Get camera's intrinsic orientation in API <9

Question

In API level 9, Android added the CameraInfo class, which includes information on each physical camera in the device. In particular, it includes an orientation attribute, which is "the angle that the camera image needs to be rotated clockwise so it shows correctly on the display in its natural orientation." This is distinct from the actual rotation of the device, which is found from getContext().getWindowManager().getDefaultDisplay().getRotation().

Android's sample code subtracts the rotation of the device from the orientation of the camera for rear-facing cameras (it's slightly more complicated for front-facing ones), and rotates the camera preview by this amount. This allows the preview to display properly in both portrait and landscape orientations of the screen.

How can I get the intrinsic orientation of the camera in API levels less than 9, where there is no CameraInfo class?

StarPinkER StarPinkER · Accepted Answer · 2013-03-18T07:51:40

There is some platform specific solutions. But there is no easy general solution.

Android has a Hardware Abstract Layer(HAL), different vendors will implement the HAL differently. For example, different camera device may have different drivers, so they have different ways to get their data out, including your cameraInfo. When Android adds an API into the HAL, it requires its vendors to implement that API based on their hardwares. Then the Android framework and Android application can use that feature in a uniform way.

However, as you said, the getCameraInfo is not in the HAL Before Froyo. So a straightforward approach would be get those info from the driver or platform-specific library yourself.

For MSM Camera, there is a mm_camera_get_camera_info function in liboemcamera.so. You can use it to get a list of camera_info_t structs.

typedef struct {
  int  modes_supported;
  int8_t camera_id;
  cam_position_t position;
  uint32_t sensor_mount_angle;
}camera_info_t;

The function encapsulates the actual system call to the target camera device. ioctl(controlfd, MSM_CAM_IOCTL_GET_CAMERA_INFO, &cameraInfo). You may directly call it if you like.

So unfortunately, you need to get that info based on the device you are working on. But may be you are expecting a general approach. Then I think the only way to achieve this is to implement the HAL yourself. Many if-else to decide which device or which ioctl command you need to use. Good luck man.

Get camera's intrinsic orientation in API <9

1 Answers