Move steps back

Author: jpnurmi

lib/src/base_spin_box.dart

@@ -54,31 +54,34 @@ mixin SpinBoxMixin<T extends BaseSpinBox> on State<T> {
   FocusNode get focusNode => _focusNode;
   SpinFormatter get formatter => SpinFormatter(_controller);
 
-  String _formatValue(double value) {
-    return formatter.formatValue(value,
-        decimals: widget.decimals, digits: widget.digits);
-  }
-
   Map<ShortcutActivator, VoidCallback> get bindings {
     return {
       // ### TODO: use SingleActivator fixed in Flutter 2.10+
       // https://github.com/flutter/flutter/issues/92717
-      LogicalKeySet(LogicalKeyboardKey.arrowUp): _controller.stepUp,
-      LogicalKeySet(LogicalKeyboardKey.arrowDown): _controller.stepDown,
-      LogicalKeySet(LogicalKeyboardKey.pageUp): _controller.pageStepUp,
-      LogicalKeySet(LogicalKeyboardKey.pageDown): _controller.pageStepDown,
+      LogicalKeySet(LogicalKeyboardKey.arrowUp): _stepUp,
+      LogicalKeySet(LogicalKeyboardKey.arrowDown): _stepDown,
+      LogicalKeySet(LogicalKeyboardKey.pageUp): _pageStepUp,
+      LogicalKeySet(LogicalKeyboardKey.pageDown): _pageStepDown,
     };
   }
 
+  String _formatValue(double value) {
+    return formatter.formatValue(value,
+        decimals: widget.decimals, digits: widget.digits);
+  }
+
+  void _stepUp() => controller.value += widget.step;
+  void _stepDown() => controller.value += -widget.step;
+  void _pageStepUp() => controller.value += widget.pageStep;
+  void _pageStepDown() => controller.value -= widget.pageStep;
+
   @override
   void initState() {
     super.initState();
     _controller = widget.controller ??
         SpinController(
           min: widget.min,
           max: widget.max,
-          step: widget.step,
-          pageStep: widget.pageStep,
           value: widget.value,
           decimals: widget.decimals,
         );

lib/src/spin_controller.dart

@@ -27,8 +27,6 @@ class SpinController extends ValueNotifier<double> {
     required double min,
     required double max,
     required double value,
-    this.step = 1,
-    this.pageStep,
     this.decimals = 0,
   })  : _min = min,
         _max = max,
@@ -37,8 +35,6 @@ class SpinController extends ValueNotifier<double> {
   double _min;
   double _max;
 
-  final double step;
-  final double? pageStep;
   final int decimals;
 
   double get min => _min;
@@ -66,11 +62,6 @@ class SpinController extends ValueNotifier<double> {
     return int.tryParse(text)?.toDouble();
   }
 
-  void stepUp() => value += step;
-  void stepDown() => value += -step;
-  void pageStepUp() => value += pageStep ?? 0;
-  void pageStepDown() => value -= pageStep ?? 0;
-
   bool canChange(double value) => true;
 
   @override