PreferenceTarget.kt

import android.support.v7.preference.Preference
import android.graphics.Bitmap
import android.graphics.drawable.BitmapDrawable
import android.graphics.drawable.Drawable
import com.squareup.picasso.Target
import java.lang.ref.WeakReference

private class PreferenceTarget(pref: Preference) : Target {
    private val ref: WeakReference<Preference?> = WeakReference(pref)

    override fun onPrepareLoad(placeHolderDrawable: Drawable?) {
        ref.get()?.icon = placeHolderDrawable
    }

    override fun onBitmapLoaded(bitmap: Bitmap, from: Picasso.LoadedFrom?) {
        ref.get()?.let { pref ->
            pref.icon = BitmapDrawable(pref.context.resources, bitmap)
        }
    }

    override fun onBitmapFailed(errorDrawable: Drawable?) {
        ref.get()?.icon = errorDrawable
    }
}