Would nice to use Shimmer to have the swipe indication animations. I used to use another library https://github.com/anirudhsharma392/Slider-Button, but it didn't have the customization I need, ended up implementing my own. But it does have a shimmer

Looks like the recent flutter version broke the library:

/c:/Runtime/flutter/.pub-cache/hosted/pub.dartlang.org/slide_to_act-0.1.3/lib/slide_to_act.dart:126:25: Error: No named parameter with the name 'overflow'.
                        overflow: Overflow.clip,
                        ^^^^^^^^
/c:/Runtime/flutter/packages/flutter/lib/src/widgets/basic.dart:3273:3: Context: Found this candidate, but the arguments don't match.
  Stack({
  ^^^^^

Fix the breaking change introduced by https://github.com/flutter/flutter/commit/7948a7863bd8931e4e029c5b109f26c1b3dcf8ea and merged into flutter master by https://github.com/flutter/flutter/pull/61366 by replacing overflow: Overflow.visible, with clipBehavior: Clip.none, in the Stack object instantiation.

Fixes #1.

I noticed that _maxDx was calculated quite complicated and wrong if you change properties that effect the size of the sliding button.

_maxDx = _containerWidth! -
          (sliderWidth / 2) -
          40 -
          widget.sliderButtonYOffset;

There is the hardcoded "40" and I noticed that sliderButtonYOffset (that should better be named sliderButtonXOffset ;) ) was just necessary because of a hardcoded horizontalPadding of 8 around the sliding button.

Therefore I did those changes and realized that the calculation of _maxDx becomes very simple:

_maxDx = _containerWidth! - sliderWidth;

Can anyone help/guide me how I can align the text. By default, it is automatically centered. I have some long text to display but when the text displayed then it is covered by the sliding widget.

Getting this sometimes, I think when I have scrolled the container that contains the slide into view and then scroll it out, but I can't reproduce it consistently.

The following _CastError was thrown during a scheduler callback:
Null check operator used on a null value

When the exception was thrown, this was the stack: 
#0      SlideActionState.initState.<anonymous closure> (package:slide_to_act/slide_to_act.dart:387:39)
#1      SchedulerBinding._invokeFrameCallback (package:flutter/src/scheduler/binding.dart:1144:15)
#2      SchedulerBinding.handleDrawFrame (package:flutter/src/scheduler/binding.dart:1090:9)
#3      SchedulerBinding._handleDrawFrame (package:flutter/src/scheduler/binding.dart:998:5)
#7      _invoke (dart:ui/hooks.dart:161:10)

Which comes from:

      final RenderBox containerBox =
          _containerKey.currentContext!.findRenderObject() as RenderBox;

I am getting this error:

════════ Exception caught by scheduler library ═════════════════════════════════
The following NoSuchMethodError was thrown during a scheduler callback:
The method 'findRenderObject' was called on null.
Receiver: null
Tried calling: findRenderObject()

When the exception was thrown, this was the stack
#0      Object.noSuchMethod (dart:core-patch/object_patch.dart:54:5)
#1      SlideToActState.initState.<anonymous closure> (package:eagl/widgets/slide_to_act.dart:372:40)
#2      SchedulerBinding._invokeFrameCallback (package:flutter/src/scheduler/binding.dart:1144:15)
#3      SchedulerBinding.handleDrawFrame (package:flutter/src/scheduler/binding.dart:1090:9)
#4      SchedulerBinding.scheduleWarmUpFrame.<anonymous closure> (package:flutter/src/scheduler/binding.dart:865:7)