Multiple bugfixes for the reader, includes double page and chapter buttons

app/src/main/java/eu/kanade/tachiyomi/ui/reader/ReaderActivity.kt

@@ -477,7 +477,12 @@ class ReaderActivity : BaseRxActivity<ReaderActivityBinding, ReaderPresenter>()
             binding.toolbarBottom,
             binding.leftChapter,
             binding.readerSeekbar,
-            binding.rightChapter
+            binding.rightChapter,
+            // SY -->
+            binding.pageSeekbarVert,
+            binding.aboveChapter,
+            binding.belowChapter
+            // SY <--
         ).forEach {
             it.backgroundTintMode = PorterDuff.Mode.DST_IN
             it.backgroundTintList = ColorStateList.valueOf(toolbarColor)
@@ -1072,6 +1077,8 @@ class ReaderActivity : BaseRxActivity<ReaderActivityBinding, ReaderPresenter>()
             binding.leftChapter.setTooltip(R.string.action_previous_chapter)
             binding.rightChapter.setTooltip(R.string.action_next_chapter)
         }
+        binding.aboveChapter.setTooltip(R.string.action_previous_chapter)
+        binding.belowChapter.setTooltip(R.string.action_next_chapter)
 
         binding.pleaseWait.isVisible = true
         binding.pleaseWait.startAnimation(AnimationUtils.loadAnimation(this, R.anim.fade_in_long))
@@ -1122,12 +1129,20 @@ class ReaderActivity : BaseRxActivity<ReaderActivityBinding, ReaderPresenter>()
         if (leftChapterObject == null && rightChapterObject == null) {
             binding.leftChapter.isVisible = false
             binding.rightChapter.isVisible = false
+            binding.aboveChapter.isVisible = false
+            binding.belowChapter.isVisible = false
         } else {
             binding.leftChapter.isEnabled = leftChapterObject != null
             binding.leftChapter.imageAlpha = if (leftChapterObject != null) ENABLED_BUTTON_IMAGE_ALPHA else DISABLED_BUTTON_IMAGE_ALPHA
 
             binding.rightChapter.isEnabled = rightChapterObject != null
             binding.rightChapter.imageAlpha = if (rightChapterObject != null) ENABLED_BUTTON_IMAGE_ALPHA else DISABLED_BUTTON_IMAGE_ALPHA
+
+            binding.aboveChapter.isEnabled = leftChapterObject != null
+            binding.aboveChapter.imageAlpha = if (leftChapterObject != null) ENABLED_BUTTON_IMAGE_ALPHA else DISABLED_BUTTON_IMAGE_ALPHA
+
+            binding.belowChapter.isEnabled = rightChapterObject != null
+            binding.belowChapter.imageAlpha = if (rightChapterObject != null) ENABLED_BUTTON_IMAGE_ALPHA else DISABLED_BUTTON_IMAGE_ALPHA
         }
 
         // Invalidate menu to show proper chapter bookmark state

app/src/main/java/eu/kanade/tachiyomi/ui/reader/ReaderPresenter.kt

@@ -380,7 +380,7 @@ class ReaderPresenter(
             .also(::add)
     }
 
-    fun loadNewChapterFromSheet(chapter: Chapter) {
+    fun loadNewChapterFromDialog(chapter: Chapter) {
         val newChapter = chapterList.firstOrNull { it.chapter.id == chapter.id } ?: return
         loadAdjacent(newChapter)
     }

app/src/main/java/eu/kanade/tachiyomi/ui/reader/chapter/ReaderChapterDialog.kt

@@ -34,7 +34,7 @@ class ReaderChapterDialog(private val activity: ReaderActivity) : ReaderChapterA
                     val item = adapter?.getItem(position)
                     if (item != null && item.id != presenter.getCurrentChapter()?.chapter?.id) {
                         dismiss()
-                        presenter.loadNewChapterFromSheet(item)
+                        presenter.loadNewChapterFromDialog(item)
                     }
                     true
                 }

app/src/main/java/eu/kanade/tachiyomi/ui/reader/viewer/pager/PagerViewer.kt

@@ -66,7 +66,7 @@ abstract class PagerViewer(val activity: ReaderActivity) : BaseViewer {
             field = value
             if (value) {
                 awaitingIdleViewerChapters?.let {
-                    setChaptersInternal(it)
+                    setChaptersDoubleShift(it)
                     awaitingIdleViewerChapters = null
                 }
             }
@@ -239,7 +239,7 @@ abstract class PagerViewer(val activity: ReaderActivity) : BaseViewer {
      */
     override fun setChapters(chapters: ViewerChapters) {
         if (isIdle) {
-            setChaptersInternal(chapters)
+            setChaptersDoubleShift(chapters)
         } else {
             awaitingIdleViewerChapters = chapters
         }