venera/lib/foundation/app_page_route.dart

import 'dart:math';
import 'dart:ui';
import 'package:flutter/gestures.dart';
import 'package:flutter/material.dart';
import 'package:venera/foundation/app.dart';

const double _kBackGestureWidth = 20.0;
const int _kMaxDroppedSwipePageForwardAnimationTime = 800;
const int _kMaxPageBackAnimationTime = 300;
const double _kMinFlingVelocity = 1.0;

class AppPageRoute<T> extends PageRoute<T> with _AppRouteTransitionMixin{
  /// Construct a MaterialPageRoute whose contents are defined by [builder].
  AppPageRoute({
    required this.builder,
    super.settings,
    this.maintainState = true,
    super.fullscreenDialog,
    super.allowSnapshotting = true,
    super.barrierDismissible = false,
    this.enableIOSGesture = true,
    this.preventRebuild = true,
  }) {
    assert(opaque);
  }

  /// Builds the primary contents of the route.
  final WidgetBuilder builder;

  String? label;

  @override
  toString() => "/$label";

  @override
  Widget buildContent(BuildContext context) {
    var widget = builder(context);
    label = widget.runtimeType.toString();
    return widget;
  }

  @override
  final bool maintainState;

  @override
  String get debugLabel => '${super.debugLabel}(${settings.name})';

  @override
  final bool enableIOSGesture;

  @override
  final bool preventRebuild;
}

mixin _AppRouteTransitionMixin<T> on PageRoute<T> {
  /// Builds the primary contents of the route.
  @protected
  Widget buildContent(BuildContext context);

  @override
  Duration get transitionDuration => const Duration(milliseconds: 300);

  @override
  Color? get barrierColor => null;

  @override
  String? get barrierLabel => null;

  @override
  bool canTransitionTo(TransitionRoute<dynamic> nextRoute) {
    // Don't perform outgoing animation if the next route is a fullscreen dialog.
    return nextRoute is PageRoute && !nextRoute.fullscreenDialog;
  }

  bool get enableIOSGesture;

  bool get preventRebuild;

  Widget? _child;

  @override
  Widget buildPage(
      BuildContext context,
      Animation<double> animation,
      Animation<double> secondaryAnimation,
      ) {
    Widget result;

    if(preventRebuild){
      result = _child ?? (_child = buildContent(context));
    } else {
      result = buildContent(context);
    }

    return Semantics(
      scopesRoute: true,
      explicitChildNodes: true,
      child: result,
    );
  }

  static bool _isPopGestureEnabled<T>(PageRoute<T> route) {
    if (route.isFirst ||
        route.willHandlePopInternally ||
        route.popDisposition == RoutePopDisposition.doNotPop ||
        route.fullscreenDialog ||
        route.animation!.status != AnimationStatus.completed ||
        route.secondaryAnimation!.status != AnimationStatus.dismissed ||
        !route.popGestureEnabled ||
        route.navigator!.userGestureInProgress) {
      return false;
    }

    return true;
  }

  @override
  Widget buildTransitions(BuildContext context, Animation<double> animation, Animation<double> secondaryAnimation, Widget child) {
    PageTransitionsBuilder builder;
    if (App.isAndroid) {
      builder = PredictiveBackPageTransitionsBuilder();
    } else {
      builder = SlidePageTransitionBuilder();
    }

    return builder.buildTransitions(
        this,
        context,
        animation,
        secondaryAnimation,
        enableIOSGesture
            ? IOSBackGestureDetector(
            gestureWidth: _kBackGestureWidth,
            enabledCallback: () => _isPopGestureEnabled<T>(this),
            onStartPopGesture: () => _startPopGesture(this),
            child: child)
            : child);
  }

  IOSBackGestureController _startPopGesture(PageRoute<T> route) {
    return IOSBackGestureController(route.controller!, route.navigator!);
  }
}

class IOSBackGestureController {
  final AnimationController controller;

  final NavigatorState navigator;

  IOSBackGestureController(this.controller, this.navigator) {
    navigator.didStartUserGesture();
  }

  void dragEnd(double velocity) {
    const Curve animationCurve = Curves.fastLinearToSlowEaseIn;
    final bool animateForward;

    if (velocity.abs() >= _kMinFlingVelocity) {
      animateForward = velocity <= 0;
    } else {
      animateForward = controller.value > 0.5;
    }

