Add onSubmitted (ubuntu-flutter-community#74)

Author: BenGMiles

lib/src/base_spin_box.dart

@@ -38,6 +38,7 @@ abstract class BaseSpinBox extends StatefulWidget {
   int get decimals;
   int get digits;
   ValueChanged<double>? get onChanged;
+  void Function(double value)? get onSubmitted;
   bool Function(double value)? get canChange;
   VoidCallback? get beforeChange;
   VoidCallback? get afterChange;
@@ -154,6 +155,7 @@ mixin SpinBoxMixin<T extends BaseSpinBox> on State<T> {
     } else {
       _cachedValue = _value;
     }
+    widget.onSubmitted?.call(_cachedValue);
   }
 
   void _handleFocusChanged() {

lib/src/cupertino/spin_box.dart

@@ -80,6 +80,7 @@ class CupertinoSpinBox extends BaseSpinBox {
     this.enableInteractiveSelection = true,
     this.spacing = 8,
     this.onChanged,
+    this.onSubmitted,
     this.canChange,
     this.beforeChange,
     this.afterChange,
@@ -255,6 +256,10 @@ class CupertinoSpinBox extends BaseSpinBox {
   /// See [CupertinoTextField.toolbarOptions].
   final ToolbarOptions? toolbarOptions;
 
+  /// See [CupertinoTextField.onSubmitted]. Is called with a formatted value.
+  @override
+  final void Function(double)? onSubmitted;
+
   @override
   State<CupertinoSpinBox> createState() => _CupertinoSpinBoxState();
 }

lib/src/material/spin_box.dart

@@ -82,6 +82,7 @@ class SpinBox extends BaseSpinBox {
     this.enableInteractiveSelection = true,
     this.spacing = 8,
     this.onChanged,
+    this.onSubmitted,
     this.canChange,
     this.beforeChange,
     this.afterChange,
@@ -263,6 +264,10 @@ class SpinBox extends BaseSpinBox {
   /// See [TextField.toolbarOptions].
   final ToolbarOptions? toolbarOptions;
 
+  /// See [TextField.onSubmitted]. Is called with a formatted value.
+  @override
+  final void Function(double)? onSubmitted;
+
   @override
   State<SpinBox> createState() => _SpinBoxState();
 }