Flutter：如何以透明背景保存小部件为PNG？

Question

Flutter：如何以透明背景保存小部件为PNG？

flutter

3

有没有将小部件保存为透明PNG并保存到图库的方法呢？谢谢。

- LilRan14

1个回答

网页内容由stack overflow 提供, 点击上面的

可以查看英文原文，
原文链接

- Ravi Singh Lodhi · Accepted Answer

Flutter 绘制每个像素，因此您可以轻松地将小部件转换为图像。

您需要按照以下步骤操作：

编辑 -- 首先在 pupspec.yaml 中导入链接 path_provider ，然后按照以下步骤操作：

Create a GlobalKey
```
final _globalKey = GlobalKey();
```
Create Uint8List
```
Uint8List pngBytes;
```

Wrap your widget with RepaintBoundary widget & pass in the key

RepaintBoundary(
  key: _globalKey,
  child: YourWidget(),
),

Create a method to convert your widget to image:

Future<void> _capturePng() async {
  try {
    final RenderRepaintBoundary boundary =
        _globalKey.currentContext.findRenderObject();
    final image = await boundary.toImage(pixelRatio: 2.0); // image quality
    final byteData = await image.toByteData(format: ui.ImageByteFormat.png);
    pngBytes = byteData.buffer.asUint8List();
  } catch (e) {
    print(e);
  }
}

Convert your image to a file so that you can save it in your app

Future<File> convertImageToFile(Uint8List image) async {
  final file = File(
      '${(await 
     getTemporaryDirectory()).path}/${DateTime.now().millisecondsSinceEpoch}.png');
  await file.writeAsBytes(image);

  return file;
}