Question

我从自定义相机中获取旋转图片，我保存图像以获取在ExifInterface上使用它的路径，并使其成为我在ExifInterface上使用的正确方向，但它始终返回值为0，可能是什么问题？（我运行模拟器）

谢谢

这是我的OnPictureTaken方法：

public async void OnPictureTaken(byte[] data, Android.Hardware.Camera camera)
    {
        var targetWidth = 1080;
        var cameraParams = camera.GetParameters();
        var ratio = ((decimal)cameraParams.PictureSize.Height) / cameraParams.PictureSize.Width;

        var w = cameraParams.PictureSize.Width >= targetWidth
            ? targetWidth
            : cameraParams.PictureSize.Width;

        var h = cameraParams.PictureSize.Width >= targetWidth
            ? (int)Math.Floor(targetWidth * ratio)
            : cameraParams.PictureSize.Height;

        Java.IO.File sdDir = Android.OS.Environment.GetExternalStoragePublicDirectory(Android.OS.Environment.DirectoryPictures);
        Java.IO.File pictureFileDir = new Java.IO.File(sdDir, "RDCCameraImages");

        if (!pictureFileDir.Exists() && !pictureFileDir.Mkdirs())
        {
            return;
        }
        String photoFile = "Picture_"   + "aaa.jpg";
        String imageFilePath = pictureFileDir.Path + Java.IO.File.Separator + photoFile;
        Java.IO.File pictureFile = new Java.IO.File(imageFilePath);

        FileOutputStream fos = new FileOutputStream(pictureFile);
        fos.Write(data);
        fos.Close();

        ExifInterface exif;

        ExifInterface ei = new ExifInterface(pictureFile.AbsolutePath);
        int orientation = ei.GetAttributeInt(ExifInterface.TagOrientation, (int)Android.Media.Orientation.Normal);//return 0

        var imageStream = new System.IO.MemoryStream();
        using (var bm = BitmapFactory.DecodeByteArray(data, 0, data.Length))
        using (var scaled = Bitmap.CreateScaledBitmap(bm, w, h, false))
        {
            Bitmap rotatedBitmap = null;
            switch (orientation)
            {

                case (int)Android.Media.Orientation.Rotate90:
                    rotatedBitmap = rotateImage(scaled, 90);
                    break;

                case (int)Android.Media.Orientation.Rotate180:
                    rotatedBitmap = rotateImage(scaled, 180);
                    break;

                case (int)Android.Media.Orientation.Rotate270:
                    rotatedBitmap = rotateImage(scaled, 270);
                    break;

                case (int)Android.Media.Orientation.Normal:
                    rotatedBitmap = scaled;
                    break;
                default:
                    rotatedBitmap = scaled;
                    break;
            }
            await scaled.CompressAsync(Bitmap.CompressFormat.Jpeg, 90, imageStream);
            await imageStream.FlushAsync();
        }
   }  
   public static Bitmap rotateImage(Bitmap source, float angle)
    {
        Matrix matrix = new Matrix();
        matrix.PostRotate(angle);
        return Bitmap.CreateBitmap(source, 0, 0, source.Width, source.Height,
                                   matrix, true);
    }

Answer 1

ExifInterface，并使其成为我在ExifInterface上使用的正确方向，但它总是返回值为0，可能是什么问题？

ExifInterface并非如此。在您的代码中，您刚刚创建了一张新图片并将其保存在您的设备中，如果我理解正确，您希望ExifInterface自动检测方向。好吧，它不是那么聪明，ExifInterface只能使用ExifInterface.SetAttribute获取我们之前保存到该图像中的信息：

ExifInterface ei = new ExifInterface(pictureFile.AbsolutePath);
//set the attribute
ei.SetAttribute(ExifInterface.TagOrientation, "90");
//save the attributes
ei.SaveAttributes();

//For Test I created a totally new ExifInterface
ExifInterface ei2 = new ExifInterface(pictureFile.AbsolutePath);
//we get the Information of previously saved orientation
var orientationInfo = ei2.GetAttribute(ExifInterface.TagOrientation);
//orientationInfo=90

如何获取相机定位？

您可以使用CameraInfo获取当前相机的方向：

int cameraId=0;
CameraInfo cameraInfo=null;
for (int i = 0; i < Camera.NumberOfCameras; i++)
{
    CameraInfo info = new CameraInfo();
    Camera.GetCameraInfo(i, info);
    if (info.Facing == CameraInfo.CameraFacingBack)
    {
                cameraId = i;
                cameraInfo = info;
    }
}
//Open Camera
mCamera = Camera.Open(cameraId);
if (cameraInfo != null)
{
     var orientation = cameraInfo.Orientation;
}

ExifInterface总是返回0

1 个答案: