I have a BoxGeometry added to a three.js scene. I have also added the scene in ReactInstance. The scene however doesn't seem to be rendered? I have tried this but doesn't work. just wanted to know in what react component the scene would be rendered?
Cube.js:
import {Module} from 'react-360-web';
import * as THREE from 'three';
export default class Cube extends Module {
scene: THREE.scene;
constructor(scene) {
super('Cube123');
this.scene = scene;
}
add() {
const geometry = new THREE.BoxGeometry(100, 100, 100);
const material = new THREE.MeshBasicMaterial({ color: Math.random() * 0xffffff });
const mesh = new THREE.Mesh(geometry, material);
mesh.position.z = -4;
this.scene.add(mesh);
}
}
client.js:
import {ReactInstance, Location, Surface} from 'react-360-web';
import Cube from './Cube';
import * as THREE from 'three';
function init(bundle, parent, options = {}) {
const scene = new THREE.Scene();
const Cube123 = new Cube(scene);
const r360 = new ReactInstance(bundle, parent, {
fullScreen: true,
nativeModules: [ Cube123 ],
scene: scene,
...options,
});
r360.scene = scene;
r360.renderToLocation(
r360.createRoot('CubeModule123'),
new Location([0, -2, -10]),
);
r360.compositor.setBackground('./static_assets/360_world.jpg');
}
window.React360 = {init};
CubeModule.js:
import * as React from 'react';
import {Animated, View, asset, NativeModules} from 'react-360';
import Entity from 'Entity';
import AmbientLight from 'AmbientLight';
import PointLight from 'PointLight';
const Cube123 = NativeModules.Cube123;
export default class CubeModule extends React.Component{
constructor() {
super();
Cube123.add();
}
render() {
return (
<Animated.View
style={{
height: 100,
width: 200,
transform: [{translate: [0, 0, -3]}],
backgroundColor: 'rgba(255, 255, 255, 0.4)',
layoutOrigin: [0.5, 0, 0],
alignItems: 'center',
}}
>
</Animated.View>
);
}
}
I know this doesn't answer the question exactly but take a look at this web page from react 360:
React 360 what is it?
Specifically, take a look at this:
How is React 360 Different from A-Frame?
A-Frame is a framework for building VR worlds using declarative HTML-like components. It has a rich collection of available components from a vibrant community, and is great for creating intricate 3D scenes that can be viewed in VR. We believe that React 360 serves a different use case optimized around applications that rely on user interfaces, or are event-driven in nature. Look through our examples to see the types of things you can easily build with React 360.
Trying to figure out which framework is right for you? Here's a quick test. If your application is driven by user interaction, and has many 2D or 3D UI elements, React 360 will provide the tools you need. If your application consists of many 3D objects, or relies on complex effects like shaders and post-processing, you'll get better support from A-Frame. Either way, you'll be building great immersive experiences that are VR-ready!
How is React 360 Different from Three.js?
Three.js is a library for 3D rendering in the web browser. It's a much lower-level tool than React 360, and requires control of raw 3D meshes and textures. React 360 is designed to hide much of this from you unless it's needed, so that you can focus on the behavior and appearance of your application.
Currently, React 360 relies on Three.js for some of its rendering work. However we are opening up the relevant APIs so that React 360 developers may soon be able to use the 3D rendering library of their choice, including raw WebGL calls.
I know it's probably not the answer you wanted but honestly as someone who has dabbled a lot with aframe and react 360, if you want to use cubes, spherse, shapes, etc. You should go with Aframe. This question has been asked on the github issues on the react360 page and the consensus was the same. Theoretically it is possible, but you'll have to bend over backwards just to make it work.
Related
How do I convince a vertical React Native FlatList to virtualize correctly inside another vertical (non-virtualizing) FlatList, in React Native Web?
So far, it seems that by default, scrolling to a certain point or responsive resize re-renderings tend to cause the virtualization to go haywire. This Snack demonstrates the problem. Be sure you're on the "Web" tab as the device builds seem to work correctly. Here's a repro through codesandbox too.
