/* SPDX-License-Identifier: BSD-2-Clause */
/*
 * Copyright (C) 2019, Raspberry Pi (Trading) Limited
 *
 * cam_helper.hpp - helper class providing camera information
 */
#pragma once

#include <memory>
#include <string>

#include <libcamera/base/span.h>
#include <libcamera/base/utils.h>

#include "camera_mode.h"
#include "controller/controller.hpp"
#include "controller/metadata.hpp"
#include "md_parser.hpp"

#include "libcamera/internal/v4l2_videodevice.h"

namespace RPiController {

// The CamHelper class provides a number of facilities that anyone trying
// to drive a camera will need to know, but which are not provided by the
// standard driver framework. Specifically, it provides:
//
// A "CameraMode" structure to describe extra information about the chosen
// mode of the driver. For example, how it is cropped from the full sensor
// area, how it is scaled, whether pixels are averaged compared to the full
// resolution.
//
// The ability to convert between number of lines of exposure and actual
// exposure time, and to convert between the sensor's gain codes and actual
// gains.
//
// A method to return the number of frames of delay between updating exposure,
// analogue gain and vblanking, and for the changes to take effect. For many
// sensors these take the values 2, 1 and 2 respectively, but sensors that are
// different will need to over-ride the default method provided.
//
// A method to query if the sensor outputs embedded data that can be parsed.
//
// A parser to parse the embedded data buffers provided by some sensors (for
// example, the imx219 does; the ov5647 doesn't). This allows us to know for
// sure the exposure and gain of the frame we're looking at. CamHelper
// provides methods for converting analogue gains to and from the sensor's
// native gain codes.
//
// Finally, a set of methods that determine how to handle the vagaries of
// different camera modules on start-up or when switching modes. Some
// modules may produce one or more frames that are not yet correctly exposed,
// or where the metadata may be suspect. We have the following methods:
// HideFramesStartup(): Tell the pipeline handler not to return this many