XamarinFilePickerImageSource

我有一個應用程式，用戶可以使用 FilePicker.PickMultipleAsync 通過圖庫添加照片。并且用戶也可以使用 CrossMedia 插件為這個功能拍照。

如果用戶以縱向格式拍攝照片（CrossMedia），則將照片轉換為 ImageSource 進行顯示。如果用戶選擇影像，它會執行與 ImageSource 相同的轉換程序，但在這種情況下，照片會自動向右旋轉。

由相機的本機應用程式拍攝的照片會發生這種情況。如果用戶下載任何影像并從圖庫中選擇它，則不會發生此問題。將插件切換到 FilePicker 后問題開始出現。

我該怎么做才能顯示原始影像？

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

插件代碼

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)));
}

我從互聯網上下載了左側的影像，它顯示正確。我用相機拍攝并從圖庫中選擇的右側影像

uj5u.com熱心網友回復：

我用代碼解決了這個問題

 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;
            }
        }
    }

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

標籤：xamarin xamarin.forms 文件选择器 xamarin 必需品

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