如何在不使用异步的情况下将图像转换为 uint8list? [英] How to convert image to uint8list in flutter without using async?

问题描述

PdfImage 需要 Uint8List 作为参数，但我有 ImageProvider.那么flutter中如何将image转为uint8list呢?

PdfImage requires Uint8List as param but I have ImageProvider. So how can we convert image to uint8list in flutter?

var imageProvider = AssetImage('assets/test.jpg');

final image = PdfImage(
  pdf.document,
  image:???, /// Uint8List required
  width: img.width,
  height: img.height,
);

使用 FutureBuilder:

推荐答案

使用rootBundle.load()

(await rootBundle.load(/*YOUR IMAGE PATH HERE*/)).buffer.asUint8List()

<小时>

更新

由于 load() 是异步操作，所以需要等到数据完全加载完毕.在此之前尝试用一些加载指示器替换 UI.

---

UPDATE

As load() is an async operation, you need to wait until the data is fully loaded. Try substituting the UI with some loading indicator until then.

ByteData imageData;

@override
void initState() {
  rootBundle.load('assets/test.jpg')
    .then((data) => setState(() => this.imageData = data));
}

@override
Widget build(BuildContext context) {
  if (imageData == null) {
    return Center(child: CircularProgressIndicator());
  }

  final image = PdfImage(
    pdf.document,
    image: imageData.buffer.asUint8List(),
    width: img.width,
    height: img.height,
  );

  ...
}

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