Why Is PNG file with Drop Shadow in Flutter Web App Grainy?

Question

I just started to learn Flutter to build a web app, and I can't figure out why the PNG images I include in the app are grainy. Here's how it looks in Chrome:

Here is the entirety of my app:

import 'package:flutter/material.dart';

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

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

  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return const MaterialApp(
      title: 'Flutter Demo',
      home: MyHomePage(),
    );
  }
}

class MyHomePage extends StatefulWidget {
  const MyHomePage({Key? key}) : super(key: key);

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

class _MyHomePageState extends State<MyHomePage> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('Test App'),
      ),
      body: Container(
        color: Colors.black,
        child: Image.asset(
          'circle.png',
          width: 208,
          height: 208,
        ),
      ),
    );
  }
}

Here is the image I am using: https://www.dropbox.com/s/barf3lcj80fqbqg/circle.png?dl=0

I've tried a few different PNG files and these are exported from Figma. They appear to have transparency and a drop shadow when I open them in macOS Finder or in Chrome directly. But something happens when Flutter renders them.

Am I missing a property on the Image widget? Or is a drop shadow on an Image not supported?

Solution 1

Version 3.0.x has this bug, but if you use the actual master branch(3.1.0-0.0.pre.2481) of flutter the issue is fixed already. Therefore it should be fixed in next stable release too.

Solution 2

I just set the filterQuality to FilterQuality.high, and it worked on 3.0.5:

Image.asset(
  'circle.png',
  width: 208,
  height: 208,
  filterQuality: FilterQuality.high,
),

Comments

[MendelG]

For me, the image does load correctly, see it here. Try running flutter clean and flutter pub get. Also, try opening a new project

[Clifton Labrum]

I'm using a MacBook Pro with a high-resolution monitor and I wonder if it's related to that. I just added a /2x and /3x folder inside /assets and then put the @2x and @3x versions of the circle.png in those respective folders, but it still looks grainy. 🤔

[MCB]

Seems like a bug of the current flutter version. I have the same problem... I used Flutter 2.10.3 and the png looked as it should. Now I changed the version to 3.0.5 and the picture has white pixels all around ...