diff options
| -rw-r--r-- | src/libcamera/include/v4l2_controls.h | 80 | ||||
| -rw-r--r-- | src/libcamera/meson.build | 1 | ||||
| -rw-r--r-- | src/libcamera/v4l2_controls.cpp | 289 |
3 files changed, 370 insertions, 0 deletions
diff --git a/src/libcamera/include/v4l2_controls.h b/src/libcamera/include/v4l2_controls.h new file mode 100644 index 00000000..2c8cb900 --- /dev/null +++ b/src/libcamera/include/v4l2_controls.h @@ -0,0 +1,80 @@ +/* SPDX-License-Identifier: LGPL-2.1-or-later */ +/* + * Copyright (C) 2019, Google Inc. + * + * v4l2_controls.h - V4L2 Controls Support + */ + +#ifndef __LIBCAMERA_V4L2_CONTROLS_H__ +#define __LIBCAMERA_V4L2_CONTROLS_H__ + +#include <string> +#include <vector> + +#include <stdint.h> + +#include <linux/v4l2-controls.h> +#include <linux/videodev2.h> + +namespace libcamera { + +class V4L2ControlInfo +{ +public: + V4L2ControlInfo(const struct v4l2_query_ext_ctrl &ctrl); + + unsigned int id() const { return id_; } + unsigned int type() const { return type_; } + size_t size() const { return size_; } + const std::string &name() const { return name_; } + +private: + unsigned int id_; + unsigned int type_; + size_t size_; + std::string name_; +}; + +class V4L2Control +{ +public: + V4L2Control(unsigned int id, int value = 0) + : id_(id), value_(value) {} + + int64_t value() const { return value_; } + void setValue(int64_t value) { value_ = value; } + + unsigned int id() const { return id_; } + +private: + unsigned int id_; + int64_t value_; +}; + +class V4L2ControlList +{ +public: + using iterator = std::vector<V4L2Control>::iterator; + using const_iterator = std::vector<V4L2Control>::const_iterator; + + iterator begin() { return controls_.begin(); } + const_iterator begin() const { return controls_.begin(); } + iterator end() { return controls_.end(); } + const_iterator end() const { return controls_.end(); } + + bool empty() const { return controls_.empty(); } + std::size_t size() const { return controls_.size(); } + + void clear() { controls_.clear(); } + void add(unsigned int id, int64_t value = 0); + + V4L2Control *getByIndex(unsigned int index); + V4L2Control *operator[](unsigned int id); + +private: + std::vector<V4L2Control> controls_; +}; + +} /* namespace libcamera */ + +#endif /* __LIBCAMERA_V4L2_CONTROLS_H__ */ diff --git a/src/libcamera/meson.build b/src/libcamera/meson.build index f26ad5b2..985aa7e8 100644 --- a/src/libcamera/meson.build +++ b/src/libcamera/meson.build @@ -23,6 +23,7 @@ libcamera_sources = files([ 'stream.cpp', 'timer.cpp', 'utils.cpp', + 'v4l2_controls.cpp', 'v4l2_device.cpp', 'v4l2_subdevice.cpp', 'v4l2_videodevice.cpp', diff --git a/src/libcamera/v4l2_controls.cpp b/src/libcamera/v4l2_controls.cpp new file mode 100644 index 00000000..78888de2 --- /dev/null +++ b/src/libcamera/v4l2_controls.cpp @@ -0,0 +1,289 @@ +/* SPDX-License-Identifier: LGPL-2.1-or-later */ +/* + * Copyright (C) 2019, Google Inc. + * + * v4l2_controls.cpp - V4L2 Controls Support + */ + +#include "v4l2_controls.h" + +/** + * \file v4l2_controls.h + * \brief Support for V4L2 Controls using the V4L2 Extended Controls APIs + * + * The V4L2 Control API allows application to inspect and modify sets of + * configurable parameters on a video device or subdevice. The nature of the + * parameters an application can modify using the control framework depends on + * what the driver implements support for, and on the characteristics of the + * underlying hardware platform. Generally controls are used to modify user + * visible settings, such as the image brightness and exposure time, or + * non-standard parameters which cannot be controlled through the V4L2 format + * negotiation API. + * + * Controls are identified by a numerical ID, defined by the V4L2 kernel headers + * and have an associated type. Each control has a value, which is the data that + * can be modified with V4L2Device::setControls() or retrieved with + * V4L2Device::getControls(). + * + * The control's type along with the control's flags define the type of the + * control's value content. Controls can transport a single data value stored in + * variable inside the control, or they might as well deal with more complex + * data types, such as arrays of matrices, stored in a contiguous memory + * locations associated with the control and called 'the