feat: 优化代码

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

@@ -219,19 +219,23 @@ class SimulationPageDelegate(pageView: PageView) : HorizontalPageDelegate(pageVi
     }
 
     override fun onDraw(canvas: Canvas) {
-        if (mDirection === Direction.NEXT) {
+        when (mDirection) {
+            Direction.NEXT -> {
                 calcPoints()
                 drawCurrentPageArea(canvas, curBitmap)
                 drawNextPageAreaAndShadow(canvas, nextBitmap)
                 drawCurrentPageShadow(canvas)
                 drawCurrentBackArea(canvas, curBitmap)
-        } else {
+            }
+            Direction.PREV -> {
                 calcPoints()
                 drawCurrentPageArea(canvas, prevBitmap)
                 drawNextPageAreaAndShadow(canvas, curBitmap)
                 drawCurrentPageShadow(canvas)
                 drawCurrentBackArea(canvas, prevBitmap)
             }
+            else -> Unit
+        }
     }
 
     /**