BindingAdapter 与协程 scope

Question

I'm not sure if I'm using CoroutineScope properly inside my Binding Adapter function:

@BindingAdapter("srcByFileName")
fun setImageViewResource(imageView: ImageView, fileName: String?) {
    if(fileName == null) return

    CoroutineScope(SupervisorJob() + Dispatchers.IO).launch {
        val bitmap = ImageStorageManager.getImageFromInternalStorage(imageView.context, fileName)
        withContext(Dispatchers.Main) {
            imageView.setImageBitmap(bitmap)
        }
    }

}

I need to move the fetching of Bitmap to a different thread hence the need of coroutine. I'm just wondering if this is the correct way of doing this.

Answer 1

If you're using Data Binding , then your logic would probably be in your ViewModel , so it's better to pass viewModelScope to the BindingAdapter function.

Just add a third parameter of type CoroutineScope which you can pass from xml layout through the predefined viewModel object.

And in ViewModel , you can just define your scope like this:

val scope: CoroutineScope
    get() = viewModelScope

And in xml:

<data>
    <variable
        name="viewModel"
        type="ViewModelType" />
</data>

...

<ImageView
   android:layout_width="wrap_content"
   android:layout_height="wrap_content"
   app:srcByFileName=@{viewModel.src}
   app:coroutineScope="@{viewModel.scope}" />