[libcamera-devel,04/12] libcamera: controls: Improve the API towards applications

2046 diff mbox series

Rework the control-related classes to improve the API towards
applications. The goal is to enable writing code similar to

	Request *req = ...;
	ControlList &controls = req->controls();
	controls->set(controls::AwbEnable, false);
	controls->set(controls::ManualExposure, 1000);

	...

	int32_t exposure = controls->get(controls::ManualExposure);

with the get and set operations ensuring type safety for the control
values. This is achieved by creating the following classes:

- Control defines controls and is the main way to reference a control.
  It is a template class to allow methods using it to refer to the
  control type.

- ControlId is the base class of Control. It stores the control ID, name
  and type, and can be used in contexts where a control needs to be
  referenced regardless of its type (for instance in lists of controls).
  This class replaces ControlIdentifier.

- ControlValue is kept as-is.

The ControlList class now exposes two template get() and set() methods
that replace the operator[]. They ensure type safety by infering the
value type from the Control reference that they receive.

The main way to refer to a control is now through the Control class, and
optionally through its base ControlId class. The ControlId enumeration
is removed, replaced by a list of global Control instances. Numerical
control IDs are turned into macros, and are still exposed as they are
required to communicate with IPAs (especially to deserialise control
lists). They should however not be used by applications.

Auto-generation of header and source files is removed for now to keep
the change simple. It will be added back in the future in a more
elaborate form.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
---
 include/libcamera/control_ids.h     |  45 ++--
 include/libcamera/controls.h        | 108 +++++++---
 src/libcamera/control_ids.cpp       |  72 +++++++
 src/libcamera/controls.cpp          | 317 ++++++++++++++--------------
 src/libcamera/gen-controls.awk      | 106 ----------
 src/libcamera/meson.build           |  11 +-
 src/libcamera/pipeline/uvcvideo.cpp |  40 ++--
 src/libcamera/pipeline/vimc.cpp     |  28 +--
 test/controls/control_info.cpp      |  25 +--
 test/controls/control_list.cpp      |  66 +++---
 10 files changed, 391 insertions(+), 427 deletions(-)
 create mode 100644 src/libcamera/control_ids.cpp
 delete mode 100755 src/libcamera/gen-controls.awk

Hi Laurent,

On Sat, Sep 28, 2019 at 06:22:30PM +0300, Laurent Pinchart wrote:
> Rework the control-related classes to improve the API towards
> applications. The goal is to enable writing code similar to
>
> 	Request *req = ...;
> 	ControlList &controls = req->controls();
> 	controls->set(controls::AwbEnable, false);
> 	controls->set(controls::ManualExposure, 1000);
>
> 	...
>
> 	int32_t exposure = controls->get(controls::ManualExposure);
>

I very much like this API!

> with the get and set operations ensuring type safety for the control
> values. This is achieved by creating the following classes:
>
> - Control defines controls and is the main way to reference a control.
>   It is a template class to allow methods using it to refer to the
>   control type.
>
> - ControlId is the base class of Control. It stores the control ID, name
>   and type, and can be used in contexts where a control needs to be
>   referenced regardless of its type (for instance in lists of controls).
>   This class replaces ControlIdentifier.
>
> - ControlValue is kept as-is.
>
> The ControlList class now exposes two template get() and set() methods
> that replace the operator[]. They ensure type safety by infering the
> value type from the Control reference that they receive.
>
> The main way to refer to a control is now through the Control class, and
> optionally through its base ControlId class. The ControlId enumeration
> is removed, replaced by a list of global Control instances. Numerical
> control IDs are turned into macros, and are still exposed as they are
> required to communicate with IPAs (especially to deserialise control
> lists). They should however not be used by applications.
>
> Auto-generation of header and source files is removed for now to keep
> the change simple. It will be added back in the future in a more
> elaborate form.
>
> Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> ---
>  include/libcamera/control_ids.h     |  45 ++--
>  include/libcamera/controls.h        | 108 +++++++---
>  src/libcamera/control_ids.cpp       |  72 +++++++
>  src/libcamera/controls.cpp          | 317 ++++++++++++++--------------
>  src/libcamera/gen-controls.awk      | 106 ----------
>  src/libcamera/meson.build           |  11 +-
>  src/libcamera/pipeline/uvcvideo.cpp |  40 ++--
>  src/libcamera/pipeline/vimc.cpp     |  28 +--
>  test/controls/control_info.cpp      |  25 +--
>  test/controls/control_list.cpp      |  66 +++---
>  10 files changed, 391 insertions(+), 427 deletions(-)
>  create mode 100644 src/libcamera/control_ids.cpp
>  delete mode 100755 src/libcamera/gen-controls.awk
>
> diff --git a/include/libcamera/control_ids.h b/include/libcamera/control_ids.h
> index 75b6a2d5cafe..81e3e2193767 100644
> --- a/include/libcamera/control_ids.h
> +++ b/include/libcamera/control_ids.h
> @@ -8,34 +8,31 @@
>  #ifndef __LIBCAMERA_CONTROL_IDS_H__
>  #define __LIBCAMERA_CONTROL_IDS_H__
>
> -#include <functional>
> +#include <stdint.h>

C++ has <cstdint> if I'm not mistaken

> +
> +#include <libcamera/controls.h>
>
>  namespace libcamera {
>
> -enum ControlId {
> -	AwbEnable,
> -	Brightness,
> -	Contrast,
> -	Saturation,
> -	ManualExposure,
> -	ManualGain,
> -};
> +namespace controls {
> +
> +#define AWB_ENABLE		1
> +#define BRIGHTNESS		2
> +#define CONTRAST		3
> +#define SATURATION		4
> +#define MANUAL_EXPOSURE		5
> +#define MANUAL_GAIN		6
> +
> +extern const Control<void> None;
> +extern const Control<bool> AwbEnable;
> +extern const Control<int32_t> Brightness;
> +extern const Control<int32_t> Contrast;
> +extern const Control<int32_t> Saturation;
> +extern const Control<int32_t> ManualExposure;
> +extern const Control<int32_t> ManualGain;
> +
> +} /* namespace controls */
>
>  } /* namespace libcamera */
>
> -namespace std {
> -
> -template<>
> -struct hash<libcamera::ControlId> {
> -	using argument_type = libcamera::ControlId;
> -	using result_type = std::size_t;
> -
> -	result_type operator()(const argument_type &key) const noexcept
> -	{
> -		return std::hash<std::underlying_type<argument_type>::type>()(key);
> -	}
> -};
> -
> -} /* namespace std */
> -
>  #endif // __LIBCAMERA_CONTROL_IDS_H__
> diff --git a/include/libcamera/controls.h b/include/libcamera/controls.h
> index a3089064c4b5..9698bd1dd383 100644
> --- a/include/libcamera/controls.h
> +++ b/include/libcamera/controls.h
> @@ -8,12 +8,9 @@
>  #ifndef __LIBCAMERA_CONTROLS_H__
>  #define __LIBCAMERA_CONTROLS_H__
>
> -#include <stdint.h>
>  #include <string>
>  #include <unordered_map>
>
> -#include <libcamera/control_ids.h>
> -
>  namespace libcamera {
>
>  class Camera;
> @@ -53,55 +50,75 @@ private:
>  	};
>  };
>
> -struct ControlIdentifier {
> -	ControlId id;
> -	const char *name;
> -	ControlType type;
> +class ControlId
> +{
> +public:
> +	unsigned int id() const { return id_; }
> +	const char *name() const { return name_; }
> +	ControlType type() const { return type_; }
> +
> +protected:
> +	ControlId(unsigned int id, const char *name, ControlType type)
> +		: id_(id), name_(name), type_(type)
> +	{
> +	}
> +
> +private:
> +	ControlId(const ControlId &) = delete;
> +	ControlId &operator=(const ControlId &) = delete;
> +
> +	unsigned int id_;
> +	const char *name_;

Thinking about serialization, is is worth transporting the name ?

As we discussed, probably re-introducing a global map of <id, Control>
would allow to re-construct the Control just by using the id. Of course
that would require linking against the file that defines the control
map also for closed source IPA. Could they live without the control
name otherwise ?

> +	ControlType type_;
> +};
> +
> +static inline bool operator==(const ControlId &lhs, const ControlId &rhs)
> +{
> +	return lhs.id() == rhs.id();
> +}
> +
> +static inline bool operator!=(const ControlId &lhs, const ControlId &rhs)
> +{
> +	return !(lhs == rhs);
> +}
> +
> +template<typename T>
> +class Control : public ControlId
> +{
> +public:
> +	using type = T;

This does not seems to be used.

> +
> +	Control(unsigned int id, const char *name);
> +
> +private:

Why private ?

> +	Control(const Control &) = delete;
> +	Control &operator=(const Control &) = delete;
>  };
>
>  class ControlInfo
>  {
>  public:
> -	explicit ControlInfo(ControlId id, const ControlValue &min = 0,
> +	explicit ControlInfo(const ControlId &id, const ControlValue &min = 0,
>  			     const ControlValue &max = 0);
>
> -	ControlId id() const { return ident_->id; }
> -	const char *name() const { return ident_->name; }
> -	ControlType type() const { return ident_->type; }
> -
> +	const ControlId &id() const { return id_; }
>  	const ControlValue &min() const { return min_; }
>  	const ControlValue &max() const { return max_; }
>
>  	std::string toString() const;
>
>  private:
> -	const struct ControlIdentifier *ident_;
> +	const ControlId &id_;
>  	ControlValue min_;
>  	ControlValue max_;
>  };
>
> -bool operator==(const ControlInfo &lhs, const ControlInfo &rhs);
> -bool operator==(const ControlId &lhs, const ControlInfo &rhs);
> -bool operator==(const ControlInfo &lhs, const ControlId &rhs);
> -static inline bool operator!=(const ControlInfo &lhs, const ControlInfo &rhs)
> -{
> -	return !(lhs == rhs);
> -}
> -static inline bool operator!=(const ControlId &lhs, const ControlInfo &rhs)
> -{
> -	return !(lhs == rhs);
> -}
> -static inline bool operator!=(const ControlInfo &lhs, const ControlId &rhs)
> -{
> -	return !(lhs == rhs);
> -}
> -
> -using ControlInfoMap = std::unordered_map<ControlId, ControlInfo>;
> +using ControlInfoMap = std::unordered_map<const ControlId *, ControlInfo>;
>
>  class ControlList
>  {
>  private:
> -	using ControlListMap = std::unordered_map<const ControlInfo *, ControlValue>;
> +	using ControlListMap = std::unordered_map<const ControlId *, ControlValue>;

I like both maps are indexed by the same key

>
>  public:
>  	ControlList(Camera *camera);
> @@ -114,18 +131,39 @@ public:
>  	const_iterator begin() const { return controls_.begin(); }
>  	const_iterator end() const { return controls_.end(); }
>
> -	bool contains(ControlId id) const;
> -	bool contains(const ControlInfo *info) const;
> +	bool contains(const ControlId &id) const;
>  	bool empty() const { return controls_.empty(); }
>  	std::size_t size() const { return controls_.size(); }
>  	void clear() { controls_.clear(); }
>
> -	ControlValue &operator[](ControlId id);
> -	ControlValue &operator[](const ControlInfo *info) { return controls_[info]; }
> +	template<typename T>
> +	const T &get(const Control<T> &ctrl) const
> +	{
> +		const ControlValue *val = find(ctrl);
> +		if (!val) {
> +			static T t(0);
> +			return t;
> +		}
> +
> +		return val->get<T>();
> +	}
> +
> +	template<typename T>
> +	void set(const Control<T> &ctrl, const T &value)
> +	{
> +		ControlValue *val = find(ctrl);
> +		if (!val)
> +			return;
> +
> +		val->set<T>(value);
> +	}

In terms of generated code this does not make any difference, but as
these functions are inlinded in the class definition, I would

	const T &get(const Control<T> &ctrl) const
	{
		const ControlValue *val = find(ctrl);
		return val ? static T t(0) :
		             val->get<T>();
	}

	template<typename T>
	void set(const Control<T> &ctrl, const T &value)
	{
		ControlValue *val = find(ctrl);
		if (val)
		        val->set<T>(value);
	}

To shorten them by a few lines (be aware, not compiled)

