Update page loading flow

app/src/main/java/org/koitharu/kotatsu/ui/reader/ChaptersDialog.kt

@@ -48,7 +48,16 @@ class ChaptersDialog : AlertDialogFragment(R.layout.dialog_chapters),
 	}
 
 	override fun onItemClick(item: MangaChapter, position: Int, view: View) {
+		((parentFragment as? OnChapterChangeListener)
+			?: (activity as? OnChapterChangeListener))?.let {
+			dismiss()
+			it.onChapterChanged(item)
+		}
+	}
 
+	interface OnChapterChangeListener {
+
+		fun onChapterChanged(chapter: MangaChapter)
 	}
 
 	companion object {

app/src/main/java/org/koitharu/kotatsu/ui/reader/PageHolder.kt

@@ -6,6 +6,7 @@ import androidx.core.view.isVisible
 import com.davemorrissey.labs.subscaleview.ImageSource
 import com.davemorrissey.labs.subscaleview.SubsamplingScaleImageView
 import kotlinx.android.synthetic.main.item_page.*
+import kotlinx.coroutines.*
 import org.koitharu.kotatsu.R
 import org.koitharu.kotatsu.core.model.MangaPage
 import org.koitharu.kotatsu.ui.common.list.BaseViewHolder
@@ -13,27 +14,36 @@ import org.koitharu.kotatsu.utils.ext.getDisplayMessage
 
 class PageHolder(parent: ViewGroup, private val loader: PageLoader) :
 	BaseViewHolder<MangaPage, Unit>(parent, R.layout.item_page),
-	SubsamplingScaleImageView.OnImageEventListener {
+	SubsamplingScaleImageView.OnImageEventListener, CoroutineScope by loader {
+
+	private var job: Job? = null
 
 	init {
 		ssiv.setOnImageEventListener(this)
 		button_retry.setOnClickListener {
-			onBind(boundData ?: return@setOnClickListener, Unit)
+			doLoad(boundData ?: return@setOnClickListener, force = true)
 		}
 	}
 
 	override fun onBind(data: MangaPage, extra: Unit) {
-		layout_error.isVisible = false
-		progressBar.isVisible = true
-		ssiv.recycle()
-		loader.load(data.url) {
-			val uri = it.getOrNull()?.toUri()
-			if (uri != null) {
+		doLoad(data, force = false)
+	}
+
+	private fun doLoad(data: MangaPage, force: Boolean) {
+		job?.cancel()
+		job = launch {
+			layout_error.isVisible = false
+			progressBar.isVisible = true
+			ssiv.recycle()
+			try {
+				val uri = withContext(Dispatchers.IO) {
+					loader.loadFile(data.url, force)
+				}.toUri()
 				ssiv.setImage(ImageSource.uri(uri))
-			}
-			val error = it.exceptionOrNull()
-			if (error != null) {
-				onError(error)
+			} catch (e: CancellationException) {
+				//do nothing
+			} catch (e: Exception) {
+				onError(e)
 			}
 		}
 	}

app/src/main/java/org/koitharu/kotatsu/ui/reader/PageLoader.kt

@@ -22,16 +22,7 @@ class PageLoader : KoinComponent, CoroutineScope, DisposableHandle {
 	override val coroutineContext: CoroutineContext
 		get() = Dispatchers.Main + job
 
-	fun load(url: String, force: Boolean = false, callback: (Result<File>) -> Unit) = launch {
-		val result = runCatching {
-			withContext(Dispatchers.IO) {
-				loadFile(url, force)
-			}
-		}
-		callback(result)
-	}
-
-	private suspend fun loadFile(url: String, force: Boolean): File {
+	suspend fun loadFile(url: String, force: Boolean): File {
 		if (!force) {
 			cache[url]?.let {
 				return it

app/src/main/java/org/koitharu/kotatsu/ui/reader/ReaderActivity.kt

@@ -14,6 +14,7 @@ import kotlinx.android.synthetic.main.activity_reader.*
 import moxy.ktx.moxyPresenter
 import org.koitharu.kotatsu.R
 import org.koitharu.kotatsu.core.model.Manga
+import org.koitharu.kotatsu.core.model.MangaChapter
 import org.koitharu.kotatsu.core.model.MangaHistory
 import org.koitharu.kotatsu.core.model.MangaPage
 import org.koitharu.kotatsu.ui.common.BaseFullscreenActivity
@@ -21,9 +22,10 @@ import org.koitharu.kotatsu.utils.GridTouchHelper
 import org.koitharu.kotatsu.utils.anim.Motion
 import org.koitharu.kotatsu.utils.ext.*
 
-class ReaderActivity : BaseFullscreenActivity(), ReaderView, GridTouchHelper.OnGridTouchListener {
+class ReaderActivity : BaseFullscreenActivity(), ReaderView, ChaptersDialog.OnChapterChangeListener,
+	GridTouchHelper.OnGridTouchListener {
 
-	private val presenter by moxyPresenter { ReaderPresenter() }
+	private val presenter by moxyPresenter(factory = ::ReaderPresenter)
 
 	private lateinit var state: ReaderState
 
@@ -146,6 +148,13 @@ class ReaderActivity : BaseFullscreenActivity(), ReaderView, GridTouchHelper.OnG
 		return super.dispatchTouchEvent(ev)
 	}
 
+	override fun onChapterChanged(chapter: MangaChapter) {
+		presenter.loadChapter(state.copy(
+			chapterId = chapter.id,
+			page = 0
+		))
+	}
+
 	companion object {
 
 		private const val EXTRA_STATE = "state"

app/src/main/res/layout/activity_reader.xml

@@ -8,6 +8,7 @@
 
 	<androidx.viewpager2.widget.ViewPager2
 		android:id="@+id/pager"
+		android:keepScreenOn="true"
 		android:layout_width="match_parent"
 		android:layout_height="match_parent" />