Improve changing chapter gesture with continuous mode.

assets/translation.json

@@ -361,7 +361,9 @@
     "Last Reading: @epName Page @page": "上次阅读: @epName 第 @page 页",
     "WebDAV Auto Sync": "WebDAV 自动同步",
     "Mark all as read": "全部标记为已读",
-    "Do you want to mark all as read?" : "您要全部标记为已读吗？"
+    "Do you want to mark all as read?" : "您要全部标记为已读吗？",
+    "Swipe down for previous chapter": "向下滑动查看上一章",
+    "Swipe up for next chapter": "向上滑动查看下一章"
   },
   "zh_TW": {
     "Home": "首頁",
@@ -725,6 +727,8 @@
     "Last Reading: @epName Page @page": "上次閱讀: @epName 第 @page 頁",
     "WebDAV Auto Sync": "WebDAV 自動同步",
     "Mark all as read": "全部標記為已讀",
-    "Do you want to mark all as read?" : "您要全部標記為已讀嗎？"
+    "Do you want to mark all as read?" : "您要全部標記為已讀嗎？",
+    "Swipe down for previous chapter": "向下滑動查看上一章",
+    "Swipe up for next chapter": "向上滑動查看下一章"
   }
 }

lib/pages/reader/images.dart

@@ -154,7 +154,6 @@ class _GalleryModeState extends State<_GalleryMode>
       builder: (BuildContext context, int index) {
         if (index == 0 || index == totalPages + 1) {
           return PhotoViewGalleryPageOptions.customChild(
-            scaleStateController: PhotoViewScaleStateController(),
             child: const SizedBox(),
           );
         } else {
@@ -168,7 +167,7 @@ class _GalleryModeState extends State<_GalleryMode>
           cached[index] = true;
           cache(index);
 
-          photoViewControllers[index] = PhotoViewController();
+          photoViewControllers[index] ??= PhotoViewController();
 
           if (reader.imagesPerPage == 1) {
             return PhotoViewGalleryPageOptions(
@@ -350,6 +349,8 @@ const Set<PointerDeviceKind> _kTouchLikeDeviceTypes = <PointerDeviceKind>{
   PointerDeviceKind.unknown
 };
 
+const double _kChangeChapterOffset = 200;
+
 class _ContinuousMode extends StatefulWidget {
   const _ContinuousMode({super.key});
 
@@ -364,7 +365,9 @@ class _ContinuousModeState extends State<_ContinuousMode>
   var itemScrollController = ItemScrollController();
   var itemPositionsListener = ItemPositionsListener.create();
   var photoViewController = PhotoViewController();
-  late ScrollController scrollController;
+  ScrollController? _scrollController;
+
+  ScrollController get scrollController => _scrollController!;
 
   var isCTRLPressed = false;
   static var _isMouseScrolling = false;
@@ -372,6 +375,7 @@ class _ContinuousModeState extends State<_ContinuousMode>
   bool disableScroll = false;
 
   late List<bool> cached;
+
   int get preCacheCount => appdata.settings["preloadImageCount"];
 
   /// Whether the user was scrolling the page.
@@ -386,6 +390,11 @@ class _ContinuousModeState extends State<_ContinuousMode>
     );
   }
 
+  bool prepareToPrevChapter = false;
+  bool prepareToNextChapter = false;
+  bool jumpToNextChapter = false;
+  bool jumpToPrevChapter = false;
+
   @override
   void initState() {
     reader = context.reader;
@@ -464,6 +473,18 @@ class _ContinuousModeState extends State<_ContinuousMode>
     }
   }
 
