import { useInternalTheme } from '../core/theming';
import { getTransition } from '../theme/tokens/sys/motion';
import { cornerFull } from '../theme/tokens/sys/shape';
import type { ThemeProp } from '../theme/types';

Expand Down Expand Up @@ -57,20 +61,17 @@ const Badge = ({
}: Props) => {
const theme = useInternalTheme(themeOverrides);

const {
animation: { scale },
} = theme;

const textColor = theme.colors.onError;

const isLarge = children != null;
const badgeSize = isLarge ? LARGE_SIZE : SMALL_SIZE;
const labelFont = theme.fonts.labelSmall;

const transitionStyle = {
const transitionStyle: CSSStyle<TextStyle> = {
opacity: visible ? 1 : 0,
transitionDuration: 150 * scale,
transitionProperty: 'opacity',
// Opacity is exempt from reduced motion (see `useReduceMotion`'s
// contract), so this always animates — pass `false`, not `reduceMotion`.
...getTransition<TextStyle>(theme, 'opacity', 'short3', 'standard', false),
};

@JKobrynski JKobrynski Sep 15, 2026

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Have you considered typing this style as CSSStyle<ViewStyle> like in Checkbox.tsx?

@rjmreis rjmreis Sep 15, 2026 •
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Good call, done! Badge renders Animated.Text, so I've updated it to CSSStyle<TextStyle>.


return (
Expand Down
42 changes: 20 additions & 22 deletions src/components/Checkbox/Checkbox.tsx
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Original file line number Diff line number Diff line change
Expand Up @@ -9,14 +9,15 @@ import type {
ViewStyle,
} from 'react-native';

import Animated, { cubicBezier, type CSSStyle } from 'react-native-reanimated';
import Animated, { type CSSStyle } from 'react-native-reanimated';

import { CheckboxTokens } from './tokens';
import { getSelectionVisualState } from './utils';
import { useLocale } from '../../core/locale';
import { useInternalTheme } from '../../core/theming';
import { useReduceMotion } from '../../theme/accessibility/ReduceMotionContext';
import { tokens } from '../../theme/tokens';
import { getTransition } from '../../theme/tokens/sys/motion';
import type { ThemeProp } from '../../theme/types';
import { isKeyboardFocusEvent } from '../../utils/isKeyboardFocusEvent';
import TouchableRipple from '../TouchableRipple/TouchableRipple';
Expand Down Expand Up @@ -144,44 +145,41 @@ const Checkbox = ({
customUncheckedColor: uncheckedColor,
});

const fillTransitionTimingFunction = cubicBezier(
...theme.motion.easing.standard
// Opacity is exempt from reduced motion (see `useReduceMotion`'s
// contract), so the fill/outline cross-fade always animates — pass
// `false`, not `reduceMotion`.
const fillTransition = getTransition<ViewStyle>(
theme,
['opacity'],
'short2',
'standard',
false
);

const fillTransitionDuration = reduceMotion
? 0
: theme.motion.duration.short2;

const checkTransitionDuration = reduceMotion
? 0
: theme.motion.duration.short3;

const checkTransitionTimingFunction = cubicBezier(
...theme.motion.easing.standard
const checkTransition = getTransition<ViewStyle>(
theme,
['width', 'opacity'],
'short3',
'standard',
reduceMotion
);

const outlineStyle: CSSStyle<ViewStyle> = {
borderColor: visual.outlineColor,
opacity: selected ? 0 : 1,
transitionDuration: fillTransitionDuration,
transitionProperty: ['opacity'],
transitionTimingFunction: fillTransitionTimingFunction,
...fillTransition,
};

const fillStyle: CSSStyle<ViewStyle> = {
backgroundColor: visual.containerColor,
opacity: selected ? 1 : 0,
transitionDuration: fillTransitionDuration,
transitionProperty: ['opacity'],
transitionTimingFunction: fillTransitionTimingFunction,
...fillTransition,
};

const maskStyle: CSSStyle<ViewStyle> = {
width: selected ? CONTAINER_SIZE : 0,
opacity: selected ? 1 : 0,
transitionDuration: checkTransitionDuration,
transitionProperty: ['width', 'opacity'],
transitionTimingFunction: checkTransitionTimingFunction,
...checkTransition,
};