>
>  	void update(const ControlList &list);
>
>  private:
> +	const ControlValue *find(const ControlId &id) const;
> +	ControlValue *find(const ControlId &id);
> +
>  	Camera *camera_;
>  	ControlListMap controls_;
>  };
> diff --git a/src/libcamera/control_ids.cpp b/src/libcamera/control_ids.cpp
> new file mode 100644
> index 000000000000..7e4e38b572f0
> --- /dev/null
> +++ b/src/libcamera/control_ids.cpp
> @@ -0,0 +1,72 @@
> +/* SPDX-License-Identifier: LGPL-2.1-or-later */
> +/*
> + * Copyright (C) 2019, Google Inc.
> + *
> + * control_ids.cpp : Control ID list
> + */
> +
> +#include <libcamera/control_ids.h>
> +
> +/**
> + * \file control_ids.h
> + * \brief Camera control identifiers
> + */
> +
> +namespace libcamera {
> +
> +namespace controls {
> +
> +/**
> + * \def AWB_ENABLE
> + * \brief Numerical value of the AwbEnable control
> + * \def BRIGHTNESS
> + * \brief Numerical value of the Brightness control
> + * \def CONTRAST
> + * \brief Numerical value of the Contrast control
> + * \def SATURATION
> + * \brief Numerical value of the Saturation control
> + * \def MANUAL_EXPOSURE
> + * \brief Numerical value of the ManualExposure control
> + * \def MANUAL_GAIN
> + * \brief Numerical value of the ManualGain control
> + */
> +
> +/**
> + * \brief Invalid control
> + */
> +extern const Control<void> None(0, "none");
> +
> +/**
> + * \brief Enables or disables the AWB.
> + * \sa ManualGain
> + */
> +extern const Control<bool> AwbEnable(AWB_ENABLE, "AwbEnable");
> +
> +/**
> + * \brief Specify a fixed brightness parameter.
> + */
> +extern const Control<int32_t> Brightness(BRIGHTNESS, "Brightness");
> +
> +/**
> + * \brief Specify a fixed contrast parameter.
> + */
> +extern const Control<int32_t> Contrast(CONTRAST, "Contrast");
> +
> +/**
> + * \brief Specify a fixed saturation parameter.
> + */
> +extern const Control<int32_t> Saturation(SATURATION, "Saturation");
> +
> +/**
> + * \brief Specify a fixed exposure time in milli-seconds
> + */
> +extern const Control<int32_t> ManualExposure(MANUAL_EXPOSURE, "ManualExposure");
> +
> +/**
> + * \brief Specify a fixed gain parameter
> + */
> +extern const Control<int32_t> ManualGain(MANUAL_GAIN, "ManualGain");
> +
> +} /* namespace controls */
> +
> +} /* namespace libcamera */

We'll really need to expand this documentation soon :(

> diff --git a/src/libcamera/controls.cpp b/src/libcamera/controls.cpp
> index 295ccd55a622..8886660b7617 100644
> --- a/src/libcamera/controls.cpp
> +++ b/src/libcamera/controls.cpp
> @@ -18,6 +18,29 @@
>  /**
>   * \file controls.h
>   * \brief Describes control framework and controls supported by a camera
> + *
> + * A control is a mean to govern or influence the operation of a camera. Every
> + * control is defined by a unique numerical ID, a name string and the data type
> + * of the value it stores. The libcamera API defines a set of standard controls
> + * in the libcamera::controls namespace, as a set of instances of the Control
> + * class.
> + *
> + * The main way for applications to interact with controls is through the
> + * ControlList stored in the Request class:
> + *
> + * \code{.cpp}
> + * Request *req = ...;
> + * ControlList &controls = req->controls();
> + * controls->set(controls::AwbEnable, false);
> + * controls->set(controls::ManualExposure, 1000);
> + *
> + * ...
> + *
> + * int32_t exposure = controls->get(controls::ManualExposure);
> + * \endcode
> + *
> + * The ControlList::get() and ControlList::set() methods automatically deduce
> + * the data type based on the control.
>   */
>
>  namespace libcamera {
> @@ -173,76 +196,120 @@ std::string ControlValue::toString() const
>  }
>
>  /**
> - * \enum ControlId
> - * \brief Numerical control ID
> + * \class ControlId
> + * \brief Control static metadata
> + *
> + * The ControlId class stores a control ID, name and data type. It provides
> + * unique identification of a control, but without support for compile-time
> + * type deduction that the derived template Control class supports. See the
> + * Control class for more information.
>   */
>
>  /**
> - * \var AwbEnable
> - * ControlType: Bool
> - *
> - * Enables or disables the AWB. See also \a libcamera::ControlId::ManualGain
> + * \fn ControlId::ControlId(unsigned int id, const char *name, ControlType type)
> + * \brief Construct a ControlId instance
> + * \param[in] id The control numerical ID
> + * \param[in] name The control name
> + * \param[in] type The control data type
>   */
>
>  /**
> - * \var Brightness
> - * ControlType: Integer32
> - *
> - * Specify a fixed brightness parameter.
> + * \fn unsigned int ControlId::id() const
> + * \brief Retrieve the control numerical ID
> + * \return The control numerical ID
>   */
>
>  /**
> - * \var Contrast
> - * ControlType: Integer32
> - *
> - * Specify a fixed contrast parameter.
> + * \fn const char *ControlId::name() const
> + * \brief Retrieve the control name
> + * \return The control name
>   */
>
>  /**
> - * \var Saturation
> - * ControlType: Integer32
> - *
> - * Specify a fixed saturation parameter.
> + * \fn ControlType ControlId::type() const
> + * \brief Retrieve the control data type
> + * \return The control data type
>   */
>
>  /**
> - * \var ManualExposure
> - * ControlType: Integer32
> + * \fn bool operator==(const ControlId &lhs, const ControlId &rhs)
> + * \brief Compare two ControlId instances for equality
> + * \param[in] lhs Left-hand side ControlId
> + * \param[in] rhs Left-hand side ControlId

Right-hand

> + *
> + * ControlId instances are compared based on the numerical ControlId::id()
> + * only, as an object may not have two separate controls with the same
> + * numerical ID.
>   *
> - * Specify a fixed exposure time in milli-seconds
> + * \return True if \a lhs and \a rhs are equal, false otherwise

      \return True if \a lhs and \a rhs have the same control Id, false
      otherwise

?

>   */
>
>  /**
> - * \var ManualGain
> - * ControlType: Integer32
> + * \class Control
> + * \brief Describe a control and its intrinsic properties
> + *
> + * The Control class models a control exposed by a camera. Its template type
> + * name T refers to the control data type, and allows methods that operate on
> + * control values to be defined as template methods using the same type T for
> + * the control value. See for instance how the ControlList::get() method
> + * returns a value corresponding to the type of the requested control.
> + *
> + * While this class is the main mean to refer to a control, the control
> + * identifying information are stored in the non-template base ControlId class.
> + * This allows code that operates on a set of controls of different types to
> + * reference those controls through a ControlId instead of a Control. For
> + * instance, the list of controls supported by a camera is exposed as ControlId
> + * instead of Control.
>   *
> - * Specify a fixed gain parameter
> + * While controls of any type can be defined through template specialisation,
> + * libcamera only supports the bool, int32_t and int64_t types natively (this
> + * includes types that are equivalent to the supported types, such as int and
> + * long int).

This is just temporary, would you like to document this?

> + *
> + * Controls IDs shall be unique. While nothing prevents multiple instances of
> + * the Control class to be created with the same ID, this may lead to undefined
> + * behaviour.
>   */
>
>  /**
> - * \struct ControlIdentifier
> - * \brief Describe a ControlId with control specific constant meta-data
> - *
> - * Defines a Control with a unique ID, a name, and a type.
> - * This structure is used as static part of the auto-generated control
> - * definitions, which are generated from the ControlId documentation.
> + * \fn Control::Control(unsigned int id, const char *name)
> + * \brief Construct a Control instance
> + * \param[in] id The control numerical ID
> + * \param[in] name The control name
>   *
> - * \var ControlIdentifier::id
> - * The unique ID for a control
> - * \var ControlIdentifier::name
> - * The string representation of the control
> - * \var ControlIdentifier::type
> - * The ValueType required to represent the control value
> + * The control data type is automatically deduced from the template type T.
>   */
>
> -/*
> - * The controlTypes are automatically generated to produce a control_types.cpp
> - * output. This file is not for public use, and so no suitable header exists
> - * for this sole usage of the controlTypes reference. As such the extern is
> - * only defined here for use during the ControlInfo constructor and should not
> - * be referenced directly elsewhere.
> +/**
> + * \typedef Control::type
> + * \brief The Control template type T
>   */
> -extern const std::unordered_map<ControlId, ControlIdentifier> controlTypes;
> +
> +#ifndef __DOXYGEN__
> +template<>
> +Control<void>::Control(unsigned int id, const char *name)
> +	: ControlId(id, name, ControlTypeNone)
> +{
> +}
> +
> +template<>
> +Control<bool>::Control(unsigned int id, const char *name)
> +	: ControlId(id, name, ControlTypeBool)
> +{
> +}
> +
> +template<>
> +Control<int32_t>::Control(unsigned int id, const char *name)
> +	: ControlId(id, name, ControlTypeInteger32)
> +{
> +}
> +
> +template<>
> +Control<int64_t>::Control(unsigned int id, const char *name)
> +	: ControlId(id, name, ControlTypeInteger64)
> +{
> +}
> +#endif /* __DOXYGEN__ */
>
>  /**
>   * \class ControlInfo
> @@ -260,17 +327,10 @@ extern const std::unordered_map<ControlId, ControlIdentifier> controlTypes;
>   * \param[in] min The control minimum value
>   * \param[in] max The control maximum value
>   */
> -ControlInfo::ControlInfo(ControlId id, const ControlValue &min,
> +ControlInfo::ControlInfo(const ControlId &id, const ControlValue &min,
>  			 const ControlValue &max)
> -	: min_(min), max_(max)
> +	: id_(id), min_(min), max_(max)
>  {
> -	auto iter = controlTypes.find(id);
> -	if (iter == controlTypes.end()) {
> -		LOG(Controls, Fatal) << "Attempt to create invalid ControlInfo";
> -		return;
> -	}
> -
> -	ident_ = &iter->second;
>  }
>
>  /**
> @@ -279,18 +339,6 @@ ControlInfo::ControlInfo(ControlId id, const ControlValue &min,
>   * \return The control ID
>   */
>
> -/**
> - * \fn ControlInfo::name()
> - * \brief Retrieve the control name string
> - * \return The control name string
> - */
> -
> -/**
> - * \fn ControlInfo::type()
> - * \brief Retrieve the control data type
> - * \return The control data type
> - */
> -
>  /**
>   * \fn ControlInfo::min()
>   * \brief Retrieve the minimum value of the control
> @@ -310,56 +358,11 @@ std::string ControlInfo::toString() const
>  {
>  	std::stringstream ss;
>
> -	ss << name() << "[" << min_.toString() << ".." << max_.toString() << "]";
> +	ss << id_.name() << "[" << min_.toString() << ".." << max_.toString() << "]";
>
>  	return ss.str();
>  }
>
> -/**
> - * \brief Compare control information for equality
> - * \param[in] lhs Left-hand side control information
> - * \param[in] rhs Right-hand side control information
> - *
> - * Control information is compared based on the ID only, as a camera may not
> - * have two separate controls with the same ID.
> - *
> - * \return True if \a lhs and \a rhs are equal, false otherwise
> - */
> -bool operator==(const ControlInfo &lhs, const ControlInfo &rhs)
> -{
> -	return lhs.id() == rhs.id();
> -}
> -
> -/**
> - * \brief Compare control ID and information for equality
> - * \param[in] lhs Left-hand side control identifier
> - * \param[in] rhs Right-hand side control information
> - *
> - * Control information is compared based on the ID only, as a camera may not
> - * have two separate controls with the same ID.
> - *
> - * \return True if \a lhs and \a rhs are equal, false otherwise
> - */
> -bool operator==(const ControlId &lhs, const ControlInfo &rhs)
> -{
> -	return lhs == rhs.id();
> -}
> -
> -/**
> - * \brief Compare control information and ID for equality
> - * \param[in] lhs Left-hand side control information
> - * \param[in] rhs Right-hand side control identifier
> - *
> - * Control information is compared based on the ID only, as a camera may not
> - * have two separate controls with the same ID.
> - *
> - * \return True if \a lhs and \a rhs are equal, false otherwise
> - */
> -bool operator==(const ControlInfo &lhs, const ControlId &rhs)
> -{
> -	return lhs.id() == rhs;
> -}
> -
>  /**
>   * \typedef ControlInfoMap
>   * \brief A map of ControlId to ControlInfo
> @@ -431,29 +434,9 @@ ControlList::ControlList(Camera *camera)
>   *
>   * \return True if the list contains a matching control, false otherwise
>   */
> -bool ControlList::contains(ControlId id) const
> +bool ControlList::contains(const ControlId &id) const
>  {
> -	const ControlInfoMap &controls = camera_->controls();
> -	const auto iter = controls.find(id);
> -	if (iter == controls.end()) {
> -		LOG(Controls, Error)
> -			<< "Camera " << camera_->name()
> -			<< " does not support control " << id;
> -
> -		return false;
> -	}
> -
> -	return controls_.find(&iter->second) != controls_.end();
> -}
> -
> -/**
> - * \brief Check if the list contains a control with the specified \a info
> - * \param[in] info The control info
> - * \return True if the list contains a matching control, false otherwise
> - */
> -bool ControlList::contains(const ControlInfo *info) const
> -{
> -	return controls_.find(info) != controls_.end();
> +	return controls_.find(&id) != controls_.end();
>  }
>
>  /**
> @@ -474,44 +457,60 @@ bool ControlList::contains(const ControlInfo *info) const
>   */
>
>  /**
> - * \brief Access or insert the control specified by \a id
> - * \param[in] id The control ID
> + * \fn template<typename T> const T &ControlList::get() const
> + * \brief Get the value of a control
> + * \param[in] ctrl The control
>   *
> - * This method returns a reference to the control identified by \a id, inserting
> - * it in the list if the ID is not already present.
> + * The behaviour is undefined if the control \a ctrl is not present in the
> + * list. Use ControlList::contains() to test for the presence of a control in
> + * the list before retrieving its value.

