From f4804faf5293d86045d0ab4a25c27587806b7973 Mon Sep 17 00:00:00 2001
From: nyne <me@nyne.dev>
Date: Tue, 11 Feb 2025 18:51:27 +0800
Subject: [PATCH] Improve reader gesture. Close #185

---
 lib/pages/reader/gesture.dart |  7 +++++-
 lib/pages/reader/images.dart  | 43 +++++++++++++++++++++++++++++++++--
 lib/pages/reader/reader.dart  |  3 +++
 3 files changed, 50 insertions(+), 3 deletions(-)

diff --git a/lib/pages/reader/gesture.dart b/lib/pages/reader/gesture.dart
index 7c513fb..72f7dac 100644
--- a/lib/pages/reader/gesture.dart
+++ b/lib/pages/reader/gesture.dart
@@ -24,6 +24,8 @@ class _ReaderGestureDetectorState extends State<_ReaderGestureDetector> {
 
   int fingers = 0;
 
+  late _ReaderState reader;
+
   @override
   void initState() {
     _tapGestureRecognizer = TapGestureRecognizer()
@@ -33,6 +35,7 @@ class _ReaderGestureDetectorState extends State<_ReaderGestureDetector> {
       };
     super.initState();
     context.readerScaffold._gestureDetectorState = this;
+    reader = context.reader;
   }
 
   @override
@@ -166,7 +169,9 @@ class _ReaderGestureDetectorState extends State<_ReaderGestureDetector> {
   }
 
   void onTap(Offset location) {
-    if (context.readerScaffold.isOpen) {
+    if (reader._imageViewController!.handleOnTap(location)) {
+      return;
+    } else if (context.readerScaffold.isOpen) {
       context.readerScaffold.openOrClose();
     } else {
       if (appdata.settings['enableTapToTurnPages']) {
diff --git a/lib/pages/reader/images.dart b/lib/pages/reader/images.dart
index 5bb1212..63493c8 100644
--- a/lib/pages/reader/images.dart
+++ b/lib/pages/reader/images.dart
@@ -335,6 +335,11 @@ class _GalleryModeState extends State<_GalleryMode>
       }
     }
   }
+
+  @override
+  bool handleOnTap(Offset location) {
+    return false;
+  }
 }
 
 const Set<PointerDeviceKind> _kTouchLikeDeviceTypes = <PointerDeviceKind>{
@@ -366,6 +371,18 @@ class _ContinuousModeState extends State<_ContinuousMode>
   var fingers = 0;
   bool disableScroll = false;
 
+  /// Whether the user was scrolling the page.
+  /// The gesture detector has a delay to detect tap event.
+  /// To handle the tap event, we need to know if the user was scrolling before the delay.
+  bool delayedIsScrolling = false;
+
+  void delayedSetIsScrolling(bool value) {
+    Future.delayed(
+      const Duration(milliseconds: 300),
+      () => delayedIsScrolling = value,
+    );
+  }
+
   @override
   void initState() {
     reader = context.reader;
@@ -374,6 +391,12 @@ class _ContinuousModeState extends State<_ContinuousMode>
     super.initState();
   }
 
+  @override
+  void dispose() {
+    itemPositionsListener.itemPositions.removeListener(onPositionChanged);
+    super.dispose();
+  }
+
   void onPositionChanged() {
     var page = itemPositionsListener.itemPositions.value.first.index;
     page = page.clamp(1, reader.maxPage);
@@ -516,8 +539,14 @@ class _ContinuousModeState extends State<_ContinuousMode>
       child: widget,
     );
 
-    widget = NotificationListener<ScrollUpdateNotification>(
+    widget = NotificationListener<ScrollNotification>(
       onNotification: (notification) {
+        if (notification is ScrollStartNotification) {
+          delayedSetIsScrolling(true);
+        } else if (notification is ScrollEndNotification) {
+          delayedSetIsScrolling(false);
+        }
+
         var length = reader.maxChapter;
         if (!scrollController.hasClients) return false;
         if (scrollController.position.pixels <=
@@ -592,7 +621,7 @@ class _ContinuousModeState extends State<_ContinuousMode>
 
   @override
   void handleLongPressDown(Offset location) {
-    if (!appdata.settings['enableLongPressToZoom']) {
+    if (!appdata.settings['enableLongPressToZoom'] || delayedIsScrolling) {
       return;
     }
     double target = photoViewController.getInitialScale!.call()! * 1.75;
@@ -667,6 +696,16 @@ class _ContinuousModeState extends State<_ContinuousMode>
       );
     }
   }
+
+  @override
+  bool handleOnTap(Offset location) {
+    if (delayedIsScrolling) {
+      print('isScrolling');
+      return true;
+    }
+    print('isNotScrolling');
+    return false;
+  }
 }
 
 ImageProvider _createImageProviderFromKey(
diff --git a/lib/pages/reader/reader.dart b/lib/pages/reader/reader.dart
index e38407b..34db62a 100644
--- a/lib/pages/reader/reader.dart
+++ b/lib/pages/reader/reader.dart
@@ -430,4 +430,7 @@ abstract interface class _ImageViewController {
   void handleLongPressUp(Offset location);
 
   void handleKeyEvent(KeyEvent event);
+
+  /// Returns true if the event is handled.
+  bool handleOnTap(Offset location);
 }