优化

app/src/main/java/io/legado/app/ui/book/info/edit/BookInfoEditActivity.kt

@@ -132,7 +132,8 @@ class BookInfoEditActivity :
         book.addType(bookType)
         val customCoverUrl = tieCoverUrl.text?.toString()
         book.customCoverUrl = if (customCoverUrl == book.coverUrl) null else customCoverUrl
-        book.customIntro = tieBookIntro.text?.toString()
+        val customIntro = tieBookIntro.text?.toString()
+        book.customIntro = if (customIntro == book.intro) null else customIntro
         BookHelp.updateCacheFolder(oldBook, book)
         viewModel.saveBook(book) {
             setResult(Activity.RESULT_OK)

app/src/main/res/layout/dialog_add_to_bookshelf.xml

@@ -95,7 +95,7 @@
         android:layout_height="wrap_content"
         android:padding="16dp"
         android:text="@string/ok"
-        android:visibility="invisible"
+        android:visibility="gone"
         app:layout_constraintBottom_toBottomOf="parent"
         app:layout_constraintRight_toRightOf="parent"
         app:layout_constraintTop_toBottomOf="@+id/book_info" />