mobile_nebula/lib/components/PlatformTextFormField.dart

import 'package:flutter/cupertino.dart';
import 'package:flutter/services.dart';
import 'package:mobile_nebula/components/SpecialTextField.dart';
//TODO: reset doesn't update the ui but clears the field

class PlatformTextFormField extends FormField<String> {
  //TODO: auto-validate, enabled?
  PlatformTextFormField({
    super.key,
    widgetKey,
    this.controller,
    focusNode,
    nextFocusNode,
    TextInputType? keyboardType,
    textInputAction,
    List<TextInputFormatter>? inputFormatters,
    textAlign,
    autofocus,
    maxLines = 1,
    maxLength,
    maxLengthEnforcement,
    onChanged,
    keyboardAppearance,
    minLines,
    expands,
    suffix,
    textAlignVertical,
    String? initialValue,
    String? placeholder,
    FormFieldValidator<String>? validator,
    super.onSaved,
  }) : super(
         initialValue: controller != null ? controller.text : (initialValue ?? ''),
         validator: (str) {
           if (validator != null) {
             return validator(str);
           }

           return null;
         },
         builder: (FormFieldState<String> field) {
           final _PlatformTextFormFieldState state = field as _PlatformTextFormFieldState;

           void onChangedHandler(String value) {
             if (onChanged != null) {
               onChanged(value);
             }
             field.didChange(value);
           }

           return Column(
             crossAxisAlignment: CrossAxisAlignment.end,
             children: <Widget>[
               SpecialTextField(
                 key: widgetKey,
                 controller: state._effectiveController,
                 focusNode: focusNode,
                 nextFocusNode: nextFocusNode,
                 keyboardType: keyboardType,
                 textInputAction: textInputAction,
                 textAlign: textAlign,
                 autofocus: autofocus,
                 maxLines: maxLines,
                 maxLength: maxLength,
                 maxLengthEnforcement: maxLengthEnforcement,
                 onChanged: onChangedHandler,
                 keyboardAppearance: keyboardAppearance,
                 minLines: minLines,
                 expands: expands,
                 textAlignVertical: textAlignVertical,
                 placeholder: placeholder,
                 inputFormatters: inputFormatters,
                 suffix: suffix,
               ),
               field.hasError
                   ? Text(
                     field.errorText!,
                     style: TextStyle(color: CupertinoColors.systemRed.resolveFrom(field.context), fontSize: 13),
                     textAlign: textAlign,
                   )
                   : Container(height: 0),
             ],
           );
         },
       );

  final TextEditingController? controller;

  @override
  _PlatformTextFormFieldState createState() => _PlatformTextFormFieldState();
}

class _PlatformTextFormFieldState extends FormFieldState<String> {
  TextEditingController? _controller;

  TextEditingController get _effectiveController => widget.controller ?? _controller!;

  @override
  PlatformTextFormField get widget => super.widget as PlatformTextFormField;

  @override
  void initState() {
    super.initState();
    if (widget.controller == null) {
      _controller = TextEditingController(text: widget.initialValue);
    } else {
      widget.controller!.addListener(_handleControllerChanged);
    }
  }

  @override
  void didUpdateWidget(PlatformTextFormField oldWidget) {
    super.didUpdateWidget(oldWidget);
    if (widget.controller != oldWidget.controller) {
      oldWidget.controller?.removeListener(_handleControllerChanged);
      widget.controller?.addListener(_handleControllerChanged);

      if (oldWidget.controller != null && widget.controller == null) {
        _controller = TextEditingController.fromValue(oldWidget.controller!.value);
      }
      if (widget.controller != null) {
        setValue(widget.controller!.text);
        if (oldWidget.controller == null) _controller = null;
      }
    }
  }

  @override
  void dispose() {
    widget.controller?.removeListener(_handleControllerChanged);
    super.dispose();
  }

  @override
  void reset() {
    super.reset();
    setState(() {
      _effectiveController.text = widget.initialValue ?? "";
    });
  }

  void _handleControllerChanged() {
    // Suppress changes that originated from within this class.
    //
    // In the case where a controller has been passed in to this widget, we
    // register this change listener. In these cases, we'll also receive change
    // notifications for changes originating from within this class -- for
    // example, the reset() method. In such cases, the FormField value will
    // already have been set.
    if (_effectiveController.text != value) didChange(_effectiveController.text);
  }
}