react-native-fast-image version 2.0.0

The @amazon-devices/react-native-fast-image library version 2.0.0 provides support on Vega for react-native-fast-image with a performant React Native image component. React Native’s Image component handles image caching like browsers for the most part. If the server is returning proper cache control headers for images, you get the built-in caching behavior you see in a browser. Others have noticed:

Flickering.
Cache misses.
Low performance loading from cache.
Low performance in general.

FastImage is an Image replacement that solves these issues on other platforms besides Web. This library is system-deployed and available to React Native for Vega apps without a separate installation process. The library is autolinking, which your app links to at runtime. The library is guaranteed to be compatible only with the version of React Native for Vega for which it’s built. When you uplevel your app’s version of React Native for Vega, consider the best practice of upleveling its library dependencies. For more information about this library and its API, see the README.md in the FastImage GitHub repo.

Installation

Add the JavaScript library dependency in the package.json file:

"dependencies": {
   ...
   "@amazon-devices/react-native-fast-image": "~2.0.0"
}

Reinstall dependencies using the npm install command.

Examples

import FastImage from 'react-native-fast-image'

const YourImage = () => (
    <FastImage
        style={{ width: 200, height: 200 }}
        source={{
            uri: 'https://unsplash.it/400/400?image=1',
            headers: { Authorization: 'someAuthToken' },
            priority: FastImage.priority.normal,
        }}
        resizeMode={FastImage.resizeMode.contain}
    />
)

Supported APIs

Component API

Prop	Description	Default
`source`	Source for the remote image to load.	None
`source.uri`	Remote URL to load the image from. For example, ''.	None
`source.priority`	`FastImage.priority.low` - Low Priority `FastImage.priority.normal` - Normal Priority `FastImage.priority.high` - High Priority	`FastImage.priority.normal`
`resizeMode`	`FastImage.resizeMode.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) `FastImage.resizeMode.cover` - Scale the image uniformly (maintain the image’s aspect ratio) so that both dimensions (width and height) of the image is equal to or larger than the corresponding dimension of the view (minus padding) `FastImage.resizeMode.stretch` - Scale width and height independently, This might change the aspect ratio of the source. `FastImage.resizeMode.center` - Do not scale the image, keep centered	`FastImage.resizeMode.cover`
`onFastImageLoadStart`	Called when the image starts to load.	None
`onFastImageLoad`	Called on a successful image fetch. Called with the width and height of the loaded image.	None
`onFastImageError`	Called on an image fetching error.	None
`onFastImageLoadEnd`	Called when the image finishes loading, whether it was successful or an error.	None

Methods

Method	Description
`preLoad`	Preload images to display later.
`clearMemoryCache`	Clear all images from memory cache.
`clearDiskCache`	Clear all images from disk cache.

Exceptions on Vega

The React Native for Vega library has a few exceptions in terms of API support. The following features are not supported on the Vega platform.

source.headers
source.cache
tintColor
defaultSource
onFastImageProgress (Has issues with the dependency Image.onProgress.)

Backward compatibility issue

Vega OS versions v0.12, OS 1.1 (201010334050), and higher are not compatible with amzn/react-native-fast-image (npm package) versions . When running an app built against an old version of the npm package on versions v0.12 and higher of the OS, you see the following crash on startup:

Volta:Invariant Violation: TurboModuleRegistry.getEnforcing(...): 'FastImageTurboModule' could not be found. Verify that a module by this name is registered in the native binary.

To avoid this crash, you must rebuild your app against the latest version of @amazon-devices/react-native-fast-image:

Make sure that your app’s package.json does not hardcode any old version of fast-image. Use the semvar version ~2.0.0, so your app can pick up the latest patch.
Delete package-lock.json to remove any locked fast-image version. If you are relying on package-lock.json to lock other dependencies, you can manually delete the entry for @amazon-devices/react-native-fast-image.
Delete the node_modules folder to make sure that npm doesn’t pick up an old cached version.
Rebuild your app.

Supported versions

Package Version	Based On	@amazon-devices/react-native-kepler version
2.0.x	8.6.3	2.0.x

Additional Resources

For information on other libraries, see Supported Third-Party Libraries and Services.

​Installation

​Examples

​Supported APIs

​Component API

​Methods

​Exceptions on Vega

​Backward compatibility issue

​Supported versions

​Additional Resources