A React component for displaying different types of images, including network images, static resources, temporary local images, and images from local disk, such as the camera roll.
This example shows fetching and displaying an image from local storage as well as one from network and even from data provided in the 'data:'
uri scheme.
Note that for network and data images, you will need to manually specify the dimensions of your image!
import React, { Component } from 'react';
import { AppRegistry, View, Image } from 'react-native';
export default class DisplayAnImage extends Component {
render() {
return (
<View>
<Image
source={require('/react-native/img/favicon.png')}
/>
<Image
style={{width: 50, height: 50}}
source={{uri: 'https://facebook.github.io/react-native/docs/assets/favicon.png'}}
/>
<Image
style={{width: 66, height: 58}}
source={{uri: 'data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAADMAAAAzCAYAAAA6oTAqAAAAEXRFWHRTb2Z0d2FyZQBwbmdjcnVzaEB1SfMAAABQSURBVGje7dSxCQBACARB+2/ab8BEeQNhFi6WSYzYLYudDQYGBgYGBgYGBgYGBgYGBgZmcvDqYGBgmhivGQYGBgYGBgYGBgYGBgYGBgbmQw+P/eMrC5UTVAAAAABJRU5ErkJggg=='}}
/>
</View>
);
}
}
// skip this line if using Create React Native App
AppRegistry.registerComponent('DisplayAnImage', () => DisplayAnImage);
You can also add style
to an image:
import React, { Component } from 'react';
import { AppRegistry, View, Image, StyleSheet } from 'react-native';
const styles = StyleSheet.create({
stretch: {
width: 50,
height: 200
}
});
export default class DisplayAnImageWithStyle extends Component {
render() {
return (
<View>
<Image
style={styles.stretch}
source={require('/react-native/img/favicon.png')}
/>
</View>
);
}
}
// skip these lines if using Create React Native App
AppRegistry.registerComponent(
'DisplayAnImageWithStyle',
() => DisplayAnImageWithStyle
);
When building your own native code, GIF and WebP are not supported by default on Android.
You will need to add some optional modules in android/app/build.gradle
, depending on the needs of your app.
dependencies {
// If your app supports Android versions before Ice Cream Sandwich (API level 14)
compile 'com.facebook.fresco:animated-base-support:1.9.0'
// For animated GIF support
compile 'com.facebook.fresco:animated-gif:1.9.0'
// For WebP support, including animated WebP
compile 'com.facebook.fresco:animated-webp:1.9.0'
compile 'com.facebook.fresco:webpsupport:1.9.0'
// For WebP support, without animations
compile 'com.facebook.fresco:webpsupport:1.9.0'
}
style
blurRadius
onLayout
onLoad
onLoadEnd
onLoadStart
resizeMode
source
loadingIndicatorSource
onError
testID
resizeMethod
accessibilityLabel
accessible
capInsets
defaultSource
onPartialLoad
onProgress
fadeDuration
style
ImageResizeMode
is an Enum
for different image resizing modes, set via the resizeMode
style property on Image
components. The values are contain
, cover
, stretch
, center
, repeat
.
Type | Required |
---|---|
style | No |
borderTopRightRadius
: number
backfaceVisibility
: enum('visible', 'hidden')
borderBottomLeftRadius
: number
borderBottomRightRadius
: number
borderColor
: color
borderRadius
: number
borderTopLeftRadius
: number
backgroundColor
: color
borderWidth
: number
opacity
: number
overflow
: enum('visible', 'hidden')
resizeMode
: Object.keys(ImageResizeMode)
tintColor
: color
Changes the color of all the non-transparent pixels to the tintColor.
overlayColor
: string (Android)
When the image has rounded corners, specifying an overlayColor will cause the remaining space in the corners to be filled with a solid color. This is useful in cases which are not supported by the Android implementation of rounded corners:
A typical way to use this prop is with images displayed on a solid background and setting the overlayColor
to the same color as the background.
For details of how this works under the hood, see http://frescolib.org/docs/rounded-corners-and-circles.html
blurRadius
blurRadius: the blur radius of the blur filter added to the image
Type | Required |
---|---|
number | No |
onLayout
Invoked on mount and layout changes with {nativeEvent: {layout: {x, y, width, height}}}
.
Type | Required |
---|---|
function | No |
onLoad
Invoked when load completes successfully.
Type | Required |
---|---|
function | No |
onLoadEnd
Invoked when load either succeeds or fails.
Type | Required |
---|---|
function | No |
onLoadStart
Invoked on load start.
e.g., onLoadStart={(e) => this.setState({loading: true})}
Type | Required |
---|---|
function | No |
resizeMode
Determines how to resize the image when the frame doesn't match the raw image dimensions.
cover
: Scale the image uniformly (maintain the image's aspect ratio) so that both dimensions (width and height) of the image will be equal to or larger than the corresponding dimension of the view (minus padding).
contain
: Scale the image uniformly (maintain the image's aspect ratio) so that both dimensions (width and height) of the image will be equal to or less than the corresponding dimension of the view (minus padding).
stretch
: Scale width and height independently, This may change the aspect ratio of the src.
repeat
: Repeat the image to cover the frame of the view. The image will keep its size and aspect ratio, unless it is larger than the view, in which case it will be scaled down uniformly so that it is contained in the view.
center
: Center the image in the view along both dimensions. If the image is larger than the view, scale it down uniformly so that it is contained in the view.
Type | Required |
---|---|
enum('cover', 'contain', 'stretch', 'repeat', 'center') | No |
source
The image source (either a remote URL or a local file resource).
