Question

我正在使用multi_image_picker包来选择图像并上传到服务器，但是在上传之前，我想调整图像的大小。我正在尝试使用dart.ui完成此操作，但是遇到了问题：

//assets is List<Asset> from MultiImagePicker.pickImages
 assets.forEach((asset) {
      Future<ByteData> byteData = asset.getByteData();
      byteData.then((d) async {
        List<int> imageData = d.buffer.asUint8List();
        String b64 =base64Encode(imageData);
        print(b64); // prints [/9j/4AAQSkZJRgABAQAAAQABAAD/2wBDAAEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQE...
        //if i send b64 to server then decode it and save as img it's working well

  //Resize
    ui.instantiateImageCodec(imageData,targetHeight: 800, targetWidth: 600)
        .then((codec) {
      codec.getNextFrame().then((frameInfo) async {
        ui.Image i = frameInfo.image;
        ByteData bytes = await i.toByteData();
        List<int> resizedImageData = bytes.buffer.asUint8List();
        String rb64 = base64Encode(resizedImageData);
        print(rb64); // prints too many backslashes:[k5KO/5qWk/+ZlZL/mpaT/5uXlP+alpP/mJSR/5iUkf+YlJH/mZSR/5uWk/+blpP/n5qX/6GcmP+gm5f/oZyY/6GcmP+fmpb/nZi..
        //If i send rb64 to server then server cannot decode and save it.
      });
    });
  });
});

Answer 1

这是我通常用来调整大小的功能：

import 'dart:ui' as skia;

Future<skia.Image> resizeImage(String path, {int width, int height}) async {
  Uint8List data = await File(path).readAsBytes();
  final codec = await skia.instantiateImageCodec(data, targetWidth: width, targetHeight: height);
  final frame = await codec.getNextFrame();
  return frame.image;
}

正如我在评论中提到的那样，当前在Flutter Web中不起作用，但这是由于希望尽快修复此错误。

如何在Flutter中使用multi_image_picker调整图像大小？

1 个答案: