[libcamera-devel,17/31] libcamera: controls: Allow passing an std::initializer list to set()

2934 diff mbox series

For array controls, the ControlList::set() function takes a value as a
type convertible to Span<T>. This allows passing an std::array or an
std::vector in addition to an explicit Span, but doesn't accept an
std::initializer list as Span has no constructor that takes an
initializer list. Callers are thus forced to create temporary objects
explicitly, which isn't nice.

Fix the issue by providing a ControlList::set() function that takes an
std::initializer_list, and convert it to a Span internally.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
---
 include/libcamera/controls.h | 10 ++++++++++
 src/libcamera/controls.cpp   |  6 ++++++
 2 files changed, 16 insertions(+)

On 29/02/2020 16:42, Laurent Pinchart wrote:
> For array controls, the ControlList::set() function takes a value as a
> type convertible to Span<T>. This allows passing an std::array or an
> std::vector in addition to an explicit Span, but doesn't accept an
> std::initializer list as Span has no constructor that takes an
> initializer list. Callers are thus forced to create temporary objects
> explicitly, which isn't nice.
> 
> Fix the issue by providing a ControlList::set() function that takes an
> std::initializer_list, and convert it to a Span internally.
> 
> Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

Aha, nice - so this is how we then get to 'create' controls like
Control{1,2,3,4} or such ?

Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>

> ---
>  include/libcamera/controls.h | 10 ++++++++++
>  src/libcamera/controls.cpp   |  6 ++++++
>  2 files changed, 16 insertions(+)
> 
> diff --git a/include/libcamera/controls.h b/include/libcamera/controls.h
> index d70a6bc4b83a..f99c90e934c1 100644
> --- a/include/libcamera/controls.h
> +++ b/include/libcamera/controls.h
> @@ -335,6 +335,16 @@ public:
>  		val->set<T>(value);
>  	}
>  
> +	template<typename T, typename V>
> +	void set(const Control<T> &ctrl, const std::initializer_list<V> &value)
> +	{
> +		ControlValue *val = find(ctrl.id());
> +		if (!val)
> +			return;
> +
> +		val->set<T>(Span<const typename std::remove_cv_t<V>>{ value.begin(), value.size() });
> +	}
> +
>  	const ControlValue &get(unsigned int id) const;
>  	void set(unsigned int id, const ControlValue &value);
>  
> diff --git a/src/libcamera/controls.cpp b/src/libcamera/controls.cpp
> index f4089c8ffb4e..829eea6f4240 100644
> --- a/src/libcamera/controls.cpp
> +++ b/src/libcamera/controls.cpp
> @@ -806,6 +806,12 @@ bool ControlList::contains(unsigned int id) const
>   * object that the list refers to.
>   */
>  
> +/**
> + * \fn template<typename T, typename V> \
> + * void ControlList::set(const Control<T> &ctrl, const std::initializer_list<V> &value)
> + * \copydoc ControlList::set(const Control<T> &ctrl, const V &value)
> + */
> +
>  /**
>   * \brief Get the value of control \a id
>   * \param[in] id The control numerical ID
>

Hi Kieran,

On Tue, Mar 03, 2020 at 12:30:28AM +0000, Kieran Bingham wrote:
> On 29/02/2020 16:42, Laurent Pinchart wrote:
> > For array controls, the ControlList::set() function takes a value as a
> > type convertible to Span<T>. This allows passing an std::array or an
> > std::vector in addition to an explicit Span, but doesn't accept an
> > std::initializer list as Span has no constructor that takes an
> > initializer list. Callers are thus forced to create temporary objects
> > explicitly, which isn't nice.
> > 
> > Fix the issue by providing a ControlList::set() function that takes an
> > std::initializer_list, and convert it to a Span internally.
> > 
> > Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> 
> Aha, nice - so this is how we then get to 'create' controls like
> Control{1,2,3,4} or such ?

This is how we can do

	ControlList &list = ...;

	list.set(controls::BayerGains, { 1.0, 1.1, 1.2, 1.0 });

> Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
> 
> > ---
> >  include/libcamera/controls.h | 10 ++++++++++
> >  src/libcamera/controls.cpp   |  6 ++++++
> >  2 files changed, 16 insertions(+)
> > 
> > diff --git a/include/libcamera/controls.h b/include/libcamera/controls.h
> > index d70a6bc4b83a..f99c90e934c1 100644
> > --- a/include/libcamera/controls.h
> > +++ b/include/libcamera/controls.h
> > @@ -335,6 +335,16 @@ public:
> >  		val->set<T>(value);
> >  	}
> >  
> > +	template<typename T, typename V>
> > +	void set(const Control<T> &ctrl, const std::initializer_list<V> &value)
> > +	{
> > +		ControlValue *val = find(ctrl.id());
> > +		if (!val)
> > +			return;
> > +
> > +		val->set<T>(Span<const typename std::remove_cv_t<V>>{ value.begin(), value.size() });
> > +	}
> > +
> >  	const ControlValue &get(unsigned int id) const;
> >  	void set(unsigned int id, const ControlValue &value);
> >  
> > diff --git a/src/libcamera/controls.cpp b/src/libcamera/controls.cpp
> > index f4089c8ffb4e..829eea6f4240 100644
> > --- a/src/libcamera/controls.cpp
> > +++ b/src/libcamera/controls.cpp
> > @@ -806,6 +806,12 @@ bool ControlList::contains(unsigned int id) const
> >   * object that the list refers to.
> >   */
> >  
> > +/**
> > + * \fn template<typename T, typename V> \
> > + * void ControlList::set(const Control<T> &ctrl, const std::initializer_list<V> &value)
> > + * \copydoc ControlList::set(const Control<T> &ctrl, const V &value)
> > + */
> > +
> >  /**
> >   * \brief Get the value of control \a id
> >   * \param[in] id The control numerical ID