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Merged
necolas merged 1 commit into from
Jun 26, 2025
Merged

Polyfill experimental 'spring()' timing function for native #323

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2 changes: 1 addition & 1 deletion apps/examples/src/components/App.js
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Original file line number Diff line number Diff line change
Expand Up @@ -739,7 +739,7 @@ const styles = css.create({
backgroundColor: 'red',
transitionDuration: '500ms',
transitionProperty: 'transform',
transitionTimingFunction: 'ease'
transitionTimingFunction: 'spring(1,100,10,0)'
},
objContain: {
objectFit: 'contain'
Expand Down
81 changes: 75 additions & 6 deletions packages/react-strict-dom/src/native/modules/useStyleTransition.js
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Expand Up @@ -8,13 +8,14 @@
*/

import type {
CompositeAnimation,
ReactNativeStyle,
ReactNativeStyleValue,
ReactNativeTransform
} from '../../types/renderer.native';

import { useEffect, useRef, useState } from 'react';
import { warnMsg } from '../../shared/logUtils';
import { errorMsg, warnMsg } from '../../shared/logUtils';
import { Animated, Easing } from 'react-native';

type AnimatedStyle = {
Expand Down Expand Up @@ -191,6 +192,74 @@ function transitionStyleHasChanged(
return false;
}

function getAnimation(
animatedValue: Animated.Value,
duration: number,
timingFunction: string | null,
shouldUseNativeDriver: boolean
): CompositeAnimation {
// Based on https://lists.w3.org/Archives/Public/www-style/2016Jun/0181.html
// spring(mass, stiffness, damping, initialVelocity)
if (timingFunction != null && timingFunction.trim().startsWith('spring(')) {
const chunk = timingFunction.split('spring(')[1];

const closingParenIndex = chunk.indexOf(')');
if (closingParenIndex === -1) {
errorMsg(
`spring() timing function of "${timingFunction}" is missing closing parenthesis.`
);
return Animated.timing(animatedValue, {
duration,
easing: getEasingFunction(null),
toValue: 1,
useNativeDriver: shouldUseNativeDriver
});
}

const str = chunk.split(')')[0];
let [mass = 1, stiffness = 100, damping = 10, initialVelocity = 0] =
str === '' ? [] : str.split(',').map((point) => parseFloat(point.trim()));

if (mass <= 0) {
errorMsg(
`spring() timing function "mass" must be greater than 0. Received ${mass}. Defaulting to 1.`
);
mass = 1;
}
if (stiffness <= 0) {
errorMsg(
`spring() timing function "stiffness" must be greater than 0. Received ${stiffness}. Defaulting to 100.`
);
stiffness = 100;
}
if (damping < 0) {
errorMsg(
`spring() timing function "damping" must be greater than or equal to 0. Received ${damping}. Defaulting to 10.`
);
damping = 10;
}
if (initialVelocity == null) {
initialVelocity = 0;
}

return Animated.spring(animatedValue, {
damping,
mass,
stiffness,
toValue: 1,
useNativeDriver: shouldUseNativeDriver,
velocity: initialVelocity
});
}

return Animated.timing(animatedValue, {
duration,
easing: getEasingFunction(timingFunction),
toValue: 1,
useNativeDriver: shouldUseNativeDriver
});
}

export function useStyleTransition(style: ReactNativeStyle): ReactNativeStyle {
const {
transitionDelay: _delay,
Expand Down Expand Up @@ -260,12 +329,12 @@ export function useStyleTransition(style: ReactNativeStyle): ReactNativeStyle {

const animation = Animated.sequence([
Animated.delay(delay),
Animated.timing(animatedValue, {
toValue: 1,
getAnimation(
animatedValue,
duration,
easing: getEasingFunction(timingFunction),
useNativeDriver: shouldUseNativeDriver
})
timingFunction,
shouldUseNativeDriver
)
]);
animation.start();

Expand Down
5 changes: 5 additions & 0 deletions packages/react-strict-dom/src/types/renderer.native.js
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Expand Up @@ -9,6 +9,10 @@

// $FlowFixMe(nonstrict-import)
import type AnimatedNode from 'react-native/Libraries/Animated/nodes/AnimatedNode';
import type {
// $FlowFixMe(nonstrict-import)
CompositeAnimation
} from 'react-native/Libraries/Animated/Animated';
import type {
// $FlowFixMe(nonstrict-import)
Props as TextInputProps
Expand Down Expand Up @@ -141,6 +145,7 @@ type ReactNativeStyleValue =
type ReactNativeStyle = { [string]: ?ReactNativeStyleValue };

export type {
CompositeAnimation,
ReactNativeProps,
ReactNativeStyle,
ReactNativeStyleValue,
Expand Down
5 changes: 5 additions & 0 deletions packages/react-strict-dom/tests/__mocks__/react-native/index.js
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Expand Up @@ -30,6 +30,11 @@ export const Animated = {
}),
stop: jest.fn()
};
}),
spring: jest.fn(() => {
return {
start: jest.fn()
};
})
};

