Elastic or other transition curves

[appinteractive]

How can I implement an elastic effect when opening the sheet be for the snapping? Discord does have a nice implemention of such effect.

Currently there is only one curve for opening and closing so I could not just use the elastic curve as the closing effect would be broken.

And for the physics there is no it do I miss something?

[fujidaiti]

Discord does have a nice implemention of such effect.

Could you post a screen capture of this?

[appinteractive]

Sure, here you can see the slight overshoot behavior. It's nice if your app needs some more character.

RPReplay_Final1708947140.MP4

[fujidaiti]

Thanks!

And for the physics there is no it do I miss something?

No, unfortunately. I'll add this to the roadmap (#51).

[appinteractive]

I think that a curve for the snapping physics is also needed or is the given "open" curve used then when you release the sheet for snapping?

[fujidaiti]

Ah sorry, I misunderstood what you said.
Currently, the physics uses ScrollSpringSimulation for the snapping animation by default, which a curve cannot be applied to. However, you can easily create a custom physics by extending SheetPhysics or one of its subclasses. Here's an example of a custom physics that has the snapping behavior and uses a curve-applied animation when it snaps:

import 'package:flutter/physics.dart';
import 'package:smooth_sheets/smooth_sheets.dart';

class CustomSheetPhysics extends StretchingSheetPhysics {
  const CustomSheetPhysics({
    super.parent,
    super.frictionCurve,
    super.stretchingRange,
    this.snappingCurve = Curves.easeInOut,
     // If you want to have multiple snap positions, use SnapToNearest instead.
    this.snappingBehavior = const SnapToNearestEdge(),
  });

  final Curve snappingCurve;
  final SnappingSheetBehavior snappingBehavior;

  @override
  Simulation? createBallisticSimulation(double velocity, SheetMetrics metrics) {
    final snapPixels = snappingBehavior.findSnapPixels(velocity, metrics);
    if (snapPixels != null &&
        !nearEqual(
          snapPixels,
          metrics.pixels,
          Tolerance.defaultTolerance.distance,
        )) {
      return InterpolationSimulation(
        start: metrics.pixels,
        end: snapPixels,
        curve: snappingCurve,
        durationInSeconds: 0.3, // 300ms
      );
    } else {
      return super.createBallisticSimulation(velocity, metrics);
    }
  }
}

The InterpolationSimulation will be available from v0.3.3.