expo-image-manipulator
provides an API to modify images stored on the local file system.Android Device | Android Emulator | iOS Device | iOS Simulator | Web |
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expo install expo-image-manipulator
If you're installing this in a bare React Native app, you should also follow these additional installation instructions.
import React, { useState, useEffect } from 'react'; import { Button, Image, StyleSheet, View } from 'react-native'; import { Asset } from 'expo-asset'; import { manipulateAsync, FlipType, SaveFormat } from 'expo-image-manipulator'; export default function App() { const [ready, setReady] = useState(false); const [image, setImage] = useState(null); useEffect(() => { (async () => { const image = Asset.fromModule(require('./assets/snack-icon.png')); await image.downloadAsync(); setImage(image); setReady(true); })(); }, []); const _rotate90andFlip = async () => { const manipResult = await manipulateAsync( image.localUri || image.uri, [ { rotate: 90 }, { flip: FlipType.Vertical }, ], { compress: 1, format: SaveFormat.PNG } ); setImage(manipResult); }; const _renderImage = () => ( <View style={styles.imageContainer}> <Image source={{ uri: image.localUri || image.uri }} style={styles.image} /> </View> ); return ( <View style={styles.container}> {ready && image && _renderImage()} <Button title="Rotate and Flip" onPress={_rotate90andFlip} /> </View> ); } %%placeholder-start%%const styles = StyleSheet.create({ ... }); %%placeholder-end%%const styles = StyleSheet.create({ container: { flex: 1, justifyContent: 'center', }, imageContainer: { marginVertical: 20, alignItems: 'center', justifyContent: 'center', }, image: { width: 300, height: 300, resizeMode: 'contain', }, });
import * as ImageManipulator from 'expo-image-manipulator';
string
) - URI of the file to manipulate. Should be on the local file system or a base64 data URI.Action[]
) - An array of objects representing manipulation options. Each object should have
only one of the keys that corresponds to specific transformation.SaveOptions
) - A map defining how modified image should be saved.Manipulate the image provided via uri
. Available modifications are rotating, flipping (mirroring),
resizing and cropping. Each invocation results in a new file. With one invocation you can provide
a set of actions to perform over the image. Overwriting the source file would not have an effect
in displaying the result as images are cached.
Acceptable values are: ActionResize
, ActionRotate
, ActionFlip
, ActionCrop
.
Name | Type | Description |
---|---|---|
crop | { height: number, originX: number, originY: number, width: number } | Fields specify top-left corner and dimensions of a crop rectangle. |
Name | Type | Description |
---|---|---|
flip | FlipType | An axis on which image will be flipped. Only one flip per transformation is available. If you want to flip according to both axes then provide two separate transformations. |
Name | Type | Description |
---|---|---|
resize | { height: number, width: number } | Values correspond to the result image dimensions. If you specify only one value, the other will be calculated automatically to preserve image ratio. |
Name | Type | Description |
---|---|---|
rotate | number | Degrees to rotate the image. Rotation is clockwise when the value is positive and counter-clockwise when negative. |
Name | Type | Description |
---|---|---|
base64 (optional) | string | It is included if the base64 save option was truthy, and is a string containing the
JPEG/PNG (depending on format ) data of the image in Base64. Prepend that with 'data:image/xxx;base64,'
to get a data URI, which you can use as the source for an Image element for example
(where xxx is jpeg or png ). |
height | number | Height of the image or video. |
uri | string | An URI to the modified image (usable as the source for an Image or Video element). |
width | number | Width of the image or video. |
A map defining how modified image should be saved.
Name | Type | Description |
---|---|---|
base64 (optional) | boolean | Whether to also include the image data in Base64 format. |
compress (optional) | number | A value in range 0.0 - 1.0 specifying compression level of the result image. 1 means
no compression (highest quality) and 0 the highest compression (lowest quality). |
format (optional) | SaveFormat | Specifies what type of compression should be used and what is the result file extension.
SaveFormat.PNG compression is lossless but slower, SaveFormat.JPEG is faster but the image
has visible artifacts. Defaults to SaveFormat.JPEG |
Horizontal
FlipType.Horizontal = "horizontal"
Vertical
FlipType.Vertical = "vertical"
JPEG
SaveFormat.JPEG = "jpeg"
PNG
SaveFormat.PNG = "png"
WEBP
- Web OnlySaveFormat.WEBP = "webp"