+  void onScroll() {
+    if (prepareToPrevChapter) {
+      jumpToNextChapter = false;
+      jumpToPrevChapter = scrollController.offset <
+          scrollController.position.minScrollExtent - _kChangeChapterOffset;
+    } else if (prepareToNextChapter) {
+      jumpToNextChapter = scrollController.offset >
+          scrollController.position.maxScrollExtent + _kChangeChapterOffset;
+      jumpToPrevChapter = false;
+    }
+  }
+
   @override
   Widget build(BuildContext context) {
     Widget widget = ScrollablePositionedList.builder(
@@ -471,7 +492,11 @@ class _ContinuousModeState extends State<_ContinuousMode>
       itemScrollController: itemScrollController,
       itemPositionsListener: itemPositionsListener,
       scrollControllerCallback: (scrollController) {
-        this.scrollController = scrollController;
+        if (_scrollController != null) {
+          _scrollController!.removeListener(onScroll);
+        }
+        _scrollController = scrollController;
+        _scrollController!.addListener(onScroll);
       },
       itemCount: reader.maxPage + 2,
       addSemanticIndexes: false,
@@ -481,7 +506,7 @@ class _ContinuousModeState extends State<_ContinuousMode>
       reverse: reader.mode == ReaderMode.continuousRightToLeft,
       physics: isCTRLPressed || _isMouseScrolling || disableScroll
           ? const NeverScrollableScrollPhysics()
-          : const ClampingScrollPhysics(),
+          : const BouncingScrollPhysics(),
       itemBuilder: (context, index) {
         if (index == 0 || index == reader.maxPage + 1) {
           return const SizedBox();
@@ -496,18 +521,28 @@ class _ContinuousModeState extends State<_ContinuousMode>
 
         ImageProvider image = _createImageProvider(index, context);
 
-        return ComicImage(
+        return ColoredBox(
-          filterQuality: FilterQuality.medium,
+          color: context.colorScheme.surface,
-          image: image,
+          child: ComicImage(
-          width: width,
+            filterQuality: FilterQuality.medium,
-          height: height,
+            image: image,
-          fit: BoxFit.contain,
+            width: width,
+            height: height,
+            fit: BoxFit.contain,
+          ),
         );
       },
       scrollBehavior: const MaterialScrollBehavior()
           .copyWith(scrollbars: false, dragDevices: _kTouchLikeDeviceTypes),
     );
 
+    widget = Stack(
+      children: [
+        Positioned.fill(child: buildBackground(context)),
+        Positioned.fill(child: widget),
+      ],
+    );
+
     widget = Listener(
       onPointerDown: (event) {
         fingers++;
@@ -530,6 +565,13 @@ class _ContinuousModeState extends State<_ContinuousMode>
             disableScroll = false;
           });
         }
+        if (fingers == 0) {
+          if (jumpToPrevChapter) {
+            reader.toPrevChapter();
+          } else if (jumpToNextChapter) {
+            reader.toNextChapter();
+          }
+        }
       },
       onPointerCancel: (event) {
         fingers--;
@@ -577,15 +619,37 @@ class _ContinuousModeState extends State<_ContinuousMode>
         if (notification is ScrollUpdateNotification) {
           if (!scrollController.hasClients) return false;
           if (scrollController.position.pixels <=
-              scrollController.position.minScrollExtent &&
+                  scrollController.position.minScrollExtent &&
               !reader.isFirstChapterOfGroup) {
-            context.readerScaffold.setFloatingButton(-1);
+            if (!prepareToPrevChapter) {
+              jumpToPrevChapter = false;
+              jumpToNextChapter = false;
+              context.readerScaffold.setFloatingButton(-1);
+              setState(() {
+                prepareToPrevChapter = true;
+              });
+            }
           } else if (scrollController.position.pixels >=
-              scrollController.position.maxScrollExtent &&
+                  scrollController.position.maxScrollExtent &&
               !reader.isLastChapterOfGroup) {
-            context.readerScaffold.setFloatingButton(1);
+            if (!prepareToNextChapter) {
+              jumpToPrevChapter = false;
+              jumpToNextChapter = false;
+              context.readerScaffold.setFloatingButton(1);
+              setState(() {
+                prepareToNextChapter = true;
+              });
+            }
           } else {
             context.readerScaffold.setFloatingButton(0);
+            if (prepareToPrevChapter || prepareToNextChapter) {
+              jumpToPrevChapter = false;
+              jumpToNextChapter = false;
+              setState(() {
+                prepareToPrevChapter = false;
+                prepareToNextChapter = false;
+              });
+            }
           }
         }
 
@@ -618,6 +682,26 @@ class _ContinuousModeState extends State<_ContinuousMode>
     );
   }
 
