[libcamera-devel] [PATCH v4 05/13] libcamera: controls: Extend ControlList to access controls by ID

[Laurent Pinchart]

Hi Niklas,

On Tue, Jul 02, 2019 at 02:06:32AM +0200, Niklas Söderlund wrote:
> On 2019-07-01 23:14:56 +0300, Laurent Pinchart wrote:
> > The ControlList class implements a map from control specifier to control
> > ID. To avoid constant lookups of ControlInfo when using the class in the
> > libcamera core or in pipeline handlers, the map uses ControlInfo
> > pointers instead of ControlId values. This is however not very
> > convenient for applications or pipeline handlers, as they would be
> > forced to first look up the ControlInfo pointers for the controls they
> > want to access. Facilitate ease of use of ControlLists by implementing
> > an internal lookup of the ControlInfo from the controls provided by the
> > Camera.
> > 
> > Signed-off-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
> > Reviewed-by: Kieran Bingham <kieran.bingham at ideasonboard.com>
> > Reviewed-by: Jacopo Mondi <jacopo at jmondi.org>
> > ---
> > Changes since v3:
> > 
> > - Typo fixes
> > ---
> >  include/libcamera/controls.h |  2 ++
> >  src/libcamera/controls.cpp   | 54 ++++++++++++++++++++++++++++++++++++
> >  2 files changed, 56 insertions(+)
> > 
> > diff --git a/include/libcamera/controls.h b/include/libcamera/controls.h
> > index 18293c9462cf..fbb3a62274c6 100644
> > --- a/include/libcamera/controls.h
> > +++ b/include/libcamera/controls.h
> > @@ -117,11 +117,13 @@ 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 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]; }
> >  
> >  	void update(const ControlList &list);
> > diff --git a/src/libcamera/controls.cpp b/src/libcamera/controls.cpp
> > index cd2cf337b379..42a2f8990bf6 100644
> > --- a/src/libcamera/controls.cpp
> > +++ b/src/libcamera/controls.cpp
> > @@ -10,6 +10,8 @@
> >  #include <sstream>
> >  #include <string>
> >  
> > +#include <libcamera/camera.h>
> > +
> >  #include "log.h"
> >  #include "utils.h"
> >  
> > @@ -387,6 +389,30 @@ ControlList::ControlList(Camera *camera)
> >   * list
> >   */
> >  
> > +/**
> > + * \brief Check if the list contains a control with the specified \a id
> > + * \param[in] id The control ID
> > + *
> > + * The behaviour is undefined if the control \a id is not supported by the
> > + * camera that the ControlList refers to.
> 
> Is it undefined ? It looks like an Error is be printed and false is 
> returned, right? Same comment bellow.

Undefined means we don't guarantee what will happen, and don't guarantee
that the current behaviour will remain stable. Applications must not do
this.

For the contains() method we may specify that the function will return
false. For the operator[], however, I think we should keep the behaviour
unspecified as we don't do much.

> With or without this nit fixed,
> 
> Reviewed-by: Niklas Söderlund <niklas.soderlund at ragnatech.se>
> 
> > + *
> > + * \return True if the list contains a matching control, false otherwise
> > + */
> > +bool ControlList::contains(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
> > @@ -414,6 +440,34 @@ bool ControlList::contains(const ControlInfo *info) const
> >   * \brief Removes all controls from the list
> >   */
> >  
> > +/**
> > + * \brief Access or insert the control specified by \a id
> > + * \param[in] id The control ID
> > + *
> > + * 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 id is not supported by the
> > + * camera that the ControlList refers to.
> > + *
> > + * \return A reference to the value of the control identified by \a id
> > + */
> > +ControlValue &ControlList::operator[](ControlId id)
> > +{
> > +	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;
> > +
> > +		static ControlValue empty;
> > +		return empty;
> > +	}
> > +
> > +	return controls_[&iter->second];
> > +}
> > +
> >  /**
> >   * \fn ControlList::operator[](const ControlInfo *info)
> >   * \brief Access or insert the control specified by \a info

-- 
Regards,

Laurent Pinchart