相机捕捉图像旋转到人像-Xamarin android

Question

private int setCameraDisplayOrientation(Activity mContext, int v)
        {
            var degrees = 0;
            var orientation =0;

            Display display = mContext.GetSystemService(Context.WindowService).JavaCast<IWindowManager>().DefaultDisplay;

            Camera.CameraInfo info = new Camera.CameraInfo();
            Camera.GetCameraInfo(v, info);
            var rotation = windowManager.DefaultDisplay.Rotation;

            DisplayMetrics dm = new DisplayMetrics();
            display.GetMetrics(dm);
            int width = dm.WidthPixels;
            int height = dm.HeightPixels;

            //Natural orientation is portrait
            if ((rotation == SurfaceOrientation.Rotation0 || rotation == SurfaceOrientation.Rotation180) && height > width ||
                (rotation == SurfaceOrientation.Rotation90 || rotation == SurfaceOrientation.Rotation270) && width > height)
            {
                switch (rotation)
                {
                    case SurfaceOrientation.Rotation0:
                        degrees = 90;
                        break;
                    case SurfaceOrientation.Rotation90:
                        degrees = 0;
                        break;
                    case SurfaceOrientation.Rotation180:
                        degrees = 270;
                        break;
                    case SurfaceOrientation.Rotation270:
                        degrees = 180;
                        break;
                }
            }
            
            return (degrees);
        }

当我捕获照片时，在某些设备中，它会以景观模式存储在某些设备中，它会存储肖像。我想让图像在肖像模式无论如何。为此，我尝试获取图像的exif数据，并相应地将其旋转到肖像模式。但在一些设备，如三星，VIVO的方向值得到“0”。我不知道该怎么处理那个值。如果我prerotate90，那么一些设备将解决此问题，而另一些设备将向上保存照片。

**Managing Rotation**

 Android.Graphics.Bitmap loadAndResizeBitmap(string filePath)
    {

        Android.Graphics.Bitmap resizedBitmap = Android.Graphics.BitmapFactory.DecodeFile(filePath);
        ExifInterface exif = null;
        try
        {
            exif = new ExifInterface(filePath);
            string orientation = exif.GetAttribute(ExifInterface.TagOrientation);

            Android.Graphics.Matrix matrix = new Android.Graphics.Matrix();
            switch (orientation)
            {
                case "1":
                    matrix.PreRotate(-90);
                    resizedBitmap = Android.Graphics.Bitmap.CreateBitmap(resizedBitmap, 0, 0, resizedBitmap.Width, resizedBitmap.Height, matrix, false);
                    matrix.Dispose();
                    matrix = null;
                    break;
                case "3":
                    matrix.PreRotate(180);
                    resizedBitmap = Android.Graphics.Bitmap.CreateBitmap(resizedBitmap, 0, 0, resizedBitmap.Width, resizedBitmap.Height, matrix, false);
                    matrix.Dispose();
                    matrix = null;
                    break;
                case "4":
                    matrix.PreRotate(180);
                    resizedBitmap = Android.Graphics.Bitmap.CreateBitmap(resizedBitmap, 0, 0, resizedBitmap.Width, resizedBitmap.Height, matrix, false);
                    matrix.Dispose();
                    matrix = null;
                    break;
                case "5":
                    matrix.PreRotate(90);
                    resizedBitmap = Android.Graphics.Bitmap.CreateBitmap(resizedBitmap, 0, 0, resizedBitmap.Width, resizedBitmap.Height, matrix, false);
                    matrix.Dispose();
                    matrix = null;
                    break;
                case "6": // portrait
                    matrix.PreRotate(90);
                    resizedBitmap = Android.Graphics.Bitmap.CreateBitmap(resizedBitmap, 0, 0, resizedBitmap.Width, resizedBitmap.Height, matrix, false);
                    matrix.Dispose();
                    matrix = null;
                    break;
                case "7":
                    matrix.PreRotate(-90);
                    resizedBitmap = Android.Graphics.Bitmap.CreateBitmap(resizedBitmap, 0, 0, resizedBitmap.Width, resizedBitmap.Height, matrix, false);
                    matrix.Dispose();
                    matrix = null;
                    break;
                case "8":
                    matrix.PreRotate(-90);
                    resizedBitmap = Android.Graphics.Bitmap.CreateBitmap(resizedBitmap, 0, 0, resizedBitmap.Width, resizedBitmap.Height, matrix, false);
                    matrix.Dispose();
                    matrix = null;
                    break;
                case "0":
                    matrix.PreRotate(-90);
                    resizedBitmap = Android.Graphics.Bitmap.CreateBitmap(resizedBitmap, 0, 0, resizedBitmap.Width, resizedBitmap.Height, matrix, false);
                    matrix.Dispose();
                    matrix = null;
                    break;
            }

            return resizedBitmap;

        }

        catch (IOException ex)
        {
            return null;
        }

    }

我从Xamarin那里得到这个主意。Andoid图像旋转。但不知怎的，我不能再继续下去了。会有什么问题？我应该传递流而不是文件路径吗？是由于表面视图旋转造成的吗？我如何在任何设备上无论什么都能让捕捉到的图像成为人像？感谢任何帮助。

Answer 1

仅针对Xamarin.android，使用依赖服务在共享项目中调用

由此得到图像的旋转角度。

public int GetImageRotation(string filePath)
        {
            try
            {
                ExifInterface ei = new ExifInterface(filePath);
                Orientation orientation = (Orientation)ei.GetAttributeInt(ExifInterface.TagOrientation, (int)Orientation.Undefined);
                switch (orientation)
                {
                    case Orientation.Rotate90:
                        return 90;
                    case Orientation.Rotate180:
                        return 180;
                    case Orientation.Rotate270:
                        return 270;
                    default:
                        return 0;
                }
            }
            catch(Exception ex)
            {
                return 0;
            }
        }

现在根据你得到的角度值旋转图像。

public byte[] RotateImage(System.IO.Stream imageStream, string filePath)
        {
            int rotationDegrees = GetImageRotation(filePath)
            byte[] byteArray = new byte[imageStream.Length];
            try
            {
                imageStream.Read(byteArray, 0, (int)imageStream.Length);

                Bitmap originalImage = BitmapFactory.DecodeByteArray(byteArray, 0, byteArray.Length);
                Matrix matrix = new Matrix();
                matrix.PostRotate((float)rotationDegrees);

                Bitmap rotatedBitmap = Bitmap.CreateBitmap(originalImage, 0, 0, originalImage.Width,
                    originalImage.Height, matrix, true);

                using (MemoryStream ms = new MemoryStream())
                {
                    rotatedBitmap.Compress(Bitmap.CompressFormat.Jpeg, 100, ms);
                    return ms.ToArray();
                }
            }
            catch(Exception ex)
            {
                return byteArray;
            }
        }