It will save image to the gallery. It uses Kotlin coroutines default thead for saving images. So user willn't experience UI blocking situation.
You need to include kotlin coroutines for your app build.gradle file
implementation "org.jetbrains.kotlinx:kotlinx-coroutines-core:$coroutines_version"
implementation "org.jetbrains.kotlinx:kotlinx-coroutines-android:$coroutines_version"
From Uint8List image
Uint8List pickedImage;
pickedImage = pickedImageMethod() //your method for picking Uint8List file
final result = await BackgroundImageGallerySaver.saveImage(pickedImage);
From file
String file;
file = pickedFileMethod() //your method for picking file url as string
final result = await BackgroundImageGallerySaver.saveFile(file);
** Only Android Support
** The plugin is based on hui-z / image_gallery_saver