+  Widget buildBackground(BuildContext context) {
+    return Column(
+      children: [
+        SizedBox(height: context.padding.top + 16),
+        if (prepareToPrevChapter)
+          _SwipeChangeChapterProgress(
+            controller: scrollController,
+            isPrev: true,
+          ),
+        const Spacer(),
+        if (prepareToNextChapter)
+          _SwipeChangeChapterProgress(
+            controller: scrollController,
+            isPrev: false,
+          ),
+        SizedBox(height: context.padding.bottom + 16),
+      ],
+    );
+  }
+
   @override
   Future<void> animateToPage(int page) {
     return itemScrollController.scrollTo(
@@ -758,3 +842,127 @@ void _precacheImage(int page, BuildContext context) {
     context,
   );
 }
+
+class _SwipeChangeChapterProgress extends StatefulWidget {
+  const _SwipeChangeChapterProgress({
+    this.controller,
+    required this.isPrev,
+  });
+
+  final ScrollController? controller;
+
+  final bool isPrev;
+
+  @override
+  State<_SwipeChangeChapterProgress> createState() =>
+      _SwipeChangeChapterProgressState();
+}
+
+class _SwipeChangeChapterProgressState
+    extends State<_SwipeChangeChapterProgress> {
+  double value = 0;
+
+  late final isPrev = widget.isPrev;
+
+  ScrollController? controller;
+
+  @override
+  void initState() {
+    super.initState();
+    if (widget.controller != null) {
+      controller = widget.controller;
+      controller!.addListener(onScroll);
+    }
+  }
+
+  @override
+  void didUpdateWidget(covariant _SwipeChangeChapterProgress oldWidget) {
+    super.didUpdateWidget(oldWidget);
+    if (oldWidget.controller != widget.controller) {
+      controller?.removeListener(onScroll);
+      controller = widget.controller;
+      controller?.addListener(onScroll);
+      if (value != 0) {
+        setState(() {
+          value = 0;
+        });
+      }
+    }
+  }
+
+  @override
+  void dispose() {
+    super.dispose();
+    controller?.removeListener(onScroll);
+  }
+
+  void onScroll() {
+    var position = controller!.position.pixels;
+    var offset = isPrev
+        ? controller!.position.minScrollExtent - position
+        : position - controller!.position.maxScrollExtent;
+    var newValue = offset / _kChangeChapterOffset;
+    newValue = newValue.clamp(0.0, 1.0);
+    if (newValue != value) {
+      setState(() {
+        value = newValue;
+      });
+    }
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    final msg = widget.isPrev
+        ? "Swipe down for previous chapter".tl
+        : "Swipe up for next chapter".tl;
+
+    return CustomPaint(
+      painter: _ProgressPainter(
+        value: value,
+        backgroundColor: context.colorScheme.surfaceContainer,
+        color: context.colorScheme.primaryContainer,
+      ),
+      child: Text(msg).paddingVertical(4).paddingHorizontal(16),
+    );
+  }
+}
+
+class _ProgressPainter extends CustomPainter {
+  final double value;
+
+  final Color backgroundColor;
+
+  final Color color;
+
+  const _ProgressPainter({
+    required this.value,
+    required this.backgroundColor,
+    required this.color,
+  });
+
+  @override
+  void paint(Canvas canvas, Size size) {
+    final paint = Paint()
+      ..color = backgroundColor
+      ..style = PaintingStyle.fill;
+    canvas.drawRRect(
+      RRect.fromLTRBR(0, 0, size.width, size.height, Radius.circular(16)),
+      paint,
+    );
+
+    paint.color = color;
+    canvas.drawRRect(
+      RRect.fromLTRBR(
+          0, 0, size.width * value, size.height, Radius.circular(16)),
+      paint,
+    );
+  }
+
+  @override
+  bool shouldRepaint(covariant CustomPainter oldDelegate) {
+    return oldDelegate is! _ProgressPainter ||
+        oldDelegate.value != value ||
+        oldDelegate.backgroundColor != backgroundColor ||
+        oldDelegate.color != color;
+  }
+}

lib/pages/reader/scaffold.dart

@@ -26,73 +26,21 @@ class _ReaderScaffoldState extends State<_ReaderScaffold> {
 
   var lastValue = 0;
 
-  var fABValue = ValueNotifier<double>(0);
-
   _ReaderGestureDetectorState? _gestureDetectorState;
 
