From b6565c8cb9d6b5ae62f3cb73dfd97d8c2ae05bf7 Mon Sep 17 00:00:00 2001
From: gedoor <gekunfei@live.com>
Date: Tue, 11 May 2021 08:43:50 +0800
Subject: [PATCH] =?UTF-8?q?=E4=BC=98=E5=8C=96?=
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---
 .../java/io/legado/app/ui/main/bookshelf/RootView.kt | 12 +++++-------
 1 file changed, 5 insertions(+), 7 deletions(-)

diff --git a/app/src/main/java/io/legado/app/ui/main/bookshelf/RootView.kt b/app/src/main/java/io/legado/app/ui/main/bookshelf/RootView.kt
index 938116e4e..0e8225fc0 100644
--- a/app/src/main/java/io/legado/app/ui/main/bookshelf/RootView.kt
+++ b/app/src/main/java/io/legado/app/ui/main/bookshelf/RootView.kt
@@ -23,12 +23,10 @@ class RootView : LinearLayout {
     private var initialX = 0f
     private var initialY = 0f
 
-    private val parentViewPager: ViewPager2
-        get() {
-            return (activity as MainActivity).getViewPager()
-        }
-
-    private val childViewPager: View get() = findViewById(R.id.view_pager_bookshelf)
+    private val parentViewPager: ViewPager2?
+        get() = (activity as? MainActivity)?.getViewPager()
+    private val childViewPager: View
+        get() = findViewById(R.id.view_pager_bookshelf)
 
     init {
         touchSlop = ViewConfiguration.get(context).scaledTouchSlop
@@ -49,7 +47,7 @@ class RootView : LinearLayout {
     }
 
     private fun handleInterceptTouchEvent(e: MotionEvent) {
-        val orientation = parentViewPager.orientation
+        val orientation = parentViewPager?.orientation ?: return
         // Early return if child can't scroll in same direction as parent
         if (!canChildScroll(orientation, -1f) && !canChildScroll(orientation, 1f)) {
             return