Flutter PageView: Disable left or right side scrolling

Question

I have a PageView, how can I disable the left or right scrolling. I know by using NeverScrollableScrollPhysics we can disable the scrolling but how to disable the scrolling in one direction.

Answer 1

You can create your own ScrollPhysics to allow only go to the right:

            class CustomScrollPhysics extends ScrollPhysics {
              CustomScrollPhysics({ScrollPhysics parent}) : super(parent: parent);

              bool isGoingLeft = false;

              @override
              CustomScrollPhysics applyTo(ScrollPhysics ancestor) {
                return CustomScrollPhysics(parent: buildParent(ancestor));
              }

              @override
              double applyPhysicsToUserOffset(ScrollMetrics position, double offset) {
                isGoingLeft = offset.sign < 0;
                return offset;
              }

              @override
              double applyBoundaryConditions(ScrollMetrics position, double value) {
                //print("applyBoundaryConditions");
                assert(() {
                  if (value == position.pixels) {
                    throw FlutterError(
                        '$runtimeType.applyBoundaryConditions() was called redundantly.\n'
                        'The proposed new position, $value, is exactly equal to the current position of the '
                        'given ${position.runtimeType}, ${position.pixels}.\n'
                        'The applyBoundaryConditions method should only be called when the value is '
                        'going to actually change the pixels, otherwise it is redundant.\n'
                        'The physics object in question was:\n'
                        '  $this\n'
                        'The position object in question was:\n'
                        '  $position\n');
                  }
                  return true;
                }());
                if (value < position.pixels && position.pixels <= position.minScrollExtent)
                  return value - position.pixels;
                if (position.maxScrollExtent <= position.pixels && position.pixels < value)
                  // overscroll
                  return value - position.pixels;
                if (value < position.minScrollExtent &&
                    position.minScrollExtent < position.pixels) // hit top edge

                  return value - position.minScrollExtent;

                if (position.pixels < position.maxScrollExtent &&
                    position.maxScrollExtent < value) // hit bottom edge
                  return value - position.maxScrollExtent;

                if (!isGoingLeft) {
                  return value - position.pixels;
                }
                return 0.0;
              }
            }

Usage:

            @override
              Widget build(BuildContext context) {
                return Scaffold(
                    appBar: AppBar(),
                    body: PageView.builder(
                      itemCount: 4,
                      physics: CustomScrollPhysics(),
                      itemBuilder: (context, index) => Center(
                            child: Text("Item $index"),
                          ),
                    ));
              }

Answer 2

You can also use the horizontal_blocked_scroll_physics library which I recently wrote that will allow you to block the left and right movements.