相机捕获图像旋转为纵向 - Xamarin android

Question

我有一个 xamarin.android 项目，它有一个自定义相机预览。每当我初始化相机时，它都会以横向默认打开。所以我像这样从SurfaceChanged 方法改变了方向。

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);
        }

它工作正常。它将纵向排列前后摄像头。

问题

当我拍摄照片时，在某些设备中，它会以横向模式存储在某些设备中，它会存储纵向。无论如何，我都希望图像处于纵向模式。为了做到这一点，我尝试获取图像的Exif 数据并相应地将其旋转到纵向模式。但在三星、VIVO 等某些设备中，方向值变为“0”。我不知道如何处理该值。如果我 PreRotate 90 ，那么有些设备会解决这个问题，而有些设备会向上保存照片。

**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.Andoid Image rotation 得到这个想法。但不知何故，我无法传达它。会有什么问题？我应该传递 Stream 而不是文件路径吗？是因为surfaceview旋转吗？无论如何，如何在任何设备上制作捕获的图像肖像？任何帮助表示赞赏。

Answer 1

仅适用于 Xamarin.Android，使用依赖服务在共享项目中调用它

由此获取图像的旋转角度。

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。

我对流而不是实际文件执行操作并以字节数组的形式返回。

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;
            }
        }

让我知道它是否有效。