Release 1.0.0-beta.7

example/lib/src/common.dart

@@ -36,8 +36,7 @@ class _ExampleListViewState extends State<ExampleListView> {
         itemCount: 50,
         itemBuilder: (_, index) {
           return ListTile(
-            onTap: () =>
-                debugPrint("onTap(index=$index, page=${widget.page})"),
+            onTap: () => debugPrint("onTap(index=$index, page=${widget.page})"),
             title: Text("Item#$index"),
             subtitle: Text("Page#${widget.page}"),
           );

example/lib/src/custom_snap_offsets_example.dart

@@ -10,22 +10,14 @@ class CustomSnapOffsetsExample extends StatefulWidget {
       _CustomSnapOffsetsExampleState();
 }
 
-class _CustomSnapOffsetsExampleState
-    extends State<CustomSnapOffsetsExample> {
+class _CustomSnapOffsetsExampleState extends State<CustomSnapOffsetsExample> {
   late final ExprollablePageController controller;
 
   @override
   void initState() {
     super.initState();
-    const peekOffset = ViewportOffset.fractional(0.5);
-    controller = ExprollablePageController(
-      initialViewportOffset: peekOffset,
-      maxViewportOffset: peekOffset,
-      snapViewportOffsets: [
-        ViewportOffset.expanded,
-        ViewportOffset.shrunk,
-        peekOffset,
-      ],
+    controller = ExprollablePageController.withAdditionalSnapOffsets(
+      const [ViewportOffset.fractional(0.5)],
     );
   }
 

package/CHANGELOG.md

@@ -1,5 +1,11 @@
 # Changelog
 
+## 1.0.0-beta.7 30-04-2023
+
+- Fix #20
+- Add a convenience constructor `ExprollablePageController.withAdditionalSnapOffsets` (proposed in #21)
+- Improve the documents
+
 ## 1.0.0-beta.6 19-04-2023
 
 - Fix #17

package/README.md

@@ -1,14 +1,14 @@
 [English](https://github.com/fujidaiti/exprollable_page_view/blob/master/package/README.md)|[日本語](https://github.com/fujidaiti/exprollable_page_view/blob/master/package/res/README.jp.md)
 
-[![Pub](https://img.shields.io/pub/v/exprollable_page_view.svg?logo=flutter&color=blue&style=flat-square)](https://pub.dev/packages/exprollable_page_view) [![Docs](https://img.shields.io/badge/-API%20Reference-orange?style=flat-square)](https://pub.dev/documentation/exprollable_page_view/latest/)
+[![Pub](https://img.shields.io/pub/v/exprollable_page_view.svg?logo=flutter&color=blue)](https://pub.dev/packages/exprollable_page_view) [![Pub Popularity](https://img.shields.io/pub/popularity/exprollable_page_view)](https://pub.dev/packages/exprollable_page_view) [![Docs](https://img.shields.io/badge/-API%20Reference-orange)](https://pub.dev/documentation/exprollable_page_view/latest/)
 
 # ExprollablePageView
 
 Yet another PageView widget that expands its viewport as it scrolls. **Exprollable** is a coined word combining the words expandable and scrollable. This project is an attemt to clone a modal sheet UI used in [Apple Books](https://www.apple.com/jp/apple-books/) app on iOS.
 
 Here is an example of what you can do with this widget:
 
-![demo](https://user-images.githubusercontent.com/68946713/231328800-03038dc6-19e8-4c7c-933b-7e7436ba6619.gif) ![demo2](https://user-images.githubusercontent.com/68946713/234313845-caa8dd75-c9e2-4fd9-b177-f4a6795c4802.gif)
+<img width="320" src="https://user-images.githubusercontent.com/68946713/231328800-03038dc6-19e8-4c7c-933b-7e7436ba6619.gif"> <img width="320" src="https://user-images.githubusercontent.com/68946713/234313845-caa8dd75-c9e2-4fd9-b177-f4a6795c4802.gif">
 
 ## Index
 
@@ -259,6 +259,12 @@ controller = ExprollablePageController(
 );
 ```
 
+You can also use `ExprollablePageController.withAdditionalSnapOffsets` as a shorthand. The following snippet is equevalent to the above:
+
+```dart
+controller = ExprollablePageController.withAdditionalSnapOffsets([peekOffset]);
+```
+
 ### observe the state of the viewport?
 
 There are 3 ways to observe changes of the viewport state.

package/lib/src/addon/modal.dart

@@ -4,7 +4,7 @@ import 'package:exprollable_page_view/src/core/controller.dart';
 import 'package:exprollable_page_view/src/core/view.dart';
 import 'package:flutter/material.dart';
 
-/// Show a [ExprollablePageView] as a modal dialog.
+/// Show an [ExprollablePageView] as a modal dialog.
 Future<T?> showModalExprollable<T>(
   BuildContext context, {
   required WidgetBuilder builder,
@@ -16,7 +16,7 @@ Future<T?> showModalExprollable<T>(
   Color initialBarrierColor = Colors.black54,
   void Function(BuildContext) dismissBehavior = _defaultDismissBehavior,
   bool barrierDismissible = true,
-  ViewportOffset dismissThresholdOffset = const ViewportOffset.fractional(0.18),
+  ViewportOffset dismissThresholdOffset = const ViewportOffset.fractional(0.1),
 }) =>
     showDialog<T>(
       context: context,
@@ -42,7 +42,7 @@ Future<T?> showModalExprollable<T>(
 void _defaultDismissBehavior(BuildContext context) =>
     Navigator.of(context).pop();
 
-/// A widget that makes a [ExprollablePageView] modal dialog style.
+/// A widget that makes a modal dialog style [ExprollablePageView].
 ///
 /// This widget adds a translucent background (barrier) and
 /// *swipe down to dismiss* action to the child page view.
@@ -61,7 +61,7 @@ class ModalExprollable extends StatefulWidget {
     this.initialBarrierColor = Colors.black54,
     this.dismissBehavior = _defaultDismissBehavior,
     this.barrierDismissible = true,
-    this.dismissThresholdOffset = const ViewportOffset.fractional(0.18),
+    this.dismissThresholdOffset = const ViewportOffset.fractional(0.1),
   }) : assert(dismissThresholdOffset > ViewportOffset.shrunk);
 
   /// Called when the dialog should be dismissed.
@@ -170,11 +170,128 @@ class _ModalExprollableState extends State<ModalExprollable> {
       ),
     );
 
-    return Stack(
-      children: [
-        Positioned.fill(child: barrier),
-        Positioned.fill(child: pageView),
-      ],
+    return ScrollConfiguration(
+      behavior: const _ModalExprollableScrollBehavior(),
+      child: Stack(
+        children: [
+          Positioned.fill(child: barrier),
+          Positioned.fill(child: pageView),
+        ],
+      ),
     );
   }
 }
+
+/// Scroll physics commonly used for descendant scrollables of [ModalExprollable].
+///
+/// This physics always lets the user overscroll making *dra down to dismiss* action
+/// is available on every platform. [ModalExprollable] provides this as the default physics
+/// for its descendants via [ScrollConfiguration].
+/// If you explicitly specify a physics for a descendant scrollable,
+/// consider to wrap that physics with this.
+///
+/// ```dart
+/// final physics = const ModalExprollableScrollPhysics(
+///   parnet: ClampScrollPhysics(),
+/// );
+/// ```
+class ModalExprollableScrollPhysics extends ScrollPhysics {
+  /// Creates a scrolling physics that always lets the user overscroll.
+  ///
+  /// This will delegate its logic to [BouncingScrollPhysics] if the user overscrolls,
+  /// so that the *drag down to dismiss* action is available on every platform.
+  /// Otherwise, it delegates to the given [parent].
+  const ModalExprollableScrollPhysics({
+    ScrollPhysics? parent,
+  }) : super(parent: parent);
+
+  @override
+  ModalExprollableScrollPhysics applyTo(ScrollPhysics? ancestor) {
+    return ModalExprollableScrollPhysics(parent: buildParent(ancestor));
+  }
+
+  @override
+  bool get allowImplicitScrolling =>
+      parent?.allowImplicitScrolling ?? super.allowImplicitScrolling;
+
+  @override
+  double adjustPositionForNewDimensions({
+    required ScrollMetrics oldPosition,
+    required ScrollMetrics newPosition,
+    required bool isScrolling,
+    required double velocity,
+  }) {
+    if (parent == null ||
+        _outOfRange(oldPosition) ||