payload'. Such controls + * are called 'compound controls' and are currently not supported by the + * libcamera V4L2 control framework. + * + * libcamera implements support for controls using the V4L2 Extended Control + * API, which allows future handling of controls with payloads of arbitrary + * sizes. + * + * The libcamera V4L2 Controls framework operates on lists of controls, wrapped + * by the V4L2ControlList class, to match the V4L2 extended controls API. The + * interface to set and get control is implemented by the V4L2Device class, and + * this file only provides the data type definitions. + * + * \todo Add support for compound controls + */ + +namespace libcamera { + +/** + * \class V4L2ControlInfo + * \brief Information on a V4L2 control + * + * The V4L2ControlInfo class represents all the information related to a V4L2 + * control, such as its ID, its type, its user-readable name and the expected + * size of its value data. + * + * V4L2ControlInfo instances are created by inspecting the fieldS of a struct + * v4l2_query_ext_ctrl structure, after it has been filled by the device driver + * as a consequence of a VIDIOC_QUERY_EXT_CTRL ioctl call. + * + * This class does not contain the control value, but only static information on + * the control, which shall be cached by the caller at initialisation time or + * the first time the control information is accessed. + */ + +/** + * \brief Construct a V4L2ControlInfo from a struct v4l2_query_ext_ctrl + * \param ctrl The struct v4l2_query_ext_ctrl as returned by the kernel + */ +V4L2ControlInfo::V4L2ControlInfo(const struct v4l2_query_ext_ctrl &ctrl) +{ + id_ = ctrl.id; + type_ = ctrl.type; + name_ = static_cast<const char *>(ctrl.name); + size_ = ctrl.elem_size * ctrl.elems; +} + +/** + * \fn V4L2ControlInfo::id() + * \brief Retrieve the control ID + * \return The V4L2 control ID + */ + +/** + * \fn V4L2ControlInfo::type() + * \brief Retrieve the control type as defined by V4L2_CTRL_TYPE_* + * \return The V4L2 control type + */ + +/** + * \fn V4L2ControlInfo::size() + * \brief Retrieve the control value data size (in bytes) + * \return The V4L2 control value data size + */ + +/** + * \fn V4L2ControlInfo::name() + * \brief Retrieve the control user readable name + * \return The V4L2 control user readable name + */ + +/** + * \class V4L2Control + * \brief A V4L2 control value + * + * The V4L2Control class represent the value of a V4L2 control. The class + * stores values that have been read from or will be applied to a V4L2 device. + * + * The value stored in the class instances does not reflect what is actually + * applied to the hardware but is a pure software cache optionally initialized + * at control creation time and modified by a control read or write operation. + * + * The write and read controls the V4L2Control class instances are not meant + * to be directly used but are instead intended to be grouped in + * V4L2ControlList instances, which are then passed as parameters to + * V4L2Device::setControls() and V4L2Device::getControls() operations. + */ + +/** + * \fn V4L2Control::V4L2Control + * \brief Construct a V4L2 control with \a id and \a value + * \param id The V4L2 control ID + * \param value The control value + */ + +/** + * \fn V4L2Control::value() + * \brief Retrieve the value of the control + * + * This method returns the cached control value, initially set by + * V4L2ControlList::add() and then updated when the controls are read or + * written with V4L2Device::getControls() and V4L2Device::setControls(). + * + * \return The V4L2 control value + */ + +/** + * \fn V4L2Control::setValue() + * \brief Set the value of the control + * \param value The new V4L2 control value + * + * This method stores the control value, which will be applied to the + * device when calling V4L2Device::setControls(). + */ + +/** + * \fn V4L2Control::id() + * \brief Retrieve the control ID this instance refers to + * \return The V4L2Control ID + */ + +/** + * \class V4L2ControlList + * \brief Container of V4L2Control instances + * + * The V4L2ControlList class works as a container for a list of V4L2Control + * instances. The class provides operations to add a new control to the list, + * get back a control value, and reset the list of controls it contains. + * + * In order to set and get