安卓Camera API CaptureRequest

解读一下CaptureRequest类的官方注释

/**
 * <p>An immutable package of settings and outputs needed to capture a single
 * image from the camera device.</p>
 *
 * <p>Contains the configuration for the capture hardware (sensor, lens, flash),
 * the processing pipeline, the control algorithms, and the output buffers. Also
 * contains the list of target Surfaces to send image data to for this
 * capture.</p>
 *
 * <p>CaptureRequests can be created by using a {@link Builder} instance,
 * obtained by calling {@link CameraDevice#createCaptureRequest}</p>
 *
 * <p>CaptureRequests are given to {@link CameraCaptureSession#capture} or
 * {@link CameraCaptureSession#setRepeatingRequest} to capture images from a camera.</p>
 *
 * <p>Each request can specify a different subset of target Surfaces for the
 * camera to send the captured data to. All the surfaces used in a request must
 * be part of the surface list given to the last call to
 * {@link CameraDevice#createCaptureSession}, when the request is submitted to the
 * session.</p>
 *
 * <p>For example, a request meant for repeating preview might only include the
 * Surface for the preview SurfaceView or SurfaceTexture, while a
 * high-resolution still capture would also include a Surface from a ImageReader
 * configured for high-resolution JPEG images.</p>
 *
 * <p>A reprocess capture request allows a previously-captured image from the camera device to be
 * sent back to the device for further processing. It can be created with
 * {@link CameraDevice#createReprocessCaptureRequest}, and used with a reprocessable capture session
 * created with {@link CameraDevice#createReprocessableCaptureSession}.</p>
 *
 * @see CameraCaptureSession#capture
 * @see CameraCaptureSession#setRepeatingRequest
 * @see CameraCaptureSession#captureBurst
 * @see CameraCaptureSession#setRepeatingBurst
 * @see CameraDevice#createCaptureRequest
 * @see CameraDevice#createReprocessCaptureRequest
 */

• CaptureRequest是什么：从Camera设置获取image图片的设置，包含硬件参数的设置，处理的pipeline，控制算法，输出buffer和surface等。
• 如何创建CaptureRequest：通过CaptureRequest.Builder实例，这个实例最开始是通过CameraDevice#createCaptureRequest得到的。
• 如果使用CaptureRequest：通过CameraCaptureSession#capture和CameraCaptureSession#setRepeatingRequest接口向Camera设备发送Request。
• 必须包含目标Surface：Request中用到的Surface必须是通过CameraDevice#createCaptureSession创建Session师的Surface列表的子集。
• 设置为预览的Request必须包含SurfaceView或SurfaceTexture的Surface，高分辨率拍照的Request包含ImageReader中的Surface。