    if (animateForward) {
      final droppedPageForwardAnimationTime = min(
        lerpDouble(
                _kMaxDroppedSwipePageForwardAnimationTime, 0, controller.value)!
            .floor(),
        _kMaxPageBackAnimationTime,
      );
      controller.animateTo(1.0,
          duration: Duration(milliseconds: droppedPageForwardAnimationTime),
          curve: animationCurve);
    } else {
      navigator.pop();
      if (controller.isAnimating) {
        final droppedPageBackAnimationTime = lerpDouble(
                0, _kMaxDroppedSwipePageForwardAnimationTime, controller.value)!
            .floor();
        controller.animateBack(0.0,
            duration: Duration(milliseconds: droppedPageBackAnimationTime),
            curve: animationCurve);
      }
    }

    if (controller.isAnimating) {
      late AnimationStatusListener animationStatusCallback;
      animationStatusCallback = (status) {
        navigator.didStopUserGesture();
        controller.removeStatusListener(animationStatusCallback);
      };
      controller.addStatusListener(animationStatusCallback);
    } else {
      navigator.didStopUserGesture();
    }
  }

  void dragUpdate(double delta) {
    controller.value -= delta;
  }
}

class IOSBackGestureDetector extends StatefulWidget {
  const IOSBackGestureDetector(
      {required this.enabledCallback,
      required this.child,
      required this.gestureWidth,
      required this.onStartPopGesture,
      super.key});

  final double gestureWidth;

  final bool Function() enabledCallback;

  final IOSBackGestureController Function() onStartPopGesture;

  final Widget child;

  @override
  State<IOSBackGestureDetector> createState() => _IOSBackGestureDetectorState();
}

class _IOSBackGestureDetectorState extends State<IOSBackGestureDetector> {
  IOSBackGestureController? _backGestureController;

  late HorizontalDragGestureRecognizer _recognizer;

  @override
  void dispose() {
    _recognizer.dispose();
    super.dispose();
  }

  @override
  void initState() {
    super.initState();
    _recognizer = HorizontalDragGestureRecognizer(debugOwner: this)
      ..onStart = _handleDragStart
      ..onUpdate = _handleDragUpdate
      ..onEnd = _handleDragEnd
      ..onCancel = _handleDragCancel;
  }

  @override
  Widget build(BuildContext context) {
    var dragAreaWidth = Directionality.of(context) == TextDirection.ltr
        ? MediaQuery.of(context).padding.left
        : MediaQuery.of(context).padding.right;
    dragAreaWidth = max(dragAreaWidth, widget.gestureWidth);
    return Stack(
      fit: StackFit.passthrough,
      children: <Widget>[
        widget.child,
        Positioned(
          width: dragAreaWidth,
          top: 0.0,
          bottom: 0.0,
          left: 0,
          child: Listener(
            onPointerDown: _handlePointerDown,
            behavior: HitTestBehavior.translucent,
          ),
        ),
      ],
    );
  }

  void _handlePointerDown(PointerDownEvent event) {
    if (widget.enabledCallback()) _recognizer.addPointer(event);
  }

  void _handleDragCancel() {
    assert(mounted);
    _backGestureController?.dragEnd(0.0);
    _backGestureController = null;
  }

  double _convertToLogical(double value) {
    switch (Directionality.of(context)) {
      case TextDirection.rtl:
        return -value;
      case TextDirection.ltr:
        return value;
    }
  }

  void _handleDragEnd(DragEndDetails details) {
    assert(mounted);
    assert(_backGestureController != null);
    _backGestureController!.dragEnd(_convertToLogical(
        details.velocity.pixelsPerSecond.dx / context.size!.width));
    _backGestureController = null;
  }

  void _handleDragStart(DragStartDetails details) {
    assert(mounted);
    assert(_backGestureController == null);
    _backGestureController = widget.onStartPopGesture();
  }

  void _handleDragUpdate(DragUpdateDetails details) {
    assert(mounted);
    assert(_backGestureController != null);
    _backGestureController!.dragUpdate(
        _convertToLogical(details.primaryDelta! / context.size!.width));
  }
}

class SlidePageTransitionBuilder extends PageTransitionsBuilder {
  @override
  Widget buildTransitions<T>(
      PageRoute<T> route,
      BuildContext context,
      Animation<double> animation,
      Animation<double> secondaryAnimation,
      Widget child) {
    return SlideTransition(
        position: Tween<Offset>(
          begin: const Offset(1, 0),
          end: Offset.zero,
        ).animate(CurvedAnimation(
          parent: animation,
          curve: Curves.ease,
        )),
        child: SlideTransition(
          position: Tween<Offset>(
            begin: Offset.zero,
            end: const Offset(-0.4, 0),
          ).animate(CurvedAnimation(
            parent: secondaryAnimation,
            curve: Curves.ease,
          )),
          child: PhysicalModel(
            color: Colors.transparent,
            borderRadius: BorderRadius.zero,
            clipBehavior: Clip.hardEdge,
            elevation: 6,
            child: Material(child: child,),
          ),
        )
    );
  }
}