Added dual page split setting (#4252)

* Add DualPageSplit option

* remove extra line

* Split double-page into two pages

* Remove !isAnimated check and add (ALPHA) to the label

* Fix missing insert pages

* Pager cleanup

* Add dual split to Webtoon and fix Vertical

* Fix L2R/R2L

* Add comments and refactor code in ImageUtil

* Use a simpler split solution in webtoon mode

Co-authored-by: weng <>
Co-authored-by: Andreas E <andreas.everos@gmail.com>

app/src/main/java/eu/kanade/tachiyomi/ui/setting/SettingsReaderController.kt

@@ -50,6 +50,11 @@ class SettingsReaderController : SettingsController() {
             summaryRes = R.string.pref_show_reading_mode_summary
             defaultValue = true
         }
+        switchPreference {
+            key = Keys.dualPageSplit
+            titleRes = R.string.pref_dual_page_split
+            defaultValue = false
+        }
         if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
             switchPreference {
                 key = Keys.trueColor