Add mouse scroll speed setting. Close #471

lib/foundation/appdata.dart

@@ -191,6 +191,7 @@ class Settings with ChangeNotifier {
     'showSystemStatusBar': false,
     'comicSpecificSettings': <String, Map<String, dynamic>>{},
     'ignoreBadCertificate': false,
+    'readerScrollSpeed': 1.0, // 0.5 - 3.0
   };
 
   operator [](String key) {

lib/pages/reader/images.dart

@@ -638,27 +638,52 @@ class _ContinuousModeState extends State<_ContinuousMode>
     cacheImages(page);
   }
 
-  double? futurePosition;
+  double? _futurePosition;
 
   void smoothTo(double offset) {
-    futurePosition ??= scrollController.offset;
-    if (futurePosition! > scrollController.position.maxScrollExtent &&
-        offset > 0) {
-      return;
-    } else if (futurePosition! < scrollController.position.minScrollExtent &&
-        offset < 0) {
+    if (HardwareKeyboard.instance.isShiftPressed) {
       return;
     }
-    futurePosition = futurePosition! + offset * 1.2;
-    futurePosition = futurePosition!.clamp(
+    var currentLocation = scrollController.position.pixels;
+    var old = _futurePosition;
+    _futurePosition ??= currentLocation;
+    double k = (_futurePosition! - currentLocation).abs() / 1600 + 1;
+    final customSpeed = appdata.settings.getReaderSetting(
+      context.reader.cid,
+      context.reader.type.sourceKey,
+      "readerScrollSpeed",
+    );
+    if (customSpeed is num) {
+      k *= customSpeed;
+    }
+    _futurePosition = _futurePosition! + offset * k;
+    var beforeOffset = (_futurePosition! - currentLocation).abs();
+    _futurePosition = _futurePosition!.clamp(
       scrollController.position.minScrollExtent,
       scrollController.position.maxScrollExtent,
     );
-    scrollController.animateTo(
-      futurePosition!,
-      duration: const Duration(milliseconds: 200),
+    var afterOffset = (_futurePosition! - currentLocation).abs();
+    if (_futurePosition == old) return;
+    var target = _futurePosition!;
+    var duration = const Duration(milliseconds: 160);
+    if (afterOffset < beforeOffset) {
+      duration = duration * (afterOffset / beforeOffset);
+      if (duration < Duration(milliseconds: 10)) {
+        duration = Duration(milliseconds: 10);
+      }
+    }
+    scrollController
+        .animateTo(
+      _futurePosition!,
+      duration: duration,
       curve: Curves.linear,
-    );
+    )
+        .then((_) {
+      var current = scrollController.position.pixels;
+      if (current == target && current == _futurePosition) {
+        _futurePosition = null;
+      }
+    });
   }
 
   void onPointerSignal(PointerSignalEvent event) {
@@ -787,7 +812,7 @@ class _ContinuousModeState extends State<_ContinuousMode>
             disableScroll = true;
           });
         }
-        futurePosition = null;
+        _futurePosition = null;
         if (_isMouseScrolling) {
           setState(() {
             _isMouseScrolling = false;
@@ -1009,7 +1034,7 @@ class _ContinuousModeState extends State<_ContinuousMode>
   @override
   void toPage(int page) {
     itemScrollController.jumpTo(index: page);
-    futurePosition = null;
+    _futurePosition = null;
   }
 
   @override

lib/pages/settings/reader.dart

@@ -177,6 +177,21 @@ class _ReaderSettingsState extends State<ReaderSettings> {
             comicSource: isEnabledSpecificSettings ? widget.comicSource : null,
           ),
         ),
+        SliverAnimatedVisibility(
+          visible: appdata.settings['readerMode']!.startsWith('continuous'),
+          child: _SliderSetting(
+            title: "Mouse scroll speed".tl,
+            settingsIndex: "readerScrollSpeed",
+            interval: 0.1,
+            min: 0.5,
+            max: 3,
+            onChanged: () {
+              widget.onChanged?.call("readerScrollSpeed");
+            },
+            comicId: isEnabledSpecificSettings ? widget.comicId : null,
+            comicSource: isEnabledSpecificSettings ? widget.comicSource : null,
+          ),
+        ),
         _SwitchSetting(
           title: 'Double tap to zoom'.tl,
           settingKey: 'enableDoubleTapToZoom',