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/* SPDX-License-Identifier: LGPL-2.1-or-later */
/*
* Copyright (C) 2018, Google Inc.
*
* pipeline_handler.cpp - Pipeline handler infrastructure
*/
#include "device_enumerator.h"
#include "log.h"
#include "pipeline_handler.h"
/**
* \file pipeline_handler.h
* \brief Create pipelines and cameras from a set of media devices
*
* Each pipeline supported by libcamera needs to be backed by a pipeline
* handler implementation that operate on a set of media devices. The pipeline
* handler is responsible for matching the media devices it requires with the
* devices present in the system, and once all those devices can be acquired,
* create corresponding Camera instances.
*
* Every subclass of PipelineHandler shall be registered with libcamera using
* the REGISTER_PIPELINE_HANDLER() macro.
*/
namespace libcamera {
/**
* \class PipelineHandler
* \brief Create and manage cameras based on a set of media devices
*
* The PipelineHandler matches the media devices provided by a DeviceEnumerator
* with the pipelines it supports and creates corresponding Camera devices.
*/
/**
* \fn PipelineHandler::match(DeviceEnumerator *enumerator)
* \brief Match media devices and create camera instances
* \param enumerator The enumerator providing all media devices found in the
* system
*
* This function is the main entry point of the pipeline handler. It is called
* by the device enumerator with the \a enumerator passed as an argument. It
* shall acquire from the \a enumerator all the media devices it needs for a
* single pipeline and create one or multiple Camera instances.
*
* If all media devices needed by the pipeline handler are found, they must all
* be acquired by a call to MediaDevice::acquire(). This function shall then
* create the corresponding Camera instances, store them internally, and return
* true. Otherwise it shall not acquire any media device (or shall release all
* the media devices is has acquired by calling MediaDevice::release()) and
* return false.
*
* If multiple instances of a pipeline are available in the system, the
* PipelineHandler class will be instanciated once per instance, and its match()
* function called for every instance. Each call shall acquire media devices for
* one pipeline instance, until all compatible media devices are exhausted.
*
* If this function returns true, a new instance of the pipeline handler will
* be created and its match() function called,
*
* \return true if media devices have been acquired and camera instances
* created, or false otherwise
*/
/**
* \fn PipelineHandler::count()
* \brief Retrieve the number of cameras handled by this pipeline handler
* \return the number of cameras that were created by the match() function
*/
/**
* \fn PipelineHandler::camera(unsigned int id)
* \brief Retrieve one of the cameras handled by this pipeline handler
* \param[in] id the camera index
* \return a pointer to the Camera identified by \a id
*/
/**
* \class PipelineHandlerFactory
* \brief Registration of PipelineHandler classes and creation of instances
*
* To facilitate discovery and instantiation of PipelineHandler classes, the
* PipelineHandlerFactory class maintains a registry of pipeline handler
* classes. Each PipelineHandler subclass shall register itself using the
* REGISTER_PIPELINE_HANDLER() macro, which will create a corresponding
* instance of a PipelineHandlerFactory subclass and register it with the
* static list of factories.
*/
/**
* \fn PipelineHandlerFactory::create()
* \brief Create an instance of the PipelineHandler corresponding to the factory
*
* This virtual function is implemented by the REGISTER_PIPELINE_HANDLER() macro.
*
* \return a pointer to a newly constructed instance of the PipelineHandler
* subclass corresponding to the factory
*/
/**
* \brief Add a pipeline handler class to the registry
* \param[in] name Name of the pipeline handler class
* \param[in] factory Factory to use to construct the pipeline handler
*
* The caller is responsible to guarantee the uniqueness of the pipeline handler
* name.
*/
void PipelineHandlerFactory::registerType(const std::string &name,
PipelineHandlerFactory *factory)
{
std::map<std::string, PipelineHandlerFactory *> &factories = registry();
if (factories.count(name)) {
LOG(Error) << "Registering '" << name << "' pipeline twice";
return;
}
LOG(Debug) << "Registered pipeline handler \"" << name << "\"";
factories[name] = factory;
}
/**
* \brief Create an instance of a pipeline handler if it matches media devices
* present in the system
* \param[in] name Name of the pipeline handler to instantiate
* \param[in] enumerator Device enumerator to search for a match for the handler
*
* This function matches the media devices required by pipeline \a name against
* the devices enumerated by \a enumerator.
*
* \return the newly created pipeline handler instance if a match was found, or
* nullptr otherwise
*/
PipelineHandler *PipelineHandlerFactory::create(const std::string &name,
DeviceEnumerator *enumerator)
{
std::map<std::string, PipelineHandlerFactory *> &factories = registry();
auto it = factories.find(name);
if (it == factories.end()) {
LOG(Error) << "Trying to create non-existing pipeline handler "
<< name;
return nullptr;
}
PipelineHandler *pipe = it->second->create();
if (pipe->match(enumerator)) {
LOG(Debug) << "Pipeline handler \"" << name << "\" matched";
return pipe;
}
delete pipe;
return nullptr;
}
/**
* \brief Retrieve the names of all pipeline handlers registered with the
* factory
*
* \return a list of all registered pipeline handler names
*/
std::vector<std::string> PipelineHandlerFactory::handlers()
{
std::map<std::string, PipelineHandlerFactory *> &factories = registry();
std::vector<std::string> handlers;
for (auto const &handler : factories)
handlers.push_back(handler.first);
return handlers;
}
/**
* \brief Retrieve the list of all pipeline handler factories
*
* The static factories map is defined inside the function to ensures it gets
* initialized on first use, without any dependency on link order.
*
* \return the list of pipeline handler factories
*/
std::map<std::string, PipelineHandlerFactory *> &PipelineHandlerFactory::registry()
{
static std::map<std::string, PipelineHandlerFactory *> factories;
return factories;
}
/**
* \def REGISTER_PIPELINE_HANDLER
* \brief Register a pipeline handler with the pipeline handler factory
* \param[in] handler Class name of PipelineHandler derived class to register
*
* Register a PipelineHandler subclass with the factory and make it available to
* try and match devices.
*/
} /* namespace libcamera */
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