Update: Per request, here's the code inline as well. This is a full program that can paste into, say, a new expo init project (or similar) to see the strange behavior and experiment with it.
import React, { useCallback } from 'react';
import { FlatList, Text, useWindowDimensions, View } from 'react-native';
// Make 200 rows for the big list (which will draw green and red with some info).
const bigListData = Array(200).fill(0).map((element, index) => index);
function onViewableChange({ viewableItems }) {
if (viewableItems.length < 2) {
console.log(`VIEWABLE CHANGE! Only ${viewableItems.length} visible...`);
} else {
console.log(`VIEWABLE CHANGE! ${viewableItems[0].index} to ${viewableItems[viewableItems.length - 1].index}`);
}
}
function BigList() {
const { height, width } = useWindowDimensions();
const betweenRows = 10;
const itemHeight = height / 8;
const totalRowHeight = itemHeight + betweenRows;
const renderer = useCallback(({ item }) => {
const key = `i_${item}`;
return <View key={key} style={{
backgroundColor: item % 2 ? "red" : "green",
height: itemHeight,
width: '90%',
marginLeft: '5%',
marginBottom: betweenRows }}>
<Text>{key}, rh: {totalRowHeight}, offset: {totalRowHeight * item}, i {item}</Text>
</View>;
}, [itemHeight, totalRowHeight]);
const getItemLayout = useCallback((__data, index) => ({
index,
length: itemHeight,
offset: index * totalRowHeight
}), [itemHeight, totalRowHeight]);
return <FlatList
data={bigListData}
getItemLayout={getItemLayout}
key={'flatList'}
numColumns={1}
onViewableItemsChanged={onViewableChange}
renderItem={renderer}
/>;
}
function NoNestedFlatLists() {
const windowHeight = useWindowDimensions().height;
return <View style={{ height: windowHeight, width: '80%' }}><BigList /></View>;
}
function renderComponent({ item }) {
if (item.type === "widget") {
// Using height 600 here, but assume we cannot easily predict this height (due to text wrappings).
return <View key={item.type} style={{ backgroundColor: 'blue', height: 600, width: '100%', marginBottom: 15 }} />
}
return <BigList key={item.type} />;
}
function NestedFlatLists() {
const windowHeight = useWindowDimensions().height;
const components = [{ type: "widget" }, { type: "bigList" }];
return <FlatList
data={components}
key={'dynamicAppFlatList'}
numColumns={1}
renderItem={renderComponent}
style={{ height: windowHeight, width: '80%' }}
/>;
}
export default function App() {
const windowHeight = useWindowDimensions().height;
// Rendering just the following has no virtualization issues.
// The viewable change events make sense, no items suddenly disappear, no complete app meltdown...
//return <NoNestedFlatLists />;
// However:
// Any useful dynamic "rows of components" architecture melts down when virtualization comes into play.
// This sample represents such an app whose feeds have asked the app to render a "widget" followed by a
// "bigList" who could well have a few hundred items itself and thus really needs virtualization to work
// well on low-end devices. This demo leans on console logs. In snack.expo.dev, at time of writing, these
// feel hidden: Click the footer bar, either on the checkmark or an empty space, and then the "Logs" tab.
// Once you scroll down about half way in the "App", even slowly, you'll get logs like the following:
// Chrome: VIEWABLE CHANGE! 83 to 90
// Chrome: VIEWABLE CHANGE! 85 to 92
// Chrome: VIEWABLE CHANGE! Only 0 visible...
// Chrome: VIEWABLE CHANGE! 176 to 183
// Chrome: VIEWABLE CHANGE! 177 to 184
// At which time, all the UI disappears. What it thinks is viewable is quite wrong. Try to scroll around,
// but none of the mid rows are drawing. There is no easy way to repair app behavior from this state. The
// only rows which still draw correctly during the problem are the top and bottom non-virtualizing rows.
//
// As an alternate repro, you can scroll to near the middle and then resize the bottom of the window, and
// similar virtualization problems can occur. (In our real app, we can be scrolled almost anywhere out of
// the non-virtualizing rows, and make a 1px window resize to break the app. We have a more complex app
// structure, but I'm hoping a fix for this snack will still be applicable to our own symptoms...)
return <NestedFlatLists />;
}
Hopefully I am missing something trivial, as it seems clear React Native is attempting to handle nested FlatLists of the same orientation, and for the most part does great. Until you happen to have enough data items to bring virtualization into play, and even then, only fails for Web. (We've tried upgrading React Native to all the way to 0.67.2 and React Native Web to 0.17.5 - the latest releases - with no luck, and none of the Expo dropdown versions yield correct behavior in the linked Snack either.) What can I change in either sample to have correct virtualization in the nested FlatList?
Short answer is: You can't convince FlatList to virtualize this way correctly. At least currently (0.17), it's broken.
