feat: 优化代码

app/src/main/java/io/legado/app/ui/book/read/page/ContentTextView.kt

@@ -35,7 +35,6 @@ class ContentTextView(context: Context, attrs: AttributeSet?) : View(context, at
     private val maxScrollOffset = 100f
     private var pageOffset = 0f
     private var linePos = 0
-    private var isLastPage = false
 
     init {
         callBack = activity as CallBack
@@ -163,7 +162,6 @@ class ContentTextView(context: Context, attrs: AttributeSet?) : View(context, at
     fun resetPageOffset() {
         pageOffset = 0f
         linePos = 0
-        isLastPage = false
     }
 
     fun selectText(x: Float, y: Float): Boolean {

app/src/main/java/io/legado/app/ui/book/read/page/ContentView.kt

@@ -111,6 +111,10 @@ class ContentView(context: Context) : FrameLayout(context) {
         content_text_view.onScroll(offset)
     }
 
+    fun resetPageOffset() {
+        content_text_view.resetPageOffset()
+    }
+
     fun upSelectAble(selectAble: Boolean) {
         content_text_view.selectAble = selectAble
     }

app/src/main/java/io/legado/app/ui/book/read/page/PageView.kt

@@ -100,6 +100,7 @@ class PageView(context: Context, attrs: AttributeSet) :
 
     fun upContent(position: Int = 0) {
         if (ReadBookConfig.isScroll) {
+            curPage.resetPageOffset()
             curPage.setContent(pageFactory.currentPage)
         } else {
             when (position) {

app/src/main/java/io/legado/app/ui/book/read/page/delegate/ScrollPageDelegate.kt

@@ -31,11 +31,14 @@ class ScrollPageDelegate(pageView: PageView) : PageDelegate(pageView) {
         }
     }
 
-    override fun onDown(e: MotionEvent): Boolean {
+    override fun onTouch(event: MotionEvent): Boolean {
+        if (event.action == MotionEvent.ACTION_DOWN) {
+            setStartPoint(event.x, event.y)
             abort()
             mVelocity.clear()
-        mVelocity.addMovement(e)
+            mVelocity.addMovement(event)
-        return super.onDown(e)
+        }
+        return super.onTouch(event)
     }
 
     override fun onScroll(