From 83a424a1726c23a96f197f28d7ad9340fbc4650b Mon Sep 17 00:00:00 2001
From: Christian Falch <875252+chrfalch@users.noreply.github.com>
Date: Fri, 1 Sep 2023 18:05:45 +0200
Subject: [PATCH] Add custom `readingOrder` to `EpubNavigatorFragment` (#376)

---
 .../r2/navigator/epub/EpubNavigatorFactory.kt |  3 +++
 .../navigator/epub/EpubNavigatorFragment.kt   | 23 ++++++++++++-------
 2 files changed, 18 insertions(+), 8 deletions(-)

diff --git a/readium/navigator/src/main/java/org/readium/r2/navigator/epub/EpubNavigatorFactory.kt b/readium/navigator/src/main/java/org/readium/r2/navigator/epub/EpubNavigatorFactory.kt
index e02a03b13c..41714aec1c 100644
--- a/readium/navigator/src/main/java/org/readium/r2/navigator/epub/EpubNavigatorFactory.kt
+++ b/readium/navigator/src/main/java/org/readium/r2/navigator/epub/EpubNavigatorFactory.kt
@@ -7,6 +7,7 @@
 package org.readium.r2.navigator.epub
 
 import org.readium.r2.shared.ExperimentalReadiumApi
+import org.readium.r2.shared.publication.Link
 import org.readium.r2.shared.publication.Locator
 import org.readium.r2.shared.publication.Publication
 import org.readium.r2.shared.publication.epub.EpubLayout
@@ -38,6 +39,7 @@ class EpubNavigatorFactory(
 
     fun createFragmentFactory(
         initialLocator: Locator?,
+        readingOrder: List<Link>? = null,
         initialPreferences: EpubPreferences = EpubPreferences(),
         listener: EpubNavigatorFragment.Listener? = null,
         paginationListener: EpubNavigatorFragment.PaginationListener? = null,
@@ -47,6 +49,7 @@ class EpubNavigatorFactory(
             publication = publication,
             baseUrl = null,
             initialLocator = initialLocator,
+            readingOrder = readingOrder,
             initialPreferences = initialPreferences,
             listener = listener,
             paginationListener = paginationListener,
diff --git a/readium/navigator/src/main/java/org/readium/r2/navigator/epub/EpubNavigatorFragment.kt b/readium/navigator/src/main/java/org/readium/r2/navigator/epub/EpubNavigatorFragment.kt
index ffb45d513a..54b5e6b5fe 100644
--- a/readium/navigator/src/main/java/org/readium/r2/navigator/epub/EpubNavigatorFragment.kt
+++ b/readium/navigator/src/main/java/org/readium/r2/navigator/epub/EpubNavigatorFragment.kt
@@ -91,6 +91,7 @@ class EpubNavigatorFragment internal constructor(
     override val publication: Publication,
     private val baseUrl: String?,
     private val initialLocator: Locator?,
+    readingOrder: List<Link>?,
     private val initialPreferences: EpubPreferences,
     internal val listener: Listener?,
     internal val paginationListener: PaginationListener?,
@@ -274,7 +275,12 @@ class EpubNavigatorFragment internal constructor(
         )
     }
 
-    internal lateinit var positionsByReadingOrder: List<List<Locator>>
+    private val readingOrder: List<Link> = readingOrder ?: publication.readingOrder
+
+    private val positionsByReadingOrder: List<List<Locator>> =
+        if (readingOrder != null) emptyList()
+        else runBlocking { publication.positionsByReadingOrder() }
+
     internal lateinit var positions: List<Locator>
     lateinit var resourcePager: R2ViewPager
 
@@ -306,13 +312,12 @@ class EpubNavigatorFragment internal constructor(
         _binding = ActivityR2ViewpagerBinding.inflate(inflater, container, false)
         val view = binding.root
 
-        positionsByReadingOrder = runBlocking { publication.positionsByReadingOrder() }
         positions = positionsByReadingOrder.flatten()
         publicationIdentifier = publication.metadata.identifier ?: publication.metadata.title
 
         when (viewModel.layout) {
             EpubLayout.REFLOWABLE -> {
-                resourcesSingle = publication.readingOrder.mapIndexed { index, link ->
+                resourcesSingle = readingOrder.mapIndexed { index, link ->
                     PageResource.EpubReflowable(
                         link = link,
                         url = viewModel.urlTo(link),
@@ -329,7 +334,7 @@ class EpubNavigatorFragment internal constructor(
                 var doublePageLeft: Link? = null
                 var doublePageRight: Link? = null
 
-                for ((index, link) in publication.readingOrder.withIndex()) {
+                for ((index, link) in readingOrder.withIndex()) {
                     val url = viewModel.urlTo(link)
                     resourcesSingle.add(PageResource.EpubFxl(leftLink = link, leftUrl = url))
 
@@ -881,7 +886,7 @@ class EpubNavigatorFragment internal constructor(
         locatorToResourceAtIndex(resourcePager.currentItem + 1)
 
     private fun locatorToResourceAtIndex(index: Int): Locator? =
-        publication.readingOrder.getOrNull(index)
+        readingOrder.getOrNull(index)
             ?.let { publication.locatorFromLink(it) }
 
     private val r2PagerAdapter: R2PagerAdapter?
@@ -919,7 +924,7 @@ class EpubNavigatorFragment internal constructor(
     override val currentLocator: StateFlow<Locator> get() = _currentLocator
     private val _currentLocator = MutableStateFlow(
         initialLocator
-            ?: requireNotNull(publication.locatorFromLink(publication.readingOrder.first()))
+            ?: requireNotNull(publication.locatorFromLink(this.readingOrder.first()))
     )
 
     /**
@@ -930,7 +935,7 @@ class EpubNavigatorFragment internal constructor(
     override suspend fun firstVisibleElementLocator(): Locator? {
         if (!::resourcePager.isInitialized) return null
 
-        val resource = publication.readingOrder[resourcePager.currentItem]
+        val resource = readingOrder[resourcePager.currentItem]
         return currentReflowablePageFragment?.webView?.findFirstVisibleLocator()
             ?.copy(
                 href = resource.href,
@@ -1035,6 +1040,7 @@ class EpubNavigatorFragment internal constructor(
          * if you use a local HTTP server.
          * @param initialLocator The first location which should be visible when rendering the
          * publication. Can be used to restore the last reading location.
+         * @param readingOrder custom reading order
          * @param listener Optional listener to implement to observe events, such as user taps.
          * @param config Additional configuration.
          */
@@ -1042,6 +1048,7 @@ class EpubNavigatorFragment internal constructor(
             publication: Publication,
             baseUrl: String? = null,
             initialLocator: Locator? = null,
+            readingOrder: List<Link>? = null,
             listener: Listener? = null,
             paginationListener: PaginationListener? = null,
             config: Configuration = Configuration(),
@@ -1049,7 +1056,7 @@ class EpubNavigatorFragment internal constructor(
         ): FragmentFactory =
             createFragmentFactory {
                 EpubNavigatorFragment(
-                    publication, baseUrl, initialLocator, initialPreferences,
+                    publication, baseUrl, initialLocator, readingOrder, initialPreferences,
                     listener, paginationListener,
                     epubLayout = publication.metadata.presentation.layout ?: EpubLayout.REFLOWABLE,
                     defaults = EpubDefaults(),