StyleableInput

import 'package:flutter/cupertino.dart';
import 'package:flutter/material.dart';

class InputField extends StatelessWidget {
  final IconData icon;
  final String hintText;
  final TextInputType textInputType;
  final Color textFieldColor, iconColor;
  final bool obscureText;
  final double bottomMargin;
  final double topMargin;
  final double rightMargin;
  final double leftMargin;
  final TextStyle textStyle, hintStyle;
  var validateFunction;
  var onSaved;
  Key key;
  final TextEditingController controller;

  //passing props in the Constructor.
  //Java like style
  InputField(
      {this.key,
      this.hintText,
      this.obscureText,
      this.textInputType,
      this.textFieldColor,
      this.icon,
      this.iconColor,
      this.bottomMargin,
      this.topMargin,
      this.rightMargin,
      this.leftMargin,
      this.textStyle,
      this.validateFunction,
      this.onSaved,
      this.hintStyle,
      this.controller});

  @override
  Widget build(BuildContext context) {
    // TODO: implement build
    return (new Container(
        padding: EdgeInsets.only(),
        margin: new EdgeInsets.only(
            bottom: bottomMargin,
            right: rightMargin,
            top: topMargin,
            left: leftMargin),
        child: new DecoratedBox(
          decoration: new BoxDecoration(
              borderRadius: new BorderRadius.all(new Radius.circular(5.0)),
              color: iconColor.withAlpha(50)),
          child: new Container(
            margin: EdgeInsets.only(left: 10.0),
            child: new TextFormField(
              controller: controller,
              style: textStyle,
              key: key,
              obscureText: obscureText,
              keyboardType: textInputType,
              validator: validateFunction,
              onSaved: onSaved,
              decoration: new InputDecoration(
                border: InputBorder.none,
                hintText: hintText,
                hintStyle: hintStyle,
                suffixIcon: new Padding(
                  padding: const EdgeInsets.all(8.0),
                  // child: new Icon(
                  //   icon,
                  //   color: iconColor,
                  // ),
                  child: new CupertinoButton(
                padding: EdgeInsets.zero,
                child: const Icon(
                  CupertinoIcons.search,
                  color: Colors.pink,
                  semanticLabel: 'Search',
                ),
                onPressed: () {
                   //Navigator.pushNamed(context, Base.favoriteScreen);
                },
              ),
                ),
              ),
            ),
          ),
        )));
  }
}

Useage

new InputField(
                        controller: searchTxtController,
                        hintText: "Search for cakes and fast foods",
                        //hintStyle: new TextStyle(color: Colors.pink),
                        obscureText: false,
                        textInputType: TextInputType.text,
                        textStyle: new TextStyle(color: Colors.pink),
                        textFieldColor: Colors.pink,
                        iconColor: Colors.pink,
                        icon: Icons.search,
                        bottomMargin: 10.0,
                        rightMargin: 10.0,
                        topMargin: 10.0,
                        leftMargin: 10.0,
                        onSaved: (String name) {},
                      ),