This prop can also contain several remote URLs, specified together with their width and height and potentially with scale/other URI arguments. The native side will then choose the best uri
to display based on the measured size of the image container. A cache
property can be added to control how networked request interacts with the local cache.
The currently supported formats are png
, jpg
, jpeg
, bmp
, gif
, webp
(Android only), psd
(iOS only).
Type | Required |
---|---|
ImageSourcePropType | No |
loadingIndicatorSource
Similarly to source
, this property represents the resource used to render the loading indicator for the image, displayed until image is ready to be displayed, typically after when it got downloaded from network.
Type | Required |
---|---|
array of ImageSourcePropTypes, number | No |
Can accept a number as returned by
require('./image.jpg')
onError
Invoked on load error with {nativeEvent: {error}}
.
Type | Required |
---|---|
function | No |
testID
A unique identifier for this element to be used in UI Automation testing scripts.
Type | Required |
---|---|
string | No |
resizeMethod
The mechanism that should be used to resize the image when the image's dimensions differ from the image view's dimensions. Defaults to auto
.
auto
: Use heuristics to pick between resize
and scale
.
resize
: A software operation which changes the encoded image in memory before it gets decoded. This should be used instead of scale
when the image is much larger than the view.
scale
: The image gets drawn downscaled or upscaled. Compared to resize
, scale
is faster (usually hardware accelerated) and produces higher quality images. This should be used if the image is smaller than the view. It should also be used if the image is slightly bigger than the view.
More details about resize
and scale
can be found at http://frescolib.org/docs/resizing.html.
Type | Required | Platform |
---|---|---|
enum('auto', 'resize', 'scale') | No | Android |
accessibilityLabel
The text that's read by the screen reader when the user interacts with the image.
Type | Required | Platform |
---|---|---|
node | No | iOS |
accessible
When true, indicates the image is an accessibility element.
Type | Required | Platform |
---|---|---|
bool | No | iOS |
capInsets
When the image is resized, the corners of the size specified by capInsets
will stay a fixed size, but the center content and borders of the image will be stretched. This is useful for creating resizable rounded buttons, shadows, and other resizable assets. More info in the official Apple documentation.
Type | Required | Platform |
---|---|---|
object: {top: number, left: number, bottom: number, right: number} | No | iOS |
defaultSource
A static image to display while loading the image source.
Type | Required | Platform |
---|---|---|
object, number | No | iOS |
If passing an object, the general shape is {uri: string, width: number, height: number, scale: number}
:
uri
- a string representing the resource identifier for the image, which should be either a local file path or the name of a static image resource (which should be wrapped in the require('./path/to/image.png')
function).width
, height
- can be specified if known at build time, in which case these will be used to set the default <Image/>
component dimensions.scale
- used to indicate the scale factor of the image. Defaults to 1.0 if unspecified, meaning that one image pixel equates to one display point / DIP.If passing a number:
number
- Opaque type returned by something like require('./image.jpg')
.onPartialLoad
Invoked when a partial load of the image is complete. The definition of what constitutes a "partial load" is loader specific though this is meant for progressive JPEG loads.
Type | Required | Platform |
---|---|---|
function | No | iOS |
onProgress
Invoked on download progress with {nativeEvent: {loaded, total}}
.
Type | Required | Platform |
---|---|---|
function | No | iOS |
fadeDuration
Android only. By default, it is 300ms.
Type | Required | Platform |
---|---|---|
number | No | Android |
getSize()
Image.getSize(uri, success, [failure]);
Retrieve the width and height (in pixels) of an image prior to displaying it. This method can fail if the image cannot be found, or fails to download.
In order to retrieve the image dimensions, the image may first need to be loaded or downloaded, after which it will be cached. This means that in principle you could use this method to preload images, however it is not optimized for that purpose, and may in future be implemented in a way that does not fully load/download the image data. A proper, supported way to preload images will be provided as a separate API.
Does not work for static image resources.
Parameters:
Name | Type | Required | Description |
---|---|---|---|
uri | string | Yes | The location of the image. |
success | function | Yes | The function that will be called if the image was successfully found and width and height retrieved. |
failure | function | No | The function that will be called if there was an error, such as failing to retrieve the image. |
prefetch()
Image.prefetch(url);
Prefetches a remote image for later use by downloading it to the disk cache
Parameters:
Name | Type | Required | Description |
---|---|---|---|
url | string | Yes | The remote location of the image. |
abortPrefetch()
Image.abortPrefetch(requestId);
Abort prefetch request. Android-only.
Parameters:
Name | Type | Required | Description |
---|---|---|---|
requestId | number | Yes | Id as returned by prefetch() |
queryCache()
Image.queryCache(urls);
Perform cache interrogation. Returns a mapping from URL to cache status, such as "disk" or "memory". If a requested URL is not in the mapping, it means it's not in the cache.
Parameters:
Name | Type | Required | Description |
---|---|---|---|
urls | array | Yes | List of image URLs to check the cache for. |
resolveAssetSource()
Image.resolveAssetSource(source);
Resolves an asset reference into an object which has the properties uri
, width
, and height
.
Parameters:
Name | Type | Required | Description |
---|---|---|---|
source | number, object | Yes | A number (opaque type returned by require('./foo.png')) or an ImageSource . |
ImageSource
is an object like{ uri: '<http location || file path>' }
© 2015–2018 Facebook Inc.
Licensed under the Creative Commons Attribution 4.0 International Public License.
https://facebook.github.io/react-native/docs/image.html