From bc760cf7b17c64a47bab0785aa93917f32d3fb62 Mon Sep 17 00:00:00 2001
From: Jays2Kings <jays@outlook.com>
Date: Sat, 24 Apr 2021 14:09:49 -0400
Subject: [PATCH] Fixes to fast scroller

Using android back gesture no longer sometimes jump the screen
Fix issue when sometimes dragging fastscroll tries to drag to the top on release
---
 .../tachiyomi/ui/base/MaterialFastScroll.kt   | 28 +++++++++++++++++--
 .../tachiyomi/ui/library/LibraryController.kt |  1 +
 .../util/view/ControllerExtensions.kt         |  1 +
 3 files changed, 28 insertions(+), 2 deletions(-)

diff --git a/app/src/main/java/eu/kanade/tachiyomi/ui/base/MaterialFastScroll.kt b/app/src/main/java/eu/kanade/tachiyomi/ui/base/MaterialFastScroll.kt
index 746623609e..5cd498eda7 100644
--- a/app/src/main/java/eu/kanade/tachiyomi/ui/base/MaterialFastScroll.kt
+++ b/app/src/main/java/eu/kanade/tachiyomi/ui/base/MaterialFastScroll.kt
@@ -9,6 +9,7 @@ import androidx.recyclerview.widget.RecyclerView
 import androidx.recyclerview.widget.StaggeredGridLayoutManager
 import eu.davidea.fastscroller.FastScroller
 import eu.kanade.tachiyomi.R
+import eu.kanade.tachiyomi.util.system.dpToPx
 import eu.kanade.tachiyomi.util.system.dpToPxEnd
 import eu.kanade.tachiyomi.util.view.marginTop
 import kotlin.math.abs
@@ -53,7 +54,7 @@ class MaterialFastScroll @JvmOverloads constructor(context: Context, attrs: Attr
             }
             MotionEvent.ACTION_MOVE -> {
                 val y = event.y
-                if (!canScroll && abs(y - startY) > 10) {
+                if (!canScroll && abs(y - startY) > 15.dpToPx) {
                     canScroll = true
                     handle.isSelected = true
                     notifyScrollStateChange(true)
@@ -69,6 +70,22 @@ class MaterialFastScroll @JvmOverloads constructor(context: Context, attrs: Attr
             MotionEvent.ACTION_UP, MotionEvent.ACTION_CANCEL -> {
                 startY = 0f
                 canScroll = false
+                val newEvent = MotionEvent.obtain(event)
+                recyclerView.post {
+                    // Mimic touch event for recycler so it doesn't scroll back
+                    val lastTag = recyclerView.tag
+                    recyclerView.tag = noUpdate
+                    newEvent.action = MotionEvent.ACTION_MOVE
+                    recyclerView.dispatchTouchEvent(newEvent)
+                    val newEvent2 = MotionEvent.obtain(newEvent)
+                    newEvent2.action = MotionEvent.ACTION_CANCEL
+                    recyclerView.dispatchTouchEvent(newEvent2)
+                    newEvent2.recycle()
+                    newEvent.recycle()
+                    recyclerView.post {
+                        recyclerView.tag = lastTag
+                    }
+                }
             }
         }
         return super.onTouchEvent(event)
@@ -91,7 +108,10 @@ class MaterialFastScroll @JvmOverloads constructor(context: Context, attrs: Attr
                     scrollOffset
                 )
             } else {
-                (layoutManager as LinearLayoutManager).scrollToPositionWithOffset(targetPos, scrollOffset)
+                (layoutManager as LinearLayoutManager).scrollToPositionWithOffset(
+                    targetPos,
+                    scrollOffset
+                )
             }
             updateBubbleText(targetPos)
         }
@@ -114,4 +134,8 @@ class MaterialFastScroll @JvmOverloads constructor(context: Context, attrs: Attr
             }
         }
     }
+
+    companion object {
+        const val noUpdate = "don't update scroll"
+    }
 }
diff --git a/app/src/main/java/eu/kanade/tachiyomi/ui/library/LibraryController.kt b/app/src/main/java/eu/kanade/tachiyomi/ui/library/LibraryController.kt
index 31c5b2c0f6..b56a109e9a 100644
--- a/app/src/main/java/eu/kanade/tachiyomi/ui/library/LibraryController.kt
+++ b/app/src/main/java/eu/kanade/tachiyomi/ui/library/LibraryController.kt
@@ -219,6 +219,7 @@ class LibraryController(
     private var scrollListener = object : RecyclerView.OnScrollListener() {
         override fun onScrolled(recyclerView: RecyclerView, dx: Int, dy: Int) {
             super.onScrolled(recyclerView, dx, dy)
+            if (recyclerView.tag == MaterialFastScroll.noUpdate) return
             val recyclerCover = binding.recyclerCover
             if (!recyclerCover.isClickable && isAnimatingHopper != true) {
                 if (preferences.autohideHopper().get()) {
diff --git a/app/src/main/java/eu/kanade/tachiyomi/util/view/ControllerExtensions.kt b/app/src/main/java/eu/kanade/tachiyomi/util/view/ControllerExtensions.kt
index b37657c6a3..dd41a06f38 100644
--- a/app/src/main/java/eu/kanade/tachiyomi/util/view/ControllerExtensions.kt
+++ b/app/src/main/java/eu/kanade/tachiyomi/util/view/ControllerExtensions.kt
@@ -251,6 +251,7 @@ fun Controller.scrollViewWith(
         object : RecyclerView.OnScrollListener() {
             override fun onScrolled(recyclerView: RecyclerView, dx: Int, dy: Int) {
                 super.onScrolled(recyclerView, dx, dy)
+                if (recyclerView.tag == MaterialFastScroll.noUpdate) return
                 if (router?.backstack?.lastOrNull()
                     ?.controller() == this@scrollViewWith && statusBarHeight > -1 &&
                     activity != null && activityBinding!!.appBar.height > 0 &&