Fix invalid total page count. Close #348

lib/pages/reader/images.dart

@@ -119,7 +119,7 @@ class _GalleryModeState extends State<_GalleryMode>
   /// [totalPages] is the total number of pages in the current chapter.
   /// More than one images can be displayed on one page.
   int get totalPages {
-    if (!showSingleImageOnFirstPage) {
+    if (!reader.showSingleImageOnFirstPage) {
       return (reader.images!.length / reader.imagesPerPage).ceil();
     } else {
       return 1 +
@@ -144,11 +144,9 @@ class _GalleryModeState extends State<_GalleryMode>
     super.initState();
   }
 
-  bool get showSingleImageOnFirstPage => appdata.settings["showSingleImageOnFirstPage"];
-
   /// Get the range of images for the given page. [page] is 1-based.
   (int start, int end) getPageImagesRange(int page) {
-    if (showSingleImageOnFirstPage) {
+    if (reader.showSingleImageOnFirstPage) {
       if (page == 1) {
         return (0, 1);
       } else {

lib/pages/reader/reader.dart

@@ -111,7 +111,13 @@ class _ReaderState extends State<Reader>
   }
 
   @override
-  int get maxPage => ((images?.length ?? 1) / imagesPerPage).ceil();
+  int get maxPage {
+    if (!showSingleImageOnFirstPage) {
+      return (images!.length / imagesPerPage).ceil();
+    } else {
+      return 1 + ((images!.length - 1) / imagesPerPage).ceil();
+    }
+  }
 
   ComicType get type => widget.type;
 
@@ -125,7 +131,8 @@ class _ReaderState extends State<Reader>
   late ReaderMode mode;
 
   @override
-  bool get isPortrait => MediaQuery.of(context).orientation == Orientation.portrait;
+  bool get isPortrait =>
+      MediaQuery.of(context).orientation == Orientation.portrait;
 
   History? history;
 
@@ -343,6 +350,9 @@ abstract mixin class _ImagePerPageHandler {
     }
   }
 
+  bool get showSingleImageOnFirstPage =>
+      appdata.settings["showSingleImageOnFirstPage"];
+
   /// The number of images displayed on one screen
   int get imagesPerPage {
     if (mode.isContinuous) return 1;