controls, user of the libcamera V4L2 control + * framework should operate on instances of the V4L2ControlList class, and use + * them as argument for the V4L2Device::setControls() and + * V4L2Device::getControls() operations, which write and read a list of + * controls to or from a V4L2 device (a video device or a subdevice). + * + * Controls are added to a V4L2ControlList instance with the add() method, with + * or without a value. + * + * To write controls to a device, the controls of interest shall be added with + * an initial value by calling V4L2ControlList::add(unsigned int id, int64_t + * value) to prepare for a write operation. Once the values of all controls of + * interest have been added, the V4L2ControlList instance is passed to the + * V4L2Device::setControls(), which sets the controls on the device. + * + * To read controls from a device, the desired controls are added with + * V4L2ControlList::add(unsigned int id) to prepare for a read operation. The + * V4L2ControlList instance is then passed to V4L2Device::getControls(), which + * reads the controls from the device and updates the values stored in + * V4L2ControlList. + * + * V4L2ControlList instances can be reset to remove all controls they contain + * and prepare to be re-used for a new control write/read sequence. + */ + +/** + * \typedef V4L2ControlList::iterator + * \brief Iterator on the V4L2 controls contained in the instance + */ + +/** + * \typedef V4L2ControlList::const_iterator + * \brief Const iterator on the V4L2 controls contained in the instance + */ + +/** + * \fn iterator V4L2ControlList::begin() + * \brief Retrieve an iterator to the first V4L2Control in the instance + * \return An iterator to the first V4L2 control + */ + +/** + * \fn const_iterator V4L2ControlList::begin() const + * \brief Retrieve a constant iterator to the first V4L2Control in the instance + * \return A constant iterator to the first V4L2 control + */ + +/** + * \fn iterator V4L2ControlList::end() + * \brief Retrieve an iterator pointing to the past-the-end V4L2Control in the + * instance + * \return An iterator to the element following the last V4L2 control in the + * instance + */ + +/** + * \fn const_iterator V4L2ControlList::end() const + * \brief Retrieve a constant iterator pointing to the past-the-end V4L2Control + * in the instance + * \return A constant iterator to the element following the last V4L2 control + * in the instance + */ + +/** + * \fn V4L2ControlList::empty() + * \brief Verify if the instance does not contain any control + * \return True if the instance does not contain any control, false otherwise + */ + +/** + * \fn V4L2ControlList::size() + * \brief Retrieve the number on controls in the instance + * \return The number of V4L2Control stored in the instance + */ + +/** + * \fn V4L2ControlList::clear() + * \brief Remove all controls in the instance + */ + +/** + * \brief Add control with \a id and optional \a value to the instance + * \param id The V4L2 control ID (V4L2_CID_*) + * \param value The V4L2 control value + * + * This method adds a new V4L2 control to the V4L2ControlList. The newly + * inserted control shall not already be present in the control lists, otherwise + * this method, and further use of the control list lead to undefined behaviour. + */ +void V4L2ControlList::add(unsigned int id, int64_t value) +{ + controls_.emplace_back(id, value); +} + +/** + * \brief Retrieve the control at \a index + * \param[in] index The control index + * + * Controls are stored in a V4L2ControlList in order of insertion and this + * method retrieves the control at \a index. + * + * \return A pointer to the V4L2Control at \a index or nullptr if the + * index is larger than the number of controls + */ +V4L2Control *V4L2ControlList::getByIndex(unsigned int index) +{ + if (index >= controls_.size()) + return nullptr; + + return &controls_[index]; +} + +/** + * \brief Retrieve the control with \a id + * \param[in] id The V4L2 control ID (V4L2_CID_xx) + * \return A pointer to the V4L2Control with \a id or nullptr if the + * control ID is not part of this instance. + */ +V4L2Control *V4L2ControlList::operator[](unsigned int id) +{ + for (V4L2Control &ctrl : controls_) { + if (ctrl.id() == id) + return &ctrl; + } + + return nullptr; +} + +} /* namespace libcamera */ |