Is it undefined? An empty control is returned if I read things right

>   *
> - * The behaviour is undefined if the control \a id is not supported by the
> - * camera that the ControlList refers to.
> + * The control value type shall match the type T, otherwise the behaviour is
> + * undefined.
>   *
> - * \return A reference to the value of the control identified by \a id
> + * \return The control value
>   */
> -ControlValue &ControlList::operator[](ControlId id)
> +
> +/**
> + * \fn template<typename T> void ControlList::set()
> + * \brief Set the control value to \a value
> + * \param[in] ctrl The control
> + * \param[in] value The control value
> + *
> + * This method sets the value of a control in the control list. If the control
> + * is already present in the list, its value is updated.

What about clearly stating the control is added if not present?

> + *
> + * The behaviour is undefined if the control \a ctrl is not supported by the
> + * camera that the list refers to.

It seems to me it just gets ignored

> + */
> +
> +const ControlValue *ControlList::find(const ControlId &id) const
> +{
> +	const auto iter = controls_.find(&id);
> +	if (iter == controls_.end()) {
> +		LOG(Controls, Error)
> +			<< "Control " << id.name() << " not found";
> +
> +		return nullptr;
> +	}
> +
> +	return &iter->second;
> +}
> +
> +ControlValue *ControlList::find(const ControlId &id)
>  {
>  	const ControlInfoMap &controls = camera_->controls();
> -	const auto iter = controls.find(id);
> +	const auto iter = controls.find(&id);
>  	if (iter == controls.end()) {
>  		LOG(Controls, Error)
>  			<< "Camera " << camera_->name()
> -			<< " does not support control " << id;
> -
> -		static ControlValue empty;
> -		return empty;
> +			<< " does not support control " << id.name();
> +		return nullptr;
>  	}
>
> -	return controls_[&iter->second];
> +	return &controls_[&id];

Double lookup ? Couldn't you re-use iter ?

