flutter - 从 Flutter 图像中的 Png 中删除白色背景

Question

我有一段代码在 DecorationImage 中显示图像(或图像路径，如果保存)，但问题是透明 png 透明度被视为白色背景(_logo 是一个文件)，这里是代码:

decoration: BoxDecoration(
      image: DecorationImage(
           image: _logopath != null
              ? FileImage(File(_logopath))
                : _logo == null
                 ? MemoryImage(kTransparentImage)
                  : FileImage(_logo),
                   fit: BoxFit.contain),

我的问题是是否有某种方法可以使所选的 png 图像实际上是透明的，并且没有白色背景填充透明度。

Answer 1

我认为它已经是透明的了。

import 'package:flutter/material.dart';

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

class MyApp extends StatelessWidget {
  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
        visualDensity: VisualDensity.adaptivePlatformDensity,
      ),
      home: MyHomePage(title: 'Flutter Demo Home Page'),
    );
  }
}

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

  final String title;

  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(widget.title),
      ),
      body: Center(
        child: Stack(
          children: [
            Container(
              color: Colors.grey,
            ),
            Container(
              decoration: BoxDecoration(
                image: DecorationImage(
                  fit: BoxFit.fitWidth,
                  image: AssetImage('images/gyvegetable.png'),
                ),
              ),
            ),
          ],
        ),
      ),
    );
  }
}