A custom extensible switch built in reanimated v2

react-native-reanimated-2-custom-switch.tsx

import React, {useEffect} from "react";
import {StyleProp, StyleSheet, TouchableOpacity, TouchableOpacityProps, ViewProps, ViewStyle} from "react-native";
import Animated, {
  interpolate,
  useAnimatedStyle,
  useSharedValue,
  withTiming,
  Easing,
  Extrapolate,
  interpolateColor, AnimateProps,
} from "react-native-reanimated";

const AnimatedTouchableOpacity = Animated.createAnimatedComponent<TouchableOpacityProps>(TouchableOpacity);

interface ICustomSwitchToggle extends Pick<
  ICustomSwitch,
  "toggleColorOff" |
  "toggleColorOn" |
  "trackColorOff" |
  "trackColorOn"
  > {
  style?: AnimateProps<ViewProps>["style"];
  animatedValue?: Animated.SharedValue<number>;
  width?: number;
  height?: number;
}
const CustomSwitchToggle = ({style}: ICustomSwitchToggle) => <Animated.View style={style} />;

// From here: https://nextcodingjs.com/create-custom-toggle-switch-button/, but added:
//
//    1. Made it a controlled component, so you can turn it off/on from some other place.
//    2. Used "onValueChange" which is more in line with react switch
//    3. Allow ability to render whatever you want on the inside of the switch, and tap into the animatedValue so you can do opacity animations.
//    4. Allow for non-circular toggle.
//    5. Fixed a few positioning bugs, so it automatically adapts to varying border widths
//    6. Allow for animating the track color
//    7. Added typescript types
//
// Hopefully this is useful, and if you like to build high quality stuff, we're hiring! aryk@tribefy.com.
interface ICustomSwitch {
  value: boolean;
  onValueChange: (value: boolean) => any;
  containerStyle?: StyleProp<ViewStyle>;
  toggleColorOff?: string;
  toggleColorOn?:  string;
  trackColorOff?:  string;
  trackColorOn?:   string;
  height?:         number;
  width?:          number;
  padding?:        number;
  borderWidth?:    number;
  borderColor?:    string;
  duration?:       number;
  toggleHeight?:   number;
  toggleWidth?:    number;
  ToggleComponent?: React.ElementType<ICustomSwitchToggle>;
}

const CustomSwitch = ({
  onValueChange,
  value = false,
  containerStyle,
  toggleColorOff  = "#c3c3c3",
  toggleColorOn   = "#008ECC",
  trackColorOff   = "#333333",
  trackColorOn    = "#CCCCCC",
  height          = 40,
  width           = height * 1.875,
  padding         = height * 0.09,
  borderWidth     = 1,
  borderColor     = toggleColorOff,
  duration        = 400,
  toggleHeight    = height - (padding + borderWidth) * 2,
  toggleWidth     = toggleHeight,
  ToggleComponent = CustomSwitchToggle,
}: ICustomSwitch) => {
  const calculateAnimatedValue = (v: boolean) => v ? 1 : 0;

  const animatedValue  = useSharedValue(calculateAnimatedValue(value));

  const setAnimatedValue = (newValue: boolean) => {
    animatedValue.value = withTiming(
      calculateAnimatedValue(newValue),
      {
        duration,
        easing: Easing.bezier(0.4, 0.0, 0.2, 1),
      },
    );
  }

  useEffect(
    () => {
      setAnimatedValue(value);
    },
    [value],
  );

  const onPress = () => {
    const newValue = animatedValue.value === 0;
    setAnimatedValue(newValue);
    onValueChange(newValue);
  };

  const switchAnimatedStyle = useAnimatedStyle(
    () => ({
      transform: [
        {
          translateX: interpolate(
            animatedValue.value,
            [0, 1],
            [padding, width - toggleWidth - padding - 2 * borderWidth],
            Extrapolate.CLAMP,
          ),
        },
      ],
      backgroundColor: interpolateColor(
        animatedValue.value,
        [0, 1],
        [toggleColorOff, toggleColorOn],
      ),
    }),
    [
      padding,
      width,
      toggleWidth,
      padding,
      borderWidth,
      toggleColorOff,
      toggleColorOn,
    ]
  );

  const containerAnimatedStyle = useAnimatedStyle(
    () => ({
      backgroundColor: interpolateColor(
        animatedValue.value,
        [0, 1],
        [trackColorOff, trackColorOn],
      ),
    }),
    [
      trackColorOff,
      trackColorOn,
    ]
  );

  return <AnimatedTouchableOpacity
    onPress={onPress}
    activeOpacity={1}
    style={[
      styles.containerStyle,
      {height, width, borderWidth, borderColor},
      containerAnimatedStyle,
      containerStyle
    ]}
  >
    <ToggleComponent
      {...{
        toggleColorOff,
        toggleColorOn,
        trackColorOff,
        trackColorOn,
        animatedValue,
      }}
      width={toggleWidth}
      height={toggleHeight}
      style={[
        styles.switchButton,
        {left: 0, height: toggleHeight, width: toggleWidth},
        switchAnimatedStyle,
      ]}
    />
  </AnimatedTouchableOpacity>;
};

const styles = StyleSheet.create({
  containerStyle: {
    justifyContent: 'center',
    alignItems: 'center',
    backgroundColor: 'white',
    borderRadius: 500,
  },
  switchButton: {
    backgroundColor: 'red',
    position: 'absolute',
    borderRadius: 100,
  },
});

export {
  ICustomSwitchToggle,
  CustomSwitchToggle,
  ICustomSwitch,
  CustomSwitch,
};