-  _DragListener? _floatingButtonDragListener;
-
   void setFloatingButton(int value) {
     lastValue = showFloatingButtonValue;
     if (value == 0) {
       if (showFloatingButtonValue != 0) {
         showFloatingButtonValue = 0;
-        fABValue.value = 0;
         update();
       }
-      if (_floatingButtonDragListener != null) {
-        _gestureDetectorState!.removeDragListener(_floatingButtonDragListener!);
-        _floatingButtonDragListener = null;
-      }
     }
-    var readerMode = context.reader.mode;
     if (value == 1 && showFloatingButtonValue == 0) {
       showFloatingButtonValue = 1;
-      _floatingButtonDragListener = _DragListener(
-        onMove: (offset) {
-          if (readerMode == ReaderMode.continuousTopToBottom) {
-            fABValue.value -= offset.dy;
-          } else if (readerMode == ReaderMode.continuousLeftToRight) {
-            fABValue.value -= offset.dx;
-          } else if (readerMode == ReaderMode.continuousRightToLeft) {
-            fABValue.value += offset.dx;
-          }
-        },
-        onEnd: () {
-          if (fABValue.value.abs() > 58 * 3) {
-            setState(() {
-              showFloatingButtonValue = 0;
-            });
-            context.reader.toNextChapter();
-          }
-          fABValue.value = 0;
-        },
-      );
-      _gestureDetectorState!.addDragListener(_floatingButtonDragListener!);
       update();
     } else if (value == -1 && showFloatingButtonValue == 0) {
       showFloatingButtonValue = -1;
-      _floatingButtonDragListener = _DragListener(
-        onMove: (offset) {
-          if (readerMode == ReaderMode.continuousTopToBottom) {
-            fABValue.value += offset.dy;
-          } else if (readerMode == ReaderMode.continuousLeftToRight) {
-            fABValue.value += offset.dx;
-          } else if (readerMode == ReaderMode.continuousRightToLeft) {
-            fABValue.value -= offset.dx;
-          }
-        },
-        onEnd: () {
-          if (fABValue.value.abs() > 58 * 3) {
-            setState(() {
-              showFloatingButtonValue = 0;
-            });
-            context.reader.toPrevChapter();
-          }
-          fABValue.value = 0;
-        },
-      );
-      _gestureDetectorState!.addDragListener(_floatingButtonDragListener!);
       update();
     }
   }
@@ -778,62 +726,35 @@ class _ReaderScaffoldState extends State<_ReaderScaffold> {
         );
       case -1:
       case 1:
-        return Container(
+        return SizedBox(
           width: 58,
           height: 58,
-          clipBehavior: Clip.antiAlias,
+          child: Material(
-          decoration: BoxDecoration(
             color: Theme.of(context).colorScheme.primaryContainer,
             borderRadius: BorderRadius.circular(16),
-          ),
+            elevation: 2,
-          child: ValueListenableBuilder(
+            child: InkWell(
-            valueListenable: fABValue,
+              onTap: () {
-            builder: (context, value, child) {
+                if (showFloatingButtonValue == 1) {
-              return Stack(
+                  context.reader.toNextChapter();
-                children: [
+                } else if (showFloatingButtonValue == -1) {
-                  Positioned.fill(
+                  context.reader.toPrevChapter();
-                    child: Material(
+                }
-                      color: Colors.transparent,
+                setFloatingButton(0);
-                      child: InkWell(
+              },
-                        onTap: () {
+              borderRadius: BorderRadius.circular(16),
-                          if (showFloatingButtonValue == 1) {
+              child: Center(
-                            context.reader.toNextChapter();
+                child: Icon(
-                          } else if (showFloatingButtonValue == -1) {
+                  showFloatingButtonValue == 1
-                            context.reader.toPrevChapter();
+                      ? Icons.arrow_forward_ios
-                          }
+                      : Icons.arrow_back_ios_outlined,
-                          setFloatingButton(0);
+                  size: 24,
-                        },
+                  color: Theme.of(context)
-                        borderRadius: BorderRadius.circular(16),
+                      .colorScheme
-                        child: Center(
+                      .onPrimaryContainer,
-                          child: Icon(
+                ),
-                            showFloatingButtonValue == 1
+              ),
-                                ? Icons.arrow_forward_ios
+            ),
-                                : Icons.arrow_back_ios_outlined,
-                            size: 24,
-                            color: Theme.of(context)
-                                .colorScheme
-                                .onPrimaryContainer,
-                          ),
-                        ),
-                      ),
-                    ),
-                  ),
-                  Positioned(
-                    bottom: 0,
-                    left: 0,
-                    right: 0,
-                    height: value.clamp(0, 58 * 3) / 3,
-                    child: ColoredBox(
-                      color: Theme.of(context)
-                          .colorScheme
-                          .surfaceTint
-                          .toOpacity(0.2),
-                      child: const SizedBox.expand(),
-                    ),
-                  ),
-                ],
-              );
-            },
           ),
         );
     }