滚动阅读时,多指触摸造成闪烁的问题

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

@@ -27,10 +27,7 @@ import io.legado.app.ui.book.read.page.entities.TextPage
 import io.legado.app.ui.book.read.page.entities.TextPos
 import io.legado.app.ui.book.read.page.provider.ChapterProvider
 import io.legado.app.ui.book.read.page.provider.TextPageFactory
-import io.legado.app.utils.activity
-import io.legado.app.utils.invisible
-import io.legado.app.utils.screenshot
-import io.legado.app.utils.showDialogFragment
+import io.legado.app.utils.*
 import java.text.BreakIterator
 import java.util.*
 import kotlin.math.abs
@@ -184,6 +181,15 @@ class ReadView(context: Context, attrs: AttributeSet) :
             }
         }
 
+        //在多点触控时，事件不走ACTION_DOWN分支而产生的特殊事件处理
+        if (event.actionMasked == MotionEvent.ACTION_POINTER_DOWN){
+            //当多个手指同时按下的情况，将最后一个按下的手指的坐标设置为起始坐标，所以只有最后一个手指的滑动事件被处理
+            setStartPoint(event.getX(event.pointerCount - 1), event.getY(event.pointerCount - 1), false)
+        } else if(event.actionMasked == MotionEvent.ACTION_POINTER_UP){
+            //当多个手指同时按下的情况，当抬起一个手指时，起始坐标恢复为第一次按下的手指的坐标
+            setStartPoint(event.x, event.y, false)
+            return true
+        }
         when (event.action) {
             MotionEvent.ACTION_DOWN -> {
                 callBack.screenOffTimerStart()

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

@@ -58,10 +58,14 @@ class ScrollPageDelegate(readView: ReadView) : PageDelegate(readView) {
     private fun onScroll(event: MotionEvent) {
         mVelocity.addMovement(event)
         mVelocity.computeCurrentVelocity(velocityDuration)
-        readView.setTouchPoint(event.getX(0), event.getY(0))
+        //取最后添加(即最新的)一个触摸点来计算滚动位置
+        //多点触控时即最后按下的手指产生的事件点
+        val pointX = event.getX(event.pointerCount - 1)
+        val pointY = event.getY(event.pointerCount - 1)
+        readView.setTouchPoint(pointX, pointY)
         if (!isMoved) {
-            val deltaX = (event.getX(0) - startX).toInt()
-            val deltaY = (event.getY(0) - startY).toInt()
+            val deltaX = (pointX - startX).toInt()
+            val deltaY = (pointY - startY).toInt()
             val distance = deltaX * deltaX + deltaY * deltaY
             isMoved = distance > readView.slopSquare
         }