// Remember the last drawn glyph so the reveal-mask can finish collapsing
Expand Down
22 changes: 11 additions & 11 deletions src/components/SegmentedButtons/SegmentedButtonItem.tsx
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Expand Up @@ -22,19 +22,14 @@ import {
} from './utils';
import { useInternalTheme } from '../../core/theming';
import { useReduceMotion } from '../../theme/accessibility/ReduceMotionContext';
import { toRawSpring } from '../../theme/tokens/sys/motion';
import type { ThemeProp } from '../../theme/types';
import type { IconSource } from '../Icon';
import Icon from '../Icon';
import TouchableRipple from '../TouchableRipple/TouchableRipple';
import type { Props as TouchableRippleProps } from '../TouchableRipple/TouchableRipple';
import Text from '../Typography/Text';

const CHECK_SPRING_CONFIG = {
stiffness: 230.2,
damping: 22,
mass: 1,
};

export type Props = {
/**
* Whether the segmented button is checked
Expand Down Expand Up @@ -139,16 +134,21 @@ const SegmentedButtonItem = ({

const checkScale = useSharedValue(0);

const checkSpringConfig = React.useMemo(
() => ({
...toRawSpring(theme.motion.spring.fast.spatial),
reduceMotion: reduceMotion ? ReduceMotion.Always : ReduceMotion.Never,
}),
[theme.motion.spring.fast.spatial, reduceMotion]
);

React.useEffect(() => {
if (!showSelectedCheck) {
return;
}

checkScale.value = withSpring(checked ? 1 : 0, {
...CHECK_SPRING_CONFIG,
reduceMotion: reduceMotion ? ReduceMotion.Always : ReduceMotion.Never,
});
}, [checked, checkScale, reduceMotion, showSelectedCheck]);
checkScale.value = withSpring(checked ? 1 : 0, checkSpringConfig);

@satya164 satya164 Oct 22, 2026

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The check animation runs on a shared value with withSpring, but it is driven by the checked prop and not by a gesture or scroll. The project rule is to use Reanimated CSS transitions (transitionProperty and transitionDuration, as in Badge.tsx and Checkbox.tsx) for state changes, and to keep shared values for gesture or scroll driven motion. Please move the check scale and the icon scale to CSS transitions on transform. Reanimated 4.3 exports linear(...), so you can keep the fast.spatial spring shape by sampling it into linear() points for transitionTimingFunction. With that change, the useMemo and the effect go away. (via Claude, verify if it makes sense)

@rjmreis rjmreis Oct 28, 2026

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I'd rather keep this one as withSpring. The checkmark gets toggled by quick taps, so it's common for the animation to get interrupted mid flight and reverse. withSpring picks up from the current position and velocity when that happens, so the reversal looks physically continuous. A linear() curve sampled from the spring only matches one specific start to end run, if it gets interrupted and restarted the sampled points no longer match the remaining distance, so the motion would snap or look off on rapid re-taps.

That's basically why the original task treats MD3 spring motion as an exception to "CSS by default", it's for motion that's genuinely spring shaped and needs to handle interruption correctly, which this is, even though the trigger is a prop rather than a gesture. Happy to revisit if you feel strongly, but wanted to explain the reasoning first.

}, [checked, checkScale, checkSpringConfig, showSelectedCheck]);

const checkAnimatedStyle = useAnimatedStyle(() => ({
transform: [{ scale: checkScale.value }],
Expand Down
6 changes: 0 additions & 6 deletions src/components/TextInput/TextInput.tsx
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Original file line number Diff line number Diff line change
Expand Up @@ -32,12 +32,6 @@ export type TextInputAnimationState = {
animatedActiveOutlineStyle?: StyleProp<AnimatedStyle<StyleProp<ViewStyle>>>;
};

export type TextInputAnimationHandlers = {
runFocusAnimation: (hasText: boolean) => void;
runBlurAnimation: (hasText: boolean) => void;
syncFloatToValue: (hasText: boolean) => void;
};

export type TextInputFlags = {
isRTL: boolean;
isDisabled: boolean;
Expand Down
10 changes: 0 additions & 10 deletions src/components/TextInput/constants.ts
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Original file line number Diff line number Diff line change
@@ -1,9 +1,6 @@
import { PixelRatio } from 'react-native';

import { Easing } from 'react-native-reanimated';

import { tokens } from '../../theme/tokens';
import { motionDuration, motionEasing } from '../../theme/tokens/sys/motion';
import { defaultShapes } from '../../theme/tokens/sys/shape';

export const fontScale = PixelRatio.getFontScale();
Expand Down Expand Up @@ -46,16 +43,9 @@ export const SUPPORTING_TEXT_FONT_SIZE =

export const SUPPORTING_TEXT_MARGIN_TOP = 4;

export const ANIMATION_DURATION_MS = motionDuration.short3;

export const ACTIVE_INDICATOR_SIZE = 2;
export const INACTIVE_INDICATOR_SIZE = 1;

export const TIMING_CONFIG = {
duration: ANIMATION_DURATION_MS,
easing: Easing.bezier(...motionEasing.standard),
} as const;

/**
* Constants for the filled variant.
*/
Expand Down
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