React-native-reanimated: Should useDerivedValue cause a rerender?

[doylemark]

Description

If I format a date on the ui thread like so..

const date = useDerivedValue(() => {
    const d = interpolate(translation.x.value, [0, width], [MIN, MAX]);
    return formatDateOnUI(d);
});

return <Text>{date}</Text>

In this example date will update (can check by logging d before return), however it will not update the UI.. I can hack around this by calling some setState with runOnJS and that triggers a re-render but of course affects fps on the JS thread

Package versions

• React: 16.13.1
• React Native: ~0.63.3
• React Native Reanimated: 2.0.0-rc.0

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[terrysahaidak]

if you want something to be updated on UI Thread - you need to pass it as animatedProps.

The React Native Text doesn't support this, but there is a library https://github.com/axelra-ag/react-native-animateable-text

[doylemark]

Hi, I checked out this library too, but found the same problems.. I'm confused if it's a library problem I'm encountering or a bug in my code

const someNum = useDerivedValue(() => {
  const c = interpolate(
    translation.y.value,
    [0, width - 48],
    [data.MIN, data.MAX]
  );

  return c.toFixed();
});

const animatedProps = useAnimatedProps(() => {
  console.log(someNum.value);
  return {
    text: someNum.value,
  };
});

return (
  <View>
    <AnimateableText animatedProps={animatedProps} />
  </View>
)

Here is a GIF of someNum.value being logged from animatedProps however it's not updated either (note the static 1336 in drawer).. The UI will update if I change some state from within useDerivedValue or animatedProps however.

[karol-bisztyga]

You can use Animated.TextInput, disable editing by the user, and append appropriate styles to it, just as a workaround to it, as input text, as far as I remember, supports such updates.

[jonsamp]

I am experiencing the same behavior, where none of the examples I can find work for updating text. I tried the npm package referenced earlier in this thread, and also using Animated.TextInput.

Here's what I'm seeing:

Similar to @doylemark, I can see the result of useDerivedValue() logging to my console, but its value never updates in my UI:

Here's my code:

const AnimatedTextInput = Animated.createAnimatedComponent(TextInput)

// ...

const stepText = useDerivedValue(() => {
  const sliderRange = SLIDER_WIDTH - KNOB_WIDTH
  const oneStepValue = sliderRange / MAX_RANGE
  const step = Math.ceil(translateX.value / oneStepValue)

  return String(step)
})

const animatedProps = useAnimatedProps(() => {
  console.log(stepText.value)
  return {
    value: stepText.value,  // this doesn't work if I use "text" as the key here either
  }
})

// ...

<AnimatedTextInput
  underlineColorAndroid="transparent"
  editable={false}
  style={{ fontSize: 24 }}
  animatedProps={animatedProps}
/>

I got to this code by following this blog. The examples in that blog do not work for me, however the author of that blog has gifs of the code working, so I suspect it _did_ work. Im running "react-native-reanimated": "^2.0.0-alpha.9.2" in a bare Expo project.

I also made a reproducible demo you can clone and run. It's adds a Slider component to the reanimated playground demo app: https://github.com/jonsamp/reanimated-animatedprops-repro

[karol-bisztyga]

I think .text is a proper approach, but it also would have to be added to NATIVE_THREAD_PROPS_WHITELIST I guess. @doylemark would it suffice as a (let's say) proper way of performing that thing you posted?

[karol-bisztyga]

@jonsamp please check this

[jonsamp]

@karol-bisztyga Thanks, adding this worked:

Animated.addWhitelistedNativeProps({text: true});

[wcandillon]

Thanks gang!

[doylemark]

So can we conclude the described issues were caused by a regression in RC.0 which is now resolved?

[wcandillon]

We can close this issue probably. Or we could close it if you would like Animated.addWhitelistedNativeProps({text: true}); to be done automatically.

[doylemark]

This seems to be resolved so I will close.

[anastely]

@karol-bisztyga Thanks, adding this worked:

Animated.addWhitelistedNativeProps({text: true});

Hey, Where you added it exactly?
Can u share final code snippet

[jakub-gonet]

@anastely, you can add it wherever you want, you only want to ensure it runs only once. index.js or App.js or any standalone configuration file that is included there is fine. Using that in a component file (outside of component definition) is also fine but you may prefer a more "global" place to keep your configs in.

[karol-bisztyga]

you only want to ensure it runs only once

I think that does not break a thing, however, it would be inefficient as it overwrites collections on both, js and the native side.