>  }
>
> -/**
> - * \fn ControlList::operator[](const ControlInfo *info)
> - * \brief Access or insert the control specified by \a info
> - * \param[in] info The control info
> - *
> - * This method returns a reference to the control identified by \a info,
> - * inserting it in the list if the info is not already present.
> - *
> - * \return A reference to the value of the control identified by \a info
> - */
> -
>  /**
>   * \brief Update the list with a union of itself and \a other
>   * \param other The other list
> @@ -533,10 +532,10 @@ void ControlList::update(const ControlList &other)
>  	}
>
>  	for (auto it : other) {
> -		const ControlInfo *info = it.first;
> +		const ControlId *id = it.first;
>  		const ControlValue &value = it.second;
>
> -		controls_[info] = value;
> +		controls_[id] = value;
>  	}
>  }
>
> diff --git a/src/libcamera/gen-controls.awk b/src/libcamera/gen-controls.awk
> deleted file mode 100755
> index a3f291e7071c..000000000000
> --- a/src/libcamera/gen-controls.awk
> +++ /dev/null
> @@ -1,106 +0,0 @@
> -#!/usr/bin/awk -f
> -
> -# SPDX-License-Identifier: LGPL-2.1-or-later
> -
> -# Controls are documented using Doxygen in the main controls.cpp source.
> -#
> -# Generate control tables directly from the documentation, creating enumerations
> -# to support the IDs and static type information regarding each control.
> -
> -BEGIN {
> -	id=0
> -	input=ARGV[1]
> -	mode=ARGV[2]
> -	output=ARGV[3]
> -}
> -
> -# Detect Doxygen style comment blocks and ignore other lines
> -/^\/\*\*$/ { in_doxygen=1; first_line=1; next }
> -// { if (!in_doxygen) next }
> -
> -# Entry point for the Control Documentation
> -/ * \\enum ControlId$/ { in_controls=1; first_line=0; next }
> -// { if (!in_controls) next }
> -
> -# Extract control information
> -/ \* \\var/ { names[++id]=$3; first_line=0; next }
> -/ \* ControlType:/ { types[id] = $3 }
> -
> -# End of comment blocks
> -/^ \*\// { in_doxygen=0 }
> -
> -# Identify the end of controls
> -/^ \* \\/ { if (first_line) exit }
> -// { first_line=0 }
> -
> -################################
> -# Support output file generation
> -
> -function basename(file) {
> -	sub(".*/", "", file)
> -	return file
> -}
> -
> -function Header(file, description) {
> -	print "/* SPDX-License-Identifier: LGPL-2.1-or-later */" > file
> -	print "/*" > file
> -	print " * Copyright (C) 2019, Google Inc." > file
> -	print " *" > file
> -	print " * " basename(file) " - " description > file
> -	print " *" > file
> -	print " * This file is auto-generated. Do not edit." > file
> -	print " */" > file
> -	print "" > file
> -}
> -
> -function EnterNameSpace(file) {
> -	print "namespace libcamera {" > file
> -	print "" > file
> -}
> -
> -function ExitNameSpace(file) {
> -	print "" > file
> -	print "} /* namespace libcamera */" > file
> -}
> -
> -function GenerateHeader(file) {
> -	Header(file, "Control ID list")
> -
> -	print "#ifndef __LIBCAMERA_CONTROL_IDS_H__" > file
> -	print "#define __LIBCAMERA_CONTROL_IDS_H__" > file
> -	print "" > file
> -
> -	EnterNameSpace(file)
> -	print "enum ControlId {" > file
> -	for (i=1; i <= id; ++i) {
> -		printf "\t%s,\n", names[i] > file
> -	}
> -	print "};" > file
> -	ExitNameSpace(file)
> -
> -	print "" > file
> -	print "#endif // __LIBCAMERA_CONTROL_IDS_H__" > file
> -}
> -
> -function GenerateTable(file) {
> -	Header(file, "Control types")
> -	print "#include <libcamera/controls.h>" > file
> -	print "" > file
> -
> -	EnterNameSpace(file)
> -
> -	print "extern const std::unordered_map<ControlId, ControlIdentifier>" > file
> -	print "controlTypes {" > file
> -	for (i=1; i <= id; ++i) {
> -		printf "\t{ %s, { %s, \"%s\", ControlType%s } },\n", names[i], names[i], names[i], types[i] > file
> -	}
> -	print "};" > file
> -	ExitNameSpace(file)
> -}
> -
> -END {
> -	if (mode == "--header")
> -		GenerateHeader(output)
> -	else
> -		GenerateTable(output)
> -}
> diff --git a/src/libcamera/meson.build b/src/libcamera/meson.build
> index 755149c55c7b..8123d1d5bee9 100644
> --- a/src/libcamera/meson.build
> +++ b/src/libcamera/meson.build
> @@ -5,6 +5,7 @@ libcamera_sources = files([
>      'camera_manager.cpp',
>      'camera_sensor.cpp',
>      'controls.cpp',
> +    'control_ids.cpp',
>      'device_enumerator.cpp',
>      'device_enumerator_sysfs.cpp',
>      'event_dispatcher.cpp',
> @@ -57,16 +58,6 @@ if libudev.found()
>      ])
>  endif
>
> -gen_controls = files('gen-controls.awk')
> -
> -control_types_cpp = custom_target('control_types_cpp',
> -                                  input : files('controls.cpp'),
> -                                  output : 'control_types.cpp',
> -                                  depend_files : gen_controls,
> -                                  command : [gen_controls, '@INPUT@', '--code', '@OUTPUT@'])
> -
> -libcamera_sources += control_types_cpp
> -
>  gen_version = join_paths(meson.source_root(), 'utils', 'gen-version.sh')
>
>  version_cpp = vcs_tag(command : [gen_version, meson.build_root()],
> diff --git a/src/libcamera/pipeline/uvcvideo.cpp b/src/libcamera/pipeline/uvcvideo.cpp
> index 0d56758e3e1d..44e19f40f1b9 100644
> --- a/src/libcamera/pipeline/uvcvideo.cpp
> +++ b/src/libcamera/pipeline/uvcvideo.cpp
> @@ -10,6 +10,7 @@
>  #include <tuple>
>
>  #include <libcamera/camera.h>
> +#include <libcamera/control_ids.h>
>  #include <libcamera/controls.h>
>  #include <libcamera/request.h>
>  #include <libcamera/stream.h>
> @@ -230,33 +231,20 @@ int PipelineHandlerUVC::processControls(UVCCameraData *data, Request *request)
>  	V4L2ControlList controls;
>
>  	for (auto it : request->controls()) {
> -		const ControlInfo *ci = it.first;
> +		const ControlId &id = *it.first;
>  		ControlValue &value = it.second;
>
> -		switch (ci->id()) {
> -		case Brightness:
> +		if (id == controls::Brightness) {
>  			controls.add(V4L2_CID_BRIGHTNESS, value.get<int32_t>());
> -			break;
> -
> -		case Contrast:
> +		} else if (id == controls::Contrast) {
>  			controls.add(V4L2_CID_CONTRAST, value.get<int32_t>());
> -			break;
> -
> -		case Saturation:
> +		} else if (id == controls::Saturation) {
>  			controls.add(V4L2_CID_SATURATION, value.get<int32_t>());
> -			break;
> -
> -		case ManualExposure:
> +		} else if (id == controls::ManualExposure) {
>  			controls.add(V4L2_CID_EXPOSURE_AUTO, 1);
>  			controls.add(V4L2_CID_EXPOSURE_ABSOLUTE, value.get<int32_t>());
> -			break;
> -
> -		case ManualGain:
> +		} else if (id == controls::ManualGain) {
>  			controls.add(V4L2_CID_GAIN, value.get<int32_t>());
> -			break;
> -
> -		default:
> -			break;
>  		}
>  	}
>
> @@ -352,23 +340,23 @@ int UVCCameraData::init(MediaEntity *entity)
>  	for (const auto &ctrl : controls) {
>  		unsigned int v4l2Id = ctrl.first;
>  		const V4L2ControlInfo &info = ctrl.second;
> -		ControlId id;
> +		const ControlId *id = &controls::None;
>
>  		switch (v4l2Id) {
>  		case V4L2_CID_BRIGHTNESS:
> -			id = Brightness;
> +			id = &controls::Brightness;
>  			break;
>  		case V4L2_CID_CONTRAST:
> -			id = Contrast;
> +			id = &controls::Contrast;
>  			break;
>  		case V4L2_CID_SATURATION:
> -			id = Saturation;
> +			id = &controls::Saturation;
>  			break;
>  		case V4L2_CID_EXPOSURE_ABSOLUTE:
> -			id = ManualExposure;
> +			id = &controls::ManualExposure;
>  			break;
>  		case V4L2_CID_GAIN:
> -			id = ManualGain;
> +			id = &controls::ManualGain;
>  			break;
>  		default:
>  			continue;
> @@ -376,7 +364,7 @@ int UVCCameraData::init(MediaEntity *entity)
>
>  		controlInfo_.emplace(std::piecewise_construct,
>  				     std::forward_as_tuple(id),
> -				     std::forward_as_tuple(id, info.min(), info.max()));
> +				     std::forward_as_tuple(*id, info.min(), info.max()));
>  	}
>
>  	return 0;
> diff --git a/src/libcamera/pipeline/vimc.cpp b/src/libcamera/pipeline/vimc.cpp
> index e549dc64b996..a48febf2172e 100644
> --- a/src/libcamera/pipeline/vimc.cpp
> +++ b/src/libcamera/pipeline/vimc.cpp
> @@ -15,6 +15,7 @@
>  #include <ipa/ipa_interface.h>
>  #include <ipa/ipa_module_info.h>
>  #include <libcamera/camera.h>
> +#include <libcamera/control_ids.h>
>  #include <libcamera/controls.h>
>  #include <libcamera/request.h>
>  #include <libcamera/stream.h>
> @@ -283,24 +284,15 @@ int PipelineHandlerVimc::processControls(VimcCameraData *data, Request *request)
>  	V4L2ControlList controls;
>
>  	for (auto it : request->controls()) {
> -		const ControlInfo *ci = it.first;
> +		const ControlId &id = *it.first;
>  		ControlValue &value = it.second;
>
> -		switch (ci->id()) {
> -		case Brightness:
> +		if (id == controls::Brightness) {
>  			controls.add(V4L2_CID_BRIGHTNESS, value.get<int32_t>());
> -			break;
> -
> -		case Contrast:
> +		} else if (id == controls::Contrast) {
>  			controls.add(V4L2_CID_CONTRAST, value.get<int32_t>());
> -			break;
> -
> -		case Saturation:
> +		} else if (id == controls::Saturation) {
>  			controls.add(V4L2_CID_SATURATION, value.get<int32_t>());
> -			break;
> -
> -		default:
> -			break;
>  		}
>  	}
>
> @@ -427,17 +419,17 @@ int VimcCameraData::init(MediaDevice *media)
>  	for (const auto &ctrl : controls) {
>  		unsigned int v4l2Id = ctrl.first;
>  		const V4L2ControlInfo &info = ctrl.second;
> -		ControlId id;
> +		const ControlId *id = &controls::None;
>
>  		switch (v4l2Id) {
>  		case V4L2_CID_BRIGHTNESS:
> -			id = Brightness;
> +			id = &controls::Brightness;
>  			break;
>  		case V4L2_CID_CONTRAST:
> -			id = Contrast;
> +			id = &controls::Contrast;
>  			break;
>  		case V4L2_CID_SATURATION:
> -			id = Saturation;
> +			id = &controls::Saturation;
>  			break;
>  		default:
>  			continue;
> @@ -445,7 +437,7 @@ int VimcCameraData::init(MediaDevice *media)
>
>  		controlInfo_.emplace(std::piecewise_construct,
>  				     std::forward_as_tuple(id),
> -				     std::forward_as_tuple(id, info.min(), info.max()));
> +				     std::forward_as_tuple(*id, info.min(), info.max()));
>  	}
>
>  	return 0;
> diff --git a/test/controls/control_info.cpp b/test/controls/control_info.cpp
> index 2aba568a302e..dbc43df8e3d3 100644
> --- a/test/controls/control_info.cpp
> +++ b/test/controls/control_info.cpp
> @@ -7,6 +7,7 @@
>
>  #include <iostream>
>
> +#include <libcamera/control_ids.h>
>  #include <libcamera/controls.h>
>
>  #include "test.h"
> @@ -23,17 +24,17 @@ protected:
>  		 * Test information retrieval from a control with no minimum
>  		 * and maximum.
>  		 */
> -		ControlInfo info(Brightness);
> +		ControlInfo brightness(controls::Brightness);
>
> -		if (info.id() != Brightness ||
> -		    info.type() != ControlTypeInteger32 ||
> -		    info.name() != std::string("Brightness")) {
> +		if (brightness.id() != controls::Brightness ||
> +		    brightness.id().type() != ControlTypeInteger32 ||
> +		    brightness.id().name() != std::string("Brightness")) {
>  			cout << "Invalid control identification for Brightness" << endl;
>  			return TestFail;
>  		}
>
> -		if (info.min().get<int32_t>() != 0 ||
> -		    info.max().get<int32_t>() != 0) {
> +		if (brightness.min().get<int32_t>() != 0 ||
> +		    brightness.max().get<int32_t>() != 0) {
>  			cout << "Invalid control range for Brightness" << endl;
>  			return TestFail;
>  		}
> @@ -42,17 +43,17 @@ protected:
>  		 * Test information retrieval from a control with a minimum and
>  		 * a maximum value.
>  		 */
> -		info = ControlInfo(Contrast, 10, 200);
> +		ControlInfo contrast(controls::Contrast, 10, 200);
>
> -		if (info.id() != Contrast ||
> -		    info.type() != ControlTypeInteger32 ||
> -		    info.name() != std::string("Contrast")) {
> +		if (contrast.id() != controls::Contrast ||
> +		    contrast.id().type() != ControlTypeInteger32 ||
> +		    contrast.id().name() != std::string("Contrast")) {
>  			cout << "Invalid control identification for Contrast" << endl;
>  			return TestFail;
>  		}
>
> -		if (info.min().get<int32_t>() != 10 ||
> -		    info.max().get<int32_t>() != 200) {
> +		if (contrast.min().get<int32_t>() != 10 ||
> +		    contrast.max().get<int32_t>() != 200) {
>  			cout << "Invalid control range for Contrast" << endl;
>  			return TestFail;
>  		}
> diff --git a/test/controls/control_list.cpp b/test/controls/control_list.cpp
> index 5215840b1c4e..053696814b67 100644
> --- a/test/controls/control_list.cpp
> +++ b/test/controls/control_list.cpp
> @@ -9,6 +9,7 @@
>
>  #include <libcamera/camera.h>
>  #include <libcamera/camera_manager.h>
> +#include <libcamera/control_ids.h>
>  #include <libcamera/controls.h>
>
>  #include "test.h"
> @@ -52,7 +53,7 @@ protected:
>  			return TestFail;
>  		}
>
> -		if (list.contains(Brightness)) {
> +		if (list.contains(controls::Brightness)) {
>  			cout << "List should not contain Brightness control" << endl;
>  			return TestFail;
>  		}
> @@ -70,7 +71,7 @@ protected:
>  		 * Set a control, and verify that the list now contains it, and
>  		 * nothing else.
>  		 */
> -		list[Brightness] = 255;
> +		list.set(controls::Brightness, 255);
>
>  		if (list.empty()) {
>  			cout << "List should not be empty" << endl;
> @@ -82,7 +83,7 @@ protected:
>  			return TestFail;
>  		}
>
> -		if (!list.contains(Brightness)) {
> +		if (!list.contains(controls::Brightness)) {
>  			cout << "List should contain Brightness control" << endl;
>  			return TestFail;
>  		}
> @@ -96,54 +97,45 @@ protected:
>  			return TestFail;
>  		}
>
> -		if (list[Brightness].get<int32_t>() != 255) {
> +		if (list.get(controls::Brightness) != 255) {
>  			cout << "Incorrest Brightness control value" << endl;
>  			return TestFail;
>  		}
>
> -		if (list.contains(Contrast)) {
> +		if (list.contains(controls::Contrast)) {
>  			cout << "List should not contain Contract control" << endl;
>  			return TestFail;
>  		}
>
> -		/*
> -		 * Set a second control through ControlInfo and retrieve it
> -		 * through both controlId and ControlInfo.
> -		 */
> -		const ControlInfoMap &controls = camera_->controls();
> -		const ControlInfo *brightness = &controls.find(Brightness)->second;
> -		const ControlInfo *contrast = &controls.find(Contrast)->second;
> +		/* Update the first control and set a second one. */
> +		list.set(controls::Brightness, 64);
> +		list.set(controls::Contrast, 128);
>
> -		list[brightness] = 64;
> -		list[contrast] = 128;
> -
> -		if (!list.contains(Contrast) || !list.contains(contrast)) {
> +		if (!list.contains(controls::Contrast) ||
> +		    !list.contains(controls::Contrast)) {
>  			cout << "List should contain Contrast control" << endl;
>  			return TestFail;
>  		}
>
> -		/*
> -		 * Test control value retrieval and update through ControlInfo.
> -		 */
> -		if (list[brightness].get<int32_t>() != 64 ||
> -		    list[contrast].get<int32_t>() != 128) {
> +		if (list.get(controls::Brightness) != 64 ||
> +		    list.get(controls::Contrast) != 128) {
>  			cout << "Failed to retrieve control value" << endl;
>  			return TestFail;
>  		}
>
> -		list[brightness] = 10;
> -		list[contrast] = 20;
> +		/*
> +		 * Update both controls and verify that the container doesn't
> +		 * grow.
> +		 */
> +		list.set(controls::Brightness, 10);
> +		list.set(controls::Contrast, 20);
>
> -		if (list[brightness].get<int32_t>() != 10 ||
> -		    list[contrast].get<int32_t>() != 20) {
> +		if (list.get(controls::Brightness) != 10 ||
> +		    list.get(controls::Contrast) != 20) {
>  			cout << "Failed to update control value" << endl;
>  			return TestFail;
>  		}
>
> -		/*
> -		 * Assert that the container has not grown with the control
> -		 * updated.
> -		 */
>  		if (list.size() != 2) {
>  			cout << "List should contain two elements" << endl;
>  			return TestFail;
> @@ -157,8 +149,8 @@ protected:
>  		 */
>  		ControlList newList(camera_.get());
>
> -		newList[Brightness] = 128;
> -		newList[Saturation] = 255;
> +		newList.set(controls::Brightness, 128);
> +		newList.set(controls::Saturation, 255);
>  		newList.update(list);
>
>  		list.clear();
> @@ -178,16 +170,16 @@ protected:
>  			return TestFail;
>  		}
>
> -		if (!newList.contains(Brightness) ||
> -		    !newList.contains(Contrast) ||
> -		    !newList.contains(Saturation)) {
> +		if (!newList.contains(controls::Brightness) ||
> +		    !newList.contains(controls::Contrast) ||
> +		    !newList.contains(controls::Saturation)) {
>  			cout << "New list contains incorrect items" << endl;
>  			return TestFail;
>  		}
>
> -		if (newList[Brightness].get<int32_t>() != 10 ||
> -		    newList[Contrast].get<int32_t>() != 20 ||
> -		    newList[Saturation].get<int32_t>() != 255) {
> +		if (newList.get(controls::Brightness) != 10 ||
> +		    newList.get(controls::Contrast) != 20 ||
> +		    newList.get(controls::Saturation) != 255) {
>  			cout << "New list contains incorrect values" << endl;
>  			return TestFail;
>  		}
> --
> Regards,
>
> Laurent Pinchart
>
> _______________________________________________
> libcamera-devel mailing list
> libcamera-devel@lists.libcamera.org
> https://lists.libcamera.org/listinfo/libcamera-devel

Hi Jacopo,

On Sun, Sep 29, 2019 at 12:00:35PM +0200, Jacopo Mondi wrote:
> On Sat, Sep 28, 2019 at 06:22:30PM +0300, Laurent Pinchart wrote:
> > Rework the control-related classes to improve the API towards
> > applications. The goal is to enable writing code similar to
> >
> > 	Request *req = ...;
> > 	ControlList &controls = req->controls();
> > 	controls->set(controls::AwbEnable, false);
> > 	controls->set(controls::ManualExposure, 1000);
> >
> > 	...
> >
> > 	int32_t exposure = controls->get(controls::ManualExposure);
> >
> 
> I very much like this API!

