优化

app/src/main/java/io/legado/app/help/config/AppConfig.kt

@@ -413,9 +413,9 @@ object AppConfig : SharedPreferences.OnSharedPreferenceChangeListener {
 
     var sourceEditMaxLine: Int
         get() {
-            val maxLine = appCtx.getPrefInt(PreferKey.sourceEditMaxLine, 99)
+            val maxLine = appCtx.getPrefInt(PreferKey.sourceEditMaxLine, Int.MAX_VALUE)
             if (maxLine < 10) {
-                return 99
+                return Int.MAX_VALUE
             }
             return maxLine
         }

app/src/main/java/io/legado/app/ui/config/OtherConfigFragment.kt

@@ -85,7 +85,7 @@ class OtherConfigFragment : PreferenceFragment(),
             PreferKey.preDownloadNum -> NumberPickerDialog(requireContext())
                 .setTitle(getString(R.string.pre_download))
                 .setMaxValue(9999)
-                .setMinValue(1)
+                .setMinValue(0)
                 .setValue(AppConfig.preDownloadNum)
                 .show {
                     AppConfig.preDownloadNum = it
@@ -123,7 +123,7 @@ class OtherConfigFragment : PreferenceFragment(),
             PreferKey.sourceEditMaxLine -> {
                 NumberPickerDialog(requireContext())
                     .setTitle(getString(R.string.source_edit_text_max_line))
-                    .setMaxValue(99)
+                    .setMaxValue(Int.MAX_VALUE)
                     .setMinValue(10)
                     .setValue(AppConfig.sourceEditMaxLine)
                     .show {

app/src/main/java/io/legado/app/ui/main/MainViewModel.kt

@@ -178,6 +178,7 @@ class MainViewModel(application: Application) : BaseViewModel(application) {
 
     @Synchronized
     private fun addDownload(source: BookSource, book: Book) {
+        if (AppConfig.preDownloadNum == 0) return
         val endIndex = min(
             book.totalChapterNum - 1,
             book.durChapterIndex.plus(AppConfig.preDownloadNum)