Flutter - Switching between two images using GestureDetector - flutter

Question

I found this code and modify it to switch between two pictures.
it seems to me that is ok but ..... iT doesn't work.
Can you help me to understand why?
Thanks.
See below the full code.
import 'dart:ui';
import 'package:flutter/material.dart';
void main() {
runApp(new MaterialApp(
home: new MyApp(),
));
}
class MyApp extends StatefulWidget {
#override
_MyAppState createState() => _MyAppState();
}
class _MyAppState extends State<MyApp> {
Image img; // variable named image to be named with the path
Image imgUp = Image.asset("assets/images/pressed.jpg"); //pressed button path
Image imgDown = Image.asset("assets/images/pressed.jpg"); //unpressed button path
#override
void initState() {super.initState();
img = imgUp; //inizialize the image as imgUp version
}
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text("Tap The Image!"),
centerTitle: true,
), //AppBar section ended
body: Center(child: GestureDetector(
child: img,
onTapDown: (tap) {
setState(() {
img = imgDown;
});
},
onTapUp: (tap) {
setState(() {
img = imgUp;
});
},
),
));
}
}

Answer 1

It probably doesn't work because you are using the same image for up and down. Please see here
Image imgUp = Image.asset("assets/images/pressed.jpg"); //pressed button path
Image imgDown = Image.asset("assets/images/pressed.jpg"); //
It works if you change the images, please see code below : [Note that the image changes back to imgUp as soon as you release the tap down.]
import 'dart:ui';
import 'package:flutter/material.dart';
void main() {
runApp(new MaterialApp(
home: new MyApp(),
));
}
class MyApp extends StatefulWidget {
#override
_MyAppState createState() => _MyAppState();
}
class _MyAppState extends State<MyApp> {
Image img; // variable named image to be named with the path
Image imgUp = Image.network("https://cdn3.iconfinder.com/data/icons/faticons/32/arrow-up-01-512.png"); //pressed button path
Image imgDown = Image.network("https://cdn3.iconfinder.com/data/icons/faticons/32/arrow-down-01-512.png"); //unpressed button path
#override
void initState() {super.initState();
img = imgUp; //inizialize the image as imgUp version
}
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text("Tap The Image!"),
centerTitle: true,
), //AppBar section ended
body: Center(child: GestureDetector(
child: img,
onTapDown: (tap) {
setState(() {
img = imgDown;
});
},
onTapUp: (tap) {
setState(() {
img = imgUp;
});
},
),
));
}
}