Thank you :-)

> > with the get and set operations ensuring type safety for the control
> > values. This is achieved by creating the following classes:
> >
> > - Control defines controls and is the main way to reference a control.
> >   It is a template class to allow methods using it to refer to the
> >   control type.
> >
> > - ControlId is the base class of Control. It stores the control ID, name
> >   and type, and can be used in contexts where a control needs to be
> >   referenced regardless of its type (for instance in lists of controls).
> >   This class replaces ControlIdentifier.
> >
> > - ControlValue is kept as-is.
> >
> > The ControlList class now exposes two template get() and set() methods
> > that replace the operator[]. They ensure type safety by infering the
> > value type from the Control reference that they receive.
> >
> > The main way to refer to a control is now through the Control class, and
> > optionally through its base ControlId class. The ControlId enumeration
> > is removed, replaced by a list of global Control instances. Numerical
> > control IDs are turned into macros, and are still exposed as they are
> > required to communicate with IPAs (especially to deserialise control
> > lists). They should however not be used by applications.
> >
> > Auto-generation of header and source files is removed for now to keep
> > the change simple. It will be added back in the future in a more
> > elaborate form.
> >
> > Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> > ---
> >  include/libcamera/control_ids.h     |  45 ++--
> >  include/libcamera/controls.h        | 108 +++++++---
> >  src/libcamera/control_ids.cpp       |  72 +++++++
> >  src/libcamera/controls.cpp          | 317 ++++++++++++++--------------
> >  src/libcamera/gen-controls.awk      | 106 ----------
> >  src/libcamera/meson.build           |  11 +-
> >  src/libcamera/pipeline/uvcvideo.cpp |  40 ++--
> >  src/libcamera/pipeline/vimc.cpp     |  28 +--
> >  test/controls/control_info.cpp      |  25 +--
> >  test/controls/control_list.cpp      |  66 +++---
> >  10 files changed, 391 insertions(+), 427 deletions(-)
> >  create mode 100644 src/libcamera/control_ids.cpp
> >  delete mode 100755 src/libcamera/gen-controls.awk
> >
> > diff --git a/include/libcamera/control_ids.h b/include/libcamera/control_ids.h
> > index 75b6a2d5cafe..81e3e2193767 100644
> > --- a/include/libcamera/control_ids.h
> > +++ b/include/libcamera/control_ids.h
> > @@ -8,34 +8,31 @@
> >  #ifndef __LIBCAMERA_CONTROL_IDS_H__
> >  #define __LIBCAMERA_CONTROL_IDS_H__
> >
> > -#include <functional>
> > +#include <stdint.h>
> 
> C++ has <cstdint> if I'm not mistaken

It does, and it has <c*> headers for pretty much all the standard C
headers. We mix and match the C and C++ headers in libcamera, which
isn't very nice, and we should decide which ones to use. I have read an
article a while ago explaining while <c*> was a bad idea, but I can't
find it anymore, and I don't remember what the rationale was :-)

In any case I think we should decide on this globally. Would you happen
to have any information on the subject ? I'm not against switching to
the C++ headers, but I think we should then use the std:: namespace
explicitly: this means std::printf, but also std::int32_t :-S

> > +
> > +#include <libcamera/controls.h>
> >
> >  namespace libcamera {
> >
> > -enum ControlId {
> > -	AwbEnable,
> > -	Brightness,
> > -	Contrast,
> > -	Saturation,
> > -	ManualExposure,
> > -	ManualGain,
> > -};
> > +namespace controls {
> > +
> > +#define AWB_ENABLE		1
> > +#define BRIGHTNESS		2
> > +#define CONTRAST		3
> > +#define SATURATION		4
> > +#define MANUAL_EXPOSURE		5
> > +#define MANUAL_GAIN		6
> > +
> > +extern const Control<void> None;
> > +extern const Control<bool> AwbEnable;
> > +extern const Control<int32_t> Brightness;
> > +extern const Control<int32_t> Contrast;
> > +extern const Control<int32_t> Saturation;
> > +extern const Control<int32_t> ManualExposure;
> > +extern const Control<int32_t> ManualGain;
> > +
> > +} /* namespace controls */
> >
> >  } /* namespace libcamera */
> >
> > -namespace std {
> > -
> > -template<>
> > -struct hash<libcamera::ControlId> {
> > -	using argument_type = libcamera::ControlId;
> > -	using result_type = std::size_t;
> > -
> > -	result_type operator()(const argument_type &key) const noexcept
> > -	{
> > -		return std::hash<std::underlying_type<argument_type>::type>()(key);
> > -	}
> > -};
> > -
> > -} /* namespace std */
> > -
> >  #endif // __LIBCAMERA_CONTROL_IDS_H__
> > diff --git a/include/libcamera/controls.h b/include/libcamera/controls.h
> > index a3089064c4b5..9698bd1dd383 100644
> > --- a/include/libcamera/controls.h
> > +++ b/include/libcamera/controls.h
> > @@ -8,12 +8,9 @@
> >  #ifndef __LIBCAMERA_CONTROLS_H__
> >  #define __LIBCAMERA_CONTROLS_H__
> >
> > -#include <stdint.h>
> >  #include <string>
> >  #include <unordered_map>
> >
> > -#include <libcamera/control_ids.h>
> > -
> >  namespace libcamera {
> >
> >  class Camera;
> > @@ -53,55 +50,75 @@ private:
> >  	};
> >  };
> >
> > -struct ControlIdentifier {
> > -	ControlId id;
> > -	const char *name;
> > -	ControlType type;
> > +class ControlId
> > +{
> > +public:
> > +	unsigned int id() const { return id_; }
> > +	const char *name() const { return name_; }
> > +	ControlType type() const { return type_; }
> > +
> > +protected:
> > +	ControlId(unsigned int id, const char *name, ControlType type)
> > +		: id_(id), name_(name), type_(type)
> > +	{
> > +	}
> > +
> > +private:
> > +	ControlId(const ControlId &) = delete;
> > +	ControlId &operator=(const ControlId &) = delete;
> > +
> > +	unsigned int id_;
> > +	const char *name_;
> 
> Thinking about serialization, is is worth transporting the name ?
> 
> As we discussed, probably re-introducing a global map of <id, Control>
> would allow to re-construct the Control just by using the id. Of course
> that would require linking against the file that defines the control
> map also for closed source IPA. Could they live without the control
> name otherwise ?

The name should only be used for debugging purpose, so we could do
without it. We could even drop it completely and go for numerical IDs,
at the cost of not so nice debugging messages. I'd rather keep the name
for now. IPAs that link against libcamera will benefit from it, IPAs
that don't will handle their own logging anyway, so nothing in them will
depend on us providing the name.

> > +	ControlType type_;
> > +};
> > +
> > +static inline bool operator==(const ControlId &lhs, const ControlId &rhs)
> > +{
> > +	return lhs.id() == rhs.id();
> > +}
> > +
> > +static inline bool operator!=(const ControlId &lhs, const ControlId &rhs)
> > +{
> > +	return !(lhs == rhs);
> > +}
> > +
> > +template<typename T>
> > +class Control : public ControlId
> > +{
> > +public:
> > +	using type = T;
> 
> This does not seems to be used.

It allows writing code such as 

	Brightness::type value = 42;

	if (foo)
		value += 10;

	controls.set(Brightness, value);

It may be used in pipeline handlers and IPAs, but it's mostly for
applications.

> > +
> > +	Control(unsigned int id, const char *name);
> > +
> > +private:
> 
> Why private ?

No reason :-) We're mixing = delete in public and private. Before C++11
brought = delete, the customary way to delete implicitly created
constructors and operators was to explicitly define them as private, so
I suppose this is where I got the private from. Once again I don't mind
much, but this should be a library-wide decision I think. What's your
preference ?

> > +	Control(const Control &) = delete;
> > +	Control &operator=(const Control &) = delete;
> >  };
> >
> >  class ControlInfo
> >  {
> >  public:
> > -	explicit ControlInfo(ControlId id, const ControlValue &min = 0,
> > +	explicit ControlInfo(const ControlId &id, const ControlValue &min = 0,
> >  			     const ControlValue &max = 0);
> >
> > -	ControlId id() const { return ident_->id; }
> > -	const char *name() const { return ident_->name; }
> > -	ControlType type() const { return ident_->type; }
> > -
> > +	const ControlId &id() const { return id_; }
> >  	const ControlValue &min() const { return min_; }
> >  	const ControlValue &max() const { return max_; }
> >
> >  	std::string toString() const;
> >
> >  private:
> > -	const struct ControlIdentifier *ident_;
> > +	const ControlId &id_;
> >  	ControlValue min_;
> >  	ControlValue max_;
> >  };
> >
> > -bool operator==(const ControlInfo &lhs, const ControlInfo &rhs);
> > -bool operator==(const ControlId &lhs, const ControlInfo &rhs);
> > -bool operator==(const ControlInfo &lhs, const ControlId &rhs);
> > -static inline bool operator!=(const ControlInfo &lhs, const ControlInfo &rhs)
> > -{
> > -	return !(lhs == rhs);
> > -}
> > -static inline bool operator!=(const ControlId &lhs, const ControlInfo &rhs)
> > -{
> > -	return !(lhs == rhs);
> > -}
> > -static inline bool operator!=(const ControlInfo &lhs, const ControlId &rhs)
> > -{
> > -	return !(lhs == rhs);
> > -}
> > -
> > -using ControlInfoMap = std::unordered_map<ControlId, ControlInfo>;
> > +using ControlInfoMap = std::unordered_map<const ControlId *, ControlInfo>;
> >
> >  class ControlList
> >  {
> >  private:
> > -	using ControlListMap = std::unordered_map<const ControlInfo *, ControlValue>;
> > +	using ControlListMap = std::unordered_map<const ControlId *, ControlValue>;
> 
> I like both maps are indexed by the same key
> 
> >
> >  public:
> >  	ControlList(Camera *camera);
> > @@ -114,18 +131,39 @@ public:
> >  	const_iterator begin() const { return controls_.begin(); }
> >  	const_iterator end() const { return controls_.end(); }
> >
> > -	bool contains(ControlId id) const;
> > -	bool contains(const ControlInfo *info) const;
> > +	bool contains(const ControlId &id) const;
> >  	bool empty() const { return controls_.empty(); }
> >  	std::size_t size() const { return controls_.size(); }
> >  	void clear() { controls_.clear(); }
> >
> > -	ControlValue &operator[](ControlId id);
> > -	ControlValue &operator[](const ControlInfo *info) { return controls_[info]; }
> > +	template<typename T>
> > +	const T &get(const Control<T> &ctrl) const
> > +	{
> > +		const ControlValue *val = find(ctrl);
> > +		if (!val) {
> > +			static T t(0);
> > +			return t;
> > +		}
> > +
> > +		return val->get<T>();
> > +	}
> > +
> > +	template<typename T>
> > +	void set(const Control<T> &ctrl, const T &value)
> > +	{
> > +		ControlValue *val = find(ctrl);
> > +		if (!val)
> > +			return;
> > +
> > +		val->set<T>(value);
> > +	}
> 
> In terms of generated code this does not make any difference, but as
> these functions are inlinded in the class definition, I would
> 
> 	const T &get(const Control<T> &ctrl) const
> 	{
> 		const ControlValue *val = find(ctrl);
> 		return val ? static T t(0) :
> 		             val->get<T>();
> 	}
> 
> 	template<typename T>
> 	void set(const Control<T> &ctrl, const T &value)
> 	{
> 		ControlValue *val = find(ctrl);
> 		if (val)
> 		        val->set<T>(value);
> 	}
> 
> To shorten them by a few lines (be aware, not compiled)

I don't mind the second one, but the first one doesn't look very nice
:-S

> >
> >  	void update(const ControlList &list);
> >
> >  private:
> > +	const ControlValue *find(const ControlId &id) const;
> > +	ControlValue *find(const ControlId &id);
> > +
> >  	Camera *camera_;
> >  	ControlListMap controls_;
> >  };
> > diff --git a/src/libcamera/control_ids.cpp b/src/libcamera/control_ids.cpp
> > new file mode 100644
> > index 000000000000..7e4e38b572f0
> > --- /dev/null
> > +++ b/src/libcamera/control_ids.cpp
> > @@ -0,0 +1,72 @@
> > +/* SPDX-License-Identifier: LGPL-2.1-or-later */
> > +/*
> > + * Copyright (C) 2019, Google Inc.
> > + *
> > + * control_ids.cpp : Control ID list
> > + */
> > +
> > +#include <libcamera/control_ids.h>
> > +
> > +/**
> > + * \file control_ids.h
> > + * \brief Camera control identifiers
> > + */
> > +
> > +namespace libcamera {
> > +
> > +namespace controls {
> > +
> > +/**
> > + * \def AWB_ENABLE
> > + * \brief Numerical value of the AwbEnable control
> > + * \def BRIGHTNESS
> > + * \brief Numerical value of the Brightness control
> > + * \def CONTRAST
> > + * \brief Numerical value of the Contrast control
> > + * \def SATURATION
> > + * \brief Numerical value of the Saturation control
> > + * \def MANUAL_EXPOSURE
> > + * \brief Numerical value of the ManualExposure control
> > + * \def MANUAL_GAIN
> > + * \brief Numerical value of the ManualGain control
> > + */
> > +
> > +/**
> > + * \brief Invalid control
> > + */
> > +extern const Control<void> None(0, "none");
> > +
> > +/**
> > + * \brief Enables or disables the AWB.
> > + * \sa ManualGain
> > + */
> > +extern const Control<bool> AwbEnable(AWB_ENABLE, "AwbEnable");
> > +
> > +/**
> > + * \brief Specify a fixed brightness parameter.
> > + */
> > +extern const Control<int32_t> Brightness(BRIGHTNESS, "Brightness");
> > +
> > +/**
> > + * \brief Specify a fixed contrast parameter.
> > + */
> > +extern const Control<int32_t> Contrast(CONTRAST, "Contrast");
> > +
> > +/**
> > + * \brief Specify a fixed saturation parameter.
> > + */
> > +extern const Control<int32_t> Saturation(SATURATION, "Saturation");
> > +
> > +/**
> > + * \brief Specify a fixed exposure time in milli-seconds
> > + */
> > +extern const Control<int32_t> ManualExposure(MANUAL_EXPOSURE, "ManualExposure");
> > +
> > +/**
> > + * \brief Specify a fixed gain parameter
> > + */
> > +extern const Control<int32_t> ManualGain(MANUAL_GAIN, "ManualGain");
> > +
> > +} /* namespace controls */
> > +
> > +} /* namespace libcamera */
> 
> We'll really need to expand this documentation soon :(

Absolutely, and I think we need to generate control_ids.h and
control_ids.cpp from a single source. I'm toying with the idea of
describing all controls using yaml.

