Minimum code to load and display an epub

[Noah-Barsky]

I know there are other threads here about this same topic but they are a few years old.
I tried to follow the other posts and ended up with

class MainActivity : AppCompatActivity() {
    private val coroutineScope: CoroutineScope = MainScope()
    var publication: Publication? = null
    override fun onCreate(savedInstanceState: Bundle?) {
        // this line crashes but is in the example https://github.com/readium/kotlin-toolkit/issues/234
        supportFragmentManager.fragmentFactory = EpubNavigatorFragment.createFactory(publication = publication!!)

        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        val streamer = Streamer(this)
        val asset = FileAsset(File("/storage/emulated/0/Download/book.epub")) // "file:///android_asset/book.epub" both of these paths return errors, file is corrupt and file is not found

        coroutineScope.async {
            publication = streamer.open(asset, allowUserInteraction = true, sender = this)
                .getOrElse { error ->
                    Log.e("error", error.getUserMessage(this@MainActivity))
                    return@async
                }
        }

        val fragment = supportFragmentManager.fragmentFactory.instantiate(classLoader, EpubNavigatorFragment::class.java.name)
        supportFragmentManager.beginTransaction().apply {
            replace(R.id.myframe, fragment) // myframe is a FrameLayout
            commit()
        }
    }
}

Is there other documentation I may have overlooked? I have of course read through the test app but didn't find it very enlightening.

edit:
I am trying to change from a different epub library which only works with epub2

[mickael-menu]

It's crashing because you are force-unwrapping the publication optional when it's not yet set.

You need to first open the publication with the streamer, and then create a fragment factory from it. Usually you would:

1. Open the Publication with the streamer in a bookshelf activity.
2. Store the Publication object in a shared store (see ReaderRepository in the test app)
3. Get the publication from the shared store when creating the reader activity, to initialize the fragment factory.

[paulocoutinhox]

@Noah-Barsky Can you post here the full solution with fixes?