Add an option to disable double tap to zoom.

lib/pages/reader/gesture.dart

@@ -152,12 +152,18 @@ class _ReaderGestureDetectorState extends AutomaticGlobalState<_ReaderGestureDet
 
   bool _dragInProgress = false;
 
+  bool get _enableDoubleTapToZoom => appdata.settings["enableDoubleTapToZoom"];
+
   void onTapUp(TapUpDetails event) {
     if (_longPressInProgress) {
       _longPressInProgress = false;
       return;
     }
     final location = event.globalPosition;
+    if (!_enableDoubleTapToZoom) {
+      onTap(location);
+      return;
+    }
     final previousLocation = _previousEvent?.globalPosition;
     if (previousLocation != null) {
       if ((location - previousLocation).distanceSquared <

lib/pages/reader/images.dart

@@ -250,6 +250,7 @@ class _GalleryModeState extends State<_GalleryMode>
             }
 
             return PhotoViewGalleryPageOptions.customChild(
+              childSize: reader.size * 2,
               controller: photoViewControllers[index],
               minScale: PhotoViewComputedScale.contained * 1.0,
               maxScale: PhotoViewComputedScale.covered * 10.0,

lib/pages/reader/reader.dart

@@ -112,6 +112,9 @@ class _ReaderState extends State<Reader>
 
   @override
   int get maxPage {
+    if (images == null) {
+      return 1;
+    }
     if (!showSingleImageOnFirstPage) {
       return (images!.length / imagesPerPage).ceil();
     } else {