Although I was able to get some FlatList virtualization improvements into React Native Web's 0.18 preview, ultimately the measurement problems are deeper than I could afford to spend more weeks to fully fix. (If someone wants to try picking up from there - I recommend to focus on reconciling RNW's ScrollView versus RN's ScrollView and then digging into the ScrollView's measurements going absolutely haywire in the repro scenario, if replicating RN's evolution of ScrollView to RNW isn't enough.)
It ended up being much faster though to build our own virtualizing list component from scratch. Ours is specialized to our needs ATM so probably won't become open source, but who knows. But if you need to go this route... think about throttling reactions to scroll events and such to ".measure" the container view ref periodically and decide which things you need to render versus just rendering reserved empty space for... etc. There are other approaches but that seems to work.
I've started using RN recently and have been doing some research on the implementation of themes and/or a dark-light mode. Here's roughly how I understand the two main options so far:
Context: Easy setup and can be accessed via hook inside the component that needs it. I count things like the React Navigation themes since that works, in essence, the same way(?)
Styled Components: Essentially just replacing the components with custom ones that access the current theme and that can then be set up to change their props on toggle if needed.
What I don't like about context, is that (the way I understand it) it wouldn't let me access the theme when using a StyleSheet, since that's outside the component. With the styled components on the other hands I'm not sure if I can cover all options inside my custom components, wouldn't I still need some sort of hook in each component anyway?
I was also thinking about just saving the current theme into my Store (in my case Zustand), together with an action that lets me toggle to a dark-mode. But so far, I haven't really seen anyone else do that, is there a downside to doing it that way?
It's not hard to pass context to your stylesheet, it just requires a bit of extra boilerplate. Something like the below:
import ThemeContext from '<path>';
export default () => {
const theme = useContext(ThemeContext);
const stylesWithTheme = styles(theme);
return <Text style={stylesWithTheme.text>Hi</Text>;
}
const styles = theme => StyleSheet.create({
text: {
color: themeStyles.color[theme];
}
});
const themeStyles = {
color: {
dark: '#FFF',
light: '#000',
},
};
I don't think using styled components would be a big departure from the above scheme.
If you did store your theme in state, and define your styles within the body of the component, that could be a savings in boilerplate. It's up to you whether having your styles in the component body is acceptable.
Side note, if you're already using a state manager, I would recommend not mixing it with the Context API without knowing more. It's simpler to have one solution there.
If user has selected light-theme, and switches to dark-theme, then all scenes will immediately render to using the dark-theme.
I am using react-native-router-flux if this helps.
Thanks in advance,
Different approaches are possible. One of them is to use React context. Generally it should be used with caution but theming is one of the official examples where it is suitable.
Theming is a good example of when you might want an entire subtree to have access to some piece of information
So the example might look like
class App extends Component {
getChildContext() {
return {theme: { primaryColor: "purple" }};
}
...
}
App.childContextTypes = {
theme: React.PropTypes.object
};
where you set the context for rest of your application and then you use it in your components
class Button extends Component {
render() {
return <TouchableHighlight underlayColor={this.context.theme.primaryColor}>...
}
}
Button.contextTypes = {
theme: React.PropTypes.object
};
If you want to switch theme, you can set context based on your state/props that can be based on user selection.
Currently we are dealing with same questions and therefore we have starting prototyping library called react-native-themeable.
The idea is to use context to store theme and (re)implement RN components so they can replace original components but supports theming.
Example of theme switching you can find in https://github.com/instea/react-native-themeable/blob/master/examples/src/SwitchTheme.js
You can start by creating one JS file containing two objects that have the colors for each theme. Then just use one as a default and if the user picks another theme save it in the database or using local storage and pull the relevant object.
export const theme1 = {
blue: '#fddd',
red: '#ddddd',
buttonColor: '#fff'
}
export const theme2 = {
blue: '#fddd',
red: '#ddddd'
buttonColor: '#fff'
}
Then just import the relevant file:
import * as themes from 'Themes'
const currentTheme = this.props.currentTheme ? this.props.currentTheme : 'theme1'
const styles = StyleSheet.create({
button: {
color: themes[currentTheme].buttonColor
},
})
Wouldn’t it be great if you could import a colors object directly, and modify the object every time you change the theme and have those new colors propagate to the entire app? Then your components wouldn’t need to have any special theme logic. I was able to achieve this using a combination of AsyncStorage, forced app restart, and async module loading.
