优化图片样式单页显示逻辑

- 当书籍图片样式为空或书源内容规则为单页样式时，自动切换为单页显示
- 在切换为单页样式时，将页面切换动画设置为覆盖

app/src/main/java/io/legado/app/model/ReadBook.kt

@@ -169,8 +169,9 @@ object ReadBook : CoroutineScope by MainScope() {
         } else {
             appDb.bookSourceDao.getBookSource(book.origin)?.let {
                 bookSource = it
-                if (book.getImageStyle().isNullOrBlank()) {
+                if (book.getImageStyle().isNullOrBlank() || it.getContentRule().imageStyle == Book.imgStyleSingle) {
                     book.setImageStyle(it.getContentRule().imageStyle)
+                    book.setPageAnim(0)
                 }
             } ?: let {
                 bookSource = null

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

@@ -571,6 +571,8 @@ class ReadBookActivity : BaseReadBookActivity(),
                     imgStyles
                 ) { _, index ->
                     ReadBook.book?.setImageStyle(imgStyles[index])
+                    ReadBook.book?.setPageAnim(0)  // 切换图片样式single后，自动切换为覆盖
+                    binding.readView.upPageAnim()
                     ReadBook.loadContent(false)
                 }
             }