how to use ? ScreenOrientation.addOrientationChangeListener ?

Help: Expo Docs
#1

Anyone have any simple example on what parameter to pass to

ScreenOrientation.addOrientationChangeListener()

After looking at the docs here and playing around with it, I still can’t understand how to use it.

The docs say

listener (OrientationChangeListener)
Each orientation update will pass an object with the new OrientationChangeEvent to the listener.

And there is a link to a change event here

This is what my code looks like:

const orientationListener = async () => {
    ScreenOrientation.addOrientationChangeListener(
      ScreenOrientation.ScreenOrientationInfo.orientation
    );
  };

but I am getting a type error in VSCode. That’s where I am stuck. What argument to pass to ScreenOrientation.addOrientationChangeListener()? I am getting an error

property 'orientationchangelistener' does not exist on type 'typeof import' (path to node_modules folder where ScreenOrientation package is installed) ts

which doesn’t make sense since I have this at the top of the file:

import * as ScreenOrientation from "expo-screen-orientation";
#2

Hey @dj-designs , as the docs say- it accepts a listener, which you can think of as just a function basically. This listener is triggered whenever a change in orientation occurs. For instance:

ScreenOrientation.addOrientationChangeListener( (event) => {
    console.log("orientation changed");
  }
);

will log that message whenever the orientation changes.

#3

Thank you for the information. Makes sense. Sounds like I can update state in the event function.

My goal is to make slight modification to css based on landscape orientation.

#4

Custom Hook

import { useState, useEffect } from "react";
import {
  Orientation,
  getOrientationAsync,
  addOrientationChangeListener,
} from "expo-screen-orientation";

export default function useOrientation() {
  const [orientation, setOrientation] = useState<Orientation>(0);

  useEffect(() => {
    getOrientationAsync().then((value) => {
      setOrientation(value);
    });

    const subscription = addOrientationChangeListener((event) => {
      setOrientation(event.orientationInfo.orientation);
    });

    return () => {
      subscription.remove;
    };
  }, []);

  return orientation;
}

// Usage
const orientation = useOrientation();
#5

looks interesting!

I’ve never seen this syntax. What is meant by < and > ?

Thank you.

#6

Typescript type/enum

export declare enum Orientation {
    UNKNOWN = 0,
    PORTRAIT_UP = 1,
    PORTRAIT_DOWN = 2,
    LANDSCAPE_LEFT = 3,
    LANDSCAPE_RIGHT = 4
}

Just ignore it if you are not using typescript.