茜素FilePicker ImageSource

Question

我有一个应用程序，用户可以使用FilePicker.PickMultipleAsync通过图库添加照片。此外，用户还可以使用CrossMedia插件拍摄这一功能。

如果用户以肖像格式拍摄照片(CrossMedia)，则将照片转换为要显示的ImageSource。如果用户选择了图像，它就会执行对ImageSource的相同转换过程，但是在这种情况下，照片会自动旋转到右边。

这种情况发生在相机的本地应用程序拍摄的照片上。如果用户下载任何图像并从图库中选择它，问题就不会发生。这个问题是在将插件切换到FilePicker之后开始的。

我能做些什么来显示原始图像？

版本: Xamarin.Forms: 5.0.0.2401 Xamarin.Essentials: 1.7.3

插件代码

var result = await FilePicker.PickMultipleAsync(new PickOptions
{
    PickerTitle = "Choose Images",
    FileTypes = FilePickerFileType.Images
});

if (result != null)
{
    foreach (var item in result)
    {
        AttachedFiles.Add(new AttachmentFiles(item));
    }
}

public AttachmentFiles(FileResult imgSource)
{
    var imageAsBytes = ImageHelper.ConvertStreamToByteArray(Task.Run(async () => await imgSource.OpenReadAsync()).Result);
    var resizer = DependencyService.Get<IImageResize>();

    this.ImageId = Guid.NewGuid();
    this.Source = ImageSource.FromStream(() => new MemoryStream(imageAsBytes));
    this.SourceT = ImageSource.FromStream(() => new MemoryStream(resizer.ResizeImage(imageAsBytes, 70, 70)));
}

​

​

我从网上下载的左边的图片显示得很正确。右边的照片是我在相机前拍摄的，然后从画廊中选择了

Answer 1

我用代码解决了这个问题

 public class PhotoPickerService : IPhotoPickerService
    {
        public async Task<byte[]> ImageToArrayAsync(string path)
        {
            try
            {
                var exif = new Android.Media.ExifInterface(path);
                string orientation = exif.GetAttribute(Android.Media.ExifInterface.TagOrientation);

                //Get the bitmap.
                var originalImage = BitmapFactory.DecodeFile(path);

                //Set imageSize and imageCompression parameters.
                var imageSize = .40;
                var imageCompression = 45;

                //Resize it and then compress it to Jpeg.
                var width = originalImage.Width * imageSize;
                var height = originalImage.Height * imageSize;
                var scaledImage = Bitmap.CreateScaledBitmap(originalImage, (int)width, (int)height, true);

                var matrix = new Matrix();

                switch (orientation)
                {
                    case "1": // landscape
                        break;
                    case "3":
                        matrix.PreRotate(180);
                        scaledImage = Bitmap.CreateBitmap(scaledImage, 0, 0, scaledImage.Width, scaledImage.Height, matrix, true);
                        matrix.Dispose();
                        matrix = null;
                        break;
                    case "4":
                        matrix.PreRotate(180);
                        scaledImage = Bitmap.CreateBitmap(scaledImage, 0, 0, scaledImage.Width, scaledImage.Height, matrix, true);
                        matrix.Dispose();
                        matrix = null;
                        break;
                    case "5":
                        matrix.PreRotate(90);
                        scaledImage = Bitmap.CreateBitmap(scaledImage, 0, 0, scaledImage.Width, scaledImage.Height, matrix, true);
                        matrix.Dispose();
                        matrix = null;
                        break;
                    case "6": // portrait
                        matrix.PreRotate(90);
                        scaledImage = Bitmap.CreateBitmap(scaledImage, 0, 0, scaledImage.Width, scaledImage.Height, matrix, true);
                        matrix.Dispose();
                        matrix = null;
                        break;
                    case "7":
                        matrix.PreRotate(-90);
                        scaledImage = Bitmap.CreateBitmap(scaledImage, 0, 0, scaledImage.Width, scaledImage.Height, matrix, true);
                        matrix.Dispose();
                        matrix = null;
                        break;
                    case "8":
                        matrix.PreRotate(-90);
                        scaledImage = Bitmap.CreateBitmap(scaledImage, 0, 0, scaledImage.Width, scaledImage.Height, matrix, true);
                        matrix.Dispose();
                        matrix = null;
                        break;
                }

                byte[] imageBytes;

                using (MemoryStream ms = new MemoryStream())
                {
                    scaledImage.Compress(Bitmap.CompressFormat.Jpeg, imageCompression, ms);
                    imageBytes = ms.ToArray();
                    await File.WriteAllBytesAsync(path, imageBytes);
                }

                originalImage.Recycle();
                scaledImage.Recycle();
                originalImage.Dispose();
                scaledImage.Dispose();

                return imageBytes;
            }

            catch (IOException ex)
            {
                _ = ex.Message;
                return null;
            }
        }
    }

来源：https://github.com/xamarin/Essentials/issues/1514#issuecomment-922233449