From de512216c42f8fd0c45386d5044269b9c1f90d7c Mon Sep 17 00:00:00 2001
From: arkon <eugcheung94@gmail.com>
Date: Mon, 9 Mar 2020 15:09:17 -0400
Subject: [PATCH] Start preloading next chapter if within last 3 pages instead
 of last page

---
 .../tachiyomi/ui/reader/viewer/pager/PagerViewer.kt       | 6 ++++--
 .../ui/reader/viewer/pager/PagerViewerAdapter.kt          | 2 +-
 .../tachiyomi/ui/reader/viewer/webtoon/WebtoonAdapter.kt  | 2 +-
 .../tachiyomi/ui/reader/viewer/webtoon/WebtoonViewer.kt   | 8 +++++---
 4 files changed, 11 insertions(+), 7 deletions(-)

diff --git a/app/src/main/java/eu/kanade/tachiyomi/ui/reader/viewer/pager/PagerViewer.kt b/app/src/main/java/eu/kanade/tachiyomi/ui/reader/viewer/pager/PagerViewer.kt
index 43af3a54e..57c48b6ce 100644
--- a/app/src/main/java/eu/kanade/tachiyomi/ui/reader/viewer/pager/PagerViewer.kt
+++ b/app/src/main/java/eu/kanade/tachiyomi/ui/reader/viewer/pager/PagerViewer.kt
@@ -144,8 +144,10 @@ abstract class PagerViewer(val activity: ReaderActivity) : BaseViewer {
         Timber.d("onReaderPageSelected: ${page.number}/${pages.size}")
         activity.onPageSelected(page)
 
-        if (page === pages.last()) {
-            Timber.d("Request preload next chapter because we're at the last page")
+        // Preload next chapter once we're within the last 3 pages of the current chapter
+        val inPreloadRange = pages.size - page.number < 3
+        if (inPreloadRange) {
+            Timber.d("Request preload next chapter because we're at page ${page.number} of ${pages.size}")
             adapter.nextTransition?.to?.let {
                 activity.requestPreloadChapter(it)
             }
diff --git a/app/src/main/java/eu/kanade/tachiyomi/ui/reader/viewer/pager/PagerViewerAdapter.kt b/app/src/main/java/eu/kanade/tachiyomi/ui/reader/viewer/pager/PagerViewerAdapter.kt
index 980674333..57a644dcf 100644
--- a/app/src/main/java/eu/kanade/tachiyomi/ui/reader/viewer/pager/PagerViewerAdapter.kt
+++ b/app/src/main/java/eu/kanade/tachiyomi/ui/reader/viewer/pager/PagerViewerAdapter.kt
@@ -42,7 +42,7 @@ class PagerViewerAdapter(private val viewer: PagerViewer) : ViewPagerAdapter() {
             }
         }
 
-        // Skip transition page if  the chapter is loaded & current page is not a transition page
+        // Skip transition page if the chapter is loaded & current page is not a transition page
         if (forceTransition || chapters.prevChapter?.state !is ReaderChapter.State.Loaded) {
             newItems.add(ChapterTransition.Prev(chapters.currChapter, chapters.prevChapter))
         }
diff --git a/app/src/main/java/eu/kanade/tachiyomi/ui/reader/viewer/webtoon/WebtoonAdapter.kt b/app/src/main/java/eu/kanade/tachiyomi/ui/reader/viewer/webtoon/WebtoonAdapter.kt
index e65a73b8f..ee0afca88 100644
--- a/app/src/main/java/eu/kanade/tachiyomi/ui/reader/viewer/webtoon/WebtoonAdapter.kt
+++ b/app/src/main/java/eu/kanade/tachiyomi/ui/reader/viewer/webtoon/WebtoonAdapter.kt
@@ -38,7 +38,7 @@ class WebtoonAdapter(val viewer: WebtoonViewer) : RecyclerView.Adapter<RecyclerV
             }
         }
 
-        // Skip transition page if  the chapter is loaded & current page is not a transition page
+        // Skip transition page if the chapter is loaded & current page is not a transition page
         if (forceTransition || chapters.prevChapter?.state !is ReaderChapter.State.Loaded) {
             newItems.add(ChapterTransition.Prev(chapters.currChapter, chapters.prevChapter))
         }
diff --git a/app/src/main/java/eu/kanade/tachiyomi/ui/reader/viewer/webtoon/WebtoonViewer.kt b/app/src/main/java/eu/kanade/tachiyomi/ui/reader/viewer/webtoon/WebtoonViewer.kt
index 90422a2c1..7805300ff 100644
--- a/app/src/main/java/eu/kanade/tachiyomi/ui/reader/viewer/webtoon/WebtoonViewer.kt
+++ b/app/src/main/java/eu/kanade/tachiyomi/ui/reader/viewer/webtoon/WebtoonViewer.kt
@@ -145,9 +145,11 @@ class WebtoonViewer(val activity: ReaderActivity) : BaseViewer {
         Timber.d("onPageSelected: ${page.number}/${pages.size}")
         activity.onPageSelected(page)
 
-        if (page === pages.last()) {
-            Timber.d("Request preload next chapter because we're at the last page")
-            val transition = adapter.items.getOrNull(position + 1) as? ChapterTransition.Next
+        // Preload next chapter once we're within the last 3 pages of the current chapter
+        val inPreloadRange = pages.size - page.number < 3
+        if (inPreloadRange) {
+            Timber.d("Request preload next chapter because we're at page ${page.number} of ${pages.size}")
+            val transition = adapter.items.getOrNull(pages.size + 1) as? ChapterTransition.Next
             if (transition?.to != null) {
                 activity.requestPreloadChapter(transition.to)
             }