Formats

Which image formats FastImage shows on iOS and Android, from which versions, and what decodes each one. The README has the short version, for recent iOS and Android versions.

These are tested on iOS 27 and Android 16 in both example apps (the regression runner’s formats cases); the minimum versions are the ones Apple and Android give for decoding the format. An image in a format that doesn’t load fails with onError. On the web, the browser shows the image, so it’s the formats the browser supports.

iOS

FastImage loads images with SDWebImage, which decodes most formats with ImageIO, Apple’s image decoder.

Format	Shows	Decoded by
JPEG	Yes	ImageIO
PNG	Yes	ImageIO
APNG	Animated	ImageIO, animated by SDWebImage
GIF	Animated	ImageIO, animated by SDWebImage
WebP	Animated; a still one iOS 14+	Still ones ImageIO, animated ones libwebp
AVIF	iOS 16+; animated	ImageIO, animated by SDWebImage
HEIC	iOS 11+	ImageIO
SVG	iOS 13+, with an SVG library	SDWebImageSVGCoder (Apple’s SVG renderer)
ICO	Yes	ImageIO
BMP	Yes	ImageIO
TIFF	Yes	ImageIO
ICNS	Yes	ImageIO
PSD	Its composite image	ImageIO

Animated WebPs are decoded with libwebp, from SDWebImageWebPCoder, which FastImage includes. FastImage registers its coder for animated WebPs, unless the app has registered a WebP coder itself (libwebp’s, or SDWebImage’s ImageIO one), which then decodes them instead. Animated AVIFs are decoded with ImageIO too, by FastImage’s coder for them (SDWebImage’s own only decodes their first frame), unless the app has registered libavif’s coder (SDWebImageAVIFCoder), which then decodes them instead. On iOS 13, a still WebP loads if the app registers libwebp’s coder for all WebPs: [[SDImageCodersManager sharedManager] addCoder:[SDImageWebPCoder sharedCoder]]; in its AppDelegate.

Android

FastImage loads images with Glide, which decodes most formats with Android’s own decoders.

Format	Shows	Decoded by
JPEG	Yes	Android’s decoder
PNG	Yes	Android’s decoder
APNG	Animated, with minSdkVersion 21+ (Animated PNG)	APNG4Android, which FastImage includes
GIF	Animated	Glide’s GIF decoder
WebP	Yes; animated ones Android 9+	Android’s decoder; animated ones ImageDecoder (an AnimatedImageDrawable)
AVIF	Android 14+1; animated	Android’s decoder; animated ones ImageDecoder (an AnimatedImageDrawable)
HEIC	Android 8+	Android’s decoder
SVG	With an SVG library	AndroidSVG
ICO	Yes	Android’s decoder
BMP	Yes	Android’s decoder
TIFF	No
ICNS	No
PSD	No

Animated WebP and AVIF need Glide 4.15 or later (FastImage uses 4.16 unless the app sets an older glideVersion, see Android build settings); with an older Glide they show their first frame.

SVG images

SVG images (remote, bundled with require(), or local files) load when the app has an SVG library: SDWebImageSVGCoder on iOS and AndroidSVG on Android. Add them to the app:

# ios/Podfile
pod 'SDWebImageSVGCoder'

android/app/build.gradle

dependencies {
    implementation 'com.caverock:androidsvg-aar:1.4'
}

On Android either of AndroidSVG’s packages works (com.caverock:androidsvg-aar or com.caverock:androidsvg), so an app that already has one needs nothing more. With Expo, add the pod with expo-build-properties ({ "ios": { "extraPods": [{ "name": "SDWebImageSVGCoder" }] } }).

An SVG is drawn at the size it’s shown at, so it’s sharp at any size, and then works like any other image: resizeMode, tintColor, blurRadius, transition and caching. onLoad reports the SVG’s own size: its width and height, or its viewBox’s (300x150 if it has neither). Animated SVGs (SMIL or CSS animations) show their first state. On iOS, SVG images need iOS 13 or later. Without the SVG library, an SVG image fails with onError, saying what to add (on iOS, for a url that ends in .svg).

Animated PNG (Android)

APNG (animated PNG) images animate on Android with APNG4Android, which FastImage includes when the app’s minSdkVersion is 21 or later (React Native 0.64 and later by default). With an older minSdkVersion they show their first frame.

APNGs work like other animated images: loop, paused (which continues from the frame it paused on), and a still first frame with blurRadius or resizeMode="repeat". Each frame is decoded as it plays, at about the size it’s shown at, off the main thread.

Footnotes

1. Android 14 is the first version that requires an AVIF decoder; many devices on Android 12 and 13 have one too. ↩