> > diff --git a/src/libcamera/controls.cpp b/src/libcamera/controls.cpp
> > index 295ccd55a622..8886660b7617 100644
> > --- a/src/libcamera/controls.cpp
> > +++ b/src/libcamera/controls.cpp
> > @@ -18,6 +18,29 @@
> >  /**
> >   * \file controls.h
> >   * \brief Describes control framework and controls supported by a camera
> > + *
> > + * A control is a mean to govern or influence the operation of a camera. Every
> > + * control is defined by a unique numerical ID, a name string and the data type
> > + * of the value it stores. The libcamera API defines a set of standard controls
> > + * in the libcamera::controls namespace, as a set of instances of the Control
> > + * class.
> > + *
> > + * The main way for applications to interact with controls is through the
> > + * ControlList stored in the Request class:
> > + *
> > + * \code{.cpp}
> > + * Request *req = ...;
> > + * ControlList &controls = req->controls();
> > + * controls->set(controls::AwbEnable, false);
> > + * controls->set(controls::ManualExposure, 1000);
> > + *
> > + * ...
> > + *
> > + * int32_t exposure = controls->get(controls::ManualExposure);
> > + * \endcode
> > + *
> > + * The ControlList::get() and ControlList::set() methods automatically deduce
> > + * the data type based on the control.
> >   */
> >
> >  namespace libcamera {
> > @@ -173,76 +196,120 @@ std::string ControlValue::toString() const
> >  }
> >
> >  /**
> > - * \enum ControlId
> > - * \brief Numerical control ID
> > + * \class ControlId
> > + * \brief Control static metadata
> > + *
> > + * The ControlId class stores a control ID, name and data type. It provides
> > + * unique identification of a control, but without support for compile-time
> > + * type deduction that the derived template Control class supports. See the
> > + * Control class for more information.
> >   */
> >
> >  /**
> > - * \var AwbEnable
> > - * ControlType: Bool
> > - *
> > - * Enables or disables the AWB. See also \a libcamera::ControlId::ManualGain
> > + * \fn ControlId::ControlId(unsigned int id, const char *name, ControlType type)
> > + * \brief Construct a ControlId instance
> > + * \param[in] id The control numerical ID
> > + * \param[in] name The control name
> > + * \param[in] type The control data type
> >   */
> >
> >  /**
> > - * \var Brightness
> > - * ControlType: Integer32
> > - *
> > - * Specify a fixed brightness parameter.
> > + * \fn unsigned int ControlId::id() const
> > + * \brief Retrieve the control numerical ID
> > + * \return The control numerical ID
> >   */
> >
> >  /**
> > - * \var Contrast
> > - * ControlType: Integer32
> > - *
> > - * Specify a fixed contrast parameter.
> > + * \fn const char *ControlId::name() const
> > + * \brief Retrieve the control name
> > + * \return The control name
> >   */
> >
> >  /**
> > - * \var Saturation
> > - * ControlType: Integer32
> > - *
> > - * Specify a fixed saturation parameter.
> > + * \fn ControlType ControlId::type() const
> > + * \brief Retrieve the control data type
> > + * \return The control data type
> >   */
> >
> >  /**
> > - * \var ManualExposure
> > - * ControlType: Integer32
> > + * \fn bool operator==(const ControlId &lhs, const ControlId &rhs)
> > + * \brief Compare two ControlId instances for equality
> > + * \param[in] lhs Left-hand side ControlId
> > + * \param[in] rhs Left-hand side ControlId
> 
> Right-hand

Good catch :-)

> > + *
> > + * ControlId instances are compared based on the numerical ControlId::id()
> > + * only, as an object may not have two separate controls with the same
> > + * numerical ID.
> >   *
> > - * Specify a fixed exposure time in milli-seconds
> > + * \return True if \a lhs and \a rhs are equal, false otherwise
> 
>       \return True if \a lhs and \a rhs have the same control Id, false
>       otherwise
> 
> ?

OK

> >   */
> >
> >  /**
> > - * \var ManualGain
> > - * ControlType: Integer32
> > + * \class Control
> > + * \brief Describe a control and its intrinsic properties
> > + *
> > + * The Control class models a control exposed by a camera. Its template type
> > + * name T refers to the control data type, and allows methods that operate on
> > + * control values to be defined as template methods using the same type T for
> > + * the control value. See for instance how the ControlList::get() method
> > + * returns a value corresponding to the type of the requested control.
> > + *
> > + * While this class is the main mean to refer to a control, the control
> > + * identifying information are stored in the non-template base ControlId class.
> > + * This allows code that operates on a set of controls of different types to
> > + * reference those controls through a ControlId instead of a Control. For
> > + * instance, the list of controls supported by a camera is exposed as ControlId
> > + * instead of Control.
> >   *
> > - * Specify a fixed gain parameter
> > + * While controls of any type can be defined through template specialisation,
> > + * libcamera only supports the bool, int32_t and int64_t types natively (this
> > + * includes types that are equivalent to the supported types, such as int and
> > + * long int).
> 
> This is just temporary, would you like to document this?

I thought it was useful to mention the equivalence between int32_t and
int, and int64_t and long int somewhere. What do you mean by "is just
temporary" ?

> > + *
> > + * Controls IDs shall be unique. While nothing prevents multiple instances of
> > + * the Control class to be created with the same ID, this may lead to undefined
> > + * behaviour.
> >   */
> >
> >  /**
> > - * \struct ControlIdentifier
> > - * \brief Describe a ControlId with control specific constant meta-data
> > - *
> > - * Defines a Control with a unique ID, a name, and a type.
> > - * This structure is used as static part of the auto-generated control
> > - * definitions, which are generated from the ControlId documentation.
> > + * \fn Control::Control(unsigned int id, const char *name)
> > + * \brief Construct a Control instance
> > + * \param[in] id The control numerical ID
> > + * \param[in] name The control name
> >   *
> > - * \var ControlIdentifier::id
> > - * The unique ID for a control
> > - * \var ControlIdentifier::name
> > - * The string representation of the control
> > - * \var ControlIdentifier::type
> > - * The ValueType required to represent the control value
> > + * The control data type is automatically deduced from the template type T.
> >   */
> >
> > -/*
> > - * The controlTypes are automatically generated to produce a control_types.cpp
> > - * output. This file is not for public use, and so no suitable header exists
> > - * for this sole usage of the controlTypes reference. As such the extern is
> > - * only defined here for use during the ControlInfo constructor and should not
> > - * be referenced directly elsewhere.
> > +/**
> > + * \typedef Control::type
> > + * \brief The Control template type T
> >   */
> > -extern const std::unordered_map<ControlId, ControlIdentifier> controlTypes;
> > +
> > +#ifndef __DOXYGEN__
> > +template<>
> > +Control<void>::Control(unsigned int id, const char *name)
> > +	: ControlId(id, name, ControlTypeNone)
> > +{
> > +}
> > +
> > +template<>
> > +Control<bool>::Control(unsigned int id, const char *name)
> > +	: ControlId(id, name, ControlTypeBool)
> > +{
> > +}
> > +
> > +template<>
> > +Control<int32_t>::Control(unsigned int id, const char *name)
> > +	: ControlId(id, name, ControlTypeInteger32)
> > +{
> > +}
> > +
> > +template<>
> > +Control<int64_t>::Control(unsigned int id, const char *name)
> > +	: ControlId(id, name, ControlTypeInteger64)
> > +{
> > +}
> > +#endif /* __DOXYGEN__ */
> >
> >  /**
> >   * \class ControlInfo
> > @@ -260,17 +327,10 @@ extern const std::unordered_map<ControlId, ControlIdentifier> controlTypes;
> >   * \param[in] min The control minimum value
> >   * \param[in] max The control maximum value
> >   */
> > -ControlInfo::ControlInfo(ControlId id, const ControlValue &min,
> > +ControlInfo::ControlInfo(const ControlId &id, const ControlValue &min,
> >  			 const ControlValue &max)
> > -	: min_(min), max_(max)
> > +	: id_(id), min_(min), max_(max)
> >  {
> > -	auto iter = controlTypes.find(id);
> > -	if (iter == controlTypes.end()) {
> > -		LOG(Controls, Fatal) << "Attempt to create invalid ControlInfo";
> > -		return;
> > -	}
> > -
> > -	ident_ = &iter->second;
> >  }
> >
> >  /**
> > @@ -279,18 +339,6 @@ ControlInfo::ControlInfo(ControlId id, const ControlValue &min,
> >   * \return The control ID
> >   */
> >
> > -/**
> > - * \fn ControlInfo::name()
> > - * \brief Retrieve the control name string
> > - * \return The control name string
> > - */
> > -
> > -/**
> > - * \fn ControlInfo::type()
> > - * \brief Retrieve the control data type
> > - * \return The control data type
> > - */
> > -
> >  /**
> >   * \fn ControlInfo::min()
> >   * \brief Retrieve the minimum value of the control
> > @@ -310,56 +358,11 @@ std::string ControlInfo::toString() const
> >  {
> >  	std::stringstream ss;
> >
> > -	ss << name() << "[" << min_.toString() << ".." << max_.toString() << "]";
> > +	ss << id_.name() << "[" << min_.toString() << ".." << max_.toString() << "]";
> >
> >  	return ss.str();
> >  }
> >
> > -/**
> > - * \brief Compare control information for equality
> > - * \param[in] lhs Left-hand side control information
> > - * \param[in] rhs Right-hand side control information
> > - *
> > - * Control information is compared based on the ID only, as a camera may not
> > - * have two separate controls with the same ID.
> > - *
> > - * \return True if \a lhs and \a rhs are equal, false otherwise
> > - */
> > -bool operator==(const ControlInfo &lhs, const ControlInfo &rhs)
> > -{
> > -	return lhs.id() == rhs.id();
> > -}
> > -
> > -/**
> > - * \brief Compare control ID and information for equality
> > - * \param[in] lhs Left-hand side control identifier
> > - * \param[in] rhs Right-hand side control information
> > - *
> > - * Control information is compared based on the ID only, as a camera may not
> > - * have two separate controls with the same ID.
> > - *
> > - * \return True if \a lhs and \a rhs are equal, false otherwise
> > - */
> > -bool operator==(const ControlId &lhs, const ControlInfo &rhs)
> > -{
> > -	return lhs == rhs.id();
> > -}
> > -
> > -/**
> > - * \brief Compare control information and ID for equality
> > - * \param[in] lhs Left-hand side control information
> > - * \param[in] rhs Right-hand side control identifier
> > - *
> > - * Control information is compared based on the ID only, as a camera may not
> > - * have two separate controls with the same ID.
> > - *
> > - * \return True if \a lhs and \a rhs are equal, false otherwise
> > - */
> > -bool operator==(const ControlInfo &lhs, const ControlId &rhs)
> > -{
> > -	return lhs.id() == rhs;
> > -}
> > -
> >  /**
> >   * \typedef ControlInfoMap
> >   * \brief A map of ControlId to ControlInfo
> > @@ -431,29 +434,9 @@ ControlList::ControlList(Camera *camera)
> >   *
> >   * \return True if the list contains a matching control, false otherwise
> >   */
> > -bool ControlList::contains(ControlId id) const
> > +bool ControlList::contains(const ControlId &id) const
> >  {
> > -	const ControlInfoMap &controls = camera_->controls();
> > -	const auto iter = controls.find(id);
> > -	if (iter == controls.end()) {
> > -		LOG(Controls, Error)
> > -			<< "Camera " << camera_->name()
> > -			<< " does not support control " << id;
> > -
> > -		return false;
> > -	}
> > -
> > -	return controls_.find(&iter->second) != controls_.end();
> > -}
> > -
> > -/**
> > - * \brief Check if the list contains a control with the specified \a info
> > - * \param[in] info The control info
> > - * \return True if the list contains a matching control, false otherwise
> > - */
> > -bool ControlList::contains(const ControlInfo *info) const
> > -{
> > -	return controls_.find(info) != controls_.end();
> > +	return controls_.find(&id) != controls_.end();
> >  }
> >
> >  /**
> > @@ -474,44 +457,60 @@ bool ControlList::contains(const ControlInfo *info) const
> >   */
> >
> >  /**
> > - * \brief Access or insert the control specified by \a id
> > - * \param[in] id The control ID
> > + * \fn template<typename T> const T &ControlList::get() const
> > + * \brief Get the value of a control
> > + * \param[in] ctrl The control
> >   *
> > - * This method returns a reference to the control identified by \a id, inserting
> > - * it in the list if the ID is not already present.
> > + * The behaviour is undefined if the control \a ctrl is not present in the
> > + * list. Use ControlList::contains() to test for the presence of a control in
> > + * the list before retrieving its value.
> 
> Is it undefined? An empty control is returned if I read things right