What exactly is the benefit of using StyleSheet.create() vs a plain object?
const styles = StyleSheet.create({
container: {
flex: 1
}
}
Vs.
const styles = {
container: {
flex: 1
}
}
There is no benefit. Period.
Myth 1: StyleSheet is more performant
There is absolutely no performance difference between StyleSheet and an object declared outside of render (it would be different if you're creating a new object inside render every time). The performance difference is a myth.
The origin of the myth is likely because React Native team tried to do this, but they weren't successful. Nowhere in the official docs you will find anything about performance: https://facebook.github.io/react-native/docs/stylesheet.html, while source code states "not implemented yet": https://github.com/facebook/react-native/blob/master/Libraries/StyleSheet/StyleSheet.js#L207
Myth 2: StyleSheet validates style object at compile time
This is not true. Plain JavaScript can't validate objects at compile time.
Two things:
It does validate at runtime, but so does when you pass the style object to a component. No difference.
It does validate at compile time if you're using Flow or TypeScript, but so does once you pass the object as a style prop to a component, or if you properly typehint object like below. No difference either.
const containerStyle: ViewStyle = {
...
}
Quoting directly from comment section of StyleSheet.js of React native
Code quality:
By moving styles away from the render function, you're making the code easier to understand.
Naming the styles is a good way to add meaning to the low level components in the render function.
Performance:
Making a stylesheet from a style object makes it possible to refer to it by ID instead of creating a new style object every time.
It also allows to send the style only once through the bridge. All subsequent uses are going to refer an id (not implemented yet).
Also StyleSheet validates your stylesheet content as well. So any error of incorrect style property is shown at time of compiling rather than at runtime when StyleSheet is actually implemented.
The accepted answer is not an answer to the OP question.
The question is not the difference between inline styles and a const outside the class, but why we should use StyleSheet.create instead of a plain object.
After a bit of researching what I found is the following (please update if you have any info).
The advatanges of StyleSheet.create should be the following:
It validates the styles
Better perfomances because it creates a mapping of the styles to an ID, and then it refers inside with this ID, instead of creating every time a new object. So even the process of updating devices is faster because you don't send everytime all the new objects.
It used to be considered that using a StyleSheet was more performant, and was recommended for this reason by the RN team up until version 0.57, but it is now no longer recommended as correctly pointed out in another answer to this question.
The RN documentation now recommends StyleSheet for the following reasons, though I think these reasons would apply equally to plain objects that are created outside of the render function:
By moving styles away from the render function, you're making the
code easier to understand.
Naming the styles is a good way to add meaning to the low level
components in the render function.
So what do I think are the possible benefits of using StyleSheet over plain objects?
1) Despite claims to the contrary my testing on RN v0.59.10 indicates that you do get some validation when calling StyleSheet.create() and typescript (and probably flow) will also report errors at compile time. Even without compile time checking I think it's still beneficial to do run time validation of styles before they are used for rendering, particularly where components that use those styles could be conditionally rendered. This will allow such errors to be picked up without having to test all rendering scenarios.
2) Given that StyleSheet is recommended by the RN team they may still have hopes of using StyleSheet to improve performance in future, and they may have other possible improvements in mind as well, for example:
3) The current StyleSheet.create() run-time validation is useful, but a bit limited. It seems to be restricted to the type checking that you would get with flow or typescript, so will pick up say flex: "1" or borderStyle: "rubbish", but not width: "rubbish" as that could be a percentage string. It's possible that the RN team may improve such validation in future by checking things like percentage strings, or range limits, or you could wrap StyleSheet.create() in your own function to do that more extensive validation.
4) By using StyleSheet you are perhaps making it easier to transition to third party alternatives/extensions like react-native-extended-stylesheet that offer more.
So, today, September of 2021, after reading all the answers and doing some researches, I created a summary about using Stylesheet instead of a plain object.
Based on React Documentation, you should use the stylesheet when the complexity starts to grow.
The style prop can be a plain old JavaScript object. That's what we usually use for example code.
As a component grows in complexity, it is often cleaner to use StyleSheet.create to define several styles in one place.
In the simulator, when using stylesheet will display an ERROR, and when using the plain object will display only a WARNING.
Based on item 2, it looks like it has some validation while compiling. (A lot of people say that’s a myth)
If you need to migrate for a third-party library in the future, for some of them like react-native-extended-stylesheet, if you are using stylesheet, it will be easier.
