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Flutter | Cookbook

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Development Workflow

TL;DR

flutter create <app>
cd <app>
flutter run

Run App

flutter
flutter run --release .\lib\go_router.dart

VSCode and DevTools

Change default browser

Press F1, find Preferences: Open Settings (UI) then search for devtoolsbrowser.

Change in DevTools Menu

Working with Modules and Classes

Import all Modules from a Folder

Suppose you have a list of modules located in the folder models and you want to import all of them.

To do this

  • create a file index.dart which exports all files
  • in your dart file, import this index.dart
export 'counter.dart';
export 'number.dart';
import 'data/models/index.dart';

Create custom code for unsupported packages

Create main file to check, if package is available. If not, then switch to custom code

export 'unsupported.dart' if (dart.library.io) 'io.dart';

Use this file in your code

import 'plugins/desktop/desktop.dart';

Create files for supported and unsupported packages

io.dart

import 'dart:io';

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

void setTargetPlatformForDesktop({TargetPlatform platform}) {
  TargetPlatform targetPlatform;
  if (platform != null) {
    targetPlatform = platform;
  }
  if (targetPlatform == null) {
    if (Platform.isMacOS) {
      targetPlatform = TargetPlatform.iOS;
    } else if (Platform.isLinux || Platform.isWindows) {
      targetPlatform = TargetPlatform.android;
    }
  }
  debugDefaultTargetPlatformOverride = targetPlatform;
}

unsupported.dart

import 'package:flutter/material.dart';

void setTargetPlatformForDesktop({TargetPlatform platform}) {}

Working with Themes

Using a Theme in MaterialApp()

return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: const MyHomePage(title: 'Flutter Demo Home Page'),
    );
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData.light().copyWith(
        primaryColor: Colors.blue,
      ),
      darkTheme: ThemeData.dark(),
      home: MyHomePage(title: 'Flutter Demo Home Page'),
    );

Working with CSS Colors

Import

import 'package:css_colors/css_colors.dart';

Usage

new Container(color: CSSColors.orange)

App Bar

How to remove a DEBUG Banner

MaterialApp(
  debugShowCheckedModeBanner: false,

  home: Scaffold(
    appBar: AppBar(
      title: const Text('Home'),
    ),
  ),  
);

Working With Data and Data Models

Replace Integer Variables with a Data Model

Examining the default Flutter App (Counter Sample), shows, that the real counter is implemented as integer with integer operations:

int _counter = 0;

void _incrementCounter() {
  setState(() {
    _counter++;
  });
}

If you want to customize the varianble and operations, you could replace the interger variable witrh your own data model

import 'data/models/counter.dart';

CounterModel _counter = CounterModel();

void _incrementCounter() {
  setState(() {
    _counter.add(1);
  });
}

The CounterModel is defined in data/models/counter.dart'

class CounterModel {
  int _value = 0;

  int get value => _value;

  void set(int val) => _value = val;
  void add(int val) => _value += val;
  void remove(int val) => _value -= val;

  void reset() => _value = 0;

  @override
  String toString() {
    return value.toString();
  }
}

Interesting Pack

device_preview

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