Undefined behaviour means that applications can't rely on the behaviour,
not that it's random :-) We could replace the return with an assert(),
and applications won't be allowed to complain.

https://en.wikipedia.org/wiki/Undefined_behavior

> >   *
> > - * The behaviour is undefined if the control \a id is not supported by the
> > - * camera that the ControlList refers to.
> > + * The control value type shall match the type T, otherwise the behaviour is
> > + * undefined.
> >   *
> > - * \return A reference to the value of the control identified by \a id
> > + * \return The control value
> >   */
> > -ControlValue &ControlList::operator[](ControlId id)
> > +
> > +/**
> > + * \fn template<typename T> void ControlList::set()
> > + * \brief Set the control value to \a value
> > + * \param[in] ctrl The control
> > + * \param[in] value The control value
> > + *
> > + * This method sets the value of a control in the control list. If the control
> > + * is already present in the list, its value is updated.
> 
> What about clearly stating the control is added if not present?

I'll reword this.

> > + *
> > + * The behaviour is undefined if the control \a ctrl is not supported by the
> > + * camera that the list refers to.
> 
> It seems to me it just gets ignored

Same explanation as above, it's still undefined.

> > + */
> > +
> > +const ControlValue *ControlList::find(const ControlId &id) const
> > +{
> > +	const auto iter = controls_.find(&id);
> > +	if (iter == controls_.end()) {
> > +		LOG(Controls, Error)
> > +			<< "Control " << id.name() << " not found";
> > +
> > +		return nullptr;
> > +	}
> > +
> > +	return &iter->second;
> > +}
> > +
> > +ControlValue *ControlList::find(const ControlId &id)
> >  {
> >  	const ControlInfoMap &controls = camera_->controls();
> > -	const auto iter = controls.find(id);
> > +	const auto iter = controls.find(&id);
> >  	if (iter == controls.end()) {
> >  		LOG(Controls, Error)
> >  			<< "Camera " << camera_->name()
> > -			<< " does not support control " << id;
> > -
> > -		static ControlValue empty;
> > -		return empty;
> > +			<< " does not support control " << id.name();
> > +		return nullptr;
> >  	}
> >
> > -	return controls_[&iter->second];
> > +	return &controls_[&id];
> 
> Double lookup ? Couldn't you re-use iter ?

iter is for controls, this is controls_.