You have some methods and properties that boost the development. For example, the property StyleSheet.absoluteFill will do position: 'absolute', left: 0, right: 0, top: 0, bottom: 0, or the method compose() will allow you to combine two styles, overriding it.
P.S.: The performance answer looks to be a myth.
My opinion?
Based on item 2 and 5, go to stylesheet instead of plain objects.
I did not find any differences between StyleSheet and plain object, except of typing validation in TypeScript.
For example, this (note the typing differences):
import { View, Text, Image, StyleSheet } from 'react-native';
import logo from './logo.svg';
export default class App extends Component {
render() {
return (
<View style={styles.someViewStyle}>
<Text style={styles.someTextStyle}>Text Here</Text>
<Image style={styles.someImageStyle} source={logo} />
</View>
);
}
}
const styles: StyleSheet.create({
someViewStyle: {
backgroundColor: '#FFF',
padding: 10,
},
someTextStyle: {
fontSize: 24,
fontWeight: '600',
},
someImageStyle: {
height: 50,
width: 100,
},
});
equals to this:
import { View, Text, Image, ViewStyle, TextStyle, ImageStyle } from 'react-native';
import logo from './logo.svg';
export default class App extends Component {
render() {
return (
<View style={styles.someViewStyle}>
<Text style={styles.someTextStyle}>Text Here</Text>
<Image style={styles.someImageStyle} source={logo} />
</View>
);
}
}
const styles: {
someViewStyle: ViewStyle;
someTextStyle: TextStyle;
someImageStyle: ImageStyle;
} = {
someViewStyle: {
backgroundColor: '#FFF',
padding: 10,
},
someTextStyle: {
fontSize: 24,
fontWeight: '600',
},
someImageStyle: {
height: 50,
width: 100,
},
};
Creating your styles via StyleSheet.create will pass though validation only when global variable __DEV__ is set to true (or while running inside Android or IOS emulators see React Native DEV and PROD variables)
The function source code is pretty simple:
create < +S: ____Styles_Internal > (obj: S): $ReadOnly < S > {
// TODO: This should return S as the return type. But first,
// we need to codemod all the callsites that are typing this
// return value as a number (even though it was opaque).
if (__DEV__) {
for (const key in obj) {
StyleSheetValidation.validateStyle(key, obj);
if (obj[key]) {
Object.freeze(obj[key]);
}
}
}
return obj;
}
I would recommend using it because it performs run-time validation during development, also it freezes the object.
i know that this is a really late answer, but I've read that it shows you errors and provides auto completion in editors when you use StyleSheet.
How do I get screen width in React native?
I need it because I use some absolute components that overlap and their position on screen changes with different devices.
In React-Native we have an Option called Dimensions
Include Dimensions at the top var where you have include the Image,and Text and other components.
Then in your Stylesheets you can use as below,
ex: {
width: Dimensions.get('window').width,
height: Dimensions.get('window').height
}
In this way you can get the device window and height.
Simply declare this code to get device width
let deviceWidth = Dimensions.get('window').width
Maybe it's obviously but, Dimensions is an react-native import
import { Dimensions } from 'react-native'
Dimensions will not work without that
April 10th 2020 Answer:
The suggested answer using Dimensions is now discouraged. See: https://reactnative.dev/docs/dimensions
The recommended approach is using the useWindowDimensions hook in React; https://reactnative.dev/docs/usewindowdimensions which uses a hook based API and will also update your value when the screen value changes (on screen rotation for example):
import {useWindowDimensions} from 'react-native';
const windowWidth = useWindowDimensions().width;
const windowHeight = useWindowDimensions().height;
Note: useWindowDimensions is only available from React Native 0.61.0: https://reactnative.dev/blog/2019/09/18/version-0.61
If you have a Style component that you can require from your Component, then you could have something like this at the top of the file:
const Dimensions = require('Dimensions');
const window = Dimensions.get('window');
And then you could provide fulscreen: {width: window.width, height: window.height}, in your Style component. Hope this helps
React Native Dimensions is only a partial answer to this question, I came here looking for the actual pixel size of the screen, and the Dimensions actually gives you density independent layout size.
You can use React Native Pixel Ratio to get the actual pixel size of the screen.
