Flutter TextField LabelText Center

The Desired Effect is to have Kartennummer and Passwort centrated.
How is this possible?

I use a custom class for this:

import 'package:flutter/material.dart';
import 'package:impex_shop/styles/impex_styles.dart';

class ImpexTextField extends StatefulWidget {
  final TextEditingController controller;
  final bool obscureText;
  final TextInputType keyboardType;
  final String labelText;
  final IconData prefixIcon;
  final int maxLines;
  final TextInputAction textInputAction;
  final void Function(String) onSubmitted;
  final bool autofocus;

  const ImpexTextField(
      {Key key,
      this.controller,
      this.obscureText,
      this.keyboardType,
      this.labelText,
      this.prefixIcon,
      this.maxLines = 1,
      this.textInputAction,
      this.onSubmitted,
      this.autofocus = false})
      : super(key: key);

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

class _ImpexTextFieldState extends State<ImpexTextField> {
  FocusNode _focusNode = FocusNode();
  Paint paint;

  InputDecoration buildTextInputDecoration(
      String labelText, TextEditingController controller, IconData prefixIcon) {
    return InputDecoration(
      labelText: labelText,
      labelStyle: TextStyle(
        color: ImpexColors.mainColor,
        height: 0.8, // 0,1 - label will sit on top of border
        background: paint,
      ),
      fillColor: ImpexColors.lightGrey,
      filled: true,
      enabledBorder: OutlineInputBorder(
        borderSide: const BorderSide(
          color: ImpexColors.grey,
          width: 1.0,
        ),
      ),
      focusedBorder: OutlineInputBorder(
        borderSide: const BorderSide(
          color: ImpexColors.secondaryColor,
          width: 2.0,
        ),
      ),
      suffixIcon: InkWell(
        onTap: () => controller.clear(),
        child: Icon(Icons.cancel),
      ),
      prefixIcon: prefixIcon == null ? null : Icon(prefixIcon),
    );
  }

  @override
  Widget build(BuildContext context) {
    return Container(
      child: ListView(
        shrinkWrap: true,
        physics: ClampingScrollPhysics(),
        children: <Widget>[
          Container(
            height: 12,
          ),
          TextField(
            textAlign: TextAlign.center,
            textAlignVertical: TextAlignVertical.center,
            focusNode: _focusNode,
            controller: widget.controller,
            obscureText: widget.obscureText ?? false,
            maxLines: widget.maxLines,
            textInputAction: widget.textInputAction,
            decoration: buildTextInputDecoration(
                widget.labelText, widget.controller, widget.prefixIcon),
            keyboardType: widget.keyboardType,
            autofocus: widget.autofocus,
            onSubmitted: widget.onSubmitted,
            onTap: () => setState(() {
              FocusScope.of(context).requestFocus(_focusNode);
            }),
          ),
        ],
      ),
    );
  }

  @override
  void dispose() {
    _focusNode.dispose();
    super.dispose();
  }
}

Solution 1:

There is a nice decision for this.
Try to use alignLabelWithHint: true.
As example:

TextField(keyboardType: TextInputType.number, textAlign: TextAlign.center, maxLines: 1, decoration: InputDecoration(alignLabelWithHint: true, enabledBorder: InputBorder.none, contentPadding: EdgeInsets.zero, focusedBorder: InputBorder.none, border: InputBorder.none, labelStyle: Theme.of(context).textTheme.headline6, labelText: 'Amount (GPB)'.toUpperCase(),),),

Solution 2:

A Very and Handy solution to Center the Label:

Since Label is accepting Widget after flutter 2.5.x, so you can wrap your Text widget into Center widget like this,

TextFormField(
  decoration: InputDecoration(
    label: const Center(
      child: Text("Your Centered Label Text"),
    ),
  ),
)

Solution 3:

I had a similar problem with labels, my solution was, as Ragu Swaminathan says, to create my own custom widget that used a Stack with the TextField on the bottom and faded Text widget above it. Obviously the text widget doesn't need to be faded but I was just mimicking the style of regular labels.

class CenteredTextField extends StatelessWidget {
  final String label;
  final TextEditingController controller;

  CenteredTextField({
    @required this.label,
    this.controller,
  });

  @override
  Widget build(BuildContext context) {
    return Stack(
      alignment: Alignment.topCenter,
      children: [
        Padding(
          padding: EdgeInsets.only(top: 12.5),
          child: TextField(
            textAlign: TextAlign.center,
            controller: controller,
          ),
        ),
        Padding(
          padding: EdgeInsets.only(top: 4.0),
          child: Opacity(
            opacity: 0.7,
            child: Text(label),
          ),
        ),
      ],
    );
  }
}