> >  }
> >
> > -/**
> > - * \fn ControlList::operator[](const ControlInfo *info)
> > - * \brief Access or insert the control specified by \a info
> > - * \param[in] info The control info
> > - *
> > - * This method returns a reference to the control identified by \a info,
> > - * inserting it in the list if the info is not already present.
> > - *
> > - * \return A reference to the value of the control identified by \a info
> > - */
> > -
> >  /**
> >   * \brief Update the list with a union of itself and \a other
> >   * \param other The other list
> > @@ -533,10 +532,10 @@ void ControlList::update(const ControlList &other)
> >  	}
> >
> >  	for (auto it : other) {
> > -		const ControlInfo *info = it.first;
> > +		const ControlId *id = it.first;
> >  		const ControlValue &value = it.second;
> >
> > -		controls_[info] = value;
> > +		controls_[id] = value;
> >  	}
> >  }
> >
> > diff --git a/src/libcamera/gen-controls.awk b/src/libcamera/gen-controls.awk
> > deleted file mode 100755
> > index a3f291e7071c..000000000000
> > --- a/src/libcamera/gen-controls.awk
> > +++ /dev/null
> > @@ -1,106 +0,0 @@
> > -#!/usr/bin/awk -f
> > -
> > -# SPDX-License-Identifier: LGPL-2.1-or-later
> > -
> > -# Controls are documented using Doxygen in the main controls.cpp source.
> > -#
> > -# Generate control tables directly from the documentation, creating enumerations
> > -# to support the IDs and static type information regarding each control.
> > -
> > -BEGIN {
> > -	id=0
> > -	input=ARGV[1]
> > -	mode=ARGV[2]
> > -	output=ARGV[3]
> > -}
> > -
> > -# Detect Doxygen style comment blocks and ignore other lines
> > -/^\/\*\*$/ { in_doxygen=1; first_line=1; next }
> > -// { if (!in_doxygen) next }
> > -
> > -# Entry point for the Control Documentation
> > -/ * \\enum ControlId$/ { in_controls=1; first_line=0; next }
> > -// { if (!in_controls) next }
> > -
> > -# Extract control information
> > -/ \* \\var/ { names[++id]=$3; first_line=0; next }
> > -/ \* ControlType:/ { types[id] = $3 }
> > -
> > -# End of comment blocks
> > -/^ \*\// { in_doxygen=0 }
> > -
> > -# Identify the end of controls
> > -/^ \* \\/ { if (first_line) exit }
> > -// { first_line=0 }
> > -
> > -################################
> > -# Support output file generation
> > -
> > -function basename(file) {
> > -	sub(".*/", "", file)
> > -	return file
> > -}
> > -
> > -function Header(file, description) {
> > -	print "/* SPDX-License-Identifier: LGPL-2.1-or-later */" > file
> > -	print "/*" > file
> > -	print " * Copyright (C) 2019, Google Inc." > file
> > -	print " *" > file
> > -	print " * " basename(file) " - " description > file
> > -	print " *" > file
> > -	print " * This file is auto-generated. Do not edit." > file
> > -	print " */" > file
> > -	print "" > file
> > -}
> > -
> > -function EnterNameSpace(file) {
> > -	print "namespace libcamera {" > file
> > -	print "" > file
> > -}
> > -
> > -function ExitNameSpace(file) {
> > -	print "" > file
> > -	print "} /* namespace libcamera */" > file
> > -}
> > -
> > -function GenerateHeader(file) {
> > -	Header(file, "Control ID list")
> > -
> > -	print "#ifndef __LIBCAMERA_CONTROL_IDS_H__" > file
> > -	print "#define __LIBCAMERA_CONTROL_IDS_H__" > file
> > -	print "" > file
> > -
> > -	EnterNameSpace(file)
> > -	print "enum ControlId {" > file
> > -	for (i=1; i <= id; ++i) {
> > -		printf "\t%s,\n", names[i] > file
> > -	}
> > -	print "};" > file
> > -	ExitNameSpace(file)
> > -
> > -	print "" > file
> > -	print "#endif // __LIBCAMERA_CONTROL_IDS_H__" > file
> > -}
> > -
> > -function GenerateTable(file) {
> > -	Header(file, "Control types")
> > -	print "#include <libcamera/controls.h>" > file
> > -	print "" > file
> > -
> > -	EnterNameSpace(file)
> > -
> > -	print "extern const std::unordered_map<ControlId, ControlIdentifier>" > file
> > -	print "controlTypes {" > file
> > -	for (i=1; i <= id; ++i) {
> > -		printf "\t{ %s, { %s, \"%s\", ControlType%s } },\n", names[i], names[i], names[i], types[i] > file
> > -	}
> > -	print "};" > file
> > -	ExitNameSpace(file)
> > -}
> > -
> > -END {
> > -	if (mode == "--header")
> > -		GenerateHeader(output)
> > -	else
> > -		GenerateTable(output)
> > -}
> > diff --git a/src/libcamera/meson.build b/src/libcamera/meson.build
> > index 755149c55c7b..8123d1d5bee9 100644
> > --- a/src/libcamera/meson.build
> > +++ b/src/libcamera/meson.build
> > @@ -5,6 +5,7 @@ libcamera_sources = files([
> >      'camera_manager.cpp',
> >      'camera_sensor.cpp',
> >      'controls.cpp',
> > +    'control_ids.cpp',
> >      'device_enumerator.cpp',
> >      'device_enumerator_sysfs.cpp',
> >      'event_dispatcher.cpp',
> > @@ -57,16 +58,6 @@ if libudev.found()
> >      ])
> >  endif
> >
> > -gen_controls = files('gen-controls.awk')
> > -
> > -control_types_cpp = custom_target('control_types_cpp',
> > -                                  input : files('controls.cpp'),
> > -                                  output : 'control_types.cpp',
> > -                                  depend_files : gen_controls,
> > -                                  command : [gen_controls, '@INPUT@', '--code', '@OUTPUT@'])
> > -
> > -libcamera_sources += control_types_cpp
> > -
> >  gen_version = join_paths(meson.source_root(), 'utils', 'gen-version.sh')
> >
> >  version_cpp = vcs_tag(command : [gen_version, meson.build_root()],
> > diff --git a/src/libcamera/pipeline/uvcvideo.cpp b/src/libcamera/pipeline/uvcvideo.cpp
> > index 0d56758e3e1d..44e19f40f1b9 100644
> > --- a/src/libcamera/pipeline/uvcvideo.cpp
> > +++ b/src/libcamera/pipeline/uvcvideo.cpp
> > @@ -10,6 +10,7 @@
> >  #include <tuple>
> >
> >  #include <libcamera/camera.h>
> > +#include <libcamera/control_ids.h>
> >  #include <libcamera/controls.h>
> >  #include <libcamera/request.h>
> >  #include <libcamera/stream.h>
> > @@ -230,33 +231,20 @@ int PipelineHandlerUVC::processControls(UVCCameraData *data, Request *request)
> >  	V4L2ControlList controls;
> >
> >  	for (auto it : request->controls()) {
> > -		const ControlInfo *ci = it.first;
> > +		const ControlId &id = *it.first;
> >  		ControlValue &value = it.second;
> >
> > -		switch (ci->id()) {
> > -		case Brightness:
> > +		if (id == controls::Brightness) {
> >  			controls.add(V4L2_CID_BRIGHTNESS, value.get<int32_t>());
> > -			break;
> > -
> > -		case Contrast:
> > +		} else if (id == controls::Contrast) {
> >  			controls.add(V4L2_CID_CONTRAST, value.get<int32_t>());
> > -			break;
> > -
> > -		case Saturation:
> > +		} else if (id == controls::Saturation) {
> >  			controls.add(V4L2_CID_SATURATION, value.get<int32_t>());
> > -			break;
> > -
> > -		case ManualExposure:
> > +		} else if (id == controls::ManualExposure) {
> >  			controls.add(V4L2_CID_EXPOSURE_AUTO, 1);
> >  			controls.add(V4L2_CID_EXPOSURE_ABSOLUTE, value.get<int32_t>());
> > -			break;
> > -
> > -		case ManualGain:
> > +		} else if (id == controls::ManualGain) {
> >  			controls.add(V4L2_CID_GAIN, value.get<int32_t>());
> > -			break;
> > -
> > -		default:
> > -			break;
> >  		}
> >  	}
> >
> > @@ -352,23 +340,23 @@ int UVCCameraData::init(MediaEntity *entity)
> >  	for (const auto &ctrl : controls) {
> >  		unsigned int v4l2Id = ctrl.first;
> >  		const V4L2ControlInfo &info = ctrl.second;
> > -		ControlId id;
> > +		const ControlId *id = &controls::None;
> >
> >  		switch (v4l2Id) {
> >  		case V4L2_CID_BRIGHTNESS:
> > -			id = Brightness;
> > +			id = &controls::Brightness;
> >  			break;
> >  		case V4L2_CID_CONTRAST:
> > -			id = Contrast;
> > +			id = &controls::Contrast;
> >  			break;
> >  		case V4L2_CID_SATURATION:
> > -			id = Saturation;
> > +			id = &controls::Saturation;
> >  			break;
> >  		case V4L2_CID_EXPOSURE_ABSOLUTE:
> > -			id = ManualExposure;
> > +			id = &controls::ManualExposure;
> >  			break;
> >  		case V4L2_CID_GAIN:
> > -			id = ManualGain;
> > +			id = &controls::ManualGain;
> >  			break;
> >  		default:
> >  			continue;
> > @@ -376,7 +364,7 @@ int UVCCameraData::init(MediaEntity *entity)
> >
> >  		controlInfo_.emplace(std::piecewise_construct,
> >  				     std::forward_as_tuple(id),
> > -				     std::forward_as_tuple(id, info.min(), info.max()));
> > +				     std::forward_as_tuple(*id, info.min(), info.max()));
> >  	}
> >
> >  	return 0;
> > diff --git a/src/libcamera/pipeline/vimc.cpp b/src/libcamera/pipeline/vimc.cpp
> > index e549dc64b996..a48febf2172e 100644
> > --- a/src/libcamera/pipeline/vimc.cpp
> > +++ b/src/libcamera/pipeline/vimc.cpp
> > @@ -15,6 +15,7 @@
> >  #include <ipa/ipa_interface.h>
> >  #include <ipa/ipa_module_info.h>
> >  #include <libcamera/camera.h>
> > +#include <libcamera/control_ids.h>
> >  #include <libcamera/controls.h>
> >  #include <libcamera/request.h>
> >  #include <libcamera/stream.h>
> > @@ -283,24 +284,15 @@ int PipelineHandlerVimc::processControls(VimcCameraData *data, Request *request)
> >  	V4L2ControlList controls;
> >
> >  	for (auto it : request->controls()) {
> > -		const ControlInfo *ci = it.first;
> > +		const ControlId &id = *it.first;
> >  		ControlValue &value = it.second;
> >
> > -		switch (ci->id()) {
> > -		case Brightness:
> > +		if (id == controls::Brightness) {
> >  			controls.add(V4L2_CID_BRIGHTNESS, value.get<int32_t>());
> > -			break;
> > -
> > -		case Contrast:
> > +		} else if (id == controls::Contrast) {
> >  			controls.add(V4L2_CID_CONTRAST, value.get<int32_t>());
> > -			break;
> > -
> > -		case Saturation:
> > +		} else if (id == controls::Saturation) {
> >  			controls.add(V4L2_CID_SATURATION, value.get<int32_t>());
> > -			break;
> > -
> > -		default:
> > -			break;
> >  		}
> >  	}
> >
> > @@ -427,17 +419,17 @@ int VimcCameraData::init(MediaDevice *media)
> >  	for (const auto &ctrl : controls) {
> >  		unsigned int v4l2Id = ctrl.first;
> >  		const V4L2ControlInfo &info = ctrl.second;
> > -		ControlId id;
> > +		const ControlId *id = &controls::None;
> >
> >  		switch (v4l2Id) {
> >  		case V4L2_CID_BRIGHTNESS:
> > -			id = Brightness;
> > +			id = &controls::Brightness;
> >  			break;
> >  		case V4L2_CID_CONTRAST:
> > -			id = Contrast;
> > +			id = &controls::Contrast;
> >  			break;
> >  		case V4L2_CID_SATURATION:
> > -			id = Saturation;
> > +			id = &controls::Saturation;
> >  			break;
> >  		default:
> >  			continue;
> > @@ -445,7 +437,7 @@ int VimcCameraData::init(MediaDevice *media)
> >
> >  		controlInfo_.emplace(std::piecewise_construct,
> >  				     std::forward_as_tuple(id),
> > -				     std::forward_as_tuple(id, info.min(), info.max()));
> > +				     std::forward_as_tuple(*id, info.min(), info.max()));
> >  	}
> >
> >  	return 0;
> > diff --git a/test/controls/control_info.cpp b/test/controls/control_info.cpp
> > index 2aba568a302e..dbc43df8e3d3 100644
> > --- a/test/controls/control_info.cpp
> > +++ b/test/controls/control_info.cpp
> > @@ -7,6 +7,7 @@
> >
> >  #include <iostream>
> >
> > +#include <libcamera/control_ids.h>
> >  #include <libcamera/controls.h>
> >
> >  #include "test.h"
> > @@ -23,17 +24,17 @@ protected:
> >  		 * Test information retrieval from a control with no minimum
> >  		 * and maximum.
> >  		 */
> > -		ControlInfo info(Brightness);
> > +		ControlInfo brightness(controls::Brightness);
> >
> > -		if (info.id() != Brightness ||
> > -		    info.type() != ControlTypeInteger32 ||
> > -		    info.name() != std::string("Brightness")) {
> > +		if (brightness.id() != controls::Brightness ||
> > +		    brightness.id().type() != ControlTypeInteger32 ||
> > +		    brightness.id().name() != std::string("Brightness")) {
> >  			cout << "Invalid control identification for Brightness" << endl;
> >  			return TestFail;
> >  		}
> >
> > -		if (info.min().get<int32_t>() != 0 ||
> > -		    info.max().get<int32_t>() != 0) {
> > +		if (brightness.min().get<int32_t>() != 0 ||
> > +		    brightness.max().get<int32_t>() != 0) {
> >  			cout << "Invalid control range for Brightness" << endl;
> >  			return TestFail;
> >  		}
> > @@ -42,17 +43,17 @@ protected:
> >  		 * Test information retrieval from a control with a minimum and
> >  		 * a maximum value.
> >  		 */
> > -		info = ControlInfo(Contrast, 10, 200);
> > +		ControlInfo contrast(controls::Contrast, 10, 200);
> >
> > -		if (info.id() != Contrast ||
> > -		    info.type() != ControlTypeInteger32 ||
> > -		    info.name() != std::string("Contrast")) {
> > +		if (contrast.id() != controls::Contrast ||
> > +		    contrast.id().type() != ControlTypeInteger32 ||
> > +		    contrast.id().name() != std::string("Contrast")) {
> >  			cout << "Invalid control identification for Contrast" << endl;
> >  			return TestFail;
> >  		}
> >
> > -		if (info.min().get<int32_t>() != 10 ||
> > -		    info.max().get<int32_t>() != 200) {
> > +		if (contrast.min().get<int32_t>() != 10 ||
> > +		    contrast.max().get<int32_t>() != 200) {
> >  			cout << "Invalid control range for Contrast" << endl;
> >  			return TestFail;
> >  		}
> > diff --git a/test/controls/control_list.cpp b/test/controls/control_list.cpp
> > index 5215840b1c4e..053696814b67 100644
> > --- a/test/controls/control_list.cpp
> > +++ b/test/controls/control_list.cpp
> > @@ -9,6 +9,7 @@
> >
> >  #include <libcamera/camera.h>
> >  #include <libcamera/camera_manager.h>
> > +#include <libcamera/control_ids.h>
> >  #include <libcamera/controls.h>
> >
> >  #include "test.h"
> > @@ -52,7 +53,7 @@ protected:
> >  			return TestFail;
> >  		}
> >
> > -		if (list.contains(Brightness)) {
> > +		if (list.contains(controls::Brightness)) {
> >  			cout << "List should not contain Brightness control" << endl;
> >  			return TestFail;
> >  		}
> > @@ -70,7 +71,7 @@ protected:
> >  		 * Set a control, and verify that the list now contains it, and
> >  		 * nothing else.
> >  		 */
> > -		list[Brightness] = 255;
> > +		list.set(controls::Brightness, 255);
> >
> >  		if (list.empty()) {
> >  			cout << "List should not be empty" << endl;
> > @@ -82,7 +83,7 @@ protected:
> >  			return TestFail;
> >  		}
> >
> > -		if (!list.contains(Brightness)) {
> > +		if (!list.contains(controls::Brightness)) {
> >  			cout << "List should contain Brightness control" << endl;
> >  			return TestFail;
> >  		}
> > @@ -96,54 +97,45 @@ protected:
> >  			return TestFail;
> >  		}
> >
> > -		if (list[Brightness].get<int32_t>() != 255) {
> > +		if (list.get(controls::Brightness) != 255) {
> >  			cout << "Incorrest Brightness control value" << endl;
> >  			return TestFail;
> >  		}
> >
> > -		if (list.contains(Contrast)) {
> > +		if (list.contains(controls::Contrast)) {
> >  			cout << "List should not contain Contract control" << endl;
> >  			return TestFail;
> >  		}
> >
> > -		/*
> > -		 * Set a second control through ControlInfo and retrieve it
> > -		 * through both controlId and ControlInfo.
> > -		 */
> > -		const ControlInfoMap &controls = camera_->controls();
> > -		const ControlInfo *brightness = &controls.find(Brightness)->second;
> > -		const ControlInfo *contrast = &controls.find(Contrast)->second;
> > +		/* Update the first control and set a second one. */
> > +		list.set(controls::Brightness, 64);
> > +		list.set(controls::Contrast, 128);
> >
> > -		list[brightness] = 64;
> > -		list[contrast] = 128;
> > -
> > -		if (!list.contains(Contrast) || !list.contains(contrast)) {
> > +		if (!list.contains(controls::Contrast) ||
> > +		    !list.contains(controls::Contrast)) {
> >  			cout << "List should contain Contrast control" << endl;
> >  			return TestFail;
> >  		}
> >
> > -		/*
> > -		 * Test control value retrieval and update through ControlInfo.
> > -		 */
> > -		if (list[brightness].get<int32_t>() != 64 ||
> > -		    list[contrast].get<int32_t>() != 128) {
> > +		if (list.get(controls::Brightness) != 64 ||
> > +		    list.get(controls::Contrast) != 128) {
> >  			cout << "Failed to retrieve control value" << endl;
> >  			return TestFail;
> >  		}
> >
> > -		list[brightness] = 10;
> > -		list[contrast] = 20;
> > +		/*
> > +		 * Update both controls and verify that the container doesn't
> > +		 * grow.
> > +		 */
> > +		list.set(controls::Brightness, 10);
> > +		list.set(controls::Contrast, 20);
> >
> > -		if (list[brightness].get<int32_t>() != 10 ||
> > -		    list[contrast].get<int32_t>() != 20) {
> > +		if (list.get(controls::Brightness) != 10 ||
> > +		    list.get(controls::Contrast) != 20) {
> >  			cout << "Failed to update control value" << endl;
> >  			return TestFail;
> >  		}
> >
> > -		/*
> > -		 * Assert that the container has not grown with the control
> > -		 * updated.
> > -		 */
> >  		if (list.size() != 2) {
> >  			cout << "List should contain two elements" << endl;
> >  			return TestFail;
> > @@ -157,8 +149,8 @@ protected:
> >  		 */
> >  		ControlList newList(camera_.get());
> >
> > -		newList[Brightness] = 128;
> > -		newList[Saturation] = 255;
> > +		newList.set(controls::Brightness, 128);
> > +		newList.set(controls::Saturation, 255);
> >  		newList.update(list);
> >
> >  		list.clear();
> > @@ -178,16 +170,16 @@ protected:
> >  			return TestFail;
> >  		}
> >
> > -		if (!newList.contains(Brightness) ||
> > -		    !newList.contains(Contrast) ||
> > -		    !newList.contains(Saturation)) {
> > +		if (!newList.contains(controls::Brightness) ||
> > +		    !newList.contains(controls::Contrast) ||
> > +		    !newList.contains(controls::Saturation)) {
> >  			cout << "New list contains incorrect items" << endl;
> >  			return TestFail;
> >  		}
> >
> > -		if (newList[Brightness].get<int32_t>() != 10 ||
> > -		    newList[Contrast].get<int32_t>() != 20 ||
> > -		    newList[Saturation].get<int32_t>() != 255) {
> > +		if (newList.get(controls::Brightness) != 10 ||
> > +		    newList.get(controls::Contrast) != 20 ||
> > +		    newList.get(controls::Saturation) != 255) {
> >  			cout << "New list contains incorrect values" << endl;
> >  			return TestFail;
> >  		}
> > --
> > Regards,
> >
> > Laurent Pinchart
> >
> > _______________________________________________
> > libcamera-devel mailing list
> > libcamera-devel@lists.libcamera.org
> > https://lists.libcamera.org/listinfo/libcamera-devel