Expand Down
39 changes: 37 additions & 2 deletions packages/react-strict-dom/tests/__snapshots__/html-test.native.js.snap-native
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Expand Up @@ -1043,7 +1043,7 @@ exports[`<html.*> style polyfills "transition" properties backgroundColor trans
/>
`;

exports[`<html.*> style polyfills "transition" properties cubic-bezier easing: end 1`] = `
exports[`<html.*> style polyfills "transition" properties cubic-bezier() timing function: end 1`] = `
<Animated.View
animated={true}
style={
Expand All @@ -1065,7 +1065,7 @@ exports[`<html.*> style polyfills "transition" properties cubic-bezier easing:
/>
`;

exports[`<html.*> style polyfills "transition" properties cubic-bezier easing: start 1`] = `
exports[`<html.*> style polyfills "transition" properties cubic-bezier() timing function: start 1`] = `
<Animated.View
animated={true}
style={
Expand Down Expand Up @@ -1328,6 +1328,41 @@ exports[`<html.*> style polyfills "transition" properties other transforms: tra
/>
`;

exports[`<html.*> style polyfills "transition" properties spring() timing function: end 1`] = `
<Animated.View
animated={true}
style={
{
"boxSizing": "content-box",
"opacity": {
"inputRange": [
0,
1,
],
"outputRange": [
1,
0,
],
},
"position": "static",
}
}
/>
`;

exports[`<html.*> style polyfills "transition" properties spring() timing function: start 1`] = `
<Animated.View
animated={true}
style={
{
"boxSizing": "content-box",
"opacity": 1,
"position": "static",
}
}
/>
`;

exports[`<html.*> style polyfills "transition" properties transform transition: end 1`] = `
<Animated.View
animated={true}
Expand Down
68 changes: 66 additions & 2 deletions packages/react-strict-dom/tests/html-test.native.js
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Expand Up @@ -701,10 +701,9 @@ describe('<html.*>', () => {
expect(Easing.out).toHaveBeenCalled();
});

test('cubic-bezier easing', () => {
test('cubic-bezier() timing function', () => {
const BEZIER_STR = 'cubic-bezier( 0.1, 0.2,0.3 ,0.4)';
let root;
// cubic-bezier easing
act(() => {
root = create(<html.div style={styles.opacity(1, BEZIER_STR)} />);
});
Expand All @@ -717,6 +716,71 @@ describe('<html.*>', () => {
expect(Easing.bezier).toHaveBeenCalledWith(0.1, 0.2, 0.3, 0.4);
});

test('spring() timing function', () => {
// spring(mass, stiffness, damping, initialVelocity)
const SPRING_STR = 'spring( 1, 2,3 , 4 )';
let root;
act(() => {
root = create(<html.div style={styles.opacity(1, SPRING_STR)} />);
});
expect(root.toJSON()).toMatchSnapshot('start');
expect(Animated.spring).not.toHaveBeenCalled();
expect(Animated.timing).not.toHaveBeenCalled();
act(() => {
root.update(<html.div style={styles.opacity(0, SPRING_STR)} />);
});
expect(root.toJSON()).toMatchSnapshot('end');
// Animated.spring(damping, mass, stiffness, toValue, useNativeDriver, velocity)
expect(Animated.spring).toHaveBeenCalledWith(
expect.anything(),
expect.objectContaining({
damping: 3,
mass: 1,
stiffness: 2,
toValue: 1,
useNativeDriver: true,
velocity: 4
})
);
expect(Animated.timing).not.toHaveBeenCalled();

// Test that we replace invalid spring params and print error msg
const SPRING_BAD_STR = 'spring(0,0,-1,0)';
let badRoot;
act(() => {
badRoot = create(
<html.div style={styles.opacity(1, SPRING_BAD_STR)} />
);
});
act(() => {
badRoot.update(
<html.div style={styles.opacity(0, SPRING_BAD_STR)} />
);
});
expect(console.error).toHaveBeenCalledWith(
expect.stringContaining('"mass" must be greater than 0')
);
expect(console.error).toHaveBeenCalledWith(
expect.stringContaining('"stiffness" must be greater than 0')
);
expect(console.error).toHaveBeenCalledWith(
expect.stringContaining(
'"damping" must be greater than or equal to 0'
)
);
expect(Animated.spring).toHaveBeenCalledWith(
expect.anything(),
expect.objectContaining({
damping: 10,
mass: 1,
stiffness: 100,
toValue: 1,
useNativeDriver: true,
velocity: 0
})
);
});

test('transition all properties (opacity and transform)', () => {
let root;
// transition all properties (opacity and transform)
Expand Down