Fetch an image from the web with a tap on a placeholder.

image_attachment_on_tap.dart

import 'package:flutter/material.dart';
import 'dart:math' as math;

final Color darkBlue = Color.fromARGB(255, 18, 32, 47);

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      debugShowCheckedModeBanner: false,
      home: Scaffold(
        body: MyWidget(),
      ),
    );
  }
}

class MyWidget extends StatefulWidget {
  @override
  _MyWidgetState createState() => _MyWidgetState();
}

class _MyWidgetState extends State<MyWidget> {
  Widget buttonIcon;

  @override
  void initState() {
    super.initState();
    buttonIcon = Icon(
      Icons.attachment,
      size: 25,
    );
  }

  @override
  Widget build(BuildContext context) {
    return Container(
        child: Column(
            mainAxisAlignment: MainAxisAlignment.start,
            children: <Widget>[
          Container(
            padding: EdgeInsets.all(0),
            height: 200,
            width: 120,
            decoration: BoxDecoration(
              border: Border.all(color: Colors.black, width: 1),
              borderRadius: BorderRadius.circular(1),
            ),
            child: Transform.rotate(
                angle: math.pi / 4,
                child: IconButton(
                  icon: buttonIcon,
                  tooltip: 'Attachment',
                  onPressed: () => setState(() => buttonIcon = Image.network(
                      'https://geeksta.net/img/large/tux-linux-hope-poster.jpg')),
                )
//  child: showImage(),
                ),
          ),
        ]));
  }
}