优化

app/src/main/java/io/legado/app/utils/PictureMirror.kt

@@ -7,13 +7,15 @@ import androidx.core.graphics.record
 import java.util.concurrent.locks.ReentrantLock
 
 class PictureMirror {
-
+    @Volatile
     var picture: Picture? = null
 
     @Volatile
-    var isDirty = true
     var lock: ReentrantLock? = null
 
+    @Volatile
+    var isDirty = true
+
     inline fun drawLocked(
         canvas: Canvas?,
         width: Int,