You need the import statement for both Dimenions and PixelRatio
import { Dimensions, PixelRatio } from 'react-native';
You can use object destructuring to create width and height globals or put it in stylesheets as others suggest, but beware this won't update on device reorientation.
const { width, height } = Dimensions.get('window');
From React Native Dimension Docs:
Note: Although dimensions are available immediately, they may change (e.g due to >device rotation) so any rendering logic or styles that depend on these constants >should try to call this function on every render, rather than caching the value >(for example, using inline styles rather than setting a value in a StyleSheet).
PixelRatio Docs link for those who are curious, but not much more there.
To actually get the screen size use:
PixelRatio.getPixelSizeForLayoutSize(width);
or if you don't want width and height to be globals you can use it anywhere like this
PixelRatio.getPixelSizeForLayoutSize(Dimensions.get('window').width);
React Native comes with "Dimensions" api which we need to import from 'react-native'
import { Dimensions } from 'react-native';
Then,
<Image source={pic} style={{width: Dimensions.get('window').width, height: Dimensions.get('window').height}}></Image>
Only two simple steps.
import { Dimensions } from 'react-native' at top of your file.
const { height } = Dimensions.get('window');
now the window screen height is stored in the height variable.
Just discovered react-native-responsive-screen repo here. Found it very handy.
react-native-responsive-screen is a small library that provides 2 simple methods so that React Native developers can code their UI elements fully responsive. No media queries needed.
It also provides an optional third method for screen orienation detection and automatic rerendering according to new dimensions.
First get Dimensions from react-native
import { Dimensions } from 'react-native';
then
const windowWidth = Dimensions.get('window').width;
const windowHeight = Dimensions.get('window').height;
in windowWidth you will find the width of the screen while in windowHeight you will find the height of the screen.
The latest method from 2020 is to use useWindowDimensions
the way i implemented it-
make a global.js file and set window width and height as global variables
const WindowDimensions= (()=>{
global.windowWidth = useWindowDimensions().width;
global.windowHeight = useWindowDimensions().height;
return (<></>);
})
in App.js file,import window dimensions and add it to return block
use width and height everywhere as global.windowHeight and global.windowWidth
using global variables is not a good design pattern. but this thing works
I think using react-native-responsive-dimensions might help you a little better on your case.
You can still get:
device-width by using and responsiveScreenWidth(100)
and
device-height by using and responsiveScreenHeight(100)
You also can more easily arrange the locations of your absolute components by setting margins and position values with proportioning it over 100% of the width and height
You can achieve this by creating a component and using it by importing it into the file you need.
import {Dimensions, PixelRatio} from "react-native";
const {width, height} = Dimensions.get("window");
const wp = (number) => {
let givenWidth = typeof number === "number" ? number : parseFloat(number);
return PixelRatio.roundToNearestPixel((width * givenWidth) / 100);
};
const hp = (number) => {
let givenHeight = typeof number === "number" ? number : parseFloat(number);
return PixelRatio.roundToNearestPixel((height * givenHeight) / 100);
};
export {wp, hp};
Now, you should use it.
import { hp, wp } from "../<YOUR PATH>";
buttonContainer: {
marginTop: hp("2%"),
height: hp("7%"),
justifyContent: "center",
alignSelf: "center",
width: wp("70%"),
backgroundColor: "#1C6AFD",
borderRadius: 5,
},
buttonText: {
fontSize: wp("3.5%"),
color: "#dddddd",
textAlign: "center",
fontFamily: "Spartan-Bold",
}
That way, you will make your design responsive. I suggest using simple pixels in the styling of circle things like avatar images, etc.
In other cases, the above code wraps components according to the density pixels of the screen.
If you have any better solution, please comment.
First, you must import Dimensions from 'react-native'
import { View, StyleSheet, Dimensions } from "react-native";
after that, you can save width and height in variables:
const windowsWidth = Dimensions.get('window').width
const windowsHeight = Dimensions.get('window').height
them you could use both as you need, i.e. in styles:
flexDirection: windowsWidth<400 ? 'column' : 'row',
Remember this, your object styles is outside your component, so the cariable declaration must be outside your component too. But if you need it inside your component, no problem, can use it:
<Text> Width: { windowsWidth }</Text>
<Text> Height: { windowsHeight }</Text>
you can get device width and height in React Native, by the following code:
const windowWidth = Dimensions.get('window').width;
const windowHeight = Dimensions.get('window').height;
docs: https://reactnative.dev/docs/dimensions
import {useWindowDimensions, Dimensions} from 'react-native'
let width1= useWindowDimensions().width // Hook can be called only inside functional component, tthis is dynamic
let width2=Dimensions.get("screen").width