BoxDecoration:DecorationImage全屏背景图片 [英] BoxDecoration: DecorationImage Fullscreen background image

问题描述

根据 Flutter文档，我正在尝试使用DecoratedBox加载全屏图像作为容器的背景图像.

As per the Flutter docs I'm trying to use the DecoratedBox to load a fullscreen image as the background image for a Container.

我的pubspec.yaml包含嵌入式资产的相关定义:

my pubspec.yaml contains the relevant definition for an embedded asset:

flutter:
  uses-material-design: true
  assets:
    - assets/background.png

和widget.dart尝试按规定填充新Container的背景:

and the widget.dart tries to fill the background of a new Container as prescribed:

@override
  Widget build(BuildContext context) {
    return new Container(
            decoration: new BoxDecoration(
              color: Colors.purple,
              image : new DecorationImage(
                image: new ExactAssetImage('assets/background.png'),
                fit: BoxFit.cover,
              ),
            ),
     ),
  }

但是出现以下错误:

Unable to load asset: assets/background.png 

Image provider: ExactAssetImage(name: "assets/background.png", scale: 1.0, bundle: null)

很显然，捆绑软件无法正确解析.有人知道我在这里到底在做什么错吗?

Clearly the bundle is not resolving correctly. Does anyone have an idea of what exactly I'm doing wrong here?

推荐答案

它对我有用.需要仔细检查的几件事:

It works for me. A few things to double check:

• 热重装/重启不会更改资产，因此请确保您要进行常规构建.
• 尝试从设备上卸载应用并执行干净的构建，有时构建系统很难替换旧的安装(例如，如果调试密钥更改了)
• 确保实际资产及其所有引用都指向资产/background.png，而不是images/background.png(默认的pubspec.yaml建议将图像放入名为images的文件夹中，但不会只要一切都匹配就可以了.
• 尝试使用AssetImage代替ExactAssetImage
• 确保容器有一个孩子或位于其父级将为其指定大小的位置(例如Stack可以，但是Column会使它为0x0)没有内在的大小或孩子)

• Hot reloading/restarting won't change assets, so make sure you're doing a regular build.
• Try uninstalling the app from the device and doing a clean build, sometimes the build system has a hard time replacing the old install (e.g. if your debug key changes)
• Make sure that the actual asset as well as all the references to it are pointing to assets/background.png and not images/background.png (the default pubspec.yaml suggests putting images into a folder called images, but it doesn't matter as long as everything matches).
• Try using AssetImage instead of ExactAssetImage
• Make sure the Container either has a child or is in a place where it will be given a size by its parent (e.g. a Stack would be fine, but a Column would cause it to be 0x0 if it has no intrinsic size or child)

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