basic flutter UI

basicRowColumn.dart

new Container(
    padding: new EdgeInsets.all(8.0),
    height: 250.0,
    child: textExample,
  )

final row = new Row(
          children: <Widget>[
            textExample,
            textExample,
            textExample
          ],
        )

final column = new Column(
      mainAxisAlignment: MainAxisAlignment.spaceAround,
      children: <Widget>[
        textExample,
        textExample
      ],
    )

final stackOfItems = new Stack(
        children: <Widget>[
          backgroundImage,
          onTopContent
        ],
      )
//RED Line
final redLine = new Container(
          height: 2.0,
          width: 150.0,
          color: Colors.redAccent,
        )

blankApp.dart

//In the declarative style, view configurations (such as Flutter’s Widgets) 
//are immutable and are only lightweight “blueprints”. 
//To change the UI, a Widget triggers a rebuild on itself
//(most commonly by calling setState() on StatefulWidgets 
//in Flutter) and constructs a new Widget subtree.

//BLANK APP
import 'package:flutter/material.dart';

//BLANK APP
void main() => runApp(new MyApp());

class MyApp extends StatelessWidget {
  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: new FirstScreen(), //calling chat_screen_item.dart
    );
  }
}

class FirstScreen extends StatelessWidget{
  final textExample = new Text("example",
    style: new TextStyle(
      color: Colors.black,
      fontWeight: FontWeight.w600,
      fontSize: 16.0,
      backgroundColor: Colors.red,
    ),);

  @override
  Widget build(BuildContext context) {
    return new Scaffold(
      appBar: new AppBar(
        title: new Text("Chat Item"),
        backgroundColor: Colors.lightGreen,
      ),
      body: textExample, //calling chat_item.dart
    );
  }
}

custom_theme.dart

import 'package:flutter/material.dart';

final baseTextStyle = const TextStyle(
  color: Colors.white,
  fontFamily: 'arial'

);
final bigHeaderTextStyle = baseTextStyle.copyWith(
    fontSize: 20.0,
    fontWeight: FontWeight.bold,
);

final descTextStyle = baseTextStyle.copyWith(
  fontSize: 12.0,
  fontWeight: FontWeight.w400,
);

final footerTextStyle = baseTextStyle.copyWith(
  fontSize: 10.0,
  fontWeight: FontWeight.w400,
);