[libcamera-devel] [PATCH v8 2/4] libcamera: controls: Define size of array controls as a shape vector

[Laurent Pinchart]

On Tue, Jul 05, 2022 at 02:37:57AM +0300, Laurent Pinchart via libcamera-devel wrote:
> Hi Christian,
> 
> Thank you for the patch.
> 
> On Fri, Jun 10, 2022 at 01:03:36PM +0100, Christian Rauch via libcamera-devel wrote:
> > This follows the convention in other Tensor APIs. Since all tensors are
> > represented as a Span with a single dimension, values provided in 'size'
> > are interpreted as fixed-size Spans, while an empty array ("[]") will be
> > interpreted as variable-sized Span.
> 
> I like the new syntax, even if it doesn't make it clear how we'll handle
> multi-dimensional arrays with variable numbers of elements in one or
> multiple dimensions, but we can worry about that later when/if needed.

Just a quick note on this. In the review of previous versions, a syntax
such as [,] was proposed for a 2D NxN array, and [,3] for a Nx3 array.
This won't work correctly, as neither are valid YAML syntax.

One workaround for this would be to turn the size element into a string,
e.g.

	size: '[,]'

I don't like this much. Another option would be to reuse 'n', e.g. [n,n]
and [n,3]. If we go that way, we should keep [n] already to denote a
dynamic 1D array.

Any other option ?

> This patch by itself introduces compilation errors, for instance, with
> clang-14,
> 
> In file included from ../../src/libcamera/camera_sensor.cpp:8:
> In file included from ../../include/libcamera/internal/camera_sensor.h:17:
> In file included from include/libcamera/control_ids.h:15:
> ../../include/libcamera/controls.h:403:8: error: no matching member function for call to 'set'
>                 val->set<T>(Span<const typename std::remove_cv_t<V>>{ value.begin(), value.size() });
>                 ~~~~~^~~~~~
> ../../src/libcamera/camera_sensor.cpp:421:14: note: in instantiation of function template specialization 'libcamera::ControlList::set<libcamera::Rectangle, libcamera::Rectangle>' requested here
>         properties_.set(properties::PixelArrayActiveAreas, { activeArea_ });
>                     ^
> ../../include/libcamera/controls.h:178:7: note: candidate function template not viable: no known conversion from 'Span<const typename std::remove_cv_t<Rectangle>>' (aka 'Span<const libcamera::Rectangle>') to 'const libcamera::Rectangle' for 1st argument
>         void set(const T &value)
>              ^
> ../../include/libcamera/controls.h:190:7: note: candidate template ignored: requirement 'details::is_span<libcamera::Rectangle>::value || std::is_same<std::string, libcamera::Rectangle>::value' was not satisfied [with T = libcamera::Rectangle]
>         void set(const T &value)
>              ^
> 1 error generated.
> 
> I'll update the Python generator script here to fix this, it will be
> part of v9.
> 
> > Signed-off-by: Christian Rauch <Rauch.Christian at gmx.de>
> > Reviewed-by: Jacopo Mondi <jacopo at jmondi.org>
> > ---
> >  src/libcamera/control_ids.yaml  | 4 ++--
> >  src/libcamera/property_ids.yaml | 4 ++--
> >  2 files changed, 4 insertions(+), 4 deletions(-)
> > 
> > diff --git a/src/libcamera/control_ids.yaml b/src/libcamera/control_ids.yaml
> > index cd1d4512..f707c1f5 100644
> > --- a/src/libcamera/control_ids.yaml
> > +++ b/src/libcamera/control_ids.yaml
> > @@ -291,7 +291,7 @@ controls:
> >          transformation. The 3x3 matrix is stored in conventional reading
> >          order in an array of 9 floating point values.
> > 
> > -      size: [3x3]
> > +      size: [3,3]
> > 
> >    - ScalerCrop:
> >        type: Rectangle
> > @@ -515,7 +515,7 @@ controls:
> >          the window where the focal distance for the objects shown in that part
> >          of the image are closest to the camera.
> > 
> > -      size: [n]
> > +      size: []
> > 
> >    - AfTrigger:
> >        type: int32_t
> > diff --git a/src/libcamera/property_ids.yaml b/src/libcamera/property_ids.yaml
> > index 11b7ebdc..a87485d7 100644
> > --- a/src/libcamera/property_ids.yaml
> > +++ b/src/libcamera/property_ids.yaml
> > @@ -497,7 +497,7 @@ controls:
> > 
> >    - PixelArrayOpticalBlackRectangles:
> >        type: Rectangle
> > -      size: [n]
> > +      size: []
> >        description: |
> >          The pixel array region(s) which contain optical black pixels
> >          considered valid for calibration purposes.
> > @@ -592,7 +592,7 @@ controls:
> > 
> >    - PixelArrayActiveAreas:
> >        type: Rectangle
> > -      size: [n]
> > +      size: []
> >        description: |
> >          The PixelArrayActiveAreas property defines the (possibly multiple and
> >          overlapping) portions of the camera sensor readable pixel matrix

-- 
Regards,

Laurent Pinchart