The android.hardware.camera2 package provides an interface to individual camera devices connected to an Android device. It replaces the deprecated Camera class.
This package models a camera device as a pipeline, which takes in input requests for capturing a single frame, captures the single image per the request, and then outputs one capture result metadata packet, plus a set of output image buffers for the request. The requests are processed in-order, and multiple requests can be in flight at once. Since the camera device is a pipeline with multiple stages, having multiple requests in flight is required to maintain full framerate on most Android devices.
To enumerate, query, and open available camera devices, obtain a CameraManager instance.
Individual CameraDevice provide a set of static property information that describes the hardware device and the available settings and output parameters for the device. This information is provided through the CameraCharacteristics object, and is available through CameraManager.GetCameraCharacteristics(String)
To capture or stream images from a camera device, the application must first create a CameraCaptureSession with a set of output Surfaces for use with the camera device, with droid.hardware.camera2.CameraCaptureSession.StateCallback,. Each Surface has to be pre-configured with an StreamConfigurationMap (if applicable) to match the sizes and formats available from the camera device. A target Surface can be obtained from a variety of classes, including SurfaceView, SurfaceTexture via Surface.Surface(SurfaceTexture), MediaCodec, MediaRecorder, Allocation, and ImageReader.
Generally, camera preview images are sent to SurfaceView or TextureView (via its SurfaceTexture). Capture of JPEG images or RAW buffers for DngCreator can be done with ImageReader with the ImageFormat.Jpeg and ImageFormat.RawSensor formats. Application-driven processing of camera data in RenderScript, OpenGL ES, or directly in managed or native code is best done through Allocation with a YUV Type, SurfaceTexture, and ImageReader with a ImageFormat.Yuv420888 format, respectively.
The application then needs to construct a CaptureRequest, which defines all the capture parameters needed by a camera device to capture a single image. The request also lists which of the configured output Surfaces should be used as targets for this capture. The CameraDevice has a CameraDevice.CreateCaptureRequest(CameraTemplate) for creating a NoType:android/hardware/camera2/CaptureRequest$Builder;Href=../../../../reference/android/hardware/camera2/CaptureRequest.Builder.html for a given use case, which is optimized for the Android device the application is running on.
Once the request has been set up, it can be handed to the active capture session either for a one-shot Android.Hardware.Camera2.CameraCaptureSession.Capture(Android.Hardware.Camera2.CaptureRequest, .CaptureCallback, .CaptureCallback) or for an endlessly Android.Hardware.Camera2.CameraCaptureSession.SetRepeatingRequest(Android.Hardware.Camera2.CaptureRequest, .CaptureCallback, .CaptureCallback) use. Both methods also have a variant that accepts a list of requests to use as a burst capture / repeating burst. Repeating requests have a lower priority than captures, so a request submitted through capture() while there's a repeating request configured will be captured before any new instances of the currently repeating (burst) capture will begin capture.
After processing a request, the camera device will produce a TotalCaptureResult object, which contains information about the state of the camera device at time of capture, and the final settings used. These may vary somewhat from the request, if rounding or resolving contradictory parameters was necessary. The camera device will also send a frame of image data into each of the output Surfaces included in the request. These are produced asynchronously relative to the output CaptureResult, sometimes substantially later.