+        _outOfRange(newPosition)) {
+      return const BouncingScrollPhysics().adjustPositionForNewDimensions(
+        oldPosition: oldPosition,
+        newPosition: newPosition,
+        isScrolling: isScrolling,
+        velocity: velocity,
+      );
+    } else {
+      return parent!.adjustPositionForNewDimensions(
+        oldPosition: oldPosition,
+        newPosition: newPosition,
+        isScrolling: isScrolling,
+        velocity: velocity,
+      );
+    }
+  }
+
+  @override
+  Simulation? createBallisticSimulation(
+    ScrollMetrics position,
+    double velocity,
+  ) {
+    return velocity < 0
+        ? const BouncingScrollPhysics()
+            .createBallisticSimulation(position, velocity)
+        : super.createBallisticSimulation(position, velocity);
+  }
+
+  @override
+  double applyBoundaryConditions(ScrollMetrics position, double value) {
+    if (parent == null ||
+        _outOfRange(position) ||
+        _outOfRange(position.copyWith(pixels: value))) {
+      return const BouncingScrollPhysics()
+          .applyBoundaryConditions(position, value);
+    } else {
+      return parent!.applyBoundaryConditions(position, value);
+    }
+  }
+
+  @override
+  double applyPhysicsToUserOffset(ScrollMetrics position, double offset) {
+    if (parent == null ||
+        _outOfRange(position) ||
+        _outOfRange(position.copyWith(
+          pixels: position.pixels + offset,
+        ))) {
+      return const BouncingScrollPhysics()
+          .applyPhysicsToUserOffset(position, offset);
+    } else {
+      return parent!.applyPhysicsToUserOffset(position, offset);
+    }
+  }
+
+  bool _outOfRange(ScrollMetrics position) {
+    return position.hasPixels &&
+        position.hasContentDimensions &&
+        position.pixels < position.minScrollExtent;
+  }
+}
+
+class _ModalExprollableScrollBehavior extends ScrollBehavior {
+  const _ModalExprollableScrollBehavior();
+
+  @override
+  ScrollPhysics getScrollPhysics(BuildContext context) {
+    final defaultPhysics = super.getScrollPhysics(context);
+    return defaultPhysics is BouncingScrollPhysics
+        ? defaultPhysics
+        : ModalExprollableScrollPhysics(parent: defaultPhysics);
+  }
+}

package/lib/src/core/controller.dart

@@ -123,6 +123,41 @@ class ExprollablePageController extends PageController {
     _currentPage = _CurrentPageNotifier(controller: this);
   }
 
+  /// Crate a page controller with additional snap viewport offsets.
+  ///
+  /// [additionalSnapOffsets] must not be empty. The viewport will snap to 
+  /// the offsets given by [additionalSnapOffsets] in addition to 
+  /// [ViewportOffset.expanded] and [ViewportOffset.shrunk].
+  /// 
+  /// If [initialViewportOffset] or [maxViewportOffset] is not specified,
+  /// the max offset in [additionalSnapOffsets] is used.
+  factory ExprollablePageController.withAdditionalSnapOffsets(
+    List<ViewportOffset> additionalSnapOffsets, {
+    int initialPage = 0,
+    bool keepPage = true,
+    double minViewportFraction = 0.9,
+    bool overshootEffect = false,
+    ViewportOffset? initialViewportOffset,
+    ViewportOffset? maxViewportOffset,
+  }) {
+    assert(additionalSnapOffsets.isNotEmpty);
+    final snapViewportOffsets = {
+      ViewportOffset.expanded,
+      ViewportOffset.shrunk,
+      ...additionalSnapOffsets,
+    }.toList()
+      ..sort();
+    return ExprollablePageController(
+      initialPage: initialPage,
+      keepPage: keepPage,
+      minViewportFraction: minViewportFraction,
+      overshootEffect: overshootEffect,
+      initialViewportOffset: initialViewportOffset ?? snapViewportOffsets.last,
+      maxViewportOffset: maxViewportOffset ?? snapViewportOffsets.last,
+      snapViewportOffsets: snapViewportOffsets,
+    );
+  }
+
   final _absorberGroup = ScrollAbsorberGroup();
   final Map<int, PageContentScrollController> _contentScrollControllers = {};
 

package/pubspec.yaml

@@ -1,6 +1,6 @@
 name: exprollable_page_view
 description: Yet another PageView widget that expands its viewport as it scrolls. Exprollable is a coined word combining the words expandable and scrollable.
-version: 1.0.0-beta.6
+version: 1.0.0-beta.7
 repository: https://github.com/fujidaiti/exprollable_page_view
 
 environment: