マップページの高速化

[r0227n]

CustomPaintからの脱却

InteractiveViewerとStackを活用し、マップ画像＆スポット画像(4枚)を1回のレンダリングで済むようにする。

デモ動画

https://user-images.githubusercontent.com/40818362/149429323-3dfdb17e-f568-4850-80c3-5e0dc0bcffac.mp4

コード

import 'package:flutter/material.dart';

void main() {
  runApp(const MyApp());
}

class MyApp extends StatelessWidget {
  const MyApp({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: const MyHomePage(title: 'Flutter Demo Home Page'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  const MyHomePage({Key? key, required this.title}) : super(key: key);

  final String title;

  @override
  State<MyHomePage> createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text(widget.title)),
      body: InteractiveViewer(
        constrained: false,
        child: Stack(
          children: <Widget>[
            Container(
              color: Colors.red,
              width: 600,
              height: 500,
            ),
            Positioned(
              left: 100,
              child: Container(
                color: Colors.blue,
                width: 100,
                height: 100,
              ),
            ),
            Positioned(
              top: 300,
              left: 200,
              child: Container(
                color: Colors.blue,
                width: 100,
                height: 100,
              ),
            ),
            Positioned(
              left: 300,
              child: Container(
                color: Colors.blue,
                width: 100,
                height: 100,
              ),
            ),
            Positioned(
              top: 300,
              left: 400,
              child: Container(
                color: Colors.blue,
                width: 100,
                height: 100,
              ),
            ),
          